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Why Do We Need Vitamin D? · So That's Why

• 0:04
  Jen Oliver: Welcome to the So that's Why Podcast, where we unpack the
• 0:07
  science behind everyday questions.
• 0:10
  I'm Jen.
• 0:11
  Chris Smith: I'm Chris.
• 0:11
  Matt Edmundson: And I'm Matt.
• 0:13
  Jen Oliver: So today's question is why do we need vitamin D?
• 0:16
  And I don't mean the vague, it's good for your bones answer.
• 0:20
  I mean, what is it actually doing inside your body that
• 0:23
  makes it absolutely essential?
• 0:26
  Chris Smith: So vitamin D really is a super vitamin as we'll today.
• 0:30
  In fact, it's not just a vitamin.
• 0:32
  It also functions as a hormone.
• 0:34
  'cause your body produces it.
• 0:35
  It regulates genes and it has receptors in virtually every cell in our body.
• 0:40
  Matt Edmundson: So vitamin D is actually a hormone.
• 0:44
  Chris Smith: Yeah.
• 0:45
  So it is still considered as a vitamin, but as you, your body can produce it and
• 0:50
  it has hormone activity and function.
• 0:52
  Many scientists now classify it as a hormone too.
• 0:55
  Jen Oliver: So in this episode we'll discuss why vitamin D is
• 0:59
  essential for everything from calcium absorption to immune function.
• 1:03
  Why deficiency is so widespread despite us being able to make it from sunlight and
• 1:08
  what happens when you don't get enough.
• 1:10
  Matt Edmundson: Yeah.
• 1:11
  'cause I've read right that nearly half.
• 1:13
  Half of the global population is deficient in vitamin D. I mean, that's
• 1:19
  a, that's a big old market right there.
• 1:21
  You know, billions of people not having enough of something that their body
• 1:26
  desperately needs to function properly.
• 1:29
  So it does beg the question, doesn't it?
• 1:32
  If we can make vitamin D from sunshine, why are almost half of
• 1:36
  us on the planet still deficient?
• 1:39
  Which is Sure.
• 1:40
  Uh, I'm sure actually something that.
• 1:43
  You guys are gonna get into.
• 1:45
  Jen Oliver: So vitamin D deficiency isn't just about weak bones, it's
• 1:48
  about why you might feel constantly exhausted, catch every bug going around
• 1:54
  and struggle with muscle weakness.
• 1:56
  It affects far more than people realize.
• 1:58
  Chris Smith: Yeah, it's true.
• 1:59
  And the consequences range from the obvious.
• 2:00
  So bone diseases in children and adults, but to also to things we don't
• 2:04
  traditionally think of in relation to vitamin D. So immune system
• 2:08
  problems, as you mentioned, muscle weakness and increased infection risk.
• 2:13
  Matt Edmundson: Okay, so let's start with the, the fundamental question here then.
• 2:17
  What is vitamin D doing that makes it so crucial?
• 2:22
  For me,
• 2:23
  Chris Smith: its primary job is regulating calcium absorption, so your intestines
• 2:28
  needed to effectively absorb that calcium,
• 2:31
  Jen Oliver: and then you've got its role in the immune system.
• 2:35
  Vitamin D controls, antimicrobial peptides, which are your first
• 2:39
  defense against bacteria and viruses.
• 2:41
  Matt Edmundson: So in mat language it gives your immune cells better
• 2:44
  weapons to deal with it all.
• 2:48
  Chris Smith: I like that.
• 2:49
  Yeah.
• 2:49
  E exactly.
• 2:49
  Better weapons.
• 2:50
  Sounds good.
• 2:51
  Um, but cleverly it also prevents immune overreaction, so it promotes
• 2:57
  regulatory cells that stop your immune system from attacking your own tissues.
• 3:01
  That's why deficiency links to autoimmune disease risk.
• 3:05
  Matt Edmundson: And again, my language.
• 3:08
  So what this is doing is making your immune system more effective against
• 3:12
  threats whilst preventing friendly fire.
