Latest / Wellness, Actually with Emily Oster & Perry Wilson, MD / What's the deal with declining sperm counts?

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What's the deal with declining sperm counts? · Wellness, Actually with Emily Oster & Perry Wilson, MD

• 0:00
  Speaker 1: Hey Perry, Hey Emily, So Perry.
• 0:03
  Speaker 2: When you were in medical school studying the kidney and
• 0:07
  Speaker 2: other body parts, did you ever imagine that people would
• 0:10
  Speaker 2: get so much of their medical information from TikTok?
• 0:14
  Speaker 3: No?
• 0:14
  Speaker 4: I did not, But of course, full disclosure, TikTok did
• 0:18
  Speaker 4: not exist when I was in medical school. But no.
• 0:22
  Speaker 4: Broadly social media was out there, but it was like
• 0:25
  Speaker 4: people sharing recipes and stuff. It was not how people
• 0:28
  Speaker 4: got medical information. And it's a completely different world now.
• 0:33
  Speaker 4: It is an influencer's world and we're just living in it.
• 0:36
  Speaker 1: It's a little bleak.
• 0:39
  Speaker 4: It is bleak, and you're more social media savvy than
• 0:43
  Speaker 4: I am, Emily, Like, I'm just sort of getting into
• 0:46
  Speaker 4: this space and it's very eye opening.
• 0:50
  Speaker 2: I think the high for me recently was a whole
• 0:54
  Speaker 2: social media era in which people were going on to
• 0:57
  Speaker 2: talk about how if you feed your baby butter, it
• 1:00
  Speaker 2: makes them sleep through the night, which was such a
• 1:02
  Speaker 2: great example.
• 1:03
  Speaker 1: You probably haven't gotten.
• 1:04
  Speaker 4: This, not gotten that one yet. My algorithm is turning
• 1:08
  Speaker 4: pretty weird, but not that weird.
• 1:10
  Speaker 1: And what was interesting about that.
• 1:12
  Speaker 2: What's interesting about this whole space is I think it's
• 1:14
  Speaker 2: so hard for people watching that to know is this
• 1:17
  Speaker 2: real People will say, oh, evidence says, studies show, but
• 1:22
  Speaker 2: they don't have any citations because it's TikTok or Instagram
• 1:25
  Speaker 2: and it's not the New England Journal of Medicine.
• 1:27
  Speaker 4: That was one hundred percent as I start, you know,
• 1:30
  Speaker 4: I was on Instagram and stuff, and my feed before
• 1:33
  Speaker 4: we started this podcast was like, you know, like improve
• 1:36
  Speaker 4: your golf swing and you know, here's a great bread recipe.
• 1:39
  Speaker 4: And then started doing research and all of a sudden,
• 1:42
  Speaker 4: now my feed is like this wellness influencer style feed,
• 1:45
  Speaker 4: which I'm sure you're familiar with. And the thing that
• 1:47
  Speaker 4: stuck with me as I was watching this as someone
• 1:49
  Speaker 4: who comes from academics, is like, oh, you can just
• 1:53
  Speaker 4: say shit, like there's no there's no peer review. You
• 1:57
  Speaker 4: could just say whatever you want. And what I kept
• 2:00
  Speaker 4: coming back to, especially with things like that that sort
• 2:03
  Speaker 4: of seem ridiculous, you know, was like, wait, does this
• 2:06
  Speaker 4: person really believe what they're saying and they're a true
• 2:10
  Speaker 4: believer in this and they are like a butter advocate,
• 2:13
  Speaker 4: or do they not believe what they're saying and they're
• 2:15
  Speaker 4: just saying it for the clicks, or they're grifting and
• 2:19
  Speaker 4: they want to sell you their butter supplement, and like,
• 2:22
  Speaker 4: it's really hard to tell the difference, and I don't
• 2:24
  Speaker 4: even know which one is worse.
• 2:26
  Speaker 2: I agree, I mean I think often you know it's
• 2:28
  Speaker 2: you know, comment supplement for my twelve step routine for
• 2:31
  Speaker 2: clearer skin, where you know, well, probably they're they're selling
• 2:35
  Speaker 2: you something. But it's really challenging when people watch this
• 2:40
  Speaker 2: kind of content to figure out what's real what's not real.
• 2:45
  Speaker 2: And you know, for me, I always think, even if
• 2:48
  Speaker 2: they're referencing studies, a lot of times those studies confuse
• 2:52
  Speaker 2: correlation and causation. You will hear me say that a
• 2:55
  Speaker 2: million times on this podcast.
• 2:57
  Speaker 1: One of my life's.
• 2:58
  Speaker 4: Passions, it's going to be on your tune.
• 3:00
  Speaker 2: One of my life's passions is the confusion of correlation
• 3:03
  Speaker 2: and causation, by which I mean that a lot of
• 3:07
  Speaker 2: times the people who are doing one health behavior are
• 3:11
  Speaker 2: really different in many other ways. So sure they're taking
• 3:15
  Speaker 2: a vitamin D supplement, but they're also exercising and not
• 3:18
  Speaker 2: smoking and doing all kinds of other stuff, and you
• 3:20
  Speaker 2: don't really know that it's the supplement as opposed to
• 3:23
  Speaker 2: all the other things.
• 3:24
  Speaker 1: And we'll talk about that a lot.
• 3:25
  Speaker 4: The type of person who takes the supplement.
• 3:27
  Speaker 2: Yeah, I get it, But for me, that's one of
• 3:29
  Speaker 2: the core confusions, even if we are taking people at
• 3:33
  Speaker 2: face value and assuming they're not trying to sell me supplements.
• 3:36
  Speaker 1: Comment in the comments.
• 3:38
  Speaker 4: Is that is why I was so excited when we
• 3:41
  Speaker 4: decided to do this podcast that we could look at
• 3:43
  Speaker 4: some of these claims. And actually, you know, you and
• 3:47
  Speaker 4: I are book people who can read a medical study,
• 3:49
  Speaker 4: like who know how to go into the literature and
• 3:51
  Speaker 4: our job figure that's what we do. That's our day jobs, right,
• 3:54
  Speaker 4: and like figure out what's true, figure out what's not true,
• 3:57
  Speaker 4: and tell people because you know, some of the stuff
• 4:00
  Speaker 4: it's not all fake, right, Some of the stuff out
• 4:02
  Speaker 4: there really can improve your health and some of it can't.
• 4:06
  Speaker 4: But we're all super busy, and if you don't know
• 4:08
  Speaker 4: which is which, you're going to like spend twenty nine
• 4:11
  Speaker 4: hours a day, you know, juggling eight different supplements and
• 4:14
  Speaker 4: shining red light therapy on your face.
• 4:16
  Speaker 2: Absolutely, I think people need to understand both will this
• 4:19
  Speaker 2: make a difference and how big is that difference? So
• 4:21
  Speaker 2: I can decide what to spend my very limited amount
• 4:24
  Speaker 2: of time on.
• 4:26
  Speaker 4: And selfishly, I will say that between the two of us.
• 4:29
  Speaker 4: Even though I'm the medical doctor and you're just whatever
• 4:32
  Speaker 4: other kind of doctor, you are the healthier one of
• 4:35
  Speaker 4: the two. So selfishly, I am excited to learn how
• 4:39
  Speaker 4: to take care of myself even a little bit better.
• 4:41
  Speaker 2: I'm going to teach you so much, Perry. Okay, so
• 4:44
  Speaker 2: this is our first episode.
• 4:46
  Speaker 1: What do we have on the menu for today?
• 4:49
  Speaker 4: I wish you hadn't phrased it like that, because it's
• 4:52
  Speaker 4: sperm amazing.
• 4:57
  Speaker 1: I'm Emily Astro, I'm an economist and a data x and.
• 5:00
  Speaker 4: I'm Harry Wilson, I'm a medical doctor.
• 5:02
  Speaker 2: It's Thursday, February twelfth, twenty twenty six, and this is
• 5:06
  Speaker 2: wellness actually.
• 5:08
  Speaker 4: Because you're getting a staggering amount of health and wellness
• 5:11
  Speaker 4: information nowadays from every source imaginable, and some of it
• 5:15
  Speaker 4: is awesome and some.
• 5:17
  Speaker 1: Of it is well actually bullshit.
• 5:21
  Speaker 2: Fortunately, we are both people who know how to read studies,
• 5:24
  Speaker 2: how to parse the data, and can tell you what's
• 5:26
  Speaker 2: worth thinking about and what you can safely ignore.
• 5:29
  Speaker 4: But before we dig in, a note that this podcast
• 5:32
  Speaker 4: is for educational purposes and should not be construed as
• 5:34
  Speaker 4: medical advice. We don't know your unique situation, so talk
• 5:38
  Speaker 4: to your doctor for personal health decisions.
• 5:40
  Speaker 2: This week we're asking what's the deal with declining sperm counts?
• 5:44
  Speaker 2: And then we'll get to your question of the week,
• 5:46
  Speaker 2: But first let's do the health news roundup after the break,
• 6:01
  Speaker 2: all right, Perry, So, last week RFK Junior, the Secretary
• 6:05
  Speaker 2: of Health and Human Services, claimed that a ketogenic diet.
• 6:08
  Speaker 1: Could cure schizophrenia.
• 6:11
  Speaker 2: He said the quote is a doctor at Harvard had
• 6:14
  Speaker 2: cured schizophrenia using the keto diet, which is a high fat,
• 6:18
  Speaker 2: low carbohydrate diet, and also claim that there were studies
• 6:22
  Speaker 2: showing that people lose their bipolar diagnosis by changing their diet.
• 6:27
  Speaker 2: So how much of this is rooted in fact as
• 6:30
  Speaker 2: opposed to just in nothing?
• 6:32
  Speaker 4: So this is really typical of Rfk's style, which is
• 6:36
  Speaker 4: like there is a kernel of fact in here that
• 6:41
  Speaker 4: then gets just like expounded to one hundredfold higher, which
• 6:45
  Speaker 4: you know, is fine if you're maybe an influencer on TikTok,
• 6:47
  Speaker 4: but is not great if you're the Secretary of Health
• 6:49
  Speaker 4: and Human Services. So ketogenic diets and what they're talking
• 6:52
  Speaker 4: about here is not like I'm keto, like you know,
• 6:55
  Speaker 4: I try to avoid carbs. A medical ketogenic diet is
• 6:59
  Speaker 4: really hard to do, like it's it's you have special
• 7:02
  Speaker 4: foods and stuff, you are in the state of ketosis.
