Sunday, March 22, 2009

Vitamin D & The Dark Side of Science

In case you missed it, Vitamin D is currently a food-group. In 2005 the Harvard School of Public Health revised the food pyramid to include, among other things, multivitamins and in particular Vitamin D.

Controversy over the traditional food pyramid – which was ingrained in my childhood memory from cereal box spines – was getting out of hand. Its large base of “bread, cereal, rice, & pasta” placed heavy emphasis on carbs, while the meats and protein section failed to differentiate between less healthy red meats and leaner sources of protein. Other complaints included questionable influence from special interests - particularly those of the pernicious potato lobby - on the original pyramid, which was formed by the USDA. Between the alarming rise of obesity in America, and those confusing dots on the old pyramid that make it look like it’s from Star Wars, many thought that the food pyramid was overdue for a makeover.

Enter the The Harvard Food Pyramid, which was formed using the very latest in peer review scientific research. And yet it’s a mockery of science and public health all the same.

You’ll notice that its base, instead of “bread, cereal, rice, & pasta”, consists of “daily exercise & weight control”, featuring a collage of cartoony clip-art sneakers, dumbbells, a ping-pong paddle, feet standing on a scale, and, at the right, a plate consisting of some of the very same foods that, above, it says to use sparingly. The food pyramid is also fiber-heavy, going so far as to place white bread in the use sparingly category. The mid-section has a whole box for “nuts, seeds, beans, & tofu”. And salt is included in the “use sparingly section”. From the pyramid’s inedible base to its strange emphasis on Vitamin D, it represents much of what is wrong with science today.

The next bit focuses on two specific criticisms (Vitamin D & salt) before returning to larger issues covering science and national policy in general.

Vitamin D

Vitamin D has very few empirically demonstrated benefits, and yet medical researchers seem to be all up in a tizzy about it. A large group of scientists has hailed that the general population’s Vitamin D deficiency is of epidemic proportions, but it’s not clear whether supplementation is the solution. And it's not like we haven't been trying. For years, almost all milk, most cereals and many juices have been Vitamin D fortified, and yet this epidemic persists. Their response is to recommend massive (up to 2x for children) increases in the amount of recommended daily intake, which is typical of what happens when you combine bad medicine with bad government: If at first you don't succeed, try doubling the dose.

Skepticism about these recommendations, however, should come from previous treatment research with Vitamin D. Deficiencies have been empirically correlated with numerous conditions – from obesity and multiple sclerosis to schizophrenia – but treatment studies have found null or inconsistent at best results using Vitamin D.

As we all know, correlation doesn’t equal causation.
And furthermore, Vitamin D correlates with sun exposure & outdoor activity, which can create all sorts of confounds.

In lack of sound theory, studies using Vitamin D as a treatment are highly speculative, and the push to expand guidelines for the public mirrors this: The results might be spurious; they might be tied to how Vitamin D’s metabolized; they might be due to poor lab testing (an issue that was raised just this week); or the original guidelines might have been wrong. The potential harms of these recommendations range from Vitamin D toxicity to wasted money and effort. While the potential benefits are speculative at best.

Most importantly, these efforts lack supporting treatment studies and sound theory – which might just cover a few basics, like why the levels are off in the general public, and how correcting them will help. Without such information, public health experts can’t afford to guess and experiment with the public at their will. For all we know, Vitamin D might be off for a good reason. That may sound silly, but the bottom line is that we just don't know, particularly in lack of any plausible & semi-backed theory. We can't just go around using correlations to dictate public policy.

Salt

Proponents of the war against obesity have declared salt as part of the axis of evil. And salt does make you fat by retaining water (although this is just temporary as it’s urinated out like most minerals). But it’s a key mineral. It’s essential for food digestion, hydration, and other basic functions. Furthermore it has a laxative effect, which may offset some of its water-retention effects on weight. Salt likely increases food satiety by aiding digesting. Long-term salt deprivation is a real concern, and insofar as it hinders absorption, it might even lead to overeating. And further, hydrating with extra fluids won’t offset the effects salt deprivation, because it’ll just cause you to urinate more of it out.

You could hear the cry of public health from the beginning of the previous paragraph: Sure, we all need salt. But in our modern diets of processed foods we generally eat way too much of it. In this context, eating too much salt is a much greater danger than eating too little salt. This sentiment may have a kernel of truth (assuming it's correct, & it might not be, given the plethora of low-sodium options that’ve popped up). But note that’s not the same as using salt sparingly.

