Nutritional Pearls: Don't Demonize Potatoes

Joe is a 32-year-old overweight man concerned about his risk of developing diabetes. In an effort to eat healthier, he has recently begun having a baked potato for lunch every day rather than his usual fast food meals. Recently, a coworker told Joe that baked potatoes could also raise his risk of diabetes. He asks if it is worth continuing to eat them, or if he should find another option.

How do you advise your patient?
(Answer and discussion on next page)

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Answer: While potatoes are a primarily a source of starch, they are also good sources of potassium, vitamin C, folate, fiber, and polyphenols.

Potatoes get a bad rap. While they're primarily a source of starch (as much as 23% by weight for some varieties), people forget that they are in fact vegetables, and as such as not only low in calorie density, but they are also good sources of potassium, vitamin C, folate (important during pregnancy), fiber, and polyphenols (a source of antioxidants).

As with many ingredients, the problem with potatoes is not the potatoes themselves, but how you cook them or what you eat them with. A baked potato with a little sour cream or cheese is one thing—a baked potato with a quarter-cup of butter and the same amount of cheese, or one cut into strips and deep fried into French fries are another thing altogether.

The Research

An article from 10 years ago suggested women who consumed the most potatoes were 13% more likely to develop type 2 diabetes than those women who ate the least potatoes. Those who ate the most French fries, however, were 29% more likely to have type 2 diabetes than those who ate the least, even after taking body mass index into account. The lowly (and plain) potato was still tarred with the brush of additional diabetic risk.

Ten years later, a team of researchers at the University of Copenhagen performed a review of published articles on potato consumption and the risk of type 2 diabetes, obesity, or heart disease. Of the 13 articles they identified that met their requirements for aim, type, and quality, 5 studies investigated a possible link between potato intake and obesity. These studies lasted between 2 and 20 years and included over 170,000 individuals. The results here were mixed: 2 studies found a link between potato intake and measures of overweight and obesity, while 2 did not. Boiled, baked, and mashed potatoes seemed to contribute to weight gain the least (about 1/4 kilogram over 4 years), while French fries contributed the most (1.5 kilograms over 4 years).

The Results

Seven of the identified studies looked at type 2 diabetes risk and potato intake and included over 300,000 persons, with a study length between 4 and 20 years. Again, 2 studies showed potato intake to be associated with higher risk of diabetes, while 2 more saw a lower risk, and another 2 found no association at all. The higher risk was seen only in studies limited to women, while one study limited to only men found no association as long as the potato intake measured did not include French fries. When only intake of French fries was considered, however, 3 large studies found that a higher intake of fries meant higher risk of type 2 diabetes.

Finally, the one large study that looked at the risk of heart disease found no association between potato intake and risk of stroke, but the authors note that the study did not look at potatoes by method of preparation, making it difficult to say whether it is the potato itself or the preparation that might be the problem.

What’s the “Take-Home”?

It's pretty clear that eating a lot of French fries is bad for you. But then, if you're eating a lot of French fries, what else are you likely to be eating? This is why demonizing a particular food ("potatoes are bad," or "bread is bad") is a bad idea. Better to enjoy a wide variety of foods prepared in a healthful way, and if you must have fries, save them for a treat.

Reference:

Borch D, Juul-Hindsgaul N, Veller M, Astrup A, Jaskolowski J, Raben A. Potatoes and risk of obesity, type 2 diabetes, and cardiovascular disease in apparently healthy adults: a systematic review of clinical intervention and observational studies. Am J Clin Nutr. 2016;104(2):489-498.