• 3:15
  Jen Oliver: Perfect description.
• 3:16
  Matt Edmundson: Thank you.
• 3:16
  Jen Oliver: It's about balance, not just strength.
• 3:19
  Chris Smith: Absolutely.
• 3:20
  And then we think about other things.
• 3:21
  So if you think about muscles for a moment.
• 3:23
  So vitamin D strength, vitamin D deficiency causes
• 3:27
  proximal muscle weakness.
• 3:28
  So those big muscles in your thighs and upper arms get notably weaker.
• 3:33
  Matt Edmundson: So basically what you're saying is if we want big guns.
• 3:35
  I need to take my vitamin D.
• 3:37
  Jen Oliver: Exactly.
• 3:38
  Matt Edmundson: There's another marketing slogan right there.
• 3:41
  Jen Oliver: But in terms where that people might to relate, be able to
• 3:44
  relate to better deficiency, can affect things like stair climbing, standing
• 3:48
  up from chairs, you know, any movement that those big muscle groups need to do.
• 3:53
  Chris Smith: It can.
• 3:53
  And when it comes to healthy bones, we, we already know there's the link with
• 3:57
  calcium absorption, but vitamin D also regulates what we call bone remodeling.
• 4:01
  So this is the constant process of breaking down old bones and
• 4:05
  building new bone without it.
• 4:07
  Bones don't mineralize properly.
• 4:09
  They're structurally there, but they're soft and weak.
• 4:11
  Matt Edmundson: Mm. So is this where bowed legs and rickets come from?
• 4:14
  Jen Oliver: Yeah.
• 4:15
  Yeah, it does.
• 4:16
  You know, bones deform under natural stress because they
• 4:19
  haven't mineralized correctly.
• 4:21
  They're not strong enough, are they?
• 4:23
  Matt Edmundson: Okay.
• 4:24
  So what then are the other issues associated with vitamin D deficiency
• 4:30
  that we need to think about?
• 4:31
  Chris Smith: There are loads and the implications are serious.
• 4:33
  So without adequate Vitamin D, your body can only absorb about half the amount
• 4:37
  of that dietary calcium that it should.
• 4:40
  Matt Edmundson: So years of drinking milk for strong bones without checking,
• 4:43
  maybe the vitamin D status might not be as effective as we think.
• 4:48
  Chris Smith: Mm, absolutely.
• 4:49
  It is essential to check that there is sufficient Vitamin D too.
• 4:52
  And now a lot of milks, including plant milks, are typically
• 4:55
  fortified with vitamin D for that.
• 4:58
  Jen Oliver: Also the consequences of low vitamin D extend beyond calcium
• 5:02
  and bone health too, don't they?
• 5:04
  You know, vitamin D deficiency increases the risk of respiratory infections
• 5:08
  and also contributes to tiredness.
• 5:10
  Chris Smith: Yeah, it's always amazing how these things are all connected, isn't it?
• 5:14
  So vitamin D manages all of these factors you mentioned simultaneously.
• 5:18
  Matt Edmundson: So then how does you know, how does sunshine
• 5:21
  actually make Vitamin D then?
• 5:22
  That is something I'm curious about.
• 5:25
  Chris Smith: So your skin contains a cholesterol derivative,
• 5:28
  and what happens is when.
• 5:30
  Ultraviolet light from the sun hits the skin.
• 5:32
  It causes a conversion process that ultimately produces vitamin D three
• 5:37
  that then travels to your liver and then to your kidneys as part of its journey
• 5:41
  to become fully active in the body.
• 5:43
  Jen Oliver: So it's a three stage production line, skin, liver,
• 5:46
  kidneys, all driven by UV light.
• 5:49
  And it's tightly regulated, isn't it, based on your, your body's calcium
• 5:52
  needs, just like other hormones.
• 5:54
  Matt Edmundson: So why is then.
• 5:57
  As I said earlier, half the world's population is deficient.
• 6:02
  Why is that?
• 6:02
  If we can make vitamin D from sunlight, because half the world is
• 6:05
  not, you know, deprived of the sun.
