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  • Salt, Sodium, & Health


    Hi,

    A while ago, I listened to a Sigma Nutrition Podcast on the impact of sodium on health (here: https://sigmanutrition.com/episode375/) which involved a few key points that I think should be brought up, seeing as I believe there is some BBM content/forum posts of yours’ that potentially contradict their conclusions.

    (sorry for long post in advance, could've formatted/edited it better to be more readable)

    In the podcast, they discuss:
    • How the data that has reported a “J” or “U” shaped curve in cardiometabolic risk when it comes to sodium intake is confounded with sodium collection methods (single 24 hour or spot urine sample) that do not take into account the interpersonal, day to day, high fluctuation of sodium intake and output with long term follow-up. The result of these single measures is the J-shaped curve.
      • To go in more depth, in Flanagan’s words “the effect of single measures appears to be to underestimate sodium intake, therefore overestimating the risk at “low” levels of intake... even if there were questions over the exact reason, the reality is that no study using multiple measures has demonstrated the J-shaped curve, but consistently demonstrate a more linear relationship. Repeated measures are always preferable in nutritional epidemiology, so I’m not sure why some are happy to reconcile the discrepancy in the literature in favour of the less robust measure. Finally, the limited data that we do have from multiple measurement studies with mortality as an outcome also suggests a linear relationship with events/mortality. For all these reasons, we find it difficult to reconcile the current literature other than in favour of the data from multiple measurements.” (taken from the comments section of the podcast).
    • They suggest that the data using more rigorous collection methods (Multiyear 24-Hour Urine Collection) have not demonstrated the J-shaped curved, or a low intake associated with risk, but a linear increase in risk.
    • They also touch on how both hyper and normotensive individuals should potentially be aware of salt intake (especially if processed food intake is high), due to reliable decreases in BP when following a low sodium diet (though the magnitude of effect is stronger in hypertensive individuals).
    • As well, in an Instagram post https://www.instagram.com/p/CE_nzcWnAKr/ , Flanagan also pulled up research (Filippou et al) on how the magnitude of effect included DASH interventions for CVD “was similar in normotensive as hypertensive participants.”
    • In the podcast, they suggest the 2300-2500mg sodium (<5g salt) WHO recommendation for both hyper and normotensive individuals was well substantiated when you really only consider the studies with more rigorous collection methods (which somewhat goes against your article here: https://www.barbellmedicine.com/blog/4196-2/ and forum post here: https://forum.barbellmedicine.com/fo...y-about-sodium ) .
    • In conclusion, I think these are my takeaways along with a few practical/clarifying questions:
      • Higher sodium intakes, from what I’ve seen from Sigma and Flanagan specifically, seem to me to be an independent risk factor for CVD/cardiorenal outcomes. Now, even with believing this, I don’t think (nor do I think the Sigma guys think) that monitoring sodium intake is as important for health outcomes as other health promoting behaviors and if no pre existing conditions (obesity, high BP, diabetes, etc) are present (especially for those who do not consume a lot of processed food). I say this because I know they are mostly talking about the general population, which may not include some of the conditions I list later below about myself and what I should pay attention to in terms of sodium intake.
        • However, that kinda leaves me with a practical question. I recently went vegan, and didn’t really realize how full of sodium a lot of meat replacements are. Even the ones that have relatively high protein and lower fat have a lot of salt in them. Of course, they are processed. Very processed. But after a few weeks of being vegan, having a non-boring (to me that means that some processed meat products are present, not just beans/lentils/soy) decently high protein vegan diet with a low amount of sodium is hard. Really hard. Soy sauce, sauces, and then added salt could get me up to 3g sodium alone in a day. Then having even a small to modest portion of processed fake meat could get that up to 4-5 grams, making the average intake quite high. Thing is, I’ve checked my BP, and it’s normal, and not “high normal”. Sometimes slightly below (not even sub-clinical) normal, with a normal BMI (20) and waist circumference <30 as a male, who regularly engages in physical activity. But on the average day, my salt intake can get fairly high. Leaves me to final questions:
          • Has any of your mind been changed on this? I know even if it was, this isn’t like 7 Priorities for Health level, but still. Any takeaway?
          • If it has been, should I (someone who is active, healthy, young, and engages in other health promoting behaviors) actively care about sodium intake considering my average intake can get quite high? As well, where does processed food fit into this? Are there unique harms from processed food, and what are they if so? Outside of hyper palatability/energy density/potential to displace more “health promoting” foods, considering someone could theoretically have a high intake of processed foods while having an otherwise healthy diet/behaviors.

