Updated 07 February 2018

Could spuds be bad for blood pressure?

Researchers suggest that replacing one serving a day of potatoes with a non-starchy vegetable might lower the risk of high blood pressure.

Potatoes are a popular staple of the American diet, but eating too many – whether boiled, baked, mashed or fried – may raise the risk for high blood pressure, a new study suggests.

Risk of hypertension

Consuming four or more servings of potatoes a week was linked with an increased risk for high blood pressure – 11 percent for baked, boiled or mashed and 17 percent for fried – compared with eating less than one serving a month. Surprisingly, potato chips didn't appear to increase the risk, the Harvard researchers reported.

"We hope that our study continues the conversation about potatoes and the risk of hypertension and other diseases," said lead researcher Dr Lea Borgi, of the renal division at Brigham and Women's Hospital in Boston.

But one dietitian not involved with the study suggested the blame shouldn't rest with potatoes, but with the add-ons people put on their spuds – such as sour cream and bacon bits.

Read: Should government ban junk food?

For the study, Borgi and her colleagues followed more than 187,000 men and women who took part in three large U.S. studies for more than 20 years. During that time, participants filled out questionnaires about their diet. None of the participants had high blood pressure at the beginning of the study.

Potatoes have what's called a high glycemic index compared with other vegetables. And, that can trigger a sharp rise in blood sugar, which might explain the findings, Borgi said. The glycemic index measures how carbohydrates raise blood sugar.

Borgi pointed out that this study didn't prove potatoes cause high blood pressure, only that they seem to be associated with an increased risk.

High potassium content

Nevertheless, the researchers suggested that replacing one serving a day of potatoes with a non-starchy vegetable might lower the risk of high blood pressure.

Because of their high potassium content, potatoes have recently been included as vegetables in the U.S. government's healthy meals program, the researchers noted.

Read: Potatoes, an affordable source of precious potassium

"Our findings have potentially important public health ramifications, as they don't support the health benefits of including potatoes in government food programs," Borgi said.

The report was published in the journal BMJ.

One nutrition expert said it's not potatoes that are the problem as much as all the fixings people put on them.

"The poor potato's reputation gets dinged again with this study," said Samantha Heller, a senior clinical nutritionist at New York University Medical Centre in New York City.

Potatoes have been a staple in human diets for centuries, long before high blood pressure was the problem it is today, she said.

Part of a balanced diet

"Americans ate, on average, close to 50 pounds of potatoes per person in 2013, the bulk of which came from french fries," Heller said. "As a dietitian, I am not sure I can even classify commercial french fries as potatoes. They have been transformed into sticks of grease, salt, trans fats and who knows what else?" she said.

And while potatoes are a good source of vitamin C, potassium, minerals, energy and fibre (if not peeled), the reality is most Americans eat potatoes coated in salt, slathered in butter or loaded with sour cream, cheese and bacon bits, Heller said.

Read: Potatoes are good for the heart

"It is no wonder that researchers found that high consumption was associated with poor health," she said.

But potatoes can be a healthy part of a balanced diet, Heller said.

"You can make mashed potatoes with olive oil, non-fat milk or soy milk and add mixed herbs and spices. I do not peel the potatoes and I mix in vegetables, such as sauteed spinach and garlic," she said.

Baked potatoes are also great with salsa, Heller said.

"But watch portions," she added. "For example, today's russet potatoes can be the size of a city bus. Alternate potatoes with other whole grain starches like brown rice or pasta. And remember, only about a quarter of your plate should be taken up with starchy foods."

Efforts made by HealthDay News to reach the National Potato Council for comment on the study were unsuccessful.

Read more:

Overeating potatoes is linked to gestational diabetes

Why you should eat potatoes

The Americans only count tomatoes, potatoes and lettuce as veg


Ask the Expert

Hypertension expert

Dr Jacomien de Villiers qualified as a specialist physician at the University of Pretoria in 1995. She worked at various clinics at the Department of Internal Medicine, Steve Biko Hospital, these include General Internal Medicine, Hypertension, Diabetes and Cardiology. She has run a private practice since 2001, as well as a consultant post at the Endocrine Clinic of Steve Biko Hospital.

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