Potatoes reduce blood pressure in people with obesity and high blood pressure

But don't reach for the catsup, vinegar or mayonnaise. The research was not done with French fries, America's favorite potato, but with potatoes cooked without oil in a microwave oven. Although researchers used purple potatoes, they believe that red-skin potatoes and white potatoes may have similar effects.

"The potato, more than perhaps any other vegetable, has an undeserved bad reputation that has led many health-conscious people to ban them from their diet," said Joe Vinson, Ph.D., who headed the research. "Mention 'potato' and people think 'fattening, high-carbs, empty calories'. In reality, when prepared without frying and served without butter, margarine or sour cream, one potato has only 110 calories and dozens of healthful phytochemicals and vitamins. We hope our research helps to remake the potato's popular nutritional image."

In the new study, 18 patients who were primarily overweight/obese with high blood pressure ate 6-8 purple potatoes (each about the size of a golf ball) with skins twice daily for a month. They used purple potatoes because the pigment, or coloring material, in fruits and vegetables is especially rich in beneficial phytochemicals. Scientists monitored the patients' blood pressure, both systolic (the higher number in a blood pressure reading like 120/80) and diastolic. The average diastolic blood pressure dropped by 4.3 percent and the systolic pressure decreased by 3.5 percent, said Vinson, who is with the University of Scranton in Pennsylvania and has done extensive research on healthful components in foods. The majority of subjects took anti-hypertensive drugs and still had a reduction in blood pressure. None of the study participants gained weight.

Vinson said that other studies have identified substances in potatoes with effects in the body similar to those of the well-known ACE-inhibitor medications, a mainstay for treating high blood pressure. Other phytochemicals in potatoes occur in amounts that rival broccoli, spinach and Brussels sprouts, and also may be involved, Vinson added.

Unfortunately for French fry and potato chip fans, those high cooking temperatures seem to destroy most of the healthy substances in a potato, leaving mainly starch, fat and minerals. Potatoes in the study were simply microwaved, which Vinson said seems to be the best way to preserve nutrients.

The purple potatoes used in the study are becoming more widely available in supermarkets and especially in specialty food stores and farmers' markets. Vinson said that he strongly suspects a future study using white potatoes, now in the planning stages, will produce similar results. Funding for the study came from the United States Department of Agriculture Agricultural Research Service (USDA-ARS) State Cooperative Potato Research Program.