Value of Salt Reduction Supported by Four Studies

For a long time, researchers have found links between high sodium intake and higher blood pressure, and between higher blood pressure and increased risk of stroke. At the same time, critics, including Gary Taubes, have argued that the data do not support the idea that most people should reduce their salt intake.

New evidence suggests the critics were wrong. Four different studies support the idea that high amounts of salt intake are generally bad.

One study recently appeared in BMJ Open.  “The UK initiated a nationwide salt reduction programme in 2003/2004. The programme has been successful and resulted in a 15% reduction in population salt intake by 2011,” write the authors. That might not seem like much but the reduction was in the salt in processed foods, which for most people is most of their salt intake. The more processed food you ate — and the more extreme your salt intake — the greater the reduction.

The main finding of the study was that over the same period, there was a large and steady decrease in both blood pressure and strokes in the UK. Mortality from stroke and ischemic heart disease (IHD) went down by 40%!

There were small changes in other environmental variables over the same period: people ate slightly more fruit and vegetables, weighed slightly more, smoked somewhat less, and so on. Maybe these other changes were what led one critic to dismiss the results in a New York Times article:

Dr. Niels Graudal, a senior consultant in the department of internal medicine at Copenhagen University Hospital, said that connecting the two events “is meaningless.”

“This paper describes two independent incidents,” he added. “That these incidents should be in any way connected is absolutely unlikely.”

Consistent with the low quality of science journalism in the New York Times, it seems the reporter, Nicholas Balakar, did not ask Dr. Graudel any hard questions — for example, for an alternative explanation of the decline.

The BMJ study did a poor job of determining the a priori likelihood of such a big decline. It could have looked at year by year changes in stroke and IHD mortality before 2003, for example. Was stroke and IHD mortality rising or falling? It could have looked at changes in stroke and IHD mortality in similar countries without a salt reduction program over the same period. Such comparisons would have helped a lot. But the BMJ study did report the results of other nationwide salt reduction programs.

Japan, in the late 1960s, carried out a government-led campaign to reduce salt intake. Over the following decade, salt intake was reduced, particularly in northern areas from 18 to 14 g/day. Paralleling this reduction in salt intake, there were falls in BP and an 80% reduction in stroke mortality in spite of large increases in fat intake, cigarette smoking, alcohol consumption and obesity which occurred during that period. Finland, in the late 1970s, initiated a systematic approach to reducing salt intake through mass media-campaigns, co-operation with the food industry and implementing salt labelling legislation. This led to a significant reduction in the average salt intake of the Finnish population from ≈14 g/day in 1972 to less than 9 g/day in 2002. The reduction in salt intake was accompanied by a fall of over 10 mm Hg in systolic and diastolic BP and a decrease of 75–80% in stroke and IHD mortality.

Again, reductions in salt intake happened just before huge decreases in stroke and IHD mortality. It is the triple repetition of an unlikely event (big reductions in mortality) and the experimental aspect (something was specifically changed) that convince me. The critics are not going to come up with a plausible alternative explanation of all three cases (UK, Japan, Finland) any time soon.

A paper co-authored by the same Dr. Graudal who dismissed the new findings found that high sodium intake was associated with increased mortality. It also found that low sodium intake was associated with increased mortality. This is why a reduction in the salt in processed food makes so much sense: 1. It’s easy. You don’t have to do anything. 2. It reduces salt intake the most in people who eat the most salt — exactly where it is likely to be the most beneficial.

Just to be clear, this data also says that if you don’t eat a lot of salt, there is no good reason to reduce your salt intake (unless you have high blood pressure).

26 Replies to “Value of Salt Reduction Supported by Four Studies”

  1. The big confounder here is processed food…

    As Gary Taubes says, “MOST” people do not need to reduce their salt intake. And, I would add, “MOST” people need to reduce their processed food intake.

  2. The Japanese decreased their salt intake from 18 *grams* to 14 grams/day? That’s a huge amount of salt! In the linked article from Adam (in the comments), Graudal says that the safest intake is between 2,645 and 4,945 mg. Maybe the opponents don’t really disagree after all?

  3. I think in most cases, not all for all people, very salty food is self limiting.

    The problem with the salt content of highly processed foods, or at least one of the many, is that it is right in the “salty enough” zone, so it is not self limiting, which is certainly not the goal of food manufacturers. And, it’s pervasive, just like soy, wheat, sugar, corn (starch & HFCS) and other un-spellable / un-pronounceable ingredients.

    1. “The problem with the salt content of highly processed foods, or at least one of the many, is that it is right in the “salty enough” zone.”

