One Serving of Butter Doubles Diabetes Risk?

Atrocious nutrition headlines are back. Health reporters are telling us that “eating two slices of buttered toast a day can double the risk of diabetes.” Fortunately, that’s not what the study says.

The study was just published in the American Journal of Clinical Nutrition. The data comes from a randomized, controlled study of the effects of the Mediterranean diet, the PREDIMED study. That’s right, this particular paper is a secondary analysis. The researchers were looking around for risks associated with different patterns of fat consumption. They zeroed in on the onset of type 2 diabetes. Contrary to the headlines, the study tells us nothing about cause and effect. In their paper, the authors are quite clear about this:

Findings from this study cannot prove causality, and it is difficult to rule out residual confounding.

What they did find was an higher risk of type 2 diabetes in people who consumed more cheese and butter. But they found a lower risk of type 2 diabetes in people who consumed more whole-fat yogurt. It may be that those foods are the cause of the changes in risks. It may be that other factors are responsible. Health consciousness might be a factor. This secondary analysis simply doesn’t have the power to tell the difference.

But if dairy fat were the whole story, we would not see risks going down for people who eat whole-fat yogurt.

So why write headlines about buttered toast causing diabetes? The answer is simple. It’s all about clicks, readers, and ad sales. Sensation sells. Facts are secondary.

Here are a few facts you can count on. Wholesome food is neither poison nor medicine. It’s just food. For health, it’s the whole of what you eat – day after day – that counts. One food in isolation is pretty meaningless, unless you become obsessed with it.

Click here for the study.

Buttered Muffins, Nooks and Crannies; photograph © Sara Stasi / flickr

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February 20, 2017