From VOA Learning English, this is the Health & Lifestyle report.

We may not need another study telling us that fruits and vegetables are good for our bodies. But research and studies can help us to understand how foods affect our bodies in good ways and bad.

Researchers at the University of Southern California's Keck School of Medicine have found another great reason to eat more fruits and vegetables. They say that potassium-rich foods like sweet potatoes, avocados, spinach and bananas could help to lower your blood pressure.

High blood pressure, or hypertension, is an international problem. Experts at the World Health Organization say more than one billion people suffer from high blood pressure. The condition causes 51 percent of deaths from stroke and 45 percent of deaths due to heart disease.

Health officials in the U.S. say heart disease and stroke together kill more Americans each year than any other cause. Years of research have linked sodium, or salt, intake to increased blood pressure. So, officials advise people to use salt in moderation.

Experts at the United States Centers for Disease Control and Prevention say Americans get most of their sodium -- about 75 % -- from processed foods and eating at restaurants.

This is a good reason to eat fresh food prepared at home.

Alicia McDonough is a professor of cell and neurobiology at the Keck School of Medicine. She led this recent study.

McDonough says that eating less sodium is a well-known way to lower blood pressure. But she also says evidence suggests that eating more potassium may have an equally important effect on hypertension.

For her research, she examined studies that looked at the link between potassium and sodium.

McDonough found that people who ate more potassium generally had lower blood pressure unconnected to how much sodium they ate. Her research suggests that the body does creates a balance, using sodium to control potassium levels in the blood.

"When dietary potassium is high," she says, "kidneys excrete more salt and water, which increases potassium excretion." This process cleans the kidneys.

She explains that as humans evolved, they ate a diet rich in potassium, but low in sodium. This has lead us to crave sodium, not potassium.

"If you eat a typical Western diet," she says, "your sodium intake is high and your potassium intake is low." She adds that this greatly "increases your chances of developing high blood pressure."

McDonough published her study in the April 2017 issue of the American Journal of Physiology - Endocrinology and Metabolism.

Health experts at the CDC agree that "eating enough potassium each day can help balance out some of the harmful effects that high sodium intake can have on blood pressure." However, they also say that eating less sodium is important as well.

On its website, the CDC lists these fruits and vegetables -- and other foods -- as being good sources of potassium.

• potato, baked with skin
• leafy greens such as cooked beet greens, spinach and Swiss chard
• bananas
• sweet potato, baked in skin
• fruit and vegetable juices such as prune, carrot, pomegranate, tomato and orange
• acorn squash
• plain nonfat yogurt
• beans and lentils
• soybeans
• and some types of fish such as salmon, mackerel, tuna and halibut

But how much potassium should we eat each day?

A 2004 study by the Institute of Medicine shows adults should eat about 4.7 grams of potassium a day to lower blood pressure. McDonough says eating about 60 grams of beans would provide 50 percent of that.

And that's the Health & Lifestyle report.

I'm Anna Matteo.

Anna Matteo adapted this VOA News story for Learning English using additional information from the Centers for Disease Control and Prevention. Caty Weaver was the editor.

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hypertension – n. medical : high blood pressure

neurobiology – n. medical : a branch of the life sciences that deals with the anatomy, physiology, and pathology of the nervous system

excrete - v. to pass (waste matter) from the body or from an organ in the body

crave - v. to have a very strong desire for (something): to want something very badly

intake - n. the amount of something (such as food or drink) that is taken into your body

physiology – n. medical : a science that deals with the ways that living things function

endocrinology – n. medical : a branch of medicine concerned with the structure, function, and disorders of the endocrine glands

metabolism - n. the chemical processes by which a plant or an animal uses food, water, etc., to grow and heal and to make energy