• 7:05
  Speaker 4: And we do use it to prevent seizures in people
• 7:08
  Speaker 4: who have refractory epilepsy that no drugs work, so it
• 7:12
  Speaker 4: does affect the brain. There was a small study which
• 7:16
  Speaker 4: showed a keutogenic diet had modest effects on schizophrenia symptoms
• 7:21
  Speaker 4: in a subset of people with schizophrenia. The author of
• 7:25
  Speaker 4: that study was asked about RFK Junior's quote and said themselves, no,
• 7:30
  Speaker 4: this is not this is not a cure. I mean,
• 7:32
  Speaker 4: it's clearly not. It's interesting, but this is just, you know,
• 7:37
  Speaker 4: it speaks to this thing that keeps happening where it's
• 7:40
  Speaker 4: like your medical problems are kind of your fault. There's
• 7:43
  Speaker 4: always this subtext that's like, oh, well, if you only
• 7:46
  Speaker 4: ate a better diet, maybe you wouldn't have schizophrenia, and
• 7:48
  Speaker 4: it's just it's really like disabling to people with this
• 7:52
  Speaker 4: kind of condition.
• 7:54
  Speaker 2: I think the other piece for me here was this
• 7:58
  Speaker 2: this sort of taking of what should be the first
• 8:02
  Speaker 2: step in a kind of research program and deciding that
• 8:07
  Speaker 2: we're done right the process of science. I mean, you
• 8:10
  Speaker 2: know this as a researcher, like the process of science
• 8:13
  Speaker 2: is like, Okay, we do an experiment with like two
• 8:15
  Speaker 2: people and we see, huh, like maybe there's something interesting there,
• 8:18
  Speaker 2: and maybe there is something interesting here. But then you
• 8:20
  Speaker 2: sort of expand it out and think about what would
• 8:23
  Speaker 2: be feasible, could it work on a larger scale, how
• 8:25
  Speaker 2: big are the effects? And this is kind of taking
• 8:28
  Speaker 2: that first step and being like, oh, we're done, we
• 8:29
  Speaker 2: fixed it, like just eat a lot of bacon or yeah,
• 8:33
  Speaker 2: And that's not the solution absolutely, And the history of
• 8:37
  Speaker 2: these interventions across all of medicine is typically that something
• 8:41
  Speaker 2: that works in a small.
• 8:42
  Speaker 4: Group or in lab animals or something's kind of interesting
• 8:45
  Speaker 4: doesn't scale up, like it doesn't work. The literature is
• 8:48
  Speaker 4: littered with failed interventions like this. So irresponsible to say,
• 8:54
  Speaker 4: but let's move on, Emily. Did you see this article
• 9:00
  Speaker 4: in the New York Times reporting that there has been
• 9:02
  Speaker 4: an increase in refusals of the vitamin K shot after birth?
• 9:07
  Speaker 4: So what is going on with vitamin K?
• 9:09
  Speaker 3: Now?
• 9:10
  Speaker 2: So it's worth saying why we might give kids a
• 9:13
  Speaker 2: vitamin K shot right after birth, which is that.
• 9:15
  Speaker 1: It prevents bleeding.
• 9:17
  Speaker 2: So infants who do not have a vitamin K shot
• 9:22
  Speaker 2: or at a much higher risk for later bleeding, which
• 9:25
  Speaker 2: can be fatal. And so there are really good reasons
• 9:28
  Speaker 2: to give infants a vitamin K shot immediately after birth.
• 9:32
  Speaker 2: It has been done for many decades. It's extremely safe.
• 9:36
  Speaker 2: But in our current vaccine hes agency environment, this shot,
• 9:42
  Speaker 2: like many others, has become sort of part of the
• 9:45
  Speaker 2: kind of we're afraid of shots thing, and more parents
• 9:48
  Speaker 2: are refusing it, which of course is very dangerous for
• 9:51
  Speaker 2: their infants.
• 9:52
  Speaker 4: But not a vaccine, right, I mean, just let's be clear.
• 9:55
  Speaker 1: It's not a vaccine. It's a vitamin shot exactly.
• 9:58
  Speaker 2: Yeah, And that's what's I mean, that's sort of a
• 9:59
  Speaker 2: maz because people are thinking, okay, this is like a vaccine.
• 10:02
  Speaker 1: No, it's a vitamin shot. It's a vitamin.
• 10:05
  Speaker 4: And yet, right, we like vitamins.
• 10:08
  Speaker 2: We like vitamins, I mean the same. What's so interesting is,
• 10:12
  Speaker 2: of course the same space they love vitamins that are useless.
• 10:15
  Speaker 2: This is a vitamin that's very helpful, and yet.
• 10:17
  Speaker 1: You know, people are refusing it.
• 10:19
  Speaker 2: I think it's just an example of where some of
• 10:22
  Speaker 2: this vaccine hesitancy has spilled over even into things that
• 10:27
  Speaker 2: are not vaccines and in this case have no side
• 10:30
  Speaker 2: effects that have very clear obvious beneth.
• 10:32
  Speaker 4: Right, there's obviously an element of mistrust of medicine here
• 10:35
  Speaker 4: that's taking place. There's also this movement towards kind of,
• 10:39
  Speaker 4: you know, a more natural experience, right, like we didn't,
• 10:41
  Speaker 4: you know, our ancestors didn't give their kids vitamin K shots.
• 10:45
  Speaker 4: But I will point out, as I often do, that
• 10:48
  Speaker 4: things were really way worse in the good old days.
• 10:51
  Speaker 4: So prior to nineteen hundred, infant mortality was twenty five
• 10:54
  Speaker 4: percent in the United States, So that's death before age
• 10:57
  Speaker 4: one one out of every four kids before age five
• 11:01
  Speaker 4: was about fifty percent. So that is not something we
• 11:05
  Speaker 4: want to go back to. And the thing that has
• 11:07
  Speaker 4: changed infant mortality rates so dramatically are interventions like this
• 11:11
  Speaker 4: kind of you know, straightforward dumb interventions like, oh, babies
• 11:15
  Speaker 4: are deficient in vitamin K and they have intro you know,
• 11:17
  Speaker 4: hemorrhage in their brain, and let's give them vitamin K.
• 11:21
  Speaker 2: Yeah, so please, if you're having an infant, get at
• 11:24
  Speaker 2: the vitamin K shot. Okay, So let's turn to a
• 11:28
  Speaker 2: I would say arguably more important topic than schizophrenia and infants,
• 11:33
  Speaker 2: which is ski jumping yeah, so it's the Olympics. I
• 11:37
  Speaker 2: love the Olympics. I like the endurance sports, but I
• 11:40
  Speaker 2: also like ski jumping, and there's a report of some
• 11:45
  Speaker 2: mechanical doping in ski jumping which is working like the following.
• 11:49
  Speaker 4: Oh, I know where you're going with this.
• 11:50
  Speaker 2: Apparently, in ski jumping you want your suit to be
• 11:53
  Speaker 2: very big because if your suit was like really loose,
• 11:56
  Speaker 2: it would be like a sale. So before you ski jump,
• 11:59
  Speaker 2: they take scan of you in your suit to make
• 12:01
  Speaker 2: sure that the suit is not too far from your body.
• 12:04
  Speaker 2: So there's a report, it is admittedly from a German tabloid,
• 12:08
  Speaker 2: that some male ski jumpers are injecting their penis with
• 12:12
  Speaker 2: acid so their penis will grow, and then the three
• 12:15
  Speaker 2: D scanner will make it seem like they're filling up
• 12:18
  Speaker 2: the suit more and so they'll be able to have
• 12:20
  Speaker 2: a bigger suit. But then the penis goes back down
• 12:22
  Speaker 2: before the ski jumping, so they get the sale like effect.
• 12:25
  Speaker 2: I just want to know will this work increase your
• 12:28
  Speaker 2: penis size and would it have other uses beyond ski
• 12:31
  Speaker 2: jumping that we should be considering.
• 12:33
  Speaker 4: I saw this article too, and yeah, real hard for
• 12:38
  Speaker 4: me to read. I have to say, I think they
• 12:42
  Speaker 4: really dropped.
• 12:43
  Speaker 1: Because you feel like you caned out on some opportunities.
• 12:47
  Speaker 4: You know, I could have been a I could have
• 12:48
  Speaker 4: been a champion ski jumper. I'll let you draw your
• 12:51
  Speaker 4: own conclusions. But but no, I mean they missed the
• 12:54
  Speaker 4: opportunity to call this inflate gate first of all, which
• 12:56
  Speaker 4: is just journalistic malpractice. I think if these ski jumpers
• 13:02
  Speaker 4: have the balls to inject their penis, you know, more
• 13:06
  Speaker 4: power to them. Just to answer the medical side of this,
• 13:09
  Speaker 4: how uronic acid which is what they're talking about, injecting it, like, yes,
• 13:13
  Speaker 4: it does swell tissues. I mean so yes, it will
• 13:16
  Speaker 4: make something bigger transiently. It then gets absorbed by the body.
• 13:20
  Speaker 4: There's some bodybuilders who have been accused of doing this
• 13:22
  Speaker 4: and they're you know, pecks and stuff to make them
• 13:23
  Speaker 4: more swollen. This is a bad idea. You do not
• 13:27
  Speaker 4: want an infection in your penis or around your penis.
• 13:32
  Speaker 4: It doesn't turn out well. If you want to never
• 13:36
  Speaker 4: sleep again, google Fournier's gangreen and you'll you will see
• 13:42
  Speaker 4: what can happen if you do something like this. So
• 13:45
  Speaker 4: just you know, fly through the air with your regular penis, please.
• 13:50
  Speaker 2: I think that's a good place to stop with our
• 13:52
  Speaker 2: health news. But after the break we'll come back and
• 13:55
  Speaker 2: ask what's the deal with declining spurm counts?
• 14:03
  Speaker 1: Okay, Perry.
• 14:04
  Speaker 2: So if your social media feed is like mine, you
• 14:08
  Speaker 2: are probably hearing a lot about declining sperm counts in
• 14:12
  Speaker 2: a very panicked way. So one of the things I
• 14:15
  Speaker 2: keep hearing is like, if we are going in this direction,
• 14:18
  Speaker 2: by twenty thirty five, no one will have any sperm.
• 14:22
  Speaker 2: And I keep thinking about this graphic novel that my
• 14:25
  Speaker 2: husband liked called Why the Last Man, which is about
• 14:28
  Speaker 2: a world in which there's just one guy who has
• 14:30
  Speaker 2: sperm and all the ladies are like chasing him?
