Even the experts don't agree

Reading the September issue of the scholarly journal, Annals of Internal Medicine, a monthly publication of the American College of Physicians, I came across a marvelously detailed article on low-carb diets. It was a joint effort by the Harvard School of Public Health and the National University of Singapore and examined the results of two huge, long-term projects. It was followed by an editorial review as major articles frequently are in the Annals; the groups reviewing the article were from Duke and the Durham VA Medical Center (staffed by Duke professors in my day there).

The Nurses Health Study prospectively followed 85,168 women, aged from mid-30s to just under 60 initially, for twenty-six years. The Health Porfessional's Follow-up Study did the same for a group of 44,548 men (podiatrists, optometrists, pharmacists, dentists and veterinarians, but not physicians), aged 40 to 75 years initially, for twenty years.

The researchers conclusions were that eating a low carb diet from animal sources led to a higher mortality risk whereas the opposite was true for eating a low carb diet based on vegetable sources.

So far, things seemed reasonable to me, but then the reviewers analyzed the article and tore it apart in many respects. It was the best of times; it was the worst of times, or to paraphrase, it wasn't the best of studies; it wasn't the worst of studies.

The first problem was this wasn't a controlled clinical trial, but just an enormous observational study. Then there were caveats about extra risk factors: sure the men who ate the most animal-based fat were at greater risk for heart-disease deaths, but they also smoked more and exercised less. And low-carb wasn't exactly really low carb; the group eating the least carbs per day really ate a fair amount (nearly 40% of their calories as carbs). And the participants in these studies aren't exactly representative of the broader (no pun intended) US population and weren't put on specific diets at all.

So what did I end up with? Just what I've been saying all along. Eating more veggies and less red meat, exercising more, not smoking...all those make sense. Moderate carb, low carb, this diet, that diet...none of those ideas has been convincingly proven. Actually low-fat hasn't been shown to reduce health outcomes either.

So eat sensibly, try cutting back on red meats and processed meats and be sure to eat your veggies (and fruits). Didn't Mom always say that?

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