• 6:07
  Significant, not
• 6:08
  Jen Oliver: significant, is it?
• 6:08
  Yeah.
• 6:09
  Yeah.
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  Chris Smith: No, that's it.
• 6:10
  And there are multiple factors coming to play here.
• 6:12
  So vitamin D synthesis, it needs UV radiation, uh, but it's
• 6:17
  gotta be at the right angle.
• 6:18
  So we're typically talking about midday sun.
• 6:21
  So if you live above, I think it's 35 degrees latitude, which is.
• 6:26
  Effectively north of Los, Los Angeles, or of Southern Spain.
• 6:30
  Winter sun never gets high enough, so your skin physically can't produce
• 6:34
  vitamin C, uh, vitamin D, sorry, for several months of the year.
• 6:38
  Matt Edmundson: So everyone in the UK basically, uh, Scandinavia, Canada,
• 6:42
  these sorts of countries, they're at risk of not getting enough sun
• 6:46
  to produce sufficient Vitamin D.
• 6:48
  Is that right?
• 6:49
  Chris Smith: It's true.
• 6:50
  In fact, there was a bizarre stat for.
• 6:52
  UK listeners only that apparently if you live north of Milton Keynes on
• 6:57
  the average year, you don't get enough UV for the entirety of the year.
• 7:00
  Matt Edmundson: Oh, wow.
• 7:00
  Chris Smith: Wow.
• 7:01
  Just to consistently Well, that
• 7:02
  Matt Edmundson: that would be me.
• 7:02
  I
• 7:03
  live
• 7:03
  north of
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  Milton Keyes.
• 7:03
  Jen Oliver: Yeah, me too.
• 7:04
  Chris Smith: Although we're had some sunny years recently.
• 7:06
  Mm-hmm.
• 7:06
  So maybe it's better.
• 7:08
  Um, but it's more about your lifestyle actually, than anything.
• 7:11
  Because even Sunny climates show high vitamin D deficiency
• 7:14
  rates among their populations.
• 7:16
  So if you look at the Middle East, for example, they've got a 65%.
• 7:20
  Deficiency rate and that's due to staying indoors.
• 7:22
  Mm-hmm.
• 7:23
  Or covering up to escape the heat of the sun.
• 7:26
  Even Australia, we think it's pretty sunny normally in Australia, right?
• 7:30
  But their deficiency rates are really high and, and some areas of India
• 7:35
  equally, they show near a hundred percent of the population in some
• 7:38
  local areas to be vitamin D deficient.
• 7:41
  Jen Oliver: And skin pigmentation matters as well, doesn't it?
• 7:43
  'cause you've got melanin in your skin, which is your natural sun
• 7:47
  protection chemical, and it helps.
• 7:49
  Protect against sun damage, but it means darker skinned individuals
• 7:53
  need more sun exposure to then produce the same amount of vitamin D.
• 7:58
  Matt Edmundson: And I guess if you've got darker skin and you
• 8:00
  live in a northern climate, that's like a double jeopardy, right?
• 8:04
  Yeah.
• 8:04
  Double challenge going on.
• 8:05
  Jen Oliver: Exactly.
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  It's a genuine health equity issue that doesn't get enough attention, really.
• 8:09
  Chris Smith: No, that's right.
• 8:10
  And, and of course, age affects it too.
• 8:12
  Uh, but what, what you might not realize is that someone in
• 8:15
  their seventies would produce.
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  On average, only about a quarter of the vitamin DA 20-year-old would
• 8:21
  make from the identical sun exposure.
• 8:23
  Mm.
• 8:24
  Matt Edmundson: So if you think then about, well, I think about the Aussies,
• 8:27
  their vitamin D, they're deficient, they've got a lot of sunshine.
• 8:33
  The thing that I hear banded about all the time is that's
• 8:37
  because they wear sunscreen.
• 8:38
  Is that a myth or is that true?
• 8:40
  Chris Smith: So this notion that vitamin D is blocked by sunscreen wearing.