• 14:32
  Speaker 4: Did you It's classic wish fulfillment graphic novel exactly.
• 14:37
  Speaker 2: So I want to talk about whether this concern about
• 14:41
  Speaker 2: our declining sperm is a real concern or just a
• 14:46
  Speaker 2: kind of imaginary panic sperm problem like many other things.
• 14:52
  Speaker 1: So we're going to talk about that today, But before we.
• 14:54
  Speaker 2: Get into it, I think we should make sure everybody
• 14:56
  Speaker 2: understands what sperm are, where they come from, and how
• 15:02
  Speaker 2: we would know how many we have and how many
• 15:04
  Speaker 2: should you have?
• 15:04
  Speaker 1: Give me doctor one on one on sperm?
• 15:06
  Speaker 4: Okay, all right, Medical school, one on one on sperm.
• 15:09
  Speaker 4: Here we go. So, sperm are the male unit of
• 15:13
  Speaker 4: fertilization to carry. A sperm carries half of your genetic information.
• 15:16
  Speaker 4: The egg has the other half. You combine and you
• 15:18
  Speaker 4: make a baby. Most people know this. Sperm are produced
• 15:21
  Speaker 4: in the testes and it's not a simple process. There
• 15:25
  Speaker 4: are stem cells in the testes that go through multiple
• 15:28
  Speaker 4: cycles of generation. There's multiple sort of stages of evolution
• 15:32
  Speaker 4: of sperm, and the testes like some kind of sexual pokemon.
• 15:37
  Speaker 4: It takes about ninety days between eighty and one hundred
• 15:42
  Speaker 4: to go from that stem cell to a fully functional
• 15:45
  Speaker 4: sperm that is ready to go, so to speak. Testes
• 15:50
  Speaker 4: are busy little guys. They are producing two hundred to
• 15:54
  Speaker 4: three hundred million sperm cells a day. That's a lot.
• 15:59
  Speaker 4: That being said, only half are viable in your typical man.
• 16:03
  Speaker 4: So you know, you produce anything at that rate, you're
• 16:05
  Speaker 4: going to get some flaws. So only half are going
• 16:08
  Speaker 4: to be good enough to sort of make it all
• 16:10
  Speaker 4: the way out. And that's where we get into sperm counts.
• 16:13
  Speaker 2: Can I ask when you make sperm that are not used? Obviously,
• 16:18
  Speaker 2: if you're making three hundred million sperm a day, Is
• 16:21
  Speaker 2: that right?
• 16:22
  Speaker 4: A day? Yeah, they got to go somewhere, right.
• 16:23
  Speaker 2: Okay, they got to go somewhere. Like, what happens? Are
• 16:26
  Speaker 2: you peeing them out? Do they get eaten?
• 16:28
  Speaker 1: What happens?
• 16:29
  Speaker 4: They kind of get eaten. They just get reabsorbed, So
• 16:32
  Speaker 4: they don't have an unlimited life span. They'll just kind
• 16:36
  Speaker 4: of die. And like any dead cell in your body,
• 16:38
  Speaker 4: once a cell dies and breaks down, these big white
• 16:42
  Speaker 4: blood cells called macrophages, which are just like big cells
• 16:45
  Speaker 4: that are specialized in eating dead stuff, come in. They
• 16:48
  Speaker 4: live in the testes and they eat them up and
• 16:50
  Speaker 4: they dissolve them and all the nutrients and stuff go
• 16:52
  Speaker 4: back into your body. So they just get recycled basically. Yeah,
• 16:55
  Speaker 4: no big all right, no big deal.
• 16:57
  Speaker 1: So you have these sperms. Some of them are good,
• 16:59
  Speaker 1: some of them good.
• 17:00
  Speaker 2: When we say that we have good sperm, and I
• 17:02
  Speaker 2: think this is relevant for talking about declining sperm counts,
• 17:05
  Speaker 2: because really what we mean is a decline.
• 17:07
  Speaker 1: In viable sperm.
• 17:09
  Speaker 2: What are the things you need for a sperm to
• 17:11
  Speaker 2: be capable of fertilization, which is its primary measure of quality.
• 17:17
  Speaker 4: Yeah, I mean it's it's a lot more than just
• 17:19
  Speaker 4: sheer numbers, I think as you're alluding to. Right, So
• 17:22
  Speaker 4: there's all this social media talk about sperm counts and
• 17:24
  Speaker 4: declining sperm counts. That's only one parameter in about ten
• 17:27
  Speaker 4: that urologists, for example, will look at to tell you
• 17:30
  Speaker 4: what your sperm quality is. So, yes, you need a
• 17:33
  Speaker 4: certain number. We'll get into what kind of normal numbers
• 17:35
  Speaker 4: are in just a second. But they have to be
• 17:38
  Speaker 4: able to move. Sperm swim, so they have to they
• 17:41
  Speaker 4: have to be motile, they have to move around. You
• 17:42
  Speaker 4: can see that under a microscope. They have to have
• 17:45
  Speaker 4: a sort of standard morphology, that tadpole ish thing that
• 17:48
  Speaker 4: you look at. Some sperm have two heads, some sperm
• 17:52
  Speaker 4: have two or three tails, and those are not going
• 17:54
  Speaker 4: to be efficient at getting into an egg. They have
• 17:57
  Speaker 4: to contain the nuclear payload of half of your genetic material.
• 18:01
  Speaker 4: If they don't, you're not going to get a viable embryo.
• 18:04
  Speaker 4: So they have a lot to do, and it's you know,
• 18:06
  Speaker 4: it's a numbers game basically. In the end, it's a
• 18:10
  Speaker 4: pretty difficult trek for a sperm to make it all
• 18:14
  Speaker 4: the way to an egg. It's a hostile environment for
• 18:18
  Speaker 4: very good reason. The week are weeded out on this
• 18:23
  Speaker 4: trek to the egg. We were all traumatized as young
• 18:27
  Speaker 4: children by watching Luk Who's talking where we saw graphic
• 18:31
  Speaker 4: depictions of sperm competing with each other to get to
• 18:33
  Speaker 4: the egg. And but that's, you know, that's how biology
• 18:38
  Speaker 4: is supposed to work. But sperm count is certainly one
• 18:41
  Speaker 4: part of all this.
• 18:43
  Speaker 2: And I also think when we talk when people talk
• 18:45
  Speaker 2: about declining sperm counts, I think they mean both counts,
• 18:48
  Speaker 2: but they also often mean some of these other things.
• 18:51
  Speaker 2: So a decline in sperm that are in decline in
• 18:55
  Speaker 2: the number of sperm, and decline and the number of
• 18:56
  Speaker 2: sperm with the right morphology, with the right motility, so
• 18:59
  Speaker 2: sort of sperm they can have the right shape, they
• 19:01
  Speaker 2: can swim, they can get to the egg. That's what
• 19:03
  Speaker 2: where that's what we're focused on. That's what we're what
• 19:05
  Speaker 2: we're worried.
• 19:05
  Speaker 4: About right now. When it comes to count though, because
• 19:08
  Speaker 4: it's always nice to put like a simple number on things,
• 19:12
  Speaker 4: there's essentially two counts that get talked about in different studies.
• 19:15
  Speaker 4: One is actually the sperm concentration, which is the count
• 19:18
  Speaker 4: per millileter of fluid basically, so how much per mili
• 19:22
  Speaker 4: leader And then one is the total count. So if
• 19:24
  Speaker 4: you take all the milli leaders in a particular sample,
• 19:28
  Speaker 4: how many sperm are in there. Most researchers are focusing
• 19:33
  Speaker 4: more on that concentration the count per mili leaders as
• 19:36
  Speaker 4: a better proxy of overall sperm health. And just to
• 19:39
  Speaker 4: give you some numbers, most men will have you know,
• 19:44
  Speaker 4: who are healthy and fertile have numbers in the sort
• 19:48
  Speaker 4: of sixty to one hundred and twenty million range per
• 19:52
  Speaker 4: milli leader. The who defines any sperm count above sixteen
• 19:57
  Speaker 4: million per milli leader as normal, they used to say
• 20:00
  Speaker 4: twenty that's been reduced. And Emily, you're going to tell
• 20:03
  Speaker 4: me in a second why or if that's for real.
• 20:06
  Speaker 4: But you know, most most people are actually quite a
• 20:08
  Speaker 4: bit above that minimum threshold. Nevertheless, lots of panic about
• 20:15
  Speaker 4: declines in the count over time. So Emily, you tell
• 20:18
  Speaker 4: me what's the deal with this, Like, what is the
• 20:21
  Speaker 4: data show? And is it for real?
• 20:23
  Speaker 2: I think what's most interesting to me here is why
• 20:25
  Speaker 2: this is so hard to answer. So if you sort
• 20:28
  Speaker 2: of think about what you would like to be able
• 20:31
  Speaker 2: to see to have a measure of sperm counts over time,
• 20:34
  Speaker 2: Really we would like to sort of take every you know,
• 20:38
  Speaker 2: person with testicles when they are eighteen, bring them in,
• 20:41
  Speaker 2: you know, have them jack off into a cup, measure
• 20:44
  Speaker 2: their sperm, and then we could have if we had
• 20:47
  Speaker 2: that starting in like nineteen twenty, you know, we could
• 20:49
  Speaker 2: really get a very good sense of how sperm has
• 20:51
  Speaker 2: changed over time because you'd have a random sample, or
• 20:55
  Speaker 2: you have everybody, even just a random sample.
• 20:57
  Speaker 1: I would take a random sample.
• 20:58
  Speaker 4: Yes, yes, as any economist would. I will point out
• 21:02
  Speaker 4: that the time of abstinence is an important factor in
• 21:07
  Speaker 4: sperm counts. So you'd need these eighteen year olds to
• 21:10
  Speaker 4: hold off on any sort of ejaculation for five days,
• 21:14
  Speaker 4: which I think is really the hurdle people aren't discussing.
• 21:18
  Speaker 4: But go ahead, that's the ideal.
• 21:21
  Speaker 1: My study is going to totally take care of that.
• 21:23
  Speaker 2: I have different ideas, but at any rate, whether I
• 21:26
  Speaker 2: would be able to do that or not, we have not.
