The U.S. Dietary Guidelines Advisory Committee made headlines in February when it announced its conclusion that the cholesterol we consume in food plays a relatively insignificant role in our blood cholesterol levels. That was—and is—a huge deal, because it reverses things our society has regarded as basic facts for decades.

With this huge reversal, as well as new nutritional studies coming out every week that seem to contradict each other, it’s natural to wonder if we really know anything about nutrition at all.

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Dr. David Allison of the University of Alabama at Birmingham’s School of Public Health is extremely skeptical of nutritional advice from all sources. He recently spoke to the Washington Post about several reasons why so many things we think we know seem to be wrong.


Some problems Dr. Allison sees in scientific research from both the food industry and the government include:

  • Inconsistent and flawed food intake measurement
  • Scientific inferences drawn from findings are often flawed
  • Presupposition—even among scientists—that eating certain things is good for us, while eating certain other things is bad for us.

When talking about the potential for flawed scientific studies, Allison adds,

“When we start to talk about how long do you live on this diet, or whether you get a cancer or stroke, that is not so easy to study in humans. You need large numbers of people to eat what you tell them for a very long period of time. Typically, you want thousands of people over a period of years. You can immediately see that if you can get them to do it at all, could you even afford to do the study? Those kinds of studies are very rare.”

Allison’s own take on nutrition science is very simple.


“There are a few things we are certain about. We know that you can’t live without food, and that if you eat too much, you get fat. There are certain essential nutrients—vitamins and minerals—that you need to have. You should make sure there is no lead or mercury or other toxins in your food.

After that the knowledge base gets thinner and thinner.

Maybe you shouldn’t have a diet that is extremely high in saturated fat or trans fats or sugars. Do we know this beyond any reasonable doubt? No. But we know enough to say this could be considered a prudent diet.

But that’s the way we need to tell people. We need to say, ‘We think,’ not ‘We know.’  We need to be careful about is not pretending we know more than we really do.”

Luckily for us, the scientific website Compound Interest has put together this helpful infographic to help us all spot bad science in the wild.

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You can check out a larger version on the Compound Interest website.

[via the Washington Post]