Critical reasoning about nutrition

I’ve ranted about bad nutrition information and HuffPo continues to publish nonsense, so what about an exercise for you, Dr. Reader, to figure out an important issue in nutrition.

The religinuts in Texas are trying to sneak creationism into science classes under the guise of “critical reasoning”. Now I’m all for critical thinking/reasoning, but not as a rebranding exercise for creationism. But can you apply critical reasoning to a nutrition issue?

The exercise I’ve found is a great one because it’s a real debate between knowledgeable and sincere advocates. And the initial article provides a balanced set of references for you to judge. The dispute is real, the data is ambiguous and confusing, and the impact (you could die) is significant. So you decide. Yes, you. I trust you – you’re smart enough, you might have enough background to understand the terminology (like what the different types of studies are) used in the articles (if not, that’s what Wikipedia is for), and if you put a bit of work into it (not the 30 second attention span gloss of typical news articles) you can reach a conclusion for yourself.

The issue itself is salt (really just sodium, one of the two elements in ordinary salt). Is there maximum amount we should consume? Is the current recommendation based on real science and evidence or just a WAG? And given that almost no one, not just in the U.S., but in the world, and as traced over >50 years, actually stays under the recommended maximum amount, is the maximum amount right (we’re not all dead, after all) and/or is the recommendation practical/helpful? Again you study the information and decide.

Here’s the starting point of the your exercise, an article at the blog Food Politics. Now while this blog is generally the standard leftie view toward food and endorses quacks like Pollan and Bittman, nonetheless I don’t find it as stupidly biased as HuffPo (with its closet full of naturopaths pretending to provide real information when in fact they not only don’t have any evidence they are also mostly wrong and are just so very chic and trendy). And for this particular post they generally are objective and don’t just present the standard leftie anti-food bias.

The article I cited is good because it provides links to differing views, by responsible sources, on the issue.

The issue itself is fairly simple. Does the current recommended maximum amount of sodium (there are actually two recommendations) make sense, is based on evidence and science, is achievable, and would make any difference. I’ll fast forward to half of this that I believe the second (and more severe) recommendation is entirely bogus. The advocates of that level readily admit there is no evidence to justify their claim, but they continue to make the claim anyway.

The advocates of the, IMHO, way too low limit, are however reasonable and care about our health, IOW, their motives are good and professional and reasonable. But the facts don’t justify their claims. But simultaneously no one actually claims too much salt is good. So the question is merely how much is too much, IOW, what is “excessive”, a term the IOM didn’t adequately define and therefore it is a matter of interpretation.

But here’s the interesting issue (at least I find it interesting) I suggest you pay attention to. In any data-driven process relating to health what measurements should you be looking for? Does a number on some analytical test tell you something or should you be looking at actual health endpoints (i.e. death, heart attacks, etc.).

In particular, both sides in this debate believe that blood pressure is increased due to salt consumption. There is a dispute whether this is dose-linear across the entire range or J-curve, but for the sake of argument let’s concede more salt means higher blood pressure. And high blood pressure is bad for us, right?

So traditionally studies have looked at BP as a “surrogate” for outcomes, lowering BP is a good thing and your health will be better. Commonsense, right?

But is this really true? If you measure a different (and, frankly, IMHO, more meaningful) endpoint, like death, isn’t that a better measure for concluding what amount of salt actually harms you. If my BP is high and I live just as well as I might otherwise, who cares what a clinical measurement says, but OTOH, if salt actually kills me, it might be a good idea to cut back.

So in the analysis this article is all about when you look at an actual health endpoint there is insufficient evidence to justify the recommended levels (as either good or bad) and some evidence (the preponderance of the evidence) to indicate the lower recommended level (just for some people) is actually bad, i.e. reducing salt too much will actually kill you too.

And the biology indicates that actually, despite all the hostility to factory food, human sodium regulation works smoothly and the actual average consumption, across many different countries and many decades is actually what our bodies themselves want our sodium levels to be. Fine, fries have a lot of salt, and so does bacon, and so forth – probably you’re wise to control consumption of these foods. But do you need to freak out over it (as the nutrition nanny nags do)? Do we need to have the government create regulations for it? (which will just give the rightwingnuts another excuse to hate the nanny state).