• 21:28
  Speaker 2: And so most of our numbers about sperm counts come
• 21:32
  Speaker 2: from selected populations without very good controls. So often we'll
• 21:39
  Speaker 2: see data from infertile men. Well, that's not very helpful
• 21:44
  Speaker 2: as a metric over time for a bunch of different reasons. Sure,
• 21:47
  Speaker 2: so we're kind of working with a lot of pretty
• 21:49
  Speaker 2: incomplete data, which is why I think the results are
• 21:53
  Speaker 2: quite vary. So I would say if you look at
• 21:56
  Speaker 2: meta analyses where they bring together a lot of different
• 22:00
  Speaker 2: studies of sperm counts over time in a global context,
• 22:05
  Speaker 2: mostly those suggest some moderate decline in sperm counts over time.
• 22:12
  Speaker 2: I think the sort of most recent data maybe is
• 22:15
  Speaker 2: a little more reassuring and suggests maybe it hasn't declined
• 22:19
  Speaker 2: very much. But I guess my read of the evidence,
• 22:22
  Speaker 2: I'm curious if you read it differently, is it does
• 22:24
  Speaker 2: seem like there's some decline, but it's probably not as
• 22:27
  Speaker 2: extreme as you would take away from some of the
• 22:32
  Speaker 2: hyperactive claims on the internet.
• 22:35
  Speaker 4: Yeah, the sort of catastrophizing of the sperm content. Yeah,
• 22:38
  Speaker 4: I mean, the one nice meta analysis actually broke down
• 22:43
  Speaker 4: this issue you're referring to, which is like selection bias
• 22:47
  Speaker 4: for men who are having fertility problems, right, or couples
• 22:50
  Speaker 4: that are having fertility problems. So overall, this study found
• 22:54
  Speaker 4: that the average sperm count in men's sperm concentration in
• 22:58
  Speaker 4: men from nineteen seventy three to twenty eighteen went from
• 23:02
  Speaker 4: one hundred million to about fifty million. And that's like, Okay,
• 23:06
  Speaker 4: all right, So that's you know, almost half, that's pretty solid.
• 23:09
  Speaker 2: That's a solid decline, that's a cline, that's a very good,
• 23:11
  Speaker 2: big decline.
• 23:12
  Speaker 4: But when they restricted to the studies that only included
• 23:17
  Speaker 4: fertile men, so you know, sperm counts for other reason,
• 23:20
  Speaker 4: the decline was from seventy seven million to seventy two million,
• 23:24
  Speaker 4: which is like, really not that much. Now, maybe there's
• 23:28
  Speaker 4: more infertile men, right, Like, it doesn't necessarily mean that
• 23:31
  Speaker 4: this is just total hocum, but you got to think
• 23:34
  Speaker 4: through it a little bit more, in a little bit
• 23:36
  Speaker 4: more detail, right.
• 23:37
  Speaker 2: Yeah, And I think that that you know, you're citing
• 23:40
  Speaker 2: sort of one particular study, and I think one that
• 23:45
  Speaker 2: got a lot of attention, But there are other meta
• 23:48
  Speaker 2: analyzes with sort of similar.
• 23:49
  Speaker 1: Approaches that to do more.
• 23:52
  Speaker 2: Adjustment for say what area you're in or or some
• 23:57
  Speaker 2: of these fertility metrics which don't actually see sort of
• 24:01
  Speaker 2: significant or see much much smaller declines. So, you know,
• 24:04
  Speaker 2: I love data so much. I love numbers and data,
• 24:07
  Speaker 2: and that in a case like this, I think what's
• 24:10
  Speaker 2: so hard is because the data is imperfect, it matters
• 24:14
  Speaker 2: very much what choices you are making about exactly who
• 24:18
  Speaker 2: you're looking at exactly how you're looking at it, exactly
• 24:20
  Speaker 2: what you're adjusting for. And so it's not that surprising
• 24:23
  Speaker 2: that the literature can kind of find everything from there's
• 24:27
  Speaker 2: no change at all to like, you know, the sperm
• 24:30
  Speaker 2: counts down by half, and if we keep going on
• 24:32
  Speaker 2: this trend, you know where we're all doomed forever.
• 24:36
  Speaker 4: Well, I'm going to force you to put your nickel
• 24:37
  Speaker 4: down here. You've read a lot about this. I've read
• 24:40
  Speaker 4: a lot about this. Yes, data is a little bit
• 24:43
  Speaker 4: you know, wishy washy here and there, But like heart
• 24:45
  Speaker 4: of hearts, do you think there's a decline in sperm
• 24:48
  Speaker 4: counts overall over time?
• 24:49
  Speaker 1: I do.
• 24:50
  Speaker 2: I mean my read is that there's been a modest
• 24:53
  Speaker 2: decline in sperm counts over the past fifty years.
• 24:56
  Speaker 1: What about you?
• 24:57
  Speaker 4: I think that's probably right. That was the vibe I'm
• 24:59
  Speaker 4: getting to.
• 25:00
  Speaker 2: Yeah, I think that there's enough data that points in
• 25:02
  Speaker 2: that direction. That's an interesting thing about how we sort
• 25:04
  Speaker 2: of look at data, Like you kind of read enough
• 25:06
  Speaker 2: of this, and you read it, and you read it,
• 25:07
  Speaker 2: you sort of get a picture. It's a little hard
• 25:10
  Speaker 2: to put your finger on. It's not that I'm saying
• 25:11
  Speaker 2: like I looked at this one study. It's that you
• 25:14
  Speaker 2: look at all of it together and kind of evaluate, basically,
• 25:19
  Speaker 2: with the background of being a person who thinks a
• 25:21
  Speaker 2: lot about evidence, you kind of come out with something.
• 25:24
  Speaker 1: So yeah, for me, modest decline. All right, So a very.
• 25:29
  Speaker 2: Reasonable follow up question if we both think there's been
• 25:31
  Speaker 2: some modest decline, is is it relevant?
• 25:34
  Speaker 1: Right?
• 25:34
  Speaker 2: So, we talked about like the who's got a threshold
• 25:38
  Speaker 2: of you know, sixteen or twenty. We talk about numbers
• 25:41
  Speaker 2: like seventy five million per you know, semen unit, you
• 25:48
  Speaker 2: really only only need one, You only need one Perry. Yes,
• 25:52
  Speaker 2: So I guess the question is, you know, is this
• 25:54
  Speaker 2: clinically relevant? Is this the reason we're talking about a
• 25:57
  Speaker 2: fertility decline in you know, the entire world?
• 26:00
  Speaker 4: Like, Okay, a lot to unpack on this, but I'll
• 26:05
  Speaker 4: start off by saying absolutely not. This is not the
• 26:08
  Speaker 4: reason for a fertility decline across the world. There are
• 26:11
  Speaker 4: many more important factors in that, including deliberate choices by
• 26:16
  Speaker 4: people who are hostly doing meal family planning, and of
• 26:20
  Speaker 4: course economic conditions that might influence those choices and many
• 26:23
  Speaker 4: other things. So let's just put that aside. Let's talk physiology.
• 26:28
  Speaker 4: We actually have pretty good data from in vitro fertilization
• 26:31
  Speaker 4: studies to know how many sperm it typically takes to
• 26:36
  Speaker 4: like fertilize an egg. And yes, it only takes one,
• 26:39
  Speaker 4: but as I said, they're running a gauntlet to get there.
• 26:42
  Speaker 4: It's very it's very hard. And what these studies show
• 26:45
  Speaker 4: is sort of a diminishing returns as sperm count increases.
• 26:50
  Speaker 4: So at the very low end, yes, there's there's less fertility, right,
• 26:54
  Speaker 4: We're talking less than twenty million per per mili leader.
• 26:58
  Speaker 4: You know, there's less fertility there. But once you start
• 27:01
  Speaker 4: getting over that threshold, it really flattens out. There's like
• 27:04
  Speaker 4: not much of a change in pregnancy rates fertility rates
• 27:09
  Speaker 4: once you get kind of into the normal range, which
• 27:13
  Speaker 4: of course leads me to the question, like why are
• 27:15
  Speaker 4: people so obsessed about this? Like why is it that
• 27:19
  Speaker 4: your social media feed like God, like I God forbid
• 27:22
  Speaker 4: searched sperm counts once and now it's just it was
• 27:27
  Speaker 4: a huge days. It's I need like a I need
• 27:29
  Speaker 4: a burner account just for this podcast. You know why
• 27:32
  Speaker 4: the obsession? And I don't want to like armchair psychologists this,
• 27:35
  Speaker 4: but like is this just a manly thing. Is this
• 27:38
  Speaker 4: totally like just like a like a tech bro like, yeah.
• 27:43
  Speaker 2: Yeah, I for for me. I mean this is a
• 27:45
  Speaker 2: very interesting question. I think really a question about psychology.
• 27:49
  Speaker 2: But I think that it is a signal of your
• 27:52
  Speaker 2: manhood that you have a lot of sperm. Like sperm
• 27:55
  Speaker 2: is like a like it's a thing you could measure.
• 27:57
  Speaker 2: And I think particularly for people who'd like to measure stuff,
• 28:00
  Speaker 2: you know, like I like to feel like you like
• 28:02
  Speaker 2: to measure HRV, you like to measure your you know,
• 28:05
  Speaker 2: this hormone and that hormone, and like you want to
• 28:07
  Speaker 2: measure a sperm count because you want to have the
• 28:09
  Speaker 2: best you want to have the best sperm.
• 28:12
  Speaker 1: But but just.
• 28:13
  Speaker 2: Like to have it, you know, not not to do
• 28:15
  Speaker 2: anything with it, just to have it around for having
• 28:18
  Speaker 2: and for telling people what it is.
• 28:20
  Speaker 4: Yeah, it's like it's like an online IQ test exactly,
• 28:25
  Speaker 4: or like joining MENSA.
• 28:28
  Speaker 2: So what about testosterone? Is testosterone? Are a tesosterone a
• 28:31
  Speaker 2: sperm count the same? Are they correlated? What do we
• 28:34
  Speaker 2: see in that?
• 28:35
  Speaker 4: Yeah, I've seen a lot of people say like, oh,
• 28:36
  Speaker 4: sperm count is this proxy for like everything about male health,
• 28:40
  Speaker 4: including testosterone? Not true? Actually true? With the tiny caveat.
