Move Over Sugar, Potatoes Seem Toxic

A new study in Diabetes Care adds to a line of research that serves the purpose of depicting “the problem with potatoes.” Isao Muraki and colleagues find an association between self-reports of higher potato consumption — especially french fries — and the risk of type 2 diabetes. This comes on top of a prior observation by some of the same investigators that self-reports of higher potato consumption are associated with long-term weight gain.

It’s worth distinguishing from facts and suppositions. It’s a fact that potatoes have a relatively high glycemic index — they cause higher spike in blood sugar than other foods after you eat them. The associations observed between potato consumption, obesity, and diabetes are facts.

But the notion that potatoes might cause diabetes or obesity is a supposition that is unsupported by evidence of cause and effect. Likewise, prescribing less potato consumption has not been shown to cause weight loss. Correlation is not the same thing as causality. Self-reports of what people eat are notoriously unreliable for drawing scientific conclusions.

What matters is the entirety of what people consume.  Some people could no doubt benefit from substituting whole grains for some of the potatoes they’re eating, as the authors of this new study suggest. Different people with different diets might need to make different adjustments to achieve their best health. This is where a skilled dietitian can be very helpful.

But lists of good foods and bad foods are not particularly helpful.

Click here to read the study by Muraki et al. Click here for more perspective on the role of potatoes for people living with diabetes.

Basket of Potatoes, painting by Vincent van Gogh / WikiArt

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December 28, 2015