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Scientists can’t agree whether salt is killing us

110 points| chmaynard | 10 years ago |washingtonpost.com | reply

142 comments

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[+] static_noise|10 years ago|reply
I'm waiting for the day that nutricionists find out that there are different kinds of people with different nutritional needs. Imposing rules on the population on a weak scientific basis harms the people, science and the government in the process.

Currently the best way to consume food is to avoid addictive and highly processed food products and then trust your gut with the rest. Eat what you like and avoid what causes problems. Use salt to taste, most likely it won't kill you - else we would have found out already.

[+] rsync|10 years ago|reply
"Currently the best way to consume food is to avoid addictive and highly processed food products and then trust your gut with the rest."

Allow me to suggest a further path forward that is superior to "trusting your gut":

Establish a regular, very high output exercise regime - incorporating both long duration aerobic/cardio and relatively intense resistance training.

Under such a regimen, you will notice what food does to you because you're pushing your physical state out to the edges. You will need to eat densely nutritious food and you will notice when you don't. It's quite striking.

An analogy: nobody notices a bad tank of gas, or slightly wrong octane in their toyota minivan. You do notice a bad tank of gas, or slightly wrong octane in a race car.

Become a racecar and you won't need to guess about food anymore.

[+] noxToken|10 years ago|reply
> Currently the best way to consume food is to avoid addictive and highly processed food products

I assume by highly processed, you mean foods altered in such that they are now high in fats, salt, sugars or some combination thereof. I ask, because the term processed gets thrown around (in my experience) for highly preserved foods like canned meat to flash frozen frozen vegetables in the freezer aisle.

The former is obviously worse for you. Taking in high amounts of sugars, bad fats, and possibly salt is detrimental. However, referring to green beans that were grown, picked, flash frozen and delivered as a processed food is somewhat misleading. Flash freezing is altering the food from its natural state. Thus, a frozen vegetable is technically a processed food. The connotative definition, however, implies that more than freezing has happened.

[+] cimbal|10 years ago|reply
Well said. The size relations of inner organs for example vary betweeen people as far as i know. That is a big hint, althought it's not a proof in itself.

I want to add to that the nutritional needs within each person vary drastically during different times of year (or times of stress, even down to times of day). Athletes know this, for example, it is common to exhibit significant drops in performance during a year of training (recurring every year).

Now combine these simple observations with the way nutritional studies are done and you know why it looks as if we have no clue.

[+] patatino|10 years ago|reply
I tried to inform myself about nutrition but at this point I have still no idea what is best. Right now I'm following your advice, avoid highly processed food and otherwise listen to my body.
[+] ocean3|10 years ago|reply
"Use salt to taste, most likely it won't kill you" - but salt has been used for centuries right. Has there been a change? As an Indian not adding salt is unthinkable.
[+] clock_tower|10 years ago|reply
> I'm waiting for the day that nutricionists find out that there are different kinds of people with different nutritional needs.

The nutritionist side of public health evolved to deal with questions where this isn't true. Everyone needs vitamin A to avoid beriberi and vitamin C to avoid scurvy; no one benefits from polluted milk or polluted water; that sort of thing. Now, the big problems have been solved, and nutritionists are trying to treat semi-ideopathic diseases of affluence as if they were the immense, obvious dietary scourges of a hundred years ago...

This is true of the whole field of public health, to an extent. Cholera and yellow fever are under control, smallpox is all but extinct, polio is on its last legs, and now we're trying to use the tools that defeated those diseases to fight drug addiction, lifestyle-induced diseases, diseases of aging, and STDs.

At least things aren't as bad now as they were. Traditional public-health approaches look nonsensical when used against 20th-century issues, but they did a wonderful job against 19th-century ones.

[+] Shorel|10 years ago|reply
Nutritionists will never find out that, because it's not their job. They simply recite memorized mantra.

However, some scientists have been creating a mathematical model that should be able to predict the best diet for a particular person, given that the microbes in said person's guts are analysed first.

You can read about it here: http://www.sciencealert.com/your-gut-bacteria-determines-whi...

[+] Mz|10 years ago|reply
I'm waiting for the day that nutricionists find out that there are different kinds of people with different nutritional needs.

I wish more people were so wise.

I have a salt wasting condition. Lack of salt was very much killing me -- though the answer was not merely more salt, but better quality salt, a detail that routinely gets me the deer-in-the-headlights look from people who respond with "But isn't salt just salt??"

[+] hardlianotion|10 years ago|reply
"the image is dominated by red and blue, a sign that scientists are more likely to cite the research that conforms to their outlook."

Or a sign that the green lines were drawn first, and test red and blue overlaid.