• 28:45
  Speaker 4: So testosterone levels are correlated with sperm counts in the
• 28:49
  Speaker 4: first three months of life. So apparently for babies AGC
• 28:53
  Speaker 4: or the three months, the testosterone level there is important
• 28:57
  Speaker 4: for proper testicular development. But that's it. Now. You will
• 29:02
  Speaker 4: see studies that show that men who have very low
• 29:06
  Speaker 4: sperm counts, like less than twenty million, are more likely
• 29:09
  Speaker 4: to have low testosterone. So when you have sperm counts
• 29:12
  Speaker 4: that are low enough to cause a fertility issue, you
• 29:14
  Speaker 4: are also more likely to have low testosterone. Those things
• 29:17
  Speaker 4: can be related. But in the normal range of sperm count,
• 29:20
  Speaker 4: there is no correlation between testosterone and sperm count. So
• 29:24
  Speaker 4: a sperm count of forty million versus eighty million, those
• 29:26
  Speaker 4: testosterone levels have no effect on that. And so if
• 29:29
  Speaker 4: you're using sperm count as a readout of your testosterone,
• 29:32
  Speaker 4: it's a bad readout, or maybe it's only a readout
• 29:34
  Speaker 4: of when you are a tiny baby. If you want
• 29:38
  Speaker 4: to know what your testosterone level is, you can measure
• 29:42
  Speaker 4: your testosterel test.
• 29:43
  Speaker 2: For that one question that I want to come back
• 29:45
  Speaker 2: to about what you said. So we talked about the.
• 29:49
  Speaker 1: Fertility environment being hostile to speram.
• 29:55
  Speaker 2: What do you mean, like the vagina eats the sperm
• 29:58
  Speaker 2: in a negative way.
• 30:00
  Speaker 4: Kind of The big issue is acidity.
• 30:03
  Speaker 3: So the.
• 30:06
  Speaker 4: Vagina, the filopian tubes of these whole areas are are
• 30:10
  Speaker 4: quite acid. I think the pH I'd have to check,
• 30:13
  Speaker 4: but it's like four point five or something like that,
• 30:16
  Speaker 4: which is certainly toxic to sperm. The semen that they
• 30:20
  Speaker 4: come with is basic, so there's a little acid base
• 30:24
  Speaker 4: reaction there, like when you do the baking soda and vinegar.
• 30:27
  Speaker 4: It's less dramatic than that, fortunately, but that's but that's
• 30:32
  Speaker 4: the primary reason. And and and as I said, it's
• 30:34
  Speaker 4: like it's for a good reason because there you want
• 30:37
  Speaker 4: to kind of select for the sperm that is most motile,
• 30:42
  Speaker 4: most robust, because that's probably the one that has the
• 30:45
  Speaker 4: best genetic material inside.
• 30:47
  Speaker 2: Yeah, so you're really using you're basically using the hostility
• 30:50
  Speaker 2: as an evolutionary mechanism to kind of find find the
• 30:53
  Speaker 2: good sperm. Men are just producing just a billion, you know,
• 30:55
  Speaker 2: so many of these, and we're kind of have a
• 30:57
  Speaker 2: million different ways that we're trying to get sort of
• 30:59
  Speaker 2: them out as opposed to taking more time to produce
• 31:02
  Speaker 2: good ones in the first place, which doesn't seem to
• 31:04
  Speaker 2: be the approach that we've taken.
• 31:06
  Speaker 4: You got it, So let's go through. Now. Okay, so
• 31:10
  Speaker 4: we're going to take it on a little bit of faith.
• 31:13
  Speaker 4: But some data that that sperm counts really are declining.
• 31:15
  Speaker 4: We both think that this is happening, And of course
• 31:17
  Speaker 4: then the next question is why. And even before we
• 31:22
  Speaker 4: get to some of the like really rigorous studies on this,
• 31:25
  Speaker 4: I think we need to address just a handful of
• 31:28
  Speaker 4: the things that I have heard on social media about this.
• 31:33
  Speaker 4: Let me start with a clip from the Hubreman podcast
• 31:37
  Speaker 4: about this issue.
• 31:39
  Speaker 3: You might have heard that carrying your phone in your
• 31:41
  Speaker 3: pocket can reduce your testosterone levels and sperm count. And
• 31:44
  Speaker 3: guess what that is true? The data contained within this
• 31:48
  Speaker 3: meta analysis and other MEDA analyzes clearly point out that
• 31:51
  Speaker 3: it can reduce sperm count and maybe testosterone levels significantly,
• 31:56
  Speaker 3: but certainly sperm count and motility significantly. It reduces sperm quality.
• 32:00
  Speaker 3: So should you avoid putting your phone in your pocket,
• 32:04
  Speaker 3: certainly your front pocket, I would suggest yes, right if
• 32:07
  Speaker 3: you are somebody who is seeking to conceive.
• 32:09
  Speaker 4: Emily, Before I get your response to that, I just
• 32:11
  Speaker 4: want to say that that was one of the most
• 32:14
  Speaker 4: epic eye rolls. I have ever seen your opinion.
• 32:19
  Speaker 2: I do not think we have good evidence that cell
• 32:23
  Speaker 2: phones reduced sperm counts. You know, we have a little
• 32:26
  Speaker 2: bit of like confounded evidence that people who talk of
• 32:29
  Speaker 2: the phone war maybe have lower sperm counts, but of
• 32:31
  Speaker 2: course that's not a piece of causal evidence. There's this
• 32:35
  Speaker 2: idea you often hear about, like when you have your
• 32:39
  Speaker 2: cell phone in your in your pocket, it reduces your
• 32:41
  Speaker 2: sperm count. But again we sort of look at the
• 32:43
  Speaker 2: better evidence on that, where they know where people are
• 32:46
  Speaker 2: carrying their phones and so on, just don't see any
• 32:48
  Speaker 2: impact on sperm count. There's also no reason to think
• 32:50
  Speaker 2: that your cell phone waves would impact your There's no
• 32:53
  Speaker 2: reason for that.
• 32:55
  Speaker 4: Yeah, yeah, there's no biologic plausibility, something we biologility always
• 32:59
  Speaker 4: always talk about. You want, at the very least the
• 33:01
  Speaker 4: sort of floor the table stakes are. There has to
• 33:06
  Speaker 4: be like a reason to believe this would be true,
• 33:08
  Speaker 4: and then you need to look for evidence that actually
• 33:11
  Speaker 4: is true. And I agree, I don't know why, but
• 33:13
  Speaker 4: this is all over the place. I actually saw a
• 33:16
  Speaker 4: clip of a woman responding I like to this Huberman clip,
• 33:20
  Speaker 4: and it was like it was like reacting to the
• 33:22
  Speaker 4: Huberman clip, and I was like, oh, this is going
• 33:23
  Speaker 4: to be one of my people who's going to be like,
• 33:25
  Speaker 4: what the hell's you talking about? And it was a
• 33:28
  Speaker 4: woman being like, good job, Andrew Huberman and also, don't
• 33:31
  Speaker 4: put your cell phone in a fanny pack if you're
• 33:34
  Speaker 4: a woman, because that can affect your eggs. And I'm like, oh, man,
• 33:37
  Speaker 4: like now we can't even use fanny packs, and they.
• 33:40
  Speaker 1: Were coming back.
• 33:41
  Speaker 2: I mean, I think that this is an example where
• 33:44
  Speaker 2: people are pulling causality of time trends, where it's sort
• 33:47
  Speaker 2: of easy to say, oh, look, you know, we think
• 33:49
  Speaker 2: sperm counts have gone down over time. Cell phones have
• 33:51
  Speaker 2: gone up over time, and so you know, those two
• 33:54
  Speaker 2: things move together. Of course, many things have gone up
• 33:57
  Speaker 2: over time, not just cell phones. And so the idea
• 33:59
  Speaker 2: that two trends that moved in the same direction is
• 34:01
  Speaker 2: not a way that we generate causality. Ever, Yeah, terrible,
• 34:05
  Speaker 2: terrible way to do causality.
• 34:06
  Speaker 4: My Nickel down here that the actual reason for declining
• 34:09
  Speaker 4: sperm counts is the rise in political violence. What about okay,
• 34:16
  Speaker 4: what about laptops on laps because okay, here we got
• 34:20
  Speaker 4: some biological plausibility. Laptops are warm. You know, the reason
• 34:25
  Speaker 4: that the testes are outside of the bodies because sperm
• 34:28
  Speaker 4: development is inhibited at ninety eight point six degrees at
• 34:34
  Speaker 4: body temperature, they have to be slightly cooler than that.
• 34:37
  Speaker 4: I saw a nice study looking at like the measured
• 34:40
  Speaker 4: scrotal temperatures. This is in a lap, so measuring scrotal
• 34:44
  Speaker 4: temperatures of people with a laptop on their lap, and
• 34:47
  Speaker 4: it found about two and a half to three degrees
• 34:49
  Speaker 4: celsius higher with the laptop on their lap, And like, okay,
• 34:54
  Speaker 4: so more biologically plausible. What do you think about laptops?
• 34:58
  Speaker 2: Yeah, so I think it's actually is pretty I want
• 35:01
  Speaker 2: to put a pin on the heat thing, because actually
• 35:03
  Speaker 2: one of the things that does reliably impede sperm production
• 35:09
  Speaker 2: is having your testicles be very hot. And there are
• 35:12
  Speaker 2: other things more important than laptops for that, like very
• 35:15
  Speaker 2: tight underwear. So like heat is an important consideration here.
• 35:21
  Speaker 2: The laptop explanation, My guess is it's like it is
• 35:26
  Speaker 2: biologically plausible. My guess is it's not very important just
• 35:30
  Speaker 2: in terms of total magnitude, partly because I don't actually
• 35:32
  Speaker 2: think people have their laptops on their laps like that much,
• 35:36
  Speaker 2: and those effect sizes are not that big, and I
• 35:40
  Speaker 2: would be surprised if this explained much of a time trend.
• 35:45
  Speaker 1: But I would say, like, from.
• 35:46
  Speaker 2: An individual standpoint, if you are worried about your sperm count,
• 35:49
  Speaker 2: if you're trying to get pregnant, if you're worried about
• 35:51
  Speaker 2: your fertility, you're thinking about your sperm count, and you're
• 35:53
  Speaker 2: carrying your laptop on your lap all the time, maybe
• 35:55
  Speaker 2: don't do that.
• 35:56
  Speaker 1: Put it on a table.
• 35:57
  Speaker 2: Yeah, all right, so we got we're we're going to
• 35:59
  Speaker 2: carry our cell phone, but we're not going to put
• 36:01
  Speaker 2: our laptop.
• 36:02
  Speaker 1: What about pesticides? Toxins?