      The amount of saltiness you think is “just right” depends on your salt intake. When your salt intake is higher, you want more salt in your food. Presumably this was a long-ago adaptation to salt scarcity. When salt was abundant, you wanted more of it — just like the theory behind the Shangri-La Diet. (When calories are abundant, you want more.)

      This means that the salt in processed foods has two effects: it increases the salt in your blood; and it increases how much salt you want in the next food you eat. This is another reason that simply reducing the salt in high-salt foods is worth trying — because it has two effects.

  4. I’m a 54 year old woman 5’6″. On the sad diet I weighed 175 lbs and BP was creeping up to slightly above normal. Fast forward 4 years Paleo style diet 135 lbs and BP low. Sometimes 80 over 60. I now make sure I get enough salt daily. I put some salt in my water and liberally salt my food. That upped my BP to 115 over 75. I also don’t drink water excessively as I can tell it depletes my sodium. When you switch to a real food diet you need to seek out salt.

  5. Could iodine be playing a role in this? I don’t know if the salt in processed food is regular, iodized salt or what’s in salty Japanese food.

    I know that some people who go on low-sodium diets get into trouble with iodine deficiency, just like people who use non-iodized sea salt. But, like most things, too much iodine is trouble.

  6. Dr. David Brownstein has been advising his patients to *supplement* unrefined salt for years and has found no increase in BP and substantial health improvements. He has written a book about salt and health based on his clinical experience.

    Unrefined (real) salt may be very different in its biological effects than refined salt. And the observational epidemiology cited here is not, to me, convincing. Beyond the obvious confounder of salt correlating with processed food, there are doubtless many others. Very easy to draw the conclusion you expect or want when establishing real causality would require far more rigorous methods. If you believe this kind of epidemiology then why not listen to the Harvard School of Public Health and avoid animal fats?

    Also, the effect sizes cited here strain credibility. How could a 10 point drop in BP explain an 80% decrease in stroke and heart disease mortality? Other things are going on, and I don’t think anyone really knows what they are.

    1. “How could a 10 point drop in BP explain an 80% decrease in stroke and heart disease mortality? Other things are going on, and I don’t think anyone really knows what they are.”

      The big decrease is plausible because it is only extremes of salt intake that are dangerous — that is, it isn’t linear — and the decrease was greater among people who ate a lot of salt.

      “Other things are going on.” If you have an alternative explanation of the UK, Finland and Japan results, what is it? A vague claim of “other things” is no help.

  7. “Other things are going on, and I don’t think anyone really knows what they are.”

    I agree. Too many moving parts.

    “Dr. David Brownstein has been advising his patients to *supplement* unrefined salt for years”

    Yes, and Light Grey Celtic sea salt in particular. Far more minerals. Plus, it tastes great! I can’t stand the taste of refined salt anymore.

  8. 14 grams of salt was normal in those places!?

    I got a lot of benefit from deliberately increasing my sodium intake to 4 grams and that tastes like a lot to me. I can’t imagine how people were managing to get down so much more in Finland and Japan.

  9. “Other things are going on.” If you have an alternative explanation of the UK, Finland and Japan results, what is it? A vague claim of “other things” is no help.”

    Stupendous intellectual error. I can perceive an error in your logic without having to come up with an explanation of my own.

    As a piece of logic this is terrible (really shockingly so), as a piece of psychology this is one of the best things I’ve seen in a long time. It’s very hard for the human mind to simply admit ignorance and suspend judgement. People would rather believe a bad theory that has little supporting evidence than simply say “I don’t know”.

    The human incapacity to simply say “I don’t know” when there is insufficient evidence is probably responsible for most of the silliness that passes as nutritional advice these days and does grave harm to our prospects for ever figuring out true causes. If you simply can’t suspend judgement until good evidence shows up and feel irresistibly compelled to adopt the first vaguely plausible theory, you are unlikely to persevere in getting at the true cause.

  10. Ah George, loosen up!

    Seth provides us with ” brain morning faces” and I’d be a tad lost without his and others’ reactions and anecdotes.

    I’ve spent 20 years at morning teas with academics and my old dept head would say something like this to goad somebody to go spend the week after hours reading up on the literature to create more outrageous discourse at morning tea the following week- might even lead to a paper or two for the dept.

  11. The sinister movement to demonize salt and destroy the health of the world’s population has been in full swing for a while now. By getting people to believe that salt is bad, and to limit salt, the agenda for population control thrives. Wars have been fought just to obtain salt. Gandhi led the native people of India in a walk to the sea to make their own salt from saltwater, to protest the British governments monopoly on salt.