[+] IshKebab|10 years ago|reply
Was about to post the same. It's hard to continue reading the article when the basic premise is so obviously flawed.
[+] Ensorceled|10 years ago|reply
Agreed. This is a terrible graphic. I have no idea what's going on for any data point except the few on the edges.
[+] ajholyoake|10 years ago|reply
This could have been improved by clustering using a d3-like force layout - The current node layout obfuscates the graph terribly!
[+] yk|10 years ago|reply
Came here to mention that. Additionally these findings are easily explained if we assume that salt has some positive and some negative effects occurring in different parts of the body. Say salt has some positive effects for the liver and negative effects for the heart, then a paper on liver disease will mostly cite positive studies about salt, that is it cites studies on the liver, and a paper on heart diseases will cite mostly negative.
[+] Ensorceled|10 years ago|reply
I think a huge problem, is that some of the guidelines are insanely low and difficult to hit without serious diet modifications. A couple of years ago, I tried to stick to the Canadian RDA for salt and found it near impossible even on a whole food diet. If you engage in strenuous exercise or in manual labour, they are dangerously low.

A couple of recent studies are pointing to this problem with the Health Canada Guidelines http://www.thestar.com/news/gta/2014/08/13/salt_guidelines_a...

So studies that compare people at or near the RDA with people who are over the RDA are essentially comparing vegans, vegetarians and other people are very closely monitoring their diet to the general population.

[+] tetraodonpuffer|10 years ago|reply
Honestly given that due to health reasons I have to stick to ~500mg of sodium a day, and have been for years with no adverse effects, I don't consider the 1,500mg Canadian guidelines that low. I do find it funny though that, for example, the Canadian guidelines are 1,500mg while the Italian ones are at 2,400 (and if you look at packaged foods sometimes the percentages seem to be based on 4,000mg)

The only way for me to do it is to be completely whole foods (the only "packaged" food I eat is canned crushed tomatoes, and only a very specific brand with absolutely no sodium added). It is obviously annoying not to be able to eat bread anymore, or to eat out, or to be able to do air travel without starving (unfortunately airlines nowadays seem to not serve full fruit meals, so I have to make do with just the little square box of salad and the one of fruit, which on an 8 hour flight is not fun) but what can you do.

This said having to severely limit your sodium makes you realize just how much of our industry relationships seem to be predicated on eating out, from interviews, to work get togethers and so on, this makes me think that likely any future job I will have will have to be fully remote because flying somewhere for an all day interview would be quite difficult to figure out food-wise.

[+] JoeAltmaier|10 years ago|reply
I guess I'm the general population. I eat my daily salt on each French fry at lunch. I like them salted so they turn white! Vegetables are edible, if salted enough. And buttered. Or oiled I guess.

And I am fine. No health issues to speak of. Of course I exercise as well - I ride 20 miles at a time all summer. It's the whole picture that matters I think. Picking out 'salt' and trying to make a rule for everyone is hopeless.

[+] tokenadult|10 years ago|reply
The article kindly submitted here is interesting. Like more and more recent articles about science in the popular press, this article, which reports on a large analysis of previously published papers on salt in the human diet, digs into the process of science to look at how (or even whether) scientists learn from one another by citing the previously published papers on the same topic. The article's key point, just below a graphic that is criticized in several previous comments here, is "Overall the papers they reviewed were 50 percent more likely to cite reports that drew a similar conclusion than to cite papers drawing a different conclusion." In other words, scientists working on the issue of how much salt in the human diet is too much are largely talking past one another, and not collaboratively seeking truth. The article further reports, "Trinquart and his colleagues also turned up another factor that might pose even more profound problems in the salt research. It appears scientists could not even agree on what ought to be counted as evidence."

Human nutrition studies are notoriously difficult because it is very hard to measure exactly what a study subject eats, especially a nutrient like salt that occurs as a hidden ingredient in wildly varying doses in many foods. So correct measurement of the initial study data is hard to get right in studies about salt. But if scientists are still not in consensus about what to look at as endpoints to tell if salt is helpful or harmful in different doses, it will be a long time before we can individualize the research or do anything else suggested in the comments already posted in this thread.

[+] jarcane|10 years ago|reply
I was recently prescribed beta blockers by my doctor, due to ongoing heart and blood pressure issues brought on by severe stress anxiety.

I also have asthma. It's a mild case, and I don't need an inhaler or any medication for it, just get pretty short on breath under heavy exercise.

Now, accumulated medical wisdom is that beta blockers are bad for asthmatics. They supposedly shorten air intake, and can even be fatal, especially in severe cases. NHS guidelines in the UK recommend against prescribing them to asthmatics and other similar lung conditions.

But ... see it turns out this wisdom basically goes back to some case reviews from back in the 70s, of patients having reactions to proplanolol, the first beta blocker released to market.