• 8:46
  It's a complete myth.
• 8:47
  So sunscreens do block a high percentage of that ultraviolet, BUVB raise, but not
• 8:53
  all of them, which means enough of that UV gets through to our skin to allow it
• 8:57
  to produce Vitamin D. And this is such an important topic because obviously
• 9:02
  skin cancer is incredibly serious.
• 9:04
  Mm-hmm.
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  So please do not believe rubbish spreading online that we shouldn't
• 9:08
  wear sunscreen because of vitamin D.
• 9:10
  It.
• 9:11
  I, I, I appreciate it's a bigger topic, but please, please, if you're spending
• 9:14
  time in the sun during the, the spring and summer months, wear sunscreen full stop.
• 9:20
  You don't need to worry about vitamin D production in, in that situation.
• 9:23
  So when it comes to the sun and avoided sun damage, the safest solution is
• 9:27
  to cover up and stay outta the sun.
• 9:29
  And of course, just take vitamin D supplements.
• 9:32
  Matt Edmundson: So speaking then of the, the supplements that,
• 9:35
  uh, we we're gonna be taking.
• 9:38
  I see it more and more, you know, fortification, fortified
• 9:41
  with vitamin D. Um, it seems to become a bigger and bigger thing.
• 9:44
  Right?
• 9:45
  Because I guess we've had to admit that our modern diets don't
• 9:49
  naturally provide enough vitamin D.
• 9:51
  Is that right?
• 9:52
  Jen Oliver: Yeah.
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  I mean, many countries fortify milk and cereals, but you know, often
• 9:57
  they still use vitamin D two because it's seen as the vegetarian option.
• 10:01
  Um, because vitamin D three is usually from animals, but at Vegetology we wanted
• 10:08
  an effective vitamin D three As D three is nearly 90% more effective than D two.
• 10:14
  Um, but we wanted a vegan source, so that's why we developed our plant source D
• 10:18
  three, which is one of our hero products.
• 10:21
  Chris Smith: Oh, it sure is.
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  And importantly, testing has shown that our plant source vitamin D three.
• 10:26
  Is directly equivalent to animal derived vitamin D three and just
• 10:29
  as bioavailable, which means it does just the same job in the body.
• 10:32
  The body basically can't tell the difference.
• 10:34
  Matt Edmundson: Okay, so the source then of our vitamin D supplementation,
• 10:38
  the D three, isn't as important as the molecular structure.
• 10:43
  Jen Oliver: Exactly.
• 10:44
  Plant derived, animal derived, or fish derived.
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  Vitamin D three is vitamin D three.
• 10:50
  The key point is looking for vitamin D three from your supplement or
• 10:53
  fortified food, not vitamin D two.
• 10:56
  Matt Edmundson: Okay, that's very useful.
• 10:58
  Uh, so let's get practical.
• 10:59
  How much vitamin D three do we need?
• 11:04
  Chris Smith: Yeah.
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  So this is frustrating because the figures are all over the place.
• 11:07
  Um, in Europe, we now use what's known as the nutrient reference value
• 11:10
  or NRV, which was previously the recommended daily amount, or RDA.
• 11:15
  And that is in Europe is 200 international units per day of vitamin D. However,
• 11:20
  many health institutes recommend more, they'll recommend 400 to 800
• 11:24
  international units per day of vitamin D with some arguing even more than that.
• 11:28
  So kind of 1000 to 2000 IU per day of vitamin D. So it really is all over the.
• 11:34
  Jen Oliver: And I guess the recommended intakes are so varied because they,
• 11:37
  they're in different places and they take into account average sun exposure,
• 11:41
  age skin tones, and medical factors that can impact vitamin D level.
• 11:45
  So it's a complicated picture.
• 11:48
  Matt Edmundson: Okay.
• 11:48
  So I guess the recommended daily amount, what did you call it?
• 11:52
  The NRV?
• 11:53
  I wish they'd just stick to one.
