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Why the 'reduce your salt intake' message is way too simple: Wisdom Wednesdays · Hardiness with Dr Paul Taylor

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  Speaker 1: Everyone, Welcome to another edition of Wisdom Wednesdays. Today, I
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  Speaker 1: want to revisit something that I've talked about before, which
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  Speaker 1: is sodium and potassium and the impact on blood pressure
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  Speaker 1: and stroke risk. But the reason I'm coming back to
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  Speaker 1: it is that I think the message around this is
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  Speaker 1: far too simplistic, and there's some interesting new research that
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  Speaker 1: I've discovered that adds a fur bit and nuance. So
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  Speaker 1: most people have heard the message that we need to
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  Speaker 1: cut our salt, reduce sodium in order to low blood pressure,
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  Speaker 1: reduce our risk of heart disease and stroke. And it's
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  Speaker 1: not wrong. There is good evidence that reducing sodium can
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  Speaker 1: reduce blood pressure, especially in people who have high blood pressure.
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  Speaker 1: But what gets talked about far less is the other
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  Speaker 1: side of the equation, which is potassium. And the reason
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  Speaker 1: this is important is that sodium and potassium work together. Now,
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  Speaker 1: Stodium acts mainly outside the sale and potassium is mainly
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  Speaker 1: inside the sale. They're both electrolytes, as you probably know,
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  Speaker 1: they're both essential. They both affect fluid balanced nerve transmission,
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  Speaker 1: muscle contraction, kidney function, and blood pressure and therefore heart
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  Speaker 1: disease and stroke risk. And so when we talk only
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  Speaker 1: about sodium and we don't talk about potassium. We do
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  Speaker 1: miss a really important part of the story. So let's
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  Speaker 1: zoom into one specific paper because it's really useful for understanding.
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  Speaker 1: And it was published in a British medical journal and
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  Speaker 1: the title of it was Effective Increased Potassium Intake on
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  Speaker 1: Cardiovascar Risk Factors and Disease Systematic Review and meta Analysis.
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  Speaker 1: So this was commissioned by the World Health Organization and
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  Speaker 1: then form part of the evidence base for the World
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  Speaker 1: Health Organization when developing tassium intake guidance. And the review
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  Speaker 1: concluded that increasing potassium reduced blood pressure in people with
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  Speaker 1: hypertension and had no significant adverse effect on blood lipids,
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  Speaker 1: on adrenaline, lower adrenaline, kidney function, and adults, and higher
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  Speaker 1: potassium intake was associated with a twenty four percent lower
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  Speaker 1: risk of stroke, which is pretty bloody impressive. So and
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  Speaker 1: this was a meta analysis, as I said, and they
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  Speaker 1: pulled and together all the available evidence from multiple studies,
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  Speaker 1: and for blood pressure and cardiovascular risk factors, they looked
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  Speaker 1: at randomized control trials and for other cardiovascar outcomes such
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  Speaker 1: as stroke, they also looked at cohort studies where they
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  Speaker 1: just observed people for a while. Now, the key blood
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  Speaker 1: pressure analysis included twenty two randomized control trials with over
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  Speaker 1: sixteen hundred adult participants, and the intervention was increased potassium intake,
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  Speaker 1: generally through supplements and datary strategies. And they looked at
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  Speaker 1: what happened to both systolic and diastolic blood pressure. And importantly,
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  Speaker 1: they separated people with hypertension from people with normal blood
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  Speaker 1: pressure because they're not the same biological group. And this
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  Speaker 1: is why the results get very interesting. Across adults with
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  Speaker 1: high blood pressure, increasing potassium lowered systolic blood pressure by
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  Speaker 1: about three and a half millimeters in mercury. Now, i
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  Speaker 1: might not sound like a lot, but at a population level,
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  Speaker 1: that reduction three to four millimeters from mercury is actually
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  Speaker 1: pretty meaningful. But in the subgroup of trials where potassium
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  Speaker 1: intake reached roughly three and a half to four point
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  Speaker 1: seven grams a day, the average drop in systolic blood
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  Speaker 1: pressure was much bigger. It was about seven point two
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  Speaker 1: millimeters of mercury. And that is pretty bloody significant. It's
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  Speaker 1: about the same effect that you would see from somebody
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  Speaker 1: taking medicare. Now here's the caveat and it's pretty important.