• 36:06
  Speaker 4: Okay, toxins. So you know, this is interesting because toxins
• 36:12
  Speaker 4: is such a huge term. It's such a huge umbrella,
• 36:16
  Speaker 4: and it can range from everything from like yeah, the
• 36:18
  Speaker 4: stuff we sparan crops to like automobile exhaust and particulate matter,
• 36:24
  Speaker 4: and depending on who you ask, like corn stuff like yeah,
• 36:28
  Speaker 4: atizes right, like all this stuff, and so it's so
• 36:31
  Speaker 4: difficult to pin down exactly what's happening. I will say
• 36:37
  Speaker 4: that there is some interesting data and pesticides, I'm not
• 36:40
  Speaker 4: quite ready to like pooh pooh this entirely. So the
• 36:46
  Speaker 4: one that people will have probably heard of. Most is
• 36:50
  Speaker 4: called atrazine. And the reason you see a lot about
• 36:53
  Speaker 4: this is because this was the pesticide that in like
• 36:58
  Speaker 4: a lab and animal or like in a frog embryo study,
• 37:02
  Speaker 4: was able to change the gender of the frogs. Right,
• 37:05
  Speaker 4: this is like the pesticides are turning frogs gay type
• 37:09
  Speaker 4: of things. So like a lot of hype, I think
• 37:12
  Speaker 4: a lot of misunderstanding of what these studies actually looked at.
• 37:15
  Speaker 4: But some of these pesticides do have hormonal activity, like
• 37:19
  Speaker 4: can be hormonally disruptive, changing levels of estrogen and testosterone
• 37:25
  Speaker 4: in animals at least and potentially humans. There was a
• 37:32
  Speaker 4: small ish case control study looking at infertility, So I'm
• 37:38
  Speaker 4: moving away from sperm counts here. I'm I'm just talking
• 37:41
  Speaker 4: about infertility. Fifty men who were infertile, fifty men who
• 37:43
  Speaker 4: weren't infertile, where the levels of pesticides were measured in
• 37:48
  Speaker 4: their blood and there was a signal that the men
• 37:52
  Speaker 4: who were infertile were more likely to have higher levels
• 37:55
  Speaker 4: of pesticides in their blood. Now, like, does that mean
• 37:58
  Speaker 4: it's the pesticides? Does it mean they tend to eat
• 38:00
  Speaker 4: that contain more pesticides? Are like they don't wash their
• 38:02
  Speaker 4: foods off with pesticides. We have no idea. But in
• 38:06
  Speaker 4: contrast to cell phones, which always feels like a little
• 38:08
  Speaker 4: like wishy washy woo science to me, you know, pesticides
• 38:11
  Speaker 4: are chemicals. They kill bugs, they may do something to us.
• 38:16
  Speaker 2: Right, So let me just say I hear you on
• 38:20
  Speaker 2: the biological plausibility. I find the study you just described
• 38:24
  Speaker 2: to be ridiculous. It is a kind of study I
• 38:28
  Speaker 2: hate called a case control study. And in a study
• 38:31
  Speaker 2: like this, I'm sorry, I'm going to nerd out for people.
• 38:33
  Speaker 2: But what we're doing is we're sort of taking people
• 38:36
  Speaker 2: who have some condition and then in this case, infertility,
• 38:38
  Speaker 2: and then finding some other people who don't have the
• 38:40
  Speaker 2: condition and then asking them.
• 38:42
  Speaker 1: We're looking at, you.
• 38:43
  Speaker 2: Know, different exposures, look different at different features of these people.
• 38:47
  Speaker 2: And the problem with the study like that is twofold one.
• 38:51
  Speaker 2: There are many other potential differences across people, so you know,
• 38:55
  Speaker 2: it's definitely not randomized, and if you look at those
• 38:58
  Speaker 2: two groups are going to be different all all kinds
• 39:00
  Speaker 2: of other things, not just pesticides, And so we're potentially
• 39:05
  Speaker 2: confusing correlation between pesticide exposure and infertility with causality, no
• 39:12
  Speaker 2: reason to think it's causal. The second thing is, in
• 39:14
  Speaker 2: that particular kind of study, you also have a problem
• 39:17
  Speaker 2: because you're selecting the people totally differently, and so that
• 39:21
  Speaker 2: makes your kind of correlation problem worse. So I hear
• 39:25
  Speaker 2: you on the biological plausibility. I think case control studies
• 39:28
  Speaker 2: are so deeply stupid. It's like one of my just
• 39:32
  Speaker 2: total pet peeves that anyone ever uses them.
• 39:35
  Speaker 4: Sorry, I'm quickly going to search my Google scholar record
• 39:39
  Speaker 4: for all case control studies that I may or may
• 39:41
  Speaker 4: not have aged totally.
• 39:48
  Speaker 2: That's the gold standard, and it probably doesn't show this, Okay.
• 39:50
  Speaker 2: So I mean, look, it's very difficult with something like toxins.
• 39:54
  Speaker 1: I think in the end it's going.
• 39:54
  Speaker 2: To be very difficult to say, well, it's not taught
• 39:56
  Speaker 2: like because that means kind of anything.
• 40:00
  Speaker 1: But I would be surprised.
• 40:02
  Speaker 4: It also perpetuates the sort of like decline of civilization
• 40:07
  Speaker 4: narrative that I think goes along with the sperm count decline. Right,
• 40:11
  Speaker 4: It's like there's this weird overlap almost from you know,
• 40:14
  Speaker 4: like everything is getting worse, right, the sperm counts are
• 40:17
  Speaker 4: going down and the pesticides are going up, and you know,
• 40:20
  Speaker 4: of course the data dogs are gay, right, So I
• 40:25
  Speaker 4: think we are. We are definitely in that sort of
• 40:27
  Speaker 4: time period, and it's going to be hard to disabuse
• 40:29
  Speaker 4: people of any notions like that.
• 40:32
  Speaker 2: All right, So what about last thing I think we
• 40:34
  Speaker 2: hear about is soy so so for your sperm.
• 40:39
  Speaker 4: So if your sperm count is like the true measure
• 40:42
  Speaker 4: of your masculinity, and the like opposite of that is
• 40:46
  Speaker 4: how much soy you drink?
• 40:47
  Speaker 1: Totally okay.
• 40:51
  Speaker 4: So the reason people even talk about this, the soy
• 40:55
  Speaker 4: boy phenomenon, right, the reason people even talk about this
• 40:58
  Speaker 4: is because soy, like many plants, contains chemicals which are
• 41:03
  Speaker 4: called phyto estrogens, which just means plant estrogens something like that.
• 41:10
  Speaker 4: These are chemical compounds that have a similar chemical structure
• 41:14
  Speaker 4: to human estrogen, and in some extraordinary cases, in very
• 41:21
  Speaker 4: high doses, can mimic some of the effects of human estrogen.
• 41:26
  Speaker 4: You can see, I'm qualifying this quite a lot. That
• 41:29
  Speaker 4: is that's it, right, Like, that's all that's based on,
• 41:32
  Speaker 4: is like there's a little molecule in soy and lots
• 41:34
  Speaker 4: of other plants, by the way, that like looks you know,
• 41:37
  Speaker 4: if you squint, kind of like the same chemical structure
• 41:39
  Speaker 4: as estrogen. There is no good data to suggest that
• 41:44
  Speaker 4: soy intake has any effect on sperm count whatsoever, really none.
• 41:47
  Speaker 4: In fact, there's there's quite good data that shows that
• 41:49
  Speaker 4: it has no effect whatsoever. There's even emily randomized trial
• 41:54
  Speaker 4: data where they took men and randomized them to have
• 41:58
  Speaker 4: like a high SOI diet versus not a high soy
• 42:00
  Speaker 4: diet and measured their sperm counts and there was still
• 42:03
  Speaker 4: no difference. So it's not soy.
• 42:06
  Speaker 1: It's not soy, it's not soil. Okay, So it's not
• 42:10
  Speaker 1: any of these things. I think we should talk about
• 42:13
  Speaker 1: what it is.
• 42:15
  Speaker 2: Yeah, potentially like what might be responsible for this change?
• 42:20
  Speaker 2: And to do that we basically like for something to
• 42:24
  Speaker 2: explain this trend, it needs to both impact sperm count
• 42:29
  Speaker 2: and be trending over time, and I actually think those
• 42:31
  Speaker 2: are like a sort of both pretty important. So there
• 42:34
  Speaker 2: are some things that are that do affect your sperm
• 42:37
  Speaker 2: count but are not trending over time, and then things
• 42:41
  Speaker 2: that are trending over time, which we've talked about many
• 42:43
  Speaker 2: that don't affet sperm size.
• 42:44
  Speaker 1: You kind of need something to intersect to matter there.
• 42:48
  Speaker 4: Yeah, So what is it? Well? All right, let me
• 42:51
  Speaker 4: let me go for low hanging fruit. You mentioned earlier
• 42:55
  Speaker 4: one when we were talking about laptops that he is
• 42:57
  Speaker 4: a major consideration here, So talk to me about heat.
• 43:00
  Speaker 4: What's going on there?
• 43:02
  Speaker 2: Yeah, So I think heat is very important because it
• 43:05
  Speaker 2: is one of the pieces here where when I talk
• 43:07
  Speaker 2: to people about sort of infertility and about male factor,
• 43:10
  Speaker 2: infertility is actually something not everybody thinks about and is
• 43:14
  Speaker 2: potentially quite important. So, as we mentioned, your testicles need
• 43:18
  Speaker 2: to be slightly cooler than body temperature in order to
• 43:21
  Speaker 2: efficiently produce sperm, which means if they're very hot, either
• 43:26
  Speaker 2: because you're making them hot with some external source like
• 43:30
  Speaker 2: a sauna or a hot tub frequently, or if they're
• 43:35
  Speaker 2: too close to your body, that can reduce spermcat And actually,
• 43:38
  Speaker 2: like one of my favorite studies of this is one
• 43:41
  Speaker 2: in which researchers took men and they gave them these
• 43:43
  Speaker 2: like super tight underwear, So you know, they had them
• 43:46
  Speaker 2: wear super tight underwear all the time for several months,
• 43:49
  Speaker 2: and you can actually see this for science, and you
• 43:52
  Speaker 2: can actually see this sperm count go to zero.
• 43:55
  Speaker 1: So there's sperm count. There's sort of a like effective
• 43:58
  Speaker 1: sperm count.
• 43:58
  Speaker 2: Basically goes to zero and then comes back up after
• 44:00
  Speaker 2: they take off the underwear. So you know, this is
• 44:03
  Speaker 2: a great system for birth control that I think we're underutilizing.
• 44:07
  Speaker 2: But also it really illustrates like this actually potentially quite
• 44:11
  Speaker 2: quite important. And so this can apply, you know to
• 44:15
  Speaker 2: again tight underwear, not clinically study tight, but just in general,
• 44:21
  Speaker 2: tighter underwear may lower.