So read these articles and decide for yourself.

I find The IOM Report Fails To Detect Evidence to Support Dietary Sodium Guidelines  the easiest to read and it is a fairly good summary of the other articles, so if you only have time to read just one, try this one.

Now, as my final $0.02, how do I explain that the CDC (a group I respect and would normally trust) and NYC Dept of Health (OK, but more political than CDC and with less evidence used as part of its process) continuing to claim the current recommendations are right when IOM (Institute of Medicine) report does not substantiate their claims (btw, you can read the entire IOM report at this location, but it’s long and you’ll really have to want to dig through how nutrition-related studies are done to understand it).

I think there are two answers:

  1. when in doubt err on the side of safety, i.e. CDC may not have the evidence to prove <2300mg is justified, but it probably won’t hurt you and might help you to go lower. So they care about us (unlike Repug denialism) and are trying to help
  2. they are an institution, like any other, who doesn’t like to admit they’re wrong and so unless they’re beat over the head with counter-evidence (which the IOM report doesn’t do) they’ll stay-the-course out of both stubbornness and conservative (don’t-change-unless-you’re-sure).

But institutional inertia and genuine concern for health cannot justify: a) unwise recommendations (<1500) that might be harmful, or, b) government regulation that could radically alter food supplies and costs and taste just because maybe it will do some good. I’m particularly oriented to not use government regulation unwisely and face the situation that years or decades later it was proved to be a false alarm because this just gives denialists more ammunition on other issues, like global warming. If the facts are there and decisive, find, let’s regulate; but don’t regulate if you are just as likely to be wrong and right because this will be counter-productive in the long-term.

You might also ask – why don’t we know the answer? If science is so powerful, why can’t we do studies and get decisive results and then make recommendations backed by undisputed evidence. My simple answers are (based on reading plus some commonsense about nutrition science):

  1. measuring blood chemistry (or other simple things like BP) is quick and cheap and reasonably accurate, so the effect of a nutrient (or any lifestyle issue) on these measures can be fairly accurately assessed within the framework of a study you can actually get funded. OTOH, real health endpoints, like death, are more relevant, but much harder and expensive to measure (a good study would take decades and very good statistical analysis to separate signal from noise). So “good” studies are rare.
  2. the really good type of study, double-blind, randomized trial, is expensive and hard to run, but also bumps into ethical issues. For instance if you suspect “excess” (whatever doses you try in the study) of the test substance might be harmful can you subject human beings to that risk? Even if you’re willing to, in the name of greater good of saving lots of other lives, will you IRB (or lawyers) let you. So while RCT is the best, often these are unpractical.
  3. it is very hard to do go studies, even if you have the money and no ethical concerns. You can’t lock people up for thirty years so you are certain what nutrients they consume or that you can subject them to rigorous standards of testing. And the question itself is complex because undoubtedly lots of factors are involved (all the other things you eat and lifestyle things you do) so measuring signal against the noise background is very difficult.
  4. And even if somehow you could do it right, so what! Would industry lobbyist still not try to undermine recommendations if it cuts their profits (hey, look at 2008 financial crash and the attempt to fix it with Dodd-Frank if you believe politics is going to do the right thing and solve problems based on evidence). Wouldn’t the leftie political food nuts (who, without evidence, make all sorts of false anti-food claims) every believe your results aren’t just an industry coverup (it’s so easy to hate Monsanto over GMO the facts that GMO have no proven harm (or vaccines don’t cause autism) is ignored by the lefties, just as the righties ignore global warming or believe in creationism).

So does this mean it’s hopeless?

No, it means studies should be done, the results will be ambiguous, and therefore, YOU must make reasonable decisions for yourself – filter out all the political noise (left and right), filter out all the dogma, understand how bias gets into these issues, look at what data does exist, consider your own situation and needs, and make an informed decision – hard, but worth it.

About dmill96

This entry was posted in comment, musing and tagged , , . Bookmark the permalink.

Leave a Reply


You are commenting using your account. Log Out / Change )

Twitter picture


Facebook photo


Google+ photo


Connecting to %s