    As always, if I misrepresented anything you claimed, or any piece of data, or took something out of context and/or are missing something, feel free to correct me. I think this is an interesting area of discussion that is worth looking into nonetheless, but I hope I represented the ideas as well as I could being the layman that I am lol.


    Thanks


    They mention these studies on the podcast:
    1. Engberink et al., 2017 - Use of a Single Baseline Versus Multiyear 24-Hour Urine Collection for Estimation of Long-Term Sodium Intake and Associated Cardiovascular and Renal Risk
    2. Intersalt, 1988 - an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion
    3. Cook et al., 2014 - Lower levels of sodium intake and reduced cardiovascular risk
    4. Graudal et al., 2014 - Compared with usual sodium intake, low- and excessive-sodium diets are associated with increased mortality: a meta-analysis
    5. Mente et al., 2016 - Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies

  • #2
    Originally posted by WhatYouExpect View Post
    [*]Has any of your mind been changed on this? I know even if it was, this isn’t like 7 Priorities for Health level, but still. Any takeaway?
    It definitely has, along with some nuance Chalk it up to new data, better analyses, etc.

    In general, I do think it's a good idea to stick to the current guidelines for sodium intake (e.g. <2300mg/d) with the best ways of manipulating that are probably via Calorie intake (higher Cals= higher sodium) and limiting processed foods.

    The problems arise when we look for recommendations for highly active individuals, athletes, and those with relatively high Calorie intakes needed to support their current body mass (assuming that is healthy). I still think avoiding highly processed foods is a solid behavior for following a health-promoting dietary pattern. However, individuals with higher Cal needs may not be able to do this or even need to do this from a health perspective. I would still look at having a high intake of fiber from fruits, vegetables, whole grains, limiting saturated fat intake, etc., but the total sodium intake may be higher than the 2300mg/d in large individuals and likely NEEDS to be higher in athletes.

    When we talk about athletes training and/or competing in warm climates, a lot of the sodium data for general health is not applicable. While mild, self-limited and clinically irrelevant hyponatremia often occurs post workout, individuals who train for very long durations and/or in very warm climates and/or who lose lots of sodium have higher sodium needs. That said, most people don't train/compete like this either so....*shoulder shrug emoji

    I think most folks should aim to consume a health-promoting dietary pattern first and foremost, as that will likely get daily sodium levels within range. If someone has elevated or high blood pressure, it may benefit that individual to restrict sodium further. If someone is a competitive athlete, they likely have additional sodium considerations.
    Barbell Medicine "With you from bench to bedside"
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    • #3
      Is there any truth to the claim that the negative health consequences of a high sodium intake can be reduced by a high potassium intake?

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      • #4
        Originally posted by 4l3x View Post
        Is there any truth to the claim that the negative health consequences of a high sodium intake can be reduced by a high potassium intake?
        If we are talking about sodium intakes far in excess of the guidelines, it doesn't really seem like it. If individuals who were close to the guidelines also consumed more potassium in their diet, there's a short-term blood pressure lowering effect. This is sometimes seen with potassium supplements (we would not recommend this btw).

        The long-term effects of increasing dietary potassium come from the dietary pattern changes (e.g. more fruits and vegetables) , which tends to reduce sodium and increase potassium intake
        Barbell Medicine "With you from bench to bedside"
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        • sjalbrec
          sjalbrec commented
          Editing a comment
          Hi, you don't recommend "taking excess salt and consuming more potassium to counter" or you don't recommend "any potassium supplements"? Is there a real-world positive cost-benefit of taking potassium supplements to reduce cramping?

      • #5
        Hi, you don't recommend "taking excess salt and consuming more potassium to counter" or you don't recommend "any potassium supplements"? Is there a real-world positive cost-benefit of taking potassium supplements to reduce cramping?
        I don't recommend either and no, they don't reduce cramps or improve performance reliably.
        Barbell Medicine "With you from bench to bedside"
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        • #6
          What's difficult to suss out in these large observational studies (or even studies with an interventional component, i.e. a reduced salt diet) is whether or not sodium is simply a proxy for poor food choices, as higher sodium intake is most often associated with higher processed food intake, particularly processed food in the form of refined carbohydrates plus vegetable oils: fast food, chips, and other things that are both not nutrient dense and are easy to over-consume. To my knowledge there are no robust RCTs on this topic (it would be difficult to design, admittedly), and the interventional studies available do not contain control groups that sufficiently account for various testing and adherence effects. I'm aware that there are proposed mechanistic explanations, but considering how often these are speculative in biology, I'm skeptical as to their explanatory power.