• 44:23
  Speaker 1: Your sperm count.
• 44:24
  Speaker 2: People who are doing like a lot of like cycling,
• 44:28
  Speaker 2: you know, not like I ride my bike to work,
• 44:31
  Speaker 2: you know, every day kind of cycling, but like you're
• 44:34
  Speaker 2: in the cycling peloton wearing the tight bike shorts on
• 44:36
  Speaker 2: your bike for nine hours a day.
• 44:38
  Speaker 1: That's not gonna be good. It's like, be good for
• 44:40
  Speaker 1: your sperm.
• 44:41
  Speaker 2: So heat is a I think actually heat is a
• 44:43
  Speaker 2: big factor. I don't think it is likely that it
• 44:46
  Speaker 2: is a factor that explains much of the trend over time,
• 44:48
  Speaker 2: because I'm not sure why people's testicles would be hotter
• 44:51
  Speaker 2: now than they were.
• 44:52
  Speaker 4: This isn't a global warming argument that you're making, Not.
• 44:54
  Speaker 1: A global warming argument.
• 44:55
  Speaker 2: This is just like, this is an individual actionable thing.
• 44:58
  Speaker 2: And I will say there's two other kind of individual
• 45:01
  Speaker 2: actionable things which I also don't think are anything about
• 45:03
  Speaker 2: the trends, which are heavy alcohol consumption and smoking. So
• 45:08
  Speaker 2: both consumption of alcohol at a very high rate and
• 45:12
  Speaker 2: cigarette smoking definitely affect sperm counts and sperm quality. But
• 45:17
  Speaker 2: those two things have both declined over time globally, so
• 45:21
  Speaker 2: unlikely to explain trends in sperm counts, even if they
• 45:24
  Speaker 2: are potentially important changes for some individual looking to improve
• 45:27
  Speaker 2: their sperm So we got to look for something else.
• 45:30
  Speaker 4: So we need to look for something that affects sperm
• 45:33
  Speaker 4: count and has been rising since the seventies.
• 45:37
  Speaker 1: And what do you think it is?
• 45:39
  Speaker 4: I will tell you. As I was digging into the
• 45:42
  Speaker 4: medical literature, scientific literature on this, thinking that there would
• 45:45
  Speaker 4: be more controversy just based on what I saw on
• 45:48
  Speaker 4: social media, I was like, oh, there are eight million
• 45:53
  Speaker 4: studies that show that higher BMIs associated with lower sperm count.
• 45:58
  Speaker 4: Obesity is nearly a major factor in sperm counts. It
• 46:03
  Speaker 4: was like not subtle. It wasn't one of those situations
• 46:05
  Speaker 4: where it's like, oh, well, this study says this, and
• 46:07
  Speaker 4: this study says that it's like a consistent finding. Did
• 46:10
  Speaker 4: you find the same thing? And like, why why isn't
• 46:12
  Speaker 4: this just like the obvious answer?
• 46:14
  Speaker 1: I found exactly the same thing.
• 46:16
  Speaker 2: I actually would take it one step further, which is
• 46:19
  Speaker 2: you can see both the impacts of obesity on sperm counts,
• 46:23
  Speaker 2: and you can see on the flip side with weight loss,
• 46:25
  Speaker 2: and particularly with GLP ones, you can actually see men
• 46:29
  Speaker 2: who go on to GLP one sperm parameters improve, sperm counts,
• 46:32
  Speaker 2: improve sperm mobility improves as.
• 46:34
  Speaker 1: A result presumably of weight loss.
• 46:37
  Speaker 2: And so this, to me, this jumped out very obviously
• 46:41
  Speaker 2: as a clear explanation something we know has trended up
• 46:45
  Speaker 2: over time, something that's very clearly associated with sperm counts.
• 46:48
  Speaker 2: And it kind of left me, as I'm often in
• 46:50
  Speaker 2: these situations, being like, Okay, given that the decline in
• 46:54
  Speaker 2: spermcout's not very big, this probably explains almost all of
• 46:58
  Speaker 2: what we have seen when we go into these like
• 47:01
  Speaker 2: cell phones and this and that and soy and all
• 47:04
  Speaker 2: this other stuff. There's like an obvious explanation staring you
• 47:07
  Speaker 2: in the face that almost certainly explains like ninety five
• 47:10
  Speaker 2: percent of anything that we're seeing.
• 47:12
  Speaker 1: Yeah, ended up being kind of it was like a little.
• 47:14
  Speaker 4: Right, right right. It's anticlimactic, and maybe that's why you
• 47:17
  Speaker 4: don't see it on social media as much as you
• 47:19
  Speaker 4: should because you know, it's more it's it's it's more
• 47:23
  Speaker 4: interesting to say, oh, it's this thing you haven't thought of, right,
• 47:26
  Speaker 4: Like you didn't realize that fluorescent lights are you know,
• 47:29
  Speaker 4: talking to your supermatosites in some weird way.
• 47:32
  Speaker 1: Yeah.
• 47:32
  Speaker 2: I also think people are looking for solutions. If you
• 47:36
  Speaker 2: sort of if this is something you're worried about, you're
• 47:38
  Speaker 2: looking for a solution. Potentially it's sort of interesting or
• 47:40
  Speaker 2: different or like you know, and things.
• 47:43
  Speaker 1: Get clicks the solution.
• 47:44
  Speaker 2: That's like people, you know, obesity is a metab issue
• 47:47
  Speaker 2: that we should be addressing in our health choices. That
• 47:51
  Speaker 2: is something people have been hearing for all kinds of reasons,
• 47:54
  Speaker 2: not just for this reason. And so just this is
• 47:56
  Speaker 2: like yet another reason and it's just like that's boring,
• 47:58
  Speaker 2: like just another like shamey, well you lose weight. It's like, yeah,
• 48:04
  Speaker 2: hear that, We hear that all the time already.
• 48:06
  Speaker 1: Yeah.
• 48:07
  Speaker 2: So we talked before about biological plausibility in this explanation
• 48:11
  Speaker 2: about obesity, is this biologically plausible explanation?
• 48:15
  Speaker 4: And why it is definitely biologically plausible, although like all things,
• 48:20
  Speaker 4: it's complicated. So fat is a hormonally active organ, so
• 48:26
  Speaker 4: so the more body fat, there is the more levels
• 48:30
  Speaker 4: of certain hormones, including estrogen like hormones even in men
• 48:33
  Speaker 4: get generated by fat tissue. And so there's this sort
• 48:38
  Speaker 4: of endocrine phenomenon that will happen with overweight and obesity
• 48:42
  Speaker 4: that could affect sperm production. But like that has not
• 48:45
  Speaker 4: been totally well elucidated. There may well be other reasons,
• 48:51
  Speaker 4: whether it's like glucose metabolism and things like that which
• 48:53
  Speaker 4: might be important for keeping sperm alive longer and stuff
• 48:56
  Speaker 4: like that. Whether it's vascular you know, there needs to
• 48:59
  Speaker 4: be a quit blood flow and things that all remains
• 49:03
  Speaker 4: to be seen. But we talk emily a lot about
• 49:05
  Speaker 4: correlation versus causation. We kind of throw that out, but
• 49:08
  Speaker 4: I just to get metaphysical for a second. I think
• 49:12
  Speaker 4: the way I define this for like my students people say, oh,
• 49:17
  Speaker 4: you know A causes B, that's important to know. The
• 49:20
  Speaker 4: reason we care if A causes B or if it
• 49:23
  Speaker 4: is just associated with B is because if A causes B,
• 49:27
  Speaker 4: then changing A changes B. And that's where the rubber
• 49:30
  Speaker 4: meets the road in terms of health. Right. And so
• 49:32
  Speaker 4: what you pointed out was like if obesity overweight causes
• 49:38
  Speaker 4: low sperm counts, then changing your weight will increase your
• 49:42
  Speaker 4: sperm counts, and that is the level of evidence we
• 49:44
  Speaker 4: have from the GLP one trials. So that's like, you know,
• 49:49
  Speaker 4: I'm sure a philosopher would take issue with that particular
• 49:51
  Speaker 4: definition of causality, but as a doctor, like, that's all
• 49:54
  Speaker 4: I care about, Like can I change this and make
• 49:55
  Speaker 4: you better? Yes? Great?
• 49:57
  Speaker 1: Yeah, yeah.
• 49:57
  Speaker 2: I think when we think about causality as economists also
• 50:00
  Speaker 2: are actually much more focused on the idea of if
• 50:05
  Speaker 2: I change this, well this other thing change, as opposed
• 50:07
  Speaker 2: to exactly why right, So I sort of asked you about.
• 50:09
  Speaker 1: Like what is the mechanism for this? But in practice, you.
• 50:12
  Speaker 2: Know, one of the things we get out of that
• 50:14
  Speaker 2: GLP one evidence is if we change this, then sperm
• 50:17
  Speaker 2: count would change, and that's the.
• 50:19
  Speaker 1: Behaviorally relevant thing.
• 50:20
  Speaker 2: It is interesting to think about, well, why, you know,
• 50:24
  Speaker 2: what would be the mechanism there, partly because it might suggest,
• 50:27
  Speaker 2: you know, variations on the behavior change, or it just
• 50:30
  Speaker 2: might help us understand people better. But causality is really
• 50:33
  Speaker 2: about if I change X, would Y change?
• 50:37
  Speaker 1: And that is very different.
• 50:38
  Speaker 2: From when we talk about correlation, and we just see
• 50:40
  Speaker 2: like these two things are moving together, which could be
• 50:44
  Speaker 2: because X causes why.
• 50:45
  Speaker 1: Could because of why causes X. It could because some.
• 50:47
  Speaker 2: Other things Z causes X and causes why. And that's
• 50:51
  Speaker 2: that's not super helpful. That's not super helpful for a decision.
• 50:55
  Speaker 4: So I want to drill down. Now, we've talked about
• 50:57
  Speaker 4: the population. We've talked about millions of people and the
• 51:00
  Speaker 4: average sperm count and stuff like that. We've said, how,
• 51:02
  Speaker 4: you know, a lowish sperm count at a very low
• 51:06
  Speaker 4: end kind of impact fertility, but beyond the very low
• 51:09
  Speaker 4: end doesn't seem to matter too much. But let's take
• 51:13
  Speaker 4: an individual like I would probably argue if a patient
• 51:16
  Speaker 4: came to me and said, you know, my sperm count
• 51:18
  Speaker 4: is sixty million, I'd like to get it up to
• 51:19
  Speaker 4: one hundred million. I think my answer would be, like,
• 51:22
  Speaker 4: why you're not having fertility issues? Like, sperm count doesn't
• 51:27
  Speaker 4: correlate with you know, how strong you are, how fast
• 51:31
  Speaker 4: you can run a mile, like how good you are
• 51:33
  Speaker 4: in bed, Like, none of these things correlate. Nevertheless, people
• 51:37
  Speaker 4: seem to care. So what is your sort of set
• 51:40
  Speaker 4: of recommendations for like, like, let's do that thing where
• 51:43
  Speaker 4: you say, oh, get your sperm count up for some reason.