The essence of the argument, then, is that modern diets are too salty, so experts have to over-compensate by telling people to err on using too little salt. This gets at the heart of the problem.

Telling People What to Do



What, then, is the role of the updated and scientific food pyramid? Is it to give people the correct amounts of food to eat, or to steer people away from eating supposedly unhealthy foods that are deemed by experts to be too prevalent in our society? It’s clear that the latter is the case, and the guidelines aren’t meant to be followed absolutely. Further evidence for this is seen in the foundation of the new food pyramid, which isn’t even food at all, but includes exercise and weighing.

What we're dealing with here is a food pyramid whose foundation, in no figurative or uncertain terms, is not food. Unfortunately, this sort of scientific double-speak extends beyond food policy.

Spiraling Further Out

The points I bring up aren’t a hot controversy because the food pyramid itself is relatively worthless. People might follow a few recommendations, but they generally eat what they want. The obesity “epidemic”, if you want to call it such, wasn’t caused by a bad food pyramid, and it won’t be corrected by a good one.

My frustrations, however, are more directed towards the source of such inane self-gratifying efforts, which include science and academia, whose recommendations and prescriptive science often overstep their bounds. This is a particular problem in this day of age, as Obama campaigned on a platform of giving “enlightened” science its due place in society. I worry that this “due place” may border on implementing a totalitarian state for the public, guided by the dimly lit headlights of power-hungry scientists and Ivory Tower academics. This paints a grim picture, particularly when combined with Obama’s socialist-leanings. With the push for universal healthcare, the individual's business will become a lot more of everyone’s business, as we’ll have to pay the price for our unhealthy citizens – a problem that I’m sure many individual researchers will claim that they can solve given enough funding and power. Global warming science and policy, which rests on an equally shaky foundation, has promulgated, & will continue to, in the much the same manner. In the meanwhile, we have the power of Vitamin D (bolstered, perhaps, by man-made global warming) to cure our existing ailments.

-KJ

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Media (in order of appearance)

Photo: (1) Strange Attractor, 04/21/2007, by Steve Jurveston; (2) USDA Food Pyramid, 1992 (3) Harvard School of Public Health, Healthy Eating Food Pyramid, 2005; (4) Comic from xkcd.com, A webcomic of romance, sarcasm, math, and language; (5) Milk Shelves at Whole Foods, 06/01/2008, by Stephanie Booth; (6) Cat Conspiracy, 09/04/2006, by Craig Elliott; (7) salt and pepper, 06/13/2006, by Hobvias Sudoneighm; (8) Joseph Stalin, 10/27/2006, Freedom Toast;

Video: (1) Music video, 03/04/2007, littlewonder80's channel, of the song "The Guns of Brixton" by The Clash from the 1979 album London Calling.
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3 comments:

  1. You know the saying about teaching someone to fish versus giving them fish? I'd like to apply that approach to teaching people to learn about the importance of balance in all things. Then we might cease to feel the need to keep telling people what to eat. This meta approach would help to alleviate the wild pendulum swings.

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  2. To a degree. I think people already know how to fish, & are relatively autonomous & innovative themselves. These sorts of efforts should work with them, rather than trying to transform them.

    One difficulty is that basic science thrives on ambiguity, whereas for public policy it's a stumbling block. If you make yourself heard (unambiguously), people often get the message, but the message may not be perfect. 25 years ago you never would've guessed that exercise would be so big today, & that's largely thanks to public health kickstarting a multi-billion dollar industry. Yet the dent this has made in the prevalence of obesity has been negligible.

    I've always thought that Consumer Reports magazine offers a great model for public health: No shoulds or judgments. Just give them the facts in an understandable & tasteful manner.

    ReplyDelete
  3. A quick update on this topic, the New York Times just had an article focusing on similar skepticism about public health's war on salt, particularly in light of New York's attempted restrictions on the amount of salt their restaurants' food items can contain. The article points to the lack evidence for the claim that salt is bad, & likewise discusses negative effects of salt deficiency. (http://www.nytimes.com/2009/04/07/science/07tier.html?_r=2&ref=science)

    Lots of people accuse big pharma of bad research & skewing results. But the movement against salt is unquestionably really coming from gov't. This might be a little taste of what a more nationalized healthcare system would look like. A large problem w/nationalized health care is that there's no incentive to innovate as there is in a private system. The gov't of course can fund research, but that doesn't guarantee that the results will be nearly as innovative as those coming out of a private system. & as the example w/salt shows, such research efforts could do more harm than good.

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