At Mother Jones, Kevin Drum talks about all the things we’ve been told about healthy eating … that just ain’t so:
For several years now I’ve been following the controversy over whether the dietary guidelines that have developed over the the past 70 years might be all wrong. And I’ve become tentatively convinced that, in fact, they are wrong. For most people — not all! — salt isn’t a big killer; cholesterol isn’t harmful; and red meat and saturated fat are perfectly OK. Healthy, even. Sugar, on the other hand, really needs to be watched.
Before I go on, a great big caveat: I’m not even an educated amateur on this subject. I’ve read a fair amount about it, but I’ve never dived into it systematically. And the plain truth is that firm proof is hard to come by when it comes to diet. It’s really, really hard to conduct the kinds of experiments that would give us concrete proof that one diet is better than another, and the studies that have been done almost all have defects of some kind.
Randomized trials are the gold standard of dietary studies, but as I said above, they’re really, really hard to conduct properly. You have to find a stable population of people. You have to pick half of them randomly and get them to change their diets. You have to trust them to actually do it. You have to follow them for years, not months. Virtually no trial can ever truly meet this standard.
Nonetheless, as Carroll says, the randomized trials we do have suggest that red meat and saturated fat have little effect on cardiovascular health — and might actually have a positive effect on cancer outcomes.
At the same time, increased consumption of sugars and carbohydrates might be actively bad for us. At the very least they contribute to obesity and diabetes, and there’s some evidence that they aren’t so great for your heart either.
So where does this leave us? As Carroll says, the literature as a whole suggests that we simply don’t know. We’ve been convinced of a lot of things for a long time, and it’s turned out that a lot of what we believed was never really backed by solid evidence in the first place. So now the dietary ship is turning. Slowly, but it’s turning.
His primary take-away from all this: moderation is probably your safest bet, unless you have a condition that requires you to avoid certain foods or types of foods. Oh, and avoid over-indulging in packaged food that uses lots of preservatives. This is certainly one area where the science sure didn’t turn out to be settled, after all.