    The body needs salt to retain life giving fluids in the body, and to transport life giving fluids through the body for nourishment and to flush wastes out of the body. For thousands of years, Chinese Doctors have known that salt is absolutely essential to health. In Chinese Medicine, salt is known to strengthen bones, strengthen teeth, strengthen kidneys, strengthen sex organs & performance, strengthen ears and hearing, strengthen brain fluid and strengthen and increase the hair on the head. It is also used to cure problems and diseases associated with the same things it strengthens. Yes, the Chinese know that too much salt or too much salty taste in the diet is not good for the heart and may increase blood pressure. But to demonize salt, to encourage people to cut back too much on salt will make people weak and lead to illness, increased doctor and dentist visits, and early death. Every person’s body is different, and people’s health conditions change all of the time. Salt is necessary for life. How much salt is needed depends on common sense and the needs of the individual.

    Personally, I would not take any government study seriously or any World Health Organization study seriously, because their agendas are the same. They are Death cults designed to trick people into submission and to cull the human population.

  12. I know, dr J, but seriously! There’s limits to bad thinking and this kind of thing permeates nutrition and diet advice in this country. It has to stop. I have no idea why the quality of thinking in the field of nutrition seems particularly bad as practiced by highly intelligent people, but it is. There’s a mystery here.

  13. “The big decrease is plausible because it is only extremes of salt intake that are dangerous — that is, it isn’t linear — and the decrease was greater among people who ate a lot of salt.”

    Seth, are you saying that four out of five strokes and heart attacks take place in people who eat “extreme” amounts of salt? Maybe that’s true, and maybe it could make credible that an average 10% BP decline could cut CVD mortality by 80%, but I’d be very surprised.

    “If you have an alternative explanation of the UK, Finland and Japan results, what is it? A vague claim of “other things” is no help.”

    I don’t think anyone knows. As you’ve pointed out, the underlying causes of CVD aren’t even known. And hasn’t CVD dramatically decreased in recent decades in general? Dr. Nortin Hadler has pointed out that CVD poses now poses a pretty low risk of shortening our lifespans, just as the hysteria about avoiding sat fat, salt, etc. and taking stains is peaking.

    If we don’t know why life-shortening from CVD is declining, just picking one thing that correlates with that decline doesn’t seem convincing to me. For now at least, I’ll keep bringing my own salt to restaurants (since it’s on the table less and less) and supplementing my 1 teaspoon of Celtic salt per Dr. Brownstein.

  14. Aren’t we just discussing levels here? I don’t see that “The value of salt reduction supported by 4 studies” doesn’t really help me determine if my salt levels are good or bad. Since going on Paleo, I have to fight to get my salt levels up to 5g a day which is where I feel the best (based on various markers). I do live in the american south and I sweat heavily and exercise heavily daily.

    I am a little shocked by how much salt is listed on processed foods. I’ve been paying attention the last few days when I go through the grocery store and its pretty shocking. I just looked up the old meal I would eat at Taco Bell in the bad old days it comes in at a shocking 3.4G. I still don’t see how I could have come close to the 14g number that Japanese had even on my old diet. I checked my old diet log and found the number to be closer to 10g.

  15. What about other minerals? E.g. potassium and magnesium (among others)? Having an aggressively high sodium intake without counter-balancing other minerals could cause for some issues as the body reels to re-balance. Laser-beam focus on just sodium, which seems to be the “salt” du jour seems to ignore a considerably more complex system.

  16. okinawans have been living till 100, illness free, for centuries in spite of a plethora of salt. of course, once they started with western food longevity decreased and illnesses increased.

  17. The problem with what you’re saying that in the world of nutrition Japan doesn’t actually exist. If Japan existed, then Taubes theories would have been laughed to scorn. If Japan existed, then Stephen Guenets theories of high palatability leading to obesity would have been considered a joke. If Japan existed, then the theory that processed food leads to obesity would have been discarded long ago as a poor joke. No, sam tanyonovski, Japan simply does not exist.

    So stop inventing countries that don’t exist to illustrate your nutritional theories. Only one country actually exists when it comes to nutrition; the United States.

  18. I don’t know if the two go hand in hand but since losing over 100lbs years ago my taste for salt went through the roof. I don’t know if it’s some kind of psychological addiction but I love salt. In the past I would probably get, not even kidding, 20+ grams a day. I never actually measured it to be that much but when I did make an effort to measure I remember weighing out 10 grams and looking at it saying “whoa this is nothing…” then I proceeded to eat the 10 grams and a lot more without weighting it throughout the day.