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  Speaker 1: The benefit was seen in people with high blood pressure
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  Speaker 1: those who had normal blood pressure, that blood pressure change reduced,
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  Speaker 1: but it wasn't statistically significant, so it's not a case
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  Speaker 1: of more potassium drops everybody's blood pressure if they affect.
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  Speaker 1: Seems to be present when blood pressure is elevated, which
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  Speaker 1: is what we're after, and the guideline for the who
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  Speaker 1: that came out of it is careful. On this point.
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  Speaker 1: It notes that increasing potassium reduce both types of blood
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  Speaker 1: pressure and adults, systolic and datastolic, and that the higher
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  Speaker 1: potassium intake was also associated with reduced stroke incidents, and
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  Speaker 1: the World Health Organization therefore recommends increasing potassium from food
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  Speaker 1: to reduce blood pressure and cardiovascar risk and adults, and
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  Speaker 1: suggests that we should be aiming for at least three
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  Speaker 1: five hundred milligrams per day or three and a half
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  Speaker 1: grams of potassium per day for adults. And I stay
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  Speaker 1: to the end and I'll tell you how to do that.
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  Speaker 1: I think it is important that we dive into the
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  Speaker 1: mechanisms because it's interesting. Well it is if you're a
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  Speaker 1: geek like meat. Now, potassium helps blood pressure through a
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  Speaker 1: few different pathways. The first, and through your kidney. Your
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  Speaker 1: kidney's constantly deciding how much sodium to hold on to
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  Speaker 1: and how much sodium to excrete, and one key sodium
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  Speaker 1: reabsorbing transporter is called the sodium chloride co transporter or NCC.
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  Speaker 1: My potassium intake influences this system. When potassium intake is higher,
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  Speaker 1: the kidney tends to excrete more sodium. So when plain English,
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  Speaker 1: potassium helps your body to get rid of sodium. And
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  Speaker 1: that matters because sodium retention increases extrastrallular fluid volume and
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  Speaker 1: more fluid and that vascular system can increase your blood pressure,
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  Speaker 1: and that's why often people will be put on a diuretic.
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  Speaker 1: But potassium is doing the same thing. The second mechanism
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  Speaker 1: is more vascular, so potassium directly affects your smooth muscles
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  Speaker 1: of your vascular system, the muscle layer in the artery wall.
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  Speaker 1: And when potassium channels open, this smooth muscle sale becomes
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  Speaker 1: more hyper polarized, which means it's less likely to contract,
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  Speaker 1: and less contraction means lower vascular tone. That means lower
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  Speaker 1: peripheral resistance. And blood pressure, especially systolic blood pressure, is
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  Speaker 1: heavily influenced by vascular resistance, So potassium is doing two
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  Speaker 1: things at once. It helps the kidney to handle sodium
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  Speaker 1: and helps the blood vessels to relax. Now this is
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  Speaker 1: where the sodium story becomes a little bit more nuanced.
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  Speaker 1: There is strong evidence that sodium reduction lowers blood pressure
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  Speaker 1: on averach, especially in people who have high blood pressure,
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  Speaker 1: and a World Health organized in summary of a Cochrane
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  Speaker 1: review founded across one hundred and eighty five randomized control trials,
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  Speaker 1: lower sodium diets significantly reduce blood pressure in hypertensive patients,
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  Speaker 1: including Caucasian, Black, and Asian groups, with larger reductions in
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  Speaker 1: hypertensive Black and Asian populations, But in normal people with
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  Speaker 1: normal blood pressure the effects were smaller and more variable,
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  Speaker 1: and for instance, in Asians who had normal blood pressure,
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  Speaker 1: that reduction was not statistically significant. So when people say
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  Speaker 1: salt reduction lowers blood pressure, it's broadly true, but it's
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  Speaker 1: not true for everybody. And there is a genetic component
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  Speaker 1: to this, and this is about salt sensitivity of blood pressure.