But recent reviews of the research shows that's pretty much all there's ever been: case studies. The only actual experimental trials done on this had significant methodological issues (one of them didn't even have a control group!), leaving little more than just a pile of what amounts to anecdotal evidence, involving two conditions (heart and lung) that have significant chance of comorbidity anyway.

On top of that, even most of that research is all based on the original "nonselective" kind of beta blockers, while initial research with the modern "selective" variety indicates they may even help. Even more fun is that the beta-agonists sometimes prescribed as an alternative to blockers, may themselves have a reaction with asthma ...

The end result is that in nearly 50 years of beta blockers being on market, no one medical professional actually seems to have any idea whether they're good or bad for asthma, but the "wisdom" gets passed down all the same ...

And meanwhile I've got a bottle of them on my desk. I'm not a doctor, or a pharmaceutical scientist, and if they don't know if it's safe for me to take them or not, how in fuck am I supposed to make that choice?

[+] oniony|10 years ago|reply
At least the we can all agree that salt is good for our passwords.
[+] amist|10 years ago|reply
Just in case they are random.
[+] Mikeb85|10 years ago|reply
The problem is that salt (and other minerals) is required to live. But we eat too much of everything (including salt).

It's not the salt that's killing us, it's the shitty diet, too-large portions, and lack of exercise. If we ate reasonable portions of well-prepared meals the salt wouldn't be a big deal. But no, instead we eat extra large portions of everything, way too much meat, starch, fat and salt, so all these food items get a bad rap because we can't simply moderate ourselves...

[+] jerf|10 years ago|reply
Why do you think you know that?

Since the answer is basically either A: "no good reason" or B: "I believe I have science on my side", this really isn't a good response to an article about how controversial the science is. Which science do you think you have? Why is it better than the other half of the science?

This is a generic reply to everybody jumping up to explain what the truth really is.

[+] norea-armozel|10 years ago|reply
Salt is a problem for people with hypertension or related blood pressure conditions. And there's a strong correlation between cutting down salt and reducing your BP in those cases. Especially since it's safer than just increasing some BP medication doses.

Also, your exercise and diet suggestions effectively reduce salt in your body. Less food, less salt. More exercise and more water means salt gets removed from your body faster.

I'm not trying to say salt is universally bad, but I'm pretty sure no one should literally swallow spoonfuls of the stuff either.

[+] _0w8t|10 years ago|reply
On cannot eat too much starch. Try to eat only potatoes or rice prepared without any oil/butter for couple of weeks with perhaps few vegetables or fruits in addition with any amount of salt or herbs for taste. You learn that it is impossible to overeat as normal appetite controlling signals kicks in and limit the consumed amount. One does not gain weight on such diet and likely even loose some.

Similarly with sugar. Try to drink plain water with sugar (not tee/coffee or anything else that bring own taste). It is just impossible to drink too much of it. In fact for many people such plain water with sugar is a useful trick to limit appetite and loose weight.

So it is not the amount of what is eaten but rather something in food or food composition that makes people overweight.

As regarding exercising consider that doing high-intensity strength training for 15 minutes once per week is often enough to get into shape. So again, it is not the amount but rather the details of the exercise that are important.

[+] vixen99|10 years ago|reply
All likely true but that's not what this is about. I think it is a concern that in many issues of public interest, some scientists are much too ready to adopt strongly polarized views and thereby operate with an aggressive agenda which precludes a cool appraisal of data which fails to reinforce their 'party line'.
[+] jbb555|10 years ago|reply
It seems to me that in otherwise healthy people, they are able to deal with excess salt by getting rid of it, but when people have issues they are unable to do so as efficiently and that's when salt is bad.
[+] jobu|10 years ago|reply
There was one recent study that seemed to indicate exactly this, but I can't find it right now. As I recall they found that salt exacerbated inflammation related to hypertension, but found no difference in healthy individuals.
[+] kazinator|10 years ago|reply
If you consciously reduce your salt, it is probably good for your health. This is not necessarily because of the salt, but because reducing your salt intake pretty much requires preparing your own food from unprocessed ingredients, rather than eating out or consuming processed food (whose sodium levels tend to be high, and not controllable by you).

A high sodium intake is widely believed to be unhealthy. Whether that is actually true or not, those who prepare high sodium food basically show that they don't give a shit about health.

[+] jdnier|10 years ago|reply
I think Dr Michael Greger's short video summary of salt research argues pretty convincingly that if you reduce your salt intake to very low levels (what he calls "normal-for-our-species salt intake"), you will not suffer from hypertension.

http://nutritionfacts.org/video/high-blood-pressure-may-be-a...

Another salt video looking at conflicts of interest:

http://nutritionfacts.org/video/sodium-skeptics-try-to-shake...