• 51:45
  Speaker 2: Yeah, So First of all, I think there are a
• 51:46
  Speaker 2: set of people who would care if you are trying
• 51:49
  Speaker 2: to get purent and maybe not to go from sixty
• 51:51
  Speaker 2: to one hundred. But I actually think we're probably in
• 51:53
  Speaker 2: some sets of populations undertesting people sperm. I think when
• 51:57
  Speaker 2: couples go to try to get pregnant, they often, like women, do.
• 52:00
  Speaker 1: A fertility work up.
• 52:01
  Speaker 2: I actually think it's a lot of value in men
• 52:02
  Speaker 2: doing some fertility work up to.
• 52:05
  Speaker 1: Begin with, partly because this is movable right in ways.
• 52:08
  Speaker 2: I will say, so, if you come you do a
• 52:10
  Speaker 2: sperm workup and you find your sperm count is, you know,
• 52:12
  Speaker 2: twenty million, there may well be things you can do
• 52:15
  Speaker 2: to raise it, which would be and this because it
• 52:17
  Speaker 2: is not too complicated. You know, don't drink heavily, So
• 52:20
  Speaker 2: if you're doing a lot of binge drinking, try to
• 52:23
  Speaker 2: cut down. If you are smoking a lot of tobacco
• 52:26
  Speaker 2: or cannabis, try to cut down or quit altogether. If
• 52:31
  Speaker 2: you are doing a lot of activities that keep your
• 52:33
  Speaker 2: testicles very hot, like regular sauna, the most common thing
• 52:37
  Speaker 2: would be people doing like regular sauna or hot tub usage,
• 52:41
  Speaker 2: try to take a break from doing those. And the
• 52:45
  Speaker 2: fourth one is you know, if people are struggling with obesity,
• 52:48
  Speaker 2: I think a GLP one is worth thinking about in
• 52:51
  Speaker 2: that situation. But again, I would recommend these things for
• 52:54
  Speaker 2: someone who was trying to use their sperm for pregnancy.
• 52:57
  Speaker 1: Right if you said I'm hoping to use sperm.
• 53:00
  Speaker 2: Pretty soon to you know, get into somebody's egg, that's
• 53:05
  Speaker 2: kind of when you want to be thinking about this.
• 53:06
  Speaker 1: You shouldn't.
• 53:07
  Speaker 2: This isn't just like you know, for fun. I mean
• 53:10
  Speaker 2: it could, but like it's it's not a point if
• 53:13
  Speaker 2: you're not using it.
• 53:14
  Speaker 4: I just to drive that point home. And I'm going
• 53:16
  Speaker 4: to geek out a little bit here now and talk
• 53:18
  Speaker 4: about this thing called the coefficient of variation. When you
• 53:22
  Speaker 4: measure something, there's a question you have to ask, which is,
• 53:26
  Speaker 4: if I measure this again at some time in the future,
• 53:29
  Speaker 4: well I get the same result. And how much that
• 53:34
  Speaker 4: changes from one measurement to another can be statistically defined
• 53:37
  Speaker 4: as this thing called the coefficient of variation. A typical
• 53:39
  Speaker 4: lab test like you might get in the hospital, like
• 53:41
  Speaker 4: your hemoglobin test, has a coefficient a variation of about
• 53:45
  Speaker 4: four percent, which means that if I measure you today
• 53:48
  Speaker 4: and I measure you tomorrow, on average, there'll be about
• 53:51
  Speaker 4: four percent different, you know, kind of bounces around just
• 53:54
  Speaker 4: a little bit, No big deal. There are few tests
• 53:58
  Speaker 4: with a higher coefficient variation sperm count. It's about fifty percent.
• 54:02
  Speaker 4: So I just want people to on the individual level, right,
• 54:04
  Speaker 4: So if you measure me today and even all like
• 54:07
  Speaker 4: taking care of all the variables, right, like remaining abstinent
• 54:10
  Speaker 4: for five days whatever, fifty percent difference on average between
• 54:15
  Speaker 4: test and retest. So everyone needs to keep in mind
• 54:18
  Speaker 4: when they see those people on social media who are like,
• 54:21
  Speaker 4: my sperm count was forty million and then I'd like,
• 54:23
  Speaker 4: you know, eight keenwa for eight meals a day, and
• 54:27
  Speaker 4: then it went up to seventy million, Like, that's within
• 54:30
  Speaker 4: the range of expected variability. So the decline of sperm
• 54:34
  Speaker 4: count is a population wide phenomenon, like it can be
• 54:37
  Speaker 4: real on a population for an individual. It's actually recommended
• 54:42
  Speaker 4: in fertility testing that men get tested multiple times because
• 54:45
  Speaker 4: of this issue because there's so much variability. And certainly
• 54:48
  Speaker 4: if you're just using it as like I want to
• 54:50
  Speaker 4: put this on my Tinder bio or whatever, well you
• 54:53
  Speaker 4: should test a bunch of times and take the average.
• 54:56
  Speaker 2: It's like retaking the essay because they only caught the
• 54:59
  Speaker 2: highest one.
• 55:00
  Speaker 1: So just keep testing and testing until you get a
• 55:02
  Speaker 1: number that you like. Put that your tender bio, and
• 55:04
  Speaker 1: then you're done. I'd say good.
• 55:06
  Speaker 2: Luck with that, all right, Perry, what's your one thing
• 55:10
  Speaker 2: on sperm Uh.
• 55:11
  Speaker 4: Here's my one thing. Here's my hot take. There's no
• 55:14
  Speaker 4: reason to care about your sperm count if you're not
• 55:16
  Speaker 4: trying to get someone pregnant, full stop.
• 55:19
  Speaker 1: My one thing is keep your balls cool.
• 55:22
  Speaker 4: Keep it cool, keep it cool. That's it for sperm counts.
• 55:26
  Speaker 4: We'll get to your listener questions after the break. We've
• 55:35
  Speaker 4: got a great question here from Anna in Columbus, Ohio.
• 55:39
  Speaker 1: Hi, Emily and Perry. I'm excited for this podcast, and
• 55:42
  Speaker 1: I have a fun question for you. Is there anything
• 55:45
  Speaker 1: health related.
• 55:45
  Speaker 2: That you do that isn't supported by data but you
• 55:48
  Speaker 2: just do it out of habit or for juju like
• 55:51
  Speaker 2: the rest of us.
• 55:52
  Speaker 1: Thank you.
• 55:53
  Speaker 4: I do have a belief that blueberries are way healthier
• 55:58
  Speaker 4: than people think they are, and I have never looked
• 56:01
  Speaker 4: it up and they just taste healthy to me. But
• 56:04
  Speaker 4: maybe I'm right. Maybe if we do a dig into that,
• 56:07
  Speaker 4: it does have data to support.
• 56:08
  Speaker 1: It, like healthier than other fruits.
• 56:11
  Speaker 4: They're the healthiest tasting food. That's so all right.
• 56:19
  Speaker 1: Can't you just say you like blueberries?
• 56:21
  Speaker 4: I don't. I mean, I like other things more than blueberries,
• 56:23
  Speaker 4: but they the taste of health to me is somewhat
• 56:28
  Speaker 4: tart blueberry, I think, But I have no data to
• 56:32
  Speaker 4: support that they're particularly healthy.
• 56:33
  Speaker 2: Wow, I cannot think of a single This is so
• 56:37
  Speaker 2: I feel like such a jerk.
• 56:39
  Speaker 1: I can't.
• 56:40
  Speaker 2: I do all kinds of weird stuff, but I feel
• 56:43
  Speaker 2: that all of it could be supported by data.
• 56:47
  Speaker 4: That's the problem with this question is that you probably
• 56:50
  Speaker 4: can find that you like, you could find data to
• 56:52
  Speaker 4: support anything, Like I can find you a study that
• 56:53
  Speaker 4: shows the blueberries to reduce the risk of cancer, right,
• 56:56
  Speaker 4: like totally.
• 56:58
  Speaker 1: Oh, I'll tell you what I do.
• 56:59
  Speaker 2: I hold a very strong superstition about I am extremely
• 57:04
  Speaker 2: neurotic about which shoes I wear at which times for
• 57:07
  Speaker 2: when I run. And I have like very strong feelings
• 57:10
  Speaker 2: like this is a shoe that you have to use
• 57:11
  Speaker 2: when you're running easy, This is a shoe when you
• 57:13
  Speaker 2: use for this kind of run. This is a shoe
• 57:14
  Speaker 2: and some of them are literally the same shoes, but
• 57:17
  Speaker 2: like one of them is an older version, Like I've
• 57:19
  Speaker 2: run on them more so they've gotten like downgraded to
• 57:21
  Speaker 2: like the medium long run from the And I think
• 57:24
  Speaker 2: that if you open the cabinets in my family room
• 57:27
  Speaker 2: where I.
• 57:28
  Speaker 1: Keep the shoes, you would be disturbed.
• 57:32
  Speaker 4: Okay, we will be sure to post a picture of
• 57:34
  Speaker 4: Emily's weird shoe closet. Stick with us next week when
• 57:38
  Speaker 4: we will ask what's the deal with peptides?
• 57:42
  Speaker 2: Wellness Actually is produced in association with iHeartMedia. Our senior
• 57:46
  Speaker 2: producer is Tamar Avishai. Our executive producer is Jennifer Bassett.
• 57:50
  Speaker 2: Our theme music is by Eric Deutsch, and our content
• 57:53
  Speaker 2: is for educational purposes only.
• 57:55
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• 58:01
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• 58:06
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  Speaker 4: to Wellness Actually dot fm and leave us a question
• 58:11
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• 58:15
  Speaker 1: We'll let the influencers have the last word.
• 58:18
  Speaker 4: Sperm counts have drop more than fifty percent in the
• 58:21
  Speaker 4: last fifty years. If this keeps up, natural conceptions going
• 58:24
  Speaker 4: to be as rare as a Cleveland Brown Super Bowl parade.
• 58:27
  Speaker 4: Your grandkids might need a lab just to exist.