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  Speaker 1: Some people are salt sensitive, meaning their blood pressure rises
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  Speaker 1: more when they consume more sodium and falls more when
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  Speaker 1: they don't, or when they reduce their sodium other people
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  Speaker 1: are more salt resistant, and I know that that's me
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  Speaker 1: from the gene panel that I have done. I'm not
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  Speaker 1: salt sensitive, and that means that my blood pressure is
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  Speaker 1: not massively affected by changes in sodium. Now, the differences
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  Speaker 1: involve the kidney, blood vessels, your sympathetic nervous system, inflammation,
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  Speaker 1: the renon and just stein and aldosterone system, age, ethnicity,
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  Speaker 1: incident resistance, kidney functioning, and genetics. So it is really
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  Speaker 1: really complicated, and we know that a number of genes
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  Speaker 1: are involved, but they're not completely deterministic. It's more that
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  Speaker 1: the genes can influence how your kidney and blood vessels
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  Speaker 1: actually respond to sodium. And that's why this blanket advice
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  Speaker 1: is a little bit clumsy. Because some people respond really
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  Speaker 1: well to more exercise. Other people exercise does nothing for
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  Speaker 1: their blood pressure. Some people reducing salt is great, other
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  Speaker 1: people reducing salt doesn't do very much at all. And
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  Speaker 1: this is the point here that if you are a
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  Speaker 1: salt sense of Indie with high blood pressure, then going
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  Speaker 1: on to a low sodium diet can be really really useful.
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  Speaker 1: But for a young lan physically active person who sweats
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  Speaker 1: a lot, it's mostly real food and has normal blood pressure,
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  Speaker 1: and reducing sodium is really not helpful and can actually
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  Speaker 1: be damaging. Sodium is not a toxin. It is essential.
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  Speaker 1: We need it for nerve transmission, muscle contraction, fluid balance,
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  Speaker 1: blood volume, and maintenance of normal cellular function. And so
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  Speaker 1: the problem generally is not sodium in the existing diet
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  Speaker 1: or a normal human diet. The problem is the massive.
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  Speaker 2: Increase in ultraprocessed foods and the huge amounts of sodium
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  Speaker 2: and low potassium that's in ultra processed foods, because real
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  Speaker 2: foods tend to have a balance, whereas ultra processed foods
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  Speaker 2: way more sodium, way less potassium, and then that balance
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  Speaker 2: really gets out of whack.
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  Speaker 1: And this is the modern problem. It's not someone putting
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  Speaker 1: a bit of salt on a home cooked meal. The
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  Speaker 1: bigger issue is the sodium of the salt that's built
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  Speaker 1: into bread sauces, processed meats, packaged snacks, takeaway foods, frozen meals,
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  Speaker 1: and all the other ultra processed stuff. And sodium is
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  Speaker 1: in name in large amounts because sodium and access to
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  Speaker 1: preservative as well as as a taste enhancer, right, and
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  Speaker 1: so there can be downsides to very low sodium intake,
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  Speaker 1: particularly if it's an aggressive thing. Cocker and View you
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  Speaker 1: found that sodium reduction increases plasma renin, aldostone, adrenaline, no adrenaline, cholesterol,
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  Speaker 1: and triglycerides, and the authors noted that these potential adverse
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  Speaker 1: effects may mean that sodium reduction does not have a
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  Speaker 1: net beneficial effect in some page right, And there's also
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  Speaker 1: evidence that low saltdats can worsen insulin resistance in some
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  Speaker 1: settings and increase your diabetes risk. So again this nuance matters. Now,
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  Speaker 1: if you have high blood pressure and you are salt sensitive,
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  Speaker 1: sodium reduction is definitely a useful layer, but it's not
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  Speaker 1: something we want to drive to zero. And in people
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  Speaker 1: who exercise a lot, sweat a lot, and have generally
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  Speaker 1: low carb dits use saunas this is my kind of category,
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  Speaker 1: and have low blood pressure and restricting sodium can actually
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  Speaker 1: be quite dangerous. Now let's come back to potassium to
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  Speaker 1: finish this off. So the intake gap between what we
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  Speaker 1: normally eat and what is suggested it is actually pretty big.
