& Alan Titchenal Tuesday , September 20, 2011
Nutrient-packed potatoes wrongfully considered 'bad'
Repetition of misinformation is a way to create “common knowledge” that might be common though incorrect. This type of misinformation, considered to be knowledge, has damaged the reputation of some perfectly healthful foods, leading people to avoid foods that are valuable sources of essential nutrients.
Much of this denigration of foods stems from good intentions to reduce chronic disease risks that started more than 35 years ago. Before then, health promotion efforts primarily recommended dietary patterns that would meet essential nutrient needs. In 1977, however, the U.S. Senate Select Committee on Nutrition and Human Needs released the Dietary Goals for the United States (also known as the McGovern report). This report initiated the change in focus toward reducing the risk of chronic disease, and meeting essential nutrient needs took a back seat.
One example of common misinformation, supported by the Dietary Goals and later by the Dietary Guidelines for Americans, is the recommendation to reduce dietary cholesterol. At that time, there were dozens of solid scientific papers showing that dietary cholesterol had little or no impact on blood cholesterol in most humans. But, it just seemed like common sense that decreasing high-cholesterol foods should lower blood cholesterol. It would be great if it were that simple.
As a result of cholesterol concerns, eggs took on the undeserved reputation of being a food that causes heart disease. This misconstrued reputation still persists in 2011.
As nutrition scientists who know this history and continue to disagree with egg recommendations, we are concerned that another nutrient-rich food is heading for a similar demise. The humble potato was recently linked to increased weight gain and increased risk of developing diabetes in the large, continuing Nurses’ Health Study. As a consequence, potatoes appear to be headed for the common-knowledge “bad-food list.”
Question: Do potatoes deserve to go on the bad-food list?
Answer: We don’t think so. The potato has been an important part of the American diet for well more than a century. National data indicate that per-capita calorie consumption of potatoes has been declining over the past few decades. Meanwhile, body weights have gone up.
When people do not eat potatoes, they generally replace them with other starchy foods like bread, rice or pasta. A cup of cooked potato provides about 115 calories. However, a single slice of whole-grain bread has about 130 calories, a cup of rice (brown or white) is more than 200 calories and a cup of pasta will range from 150 to 200 calories. Do the math and potatoes look pretty good.
Q: Are potatoes a good source of nutrients?
A: Compared with their most common starchy food alternatives, potatoes provide much more potassium, vitamin C, vitamin B-6 and copper. Potassium, in particular, tends to be too low in the U.S. diet. It doesn’t seem wise to discourage consumption of a high-potassium staple food like potatoes.
Recently a small study of obese hypertensive adults found that consuming purple potatoes twice a day lowered blood pressure without any weight gain. It is not known whether this was due to the purple phytochemical compounds or due to the potassium content.
Joannie Dobbs, PhD, CNS and Alan Titchenal, PhD, CNS
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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