[+] jsprogrammer|10 years ago|reply
In case someone doesnt want to watch the videos: the amount of sodium discussed in the first video as "normal" is <1g/day.
[+] Trumpitron|10 years ago|reply
I think the core issue is that biology doesn't know as much as the media likes to claim it does. I mean read this: http://www.eurekalert.org/pub_releases/2015-06/uovh-mlf05291.... If true, this effectively invalidates nearly all previous research regarding the safety of anything we inject into our blood stream because they may in fact impact the brain.

Many people have a choice to make. Although the scientific community may make a consistently supported claim about something does not mean that something will turn out to be true. Creating a near-perfect predictive model of the human body for doctors to use is about as complex a task as reverse engineering a UFO (actually reverse engineering an alien space craft is still probably more simple). They are going to make mistakes along the way.

So you are faced with a choice. Either take a risk with incomplete knowledge that something man made will not be harmful in the long term or keep doing most of the same stuff that we've been doing for centuries that has a known, if imperfect, outcome. Yes there are a lot of things can will probably kill you first, but does that mean you should continue to assume more risk on the claim that a predictive model that the scientific community generally endorses is correct enough to avoid harm?

Then again "organic" can mean a lot of things and the lack of regulation and quality control can and has made things worse on the other end. Just because it has the label "USDA Organic" doesn't mean that the USDA or FDA has done the job you think it does. There is risk and uncertainty either way.

[+] Kwastie|10 years ago|reply
Why does a respectable news outlet/paper like the Washington Post lower itself to clickbait titles.. I don't get it.
[+] Profan|10 years ago|reply
Titles like "Scientists can't decide" always grate on me. Almost as bad as "Science has found out x!".
[+] Cthulhu_|10 years ago|reply
Because clickbait leads to higher click through rate and view and thus income. The consumer decides, simple as.
[+] logfromblammo|10 years ago|reply
In lieu of any conclusive evidence that has percolated down to the mainstream news media, I'm just going to operate under the entirely baseless hypothesis that the human body can tolerate any amount of sodium above its absolute minimum required for basic functioning, provided that it is consumed within a certain range of proportions with potassium, calcium, magnesium, and water.

I suspect that the mineral content of seawater diluted to 1.5% salinity (from 3.5%) would have a bit too much sodium, and not enough potassium, but would otherwise be safe to consume in any quantity.

Needless to say, testing this hypothesis on humans might raise a few ethical concerns. Finding enough people who already drink nothing but diluted seawater to claim significance might also prove difficult.

[+] jostmey|10 years ago|reply
I think this speaks more about a broken research system than it does about the challenges in determining how bad excess salt is on our health.
[+] Shivetya|10 years ago|reply
Being an avid cook I have a hard time with believing that salt is the evil some claim it is. It has always been with us, it is in so many recipes and many don't work without it. It is the basis for brine solutions which produce make even some of the worst cuts of meat palatable and take good pieces and makes them better.

I am more of the idea that the sedentary lifestyle of many and lack of water as the go to drink for a lot of people combined with the excess of salt in snacks as a triple whammy that exaggerates salt's place on some people's lists of it being bad.

[+] itchyouch|10 years ago|reply
One thing to consider is pre-made processed food has tons of sodium in them to bring out taste due to the absorption of salt.

When I cook for myself, I use a fraction of the salt that a pre-made equivalent normally ships with.

I recall reading a blurb about how when processed foods don't do well in taste-testing research panels, they are instructed to dump in the sodium, with the result of positive results to follow up panels.

[+] denzil_correa|10 years ago|reply
WaPo titles are sounding more like Buzzfeed or Quartz.
[+] vzip|10 years ago|reply
Remove the sugar and starches from your diet, and be physically active. You'll need ample salt, maybe even more than you'd expect.
[+] kazinator|10 years ago|reply
I eat low sodium, cycle 70 miles a week, run 30, and sweat buckets. I'm fine.

When I go traveling, I end up eating out a lot due to circumstances. The sodium intake bloats up the skin, yowzers! My wedding band gets stuck on my finger, when normally it slides off easily, and I lose a bit of definition. I hate how that looks and feels.

[+] darkerside|10 years ago|reply
In the image showing how polarized research has become, does the yellow or green category include "Inconclusive citing supportive and/or contradictory"? I would suspect as much, otherwise the image ends up being quite misleading, but I didn't see any confirmation in the article.
[+] malsun|10 years ago|reply
I think it's better to enjoy life than worry about nutritional guidelines, which might extend our time in some retirement home. Especially something that's been in our diet for a long time. Just don't overdo it.
[+] Ensorceled|10 years ago|reply
My in-laws, who have always regularly exercised and eat healthy are 10 years older but have a much higher quality of life than my parents who have done neither.

It's about staying out of the retirement home for as long as possible not how long you're there before you die.

[+] maxerickson|10 years ago|reply
Looking after your health can be an important component of being able to enjoy life well before the retirement home. Plenty of people are having heart attacks and strokes before age 60, before age 50.