• 11:54
  It just,
• 11:55
  Jen Oliver: yeah,
• 11:55
  I
• 11:55
  know.
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  Chris Smith: I dunno what was wrong with RDA?
• 11:57
  Everyone knew Recommended daily amount.
• 11:58
  RDA.
• 11:59
  Matt Edmundson: Yeah.
• 11:59
  Makes sense.
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  Why change it?
• 12:00
  Why change it Europe?
• 12:01
  I have more questions for you, but that's one of them.
• 12:03
  So I guess if the amounts is varied, my question would be,
• 12:11
  can I take too much Vitamin D?
• 12:13
  Chris Smith: Yeah.
• 12:13
  So in Europe there is an established upper safe limit when it comes
• 12:17
  to vitamin D and it's 4,000 IU or international units per day.
• 12:22
  So that seems the maximum amount considered safer, ongoing
• 12:25
  and continuous daily intake.
• 12:27
  Matt Edmundson: Okay, so find a supplement then.
• 12:30
  Of course the next problem is remember to take that supplement, right?
• 12:34
  That can be the harder part.
• 12:35
  Like, you know, gym memberships are great, aren't they?
• 12:37
  They start well in January, but by March it's, it's not being used.
• 12:41
  And I guess vitamin D is one of those where it could just be a bottle gathering
• 12:46
  dust, uh, on the side of the counter.
• 12:49
  Jen Oliver: Yeah.
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  But the good news is.
• 12:51
  Vitamin D is fat soluble, so it's stored in your body.
• 12:54
  So you do have a little bit of a buffer, but I don't think you can rely
• 12:57
  on the summer sun, especially in the UK to carry you through the winter.
• 13:02
  Matt Edmundson: Fair enough.
• 13:02
  Okay, so we've talked about supplement centers a, a really sensible option,
• 13:07
  um, especially if we're thinking about sensibly staying out of the sun.
• 13:12
  What about food sources that can give us vitamin D.
• 13:17
  Chris Smith: Yeah, so food sources really are limited.
• 13:19
  So oily fish, egg yolk, and some meats contain a little vitamin
• 13:24
  D, but even then, the levels are hit and miss and sometimes zero.
• 13:27
  So it's challenging for everyone to get meaningful vitamin
• 13:30
  D levels from food alone.
• 13:31
  Especially, of course, vegans are vegetarians that
• 13:33
  won't consume those items.
• 13:35
  So plant sources in our diets are really limited in vitamin D levels.
• 13:39
  So really we're looking at either fortified foods or for
• 13:43
  most people, supplementation is the most reliable option.
• 13:46
  Matt Edmundson: Okay, and this for us is where plant source
• 13:49
  D three really matters, right?
• 13:50
  Jen Oliver: Yeah, absolutely.
• 13:51
  Especially for those that don't eat meat.
• 13:54
  Plant source Vitamin D three means that nobody needs to
• 13:56
  compromise either by missing out or using a less effective DD two.
• 14:02
  Chris Smith: Yeah.
• 14:02
  And it's worth pointing out that when you've got meats and dairy with vitamin
• 14:06
  D, they've often been fortified.
• 14:07
  So it's just the meat's taking a supplement rather than you,
• 14:12
  I
• 14:12
  Matt Edmundson: suppose that's what fortified means.
• 14:14
  Jen Oliver: Yeah, yeah, yeah, yeah.
• 14:15
  With added extras.
• 14:16
  Chris Smith: Well, going back to the, the sun, obviously it's very important
• 14:19
  for us, you know, sun exposure remains incredibly valuable for our health, but
• 14:23
  it shouldn't be our only strategy when it comes to vitamin D. Um, especially in
• 14:27
  those tima winter months, as I mentioned.
• 14:29
  You're just not gonna get enough intensity.
• 14:31
  Matt Edmundson: Yeah.
• 14:31
  So the best strategy, I guess is whatever you'll actually stick to, like exercise,
• 14:35
  just what can you do consistently?
• 14:37
  Right,
• 14:38
  Jen Oliver: exactly.
