SOUTHFIELD (WWJ) – A new study finds a couple of servings of potatoes a day reduces blood pressure for the hypertensive obese.

In the study, 18 overweight and obese people with high blood pressure either ate six to eight small purple potatoes, about the size of a golf ball, with the skins twice daily or no potatoes, as a part of their normal diet for four weeks.

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The results showed that people who ate purple potatoes lowered their diastolic (the bottom number in a blood pressure reading) blood pressure by an average of 4.3 percent and systolic (the top number) by 3.5 percent.

Researchers said that blood pressure-lowering effect is nearly the same as with oatmeal..

Joe Vinson, who led the research for the American Chemical Society, said it only works when the potatoes are baked in a microwave.

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“The microwave is the most gentle processing that you do,” Vinson told WWJ Newsradio 950’s Sandra McNeil. “Anything else, there’s more drop in the antioxidant level in potatoes.”

Although the study used purple potatoes, which can increasingly be found in farmers markets, researchers say red and white potatoes may have similar effects.

Providence Hospital cardiologist Dr. Shukri David is not impressed by the study.

“I’m not certain that that is the best way to reduce your blood pressure. Many folks will use salt added to their baked potatoes, which will increase your blood pressure, and the calories in the potatoes would certainly be a factor,” David said.

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Dr. David said there’s no substitute for weight loss and exercise.