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  Speaker 1: So recommended potassium intake for adult men is about three
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  Speaker 1: and four hundred milligrams per day, almost three and a
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  Speaker 1: half grams and for women adult women's twenty six hundred
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  Speaker 1: milligrams per day. And now data for the National Institute
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  Speaker 1: of Healthy United States shows that average adults intakes are
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  Speaker 1: about are about ten percent lower than they should be
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  Speaker 1: for both men and women, and the wto target is
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  Speaker 1: that it's actually a little bit higher. It's three and
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  Speaker 1: five hundred milligrams per day. So how do we fix it? Generally,
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  Speaker 1: not potassium pills and not potassium salt substitutes, because salt,
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  Speaker 1: the salt substitute can can contain up to three thousand
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  Speaker 1: milligrams per taste bound and that can be dangerous with
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  Speaker 1: people with chronic kidney disease or those taking certain medications.
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  Speaker 1: As always, the message is food first, and it's actually
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  Speaker 1: pretty easy to get there. A medium banana will give
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  Speaker 1: you about just over four hundred milligrams, a potassium cup
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  Speaker 1: of cooked lentils about seven hundred, half a cup of
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  Speaker 1: dry apricots about over seven hundred, and medium baked potato
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  Speaker 1: about six hundred milligrams, and that's the flesh only, and
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  Speaker 1: more if you include the skin, which you should be
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  Speaker 1: As an irishman, I'm telling you should eat the skin
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  Speaker 1: of potatoes. A couple of kidney beans about six hundred milligrams,
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  Speaker 1: a cup of milk about three hundred and sixty a
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  Speaker 1: serving of salmon about three hundred and thirty milligrams. And
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  Speaker 1: you also get it in chicken, beef, yogurt, tomatoes, spinach, squash,
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  Speaker 1: soy beans, and even a little bit in coffee as well.
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  Speaker 1: So if you're eating a very dad of whole foods
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  Speaker 1: the low heats eye dit that I talk about, you
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  Speaker 1: probably don't need to supplement with potassium. You know. Can
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  Speaker 1: you have a potato with your dinner or lentils and
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  Speaker 1: beans and Launcher have yogurt and fruit. I have spinach
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  Speaker 1: with eggs and have salmon a couple of times a week,
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  Speaker 1: which should probably be doing anyway. But really it's about
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  Speaker 1: reducing our ultra processed foods and eating more real foods.
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  Speaker 1: It's another reason to do this because the sodya potassium
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  Speaker 1: ratio proves dramatically when you move away from ultra processed
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  Speaker 1: foods towards real foods. And not only that, but you
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  Speaker 1: don't get all the other health risks associated with ultra
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  Speaker 1: processed foods. So hopefully that adds a little bit of
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  Speaker 1: nuance to this whole idea about salt and blood pressure.
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  Speaker 1: The key takeaway is really reducing your amounts of ultra
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  Speaker 1: processed foods in your diet and eating more real foods,
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  Speaker 1: particularly the ones that I talked about that are highest
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  Speaker 1: in potassium, because that will really balance you out in
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  Speaker 1: terms of blood pressure and cryovascular risk. So that's it
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  Speaker 1: for this week, folks, Catch you next time.