• 14:38
  Daily supplement, weekly high dose or fortified foods plus supplementation.
• 14:43
  You know, consistency beats perfection.
• 14:46
  Chris Smith: Yep, it's true.
• 14:47
  And um, if we look at how things connect, you've got sleep quality, for instance.
• 14:52
  So vitamin D receptors exist in the brain areas, regulated sleep,
• 14:56
  wake cycles, deficiency links to poor sleep and difficulty falling
• 15:00
  asleep and reduced deep sleep.
• 15:03
  Jen Oliver: And the immune connection affects both fighting
• 15:05
  infections, preventing autoimmune conditions where your body basically
• 15:09
  attacks its healthy tissue.
• 15:11
  Chris Smith: That's it.
• 15:12
  And if we go all the way back to muscle function that we talked about earlier.
• 15:15
  Deficiency means muscles can't work optimally.
• 15:17
  And that's regardless of the training that you do.
• 15:19
  Jen Oliver: Exactly.
• 15:20
  Fighting a handicap you might not know about.
• 15:22
  Chris Smith: Yeah.
• 15:23
  Yeah.
• 15:23
  So vitamin D functions as the ultimate regulator in our body.
• 15:26
  So it's constantly coordinating multiple biological systems, but these things
• 15:32
  have a huge impact on our health.
• 15:34
  Mm-hmm.
• 15:34
  So it is so important.
• 15:35
  Matt Edmundson: Yeah.
• 15:35
  And it explains.
• 15:37
  There's sort of the varied symptoms, doesn't it?
• 15:39
  Fatigue, muscle weakness, free frequent infections, mood changes.
• 15:44
  In effect, there are multiple systems we have running below capacity,
• 15:49
  Jen Oliver: and with nearly half the world's population deficient.
• 15:52
  This means that billions of people are at risk of conditions
• 15:55
  that could be prevented.
• 15:57
  Chris Smith: Yep.
• 15:57
  And when it comes to vitamin D, supplementation's, one of
• 16:00
  the most cost effective health interventions available anywhere.
• 16:04
  If I, I mean, let's be honest, I dunno.
• 16:06
  Anyone that works in the healthcare sector that doesn't take vitamin D supplements
• 16:09
  themselves and no one that, uh, would not push the importance of vitamin D.
• 16:13
  Jen Oliver: Mm-hmm.
• 16:14
  Matt Edmundson: And understanding the why helps prioritize it, isn't it?
• 16:17
  Because it's fair to say, traditionally the daily vitamin focus has always
• 16:22
  been on vitamins like vitamin C rather than vitamin D three.
• 16:27
  Jen Oliver: So why do we need vitamin D?
• 16:29
  Because it's a vitamin and a hormone that regulates over a thousand genes.
• 16:34
  It coordinates calcium absorption, it manages immune function, it helps
• 16:38
  maintain muscle strength and influences cellular processes throughout your body.
• 16:44
  Matt Edmundson: Yeah.
• 16:44
  And nearly half of us don't have enough of this master regulator,
• 16:51
  uh, but we keep calling it a vitamin, like it's just another
• 16:55
  supplement when actually maybe it's.
• 16:58
  I don't know.
• 16:58
  Conducting your cellular orchestra.
• 17:02
  Chris Smith: Cellular orchestra.
• 17:03
  I like that.
• 17:03
  That's one I've never heard before.
• 17:04
  Matt Edmundson: Yeah, I'm, I'm trademarking it.
• 17:06
  I just want you to know,
• 17:08
  Jen Oliver: so that's why we need vitamin D. Checking levels and supplementing
• 17:13
  when's needed isn't optional.
• 17:15
  It's actually essential.
• 17:17
  That's it for this week.
• 17:18
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• 17:19
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• 17:26
  Thanks for geeking out with us.
• 17:27
  That's it from me.
• 17:29
  Matt Edmundson: That's it
• 17:29
  Chris Smith: from me.
• 17:30
  Matt Edmundson: And that's it from me.
• 17:31
  Jen Oliver: Bye for now.