    It doesn’t increase my blood pressure (maybe by 10pts max to an already low blood pressure)… at least not according to the cuff I bought. What does happen, however, is that I retain an ungodly amount of water. Always. I can retain, and I am not kidding, 15lbs of water if I have an extreme salt intake for a couple of days in a row. That’s finally the point when I HAVE to cut back because I will literally feel heavier when I walk around. My shoes get tighter and I just look really really fat. People have even made comments that I’ve put on weight. They don’t believe me when I tell them it’s water weight. For that reason I HAVE to watch my salt intake… which I hate because I really really really love the salt which is funny because I never cared about it when I was super overweight.

    I really do think salt sensitivity is very very individual. I can’t tell you how many times I’ve read that the body adjusts homeostasis and fluid balance to match CONSISTENT levels of salt intake. Not in my case. For years it’s been- eat a little salt consistently, hold a little water. Eat a lot of salt consistently for a couple of months, hold a lot of water for a couple of months.

  19. @Tom,

    I, too, take in a lot of salt. I’ve not measured it to date, but I salt like a fiend. Usually sea salt but I’m not afraid of typical table salt. I also take in a decent bit of magnesium daily.

    Like you, I can tack on some serious water weight under the right circumstances. The most consistent water-weight add is related to carb/glycogen replenishment–something I”ve blogged about here:

    One thing I’ve noticed that I’m curious about in your experience is that while my salt intake is high, I think my potassium intake can be low at times _relative to other salts_, which can lead to cramps/issues that seem to be dealt with by adding some “NoSalt” to water or literally licking it off my hand (doesn’t taste the best as far as salt goes but seems to work).

    I’ve also noticed that alcohol consumption can lead to some serious water retention — not unlike what you describe with people noticing weight gain. I can clearly see the impact of water retention on my “softness” when I see a material change in the scale. For example, yesterday I started the day at 164. Ate a high protein diet that was low in fat and low in carb (call it 200g protein, 30g fat, 70g carbs but probably 40 of that was dietary fiber). ALSO had 6 oz of tequila — 68 g of alcohol. Weight this morning = 169. By tomorrow morning my weight will probably be around 163 if I had to guess. Crazy, right? Maybe not to you.

    I hate water weight fluctuations though — they’re just annoying. I prefer looking more lean to puffy and the worst I’ve had it on water retention was at the tail end of a week at the beach where my legs literally got swollen from the water weight. Given my body comp at the time was only about 10-12% BF, that kinda water retention made for serious swing in my appearance — particularly on my legs.

    TL;DR — water weight is a major force to be reckoned with! And it seems pretty poorly understood.

    Btw, I have very low BP (and a low resting HR), too.

  20. Thanks for your reply Justin,

    I’ll get to potassium but first I want to talk about alcohol consumption and water retention. It’s really interesting that you mention alcohol because I, unfortunately, have a lot of personal experience with this. I use to drink a lot during my college days. Thankfully, though it was hard to completely stop… once I did finally stop I haven’t been tempted to go back. This was many years ago. The first time I ever got pretty drunk I woke up the next morning feeling light as a feather and feeling the best I had in months. Alcohol is a natural diuretic as it inhibits anti-diuretic hormone. It’s well known in bodybuilding circles that drinking some hard liquor before a show can help drop water weight and increase muscle definition.
    Aside from that I never noticed alcohol to CAUSE water retention. Of course I was really obese at the time so it may have happened. I would imagine it’s possible, probably from an overcompensation effect from it greatly inhibiting anti-diuretic hormone while the body is metabolizing the alcohol.

    As for the potassium… I started using lite salt mixed with nu-salt to combat the high sodium. I’m probably using %75 potassium and %25 sodium while measuring everything out carefully. Excess potassium can be dangerous. It takes a lot though. I don’t think the potassium does anything special to help eliminate excess salt. The decrease in sodium intake as a result of the potassium replacement probably helps reduce water retention a lot more than taking in potassium does. Interestingly I find that the potassium does make me quite thirsty but I don’t hold the water. I’ll drink like crazy then urinate a lot over the next couple of hours.

    One thing that I swear works… eating a lot of cranberries. There doesn’t seem to be a lot of research on this but a lot of people swear that cranberries help with water weight. My experience has been that when I make a cranberry smoothie (with real cranberries I don’t use the juice) I get a dull, almost uncomfortable, mild sensation in my midsection followed by increased urination for a couple of hours.

    Of course if you really really want to eliminate water weight… eliminate carbs for a couple of days, like you mentioned, lower salt, sweat a lot, be in a calorie defect etc… the body loses a lot of what it uses to hold on to the water this way.

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