          It's the problem with the baseline being the Standard American Diet and little data being available on healthy and athletic populations, as Dr. Feigenbaum points out. Is it the relatively modest decrease in blood pressure that accounts for improvements? Is it a proxy for poor eating? What kind of interactive effects are there regarding various dietary strategies (keto adherents seem to need more salt)? What happens when your dietary strategy deviates from the norm? I'm not sure there's robust evidence to suggest that sodium intake within a certain threshold is an independent risk factor for CVD, but I'm happy to be wrong.

          We run into this with saturated fat. There is evidence that saturated fat increases risk of CVD, but it is mostly associative and the baseline is again the SAD. In at least some individuals some of the time, a high saturated fat diet in the absence of various other foods (high doses of vegetable oils and refined carbohydrates) does not increase the biomarkers reliably predictive of CVD.

          Personally, I've found I seem to need a lot more salt eating less carbs. I had pretty substantial leg cramps at night for months until I started supplementing extra salt in the evening, after which leg cramps disappeared. Potassium and magnesium supplementation did nothing to alleviate this and there is a direct relationship between how much I sweat during the day, the amount of carbohydrates I've consumed and how much salt I seem to need to intake. Still haven't figured out if that's a bad thing or not.

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          • #7
            Originally posted by RVR View Post
            What's difficult to suss out in these large observational studies (or even studies with an interventional component, i.e. a reduced salt diet) is whether or not sodium is simply a proxy for poor food choices, as higher sodium intake is most often associated with higher processed food intake, particularly processed food in the form of refined carbohydrates plus vegetable oils: fast food, chips, and other things that are both not nutrient dense and are easy to over-consume. To my knowledge there are no robust RCTs on this topic (it would be difficult to design, admittedly), and the interventional studies available do not contain control groups that sufficiently account for various testing and adherence effects. I'm aware that there are proposed mechanistic explanations, but considering how often these are speculative in biology, I'm skeptical as to their explanatory power.
            This (and the post) is not correct and, similar to the reply on vitamin D/sun/sunscreen, lengthy and with misinformation. For more on the "gold standard RCT'" trope, see this series and other articles cited here.


            Originally posted by RVR View Post
            It's the problem with the baseline being the Standard American Diet and little data being available on healthy and athletic populations, as Dr. Feigenbaum points out.
            This is incorrect. The majority of Americans do not eat the recommended diet, which includes sodium guidelines. When looking at this issue, the comparator groups can vary depending on the clinical question. Still, there may be some generalizability issues with larger individuals and/or athletes for the current sodium guidelines.

            Originally posted by RVR View Post
            Is it the relatively modest decrease in blood pressure that accounts for improvements?
            This is a known ASCVD risk factor, so yes.


            Originally posted by RVR View Post
            I'm not sure there's robust evidence to suggest that sodium intake within a certain threshold is an independent risk factor for CVD, but I'm happy to be wrong.
            Yes, this is incorrect.

            https://pubmed.ncbi.nlm.nih.gov/1583626/
            https://pubmed.ncbi.nlm.nih.gov/28655835/
            https://pubmed.ncbi.nlm.nih.gov/24415713/
            https://www.bmj.com/content/369/bmj.m2440
            https://pubmed.ncbi.nlm.nih.gov/19139321/


            Originally posted by RVR View Post
            We run into this with saturated fat.
            No, we don't, unless someone is unfamiliar with the actual evidence. This is well-described here.

            Originally posted by RVR View Post
            Personally, I've found I seem to need a lot more salt eating less carbs. I had pretty substantial leg cramps at night for months until I started supplementing extra salt in the evening, after which leg cramps disappeared. Potassium and magnesium supplementation did nothing to alleviate this

            Cramps from exercise are unrelated to any of these electrolytes.



            Barbell Medicine "With you from bench to bedside"
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