In Defense Of The Potato

The explanation can be found in the School of Public Health’s website in an article entitled The Problem with Potatoes. I found the update of potato’s reclassification upsetting, far more so than the belief that ketchup, derived from the tomato, a fruit, was a vegetable.  The authors point at the glycemic index of a potato which is high – meaning that the carbohydrates are easily digested and bring a surge in blood sugar. They go on to argue that “Potatoes seem to be a particular culprit for weight gain and diabetes.”

“…a cup of potatoes has a similar effect on blood sugar as a can of cola or a handful of jelly beans.”

We begin with this bit of hyperbole along with a cited article. The article indicated “a modest positive association between the consumption of potatoes and the risk of type 2 diabetes in women” in the abstract. In the body of the results, potato consumption had a slightly decreased risk of diabetes in those overweight or less; the risk was for those categorized as obese. French fries were worse, but I am speaking today on behalf of the potato. In fact, those who ate the most potatoes, two-thirds of a potato daily, took in 500 more calories, fruits and vegetables, fiber, red meat, whole, and refined grains – they ate more, worth a pound of additional weight a week. Obesity stresses your glycemic response; there is good evidence for that, but which came first, overeating or the 161 calories potato?

“People who increased their consumption of French fries and baked or mashed potatoes gained more weight over time—an extra 3.4 and 1.3 pounds every four years, respectively.” 

This statement is again based on a cited article. They do not mention that it comes from Harvard’s faculty, has been promoted on their website, or that it makes use of the same population, the Nurses Health Study. [1] Having more free time on my hands than the average reader, I went to the primary source. Here is what I found,  “A secondary analysis of potato subtypes showed that weight changes were positively associated with increases in the consumption of french fries (3.35 lb) and of boiled, baked, or mashed potatoes (0.57 lb).” Once again, leave the less innocent French fry out of the equation. That increase in weight was comparable to watching television, which added 0.31 pounds and gave the term couch potato a whole new meaning for me. [2]

“A similar long-term study found that high potato and French fry intakes were linked to a greater risk of diabetes in women, and that replacing potatoes with whole grains could lower diabetes risk.”

Once again, the data is from the Nurses Health Study and looked at the effect of a low carbohydrate, high fat, and protein diet on the onset of Type II diabetes. It was true that the glycemic index rose as the fat and protein came from animal rather than plant sources, but the effect was absent when those fats and proteins came from vegetables. If the researcher’s findings are correct, it helps explain where the potato went on Harvard’s Healthy Eating Plate; it must be an animal!

They do give the potato a thinly veiled compliment

“Potatoes do contain important nutrients – vitamin C, potassium, and vitamin B₆, to name a few. But the potato is not the only source of these nutrients, nor is it the best.”

While I am sure other foods can supply those nutrients, why not the potato? They offer up the newest favorite, cauliflower, along with the perennial, whole grains, and the oh so last year, quinoa.  

[1] All of the data is based upon dietary surveys along with self-reported weights reported every four years. That a recall survey may not truly capture our eating habits has been discussed ad nausea.

[2] The one factor they identified showing the most significant decrease in weight during a four-year period was a former smoker who went back to smoking. How is that for scary? It also suggests that how you lose weight may have a more significant impact on your health than how much weight you lose.