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Experts say the anti-inflammatory properties of flavonoid-rich foods, such as apples, may help reduce the risk of cancer and heart disease. Getty Images
  • Researchers say foods rich in flavonoids, such as apples and green tea, can reduce your risk for cancer and heart disease.
  • The research indicated that consuming 500 milligrams of flavonoids per day reduced the risk of disease.
  • Additional flavonoid consumption didn’t lower the risk of heart disease more, but extra flavonoids did decrease the risk of cancer more.

An apple a day could help keep cancer and heart disease away.

And the same applies to other foods, such as green tea, that are rich in flavonoids. These are plant nutrients known to reduce inflammation and act as potent antioxidants.

People who ate more flavonoid-rich foods were less likely to die of cancer and heart disease than those who ate fewer such foods, according to a new report published in the journal Nature Communications.

The protective effects of flavonoids are particularly strong for people who heavily use alcohol or smoke, according to the study led by researchers from Edith Cowan University in Australia.

The findings come from an analysis of the diets consumed by more than 53,000 Danish people over a 23-year period.

Nicola Bondonno, PhD, a postdoctoral research fellow at Edith Cowan University and a lead researcher of the study, says the findings should encourage people to eat more fruits and vegetables, especially if they have a high risk for cancer or heart disease.

Past research estimates 7.8 million people worldwide die prematurely each year due to low fruit and vegetable consumption. That’s defined as eating less than 800 grams total per day.

“The best thing to do for your health is to not smoke and cut down on alcohol,” Bondonno told Healthline. “But these kind of lifestyle changes can be challenging, so encouraging flavonoid consumption might be a novel way to alleviate the increased risk while also encouraging people to quit smoking and reduce their alcohol intake.”

The study found that consuming about 500 milligrams (mg) of flavonoids daily seemed to provide the greatest protection against disease.

No added protection against heart disease or all-cause mortality was observed for nonsmokers and moderate drinkers who consumed a higher level of flavonoids.

However, protection against cancer seemed to increase for up to 1,000 mg of flavonoids consumed daily.

“These levels exist well within daily dietary achievable limits,” the study noted.

“This is a remarkable study that contains convincing evidence that what we eat can improve health outcomes — something we initiatively know,” Dr. William Li, author of the book “Eat to Beat Disease: The New Science of How Your Body Can Heal Itself” and president of the Angiogenesis Foundation, told Healthline. “Flavonoids can play a more powerful role in nutrition than we thought.”

“These types of results shed light on the possibility of fixed doses of nutrients being studied for their health benefits,” Li said. “We may not all need to become vegans to improve health.”

Foods containing flavonoids include fruits, vegetables, dark chocolate, tea, and red wine.

“No one flavonoid or compound stands alone,” Teresa Baczkowski, manager of clinical nutrition at the Adventist Health White Memorial Hospital in Los Angeles, told Healthline. “It’s the balance of these and other compounds in natural foods that keeps us healthy.”

“It’s important to consume a variety of different flavonoid compounds found in different plant-based food and drink,” Bondonno said.

“This is easily achievable through the diet. One cup of tea, one apple, one orange, 100 grams of blueberries, and 100 grams of broccoli would provide a wide range of flavonoid compounds and over 500 mg of total flavonoids,” she said.

More than 6,000 compounds found in plant-based foods have been identified as flavonoids.

The Australian researchers were unable to pinpoint why flavonoids seem to protect against cancer and heart disease, but Bondonno suspects their anti-inflammatory action may play a role.

“Alcohol consumption and smoking both increase inflammation and damage blood vessels, which can increase the risk of a range of diseases,” Bondonno said.

“Flavonoids have been shown to be anti-inflammatory and improve blood vessel function, which may explain why they are associated with a lower risk of death from heart disease and cancer,” she said.

A 2017 study published in the International Journal of Epidemiology also found that flavonoids seem to inhibit the growth of cancer cells.

“Tobacco smoke limits absorption of nutrients in the gut and draws upon the need for increased vitamin C and the variety of these compounds found in fruits and vegetables,” Baczkowski said.

A potential follow-up study will look at which types of flavonoids best protect against cancer and heart disease, Bondonno says.

Dr. Anton J. Bilchik, chief of medicine at the John Wayne Cancer Institute in Santa Monica, California, praises the study for its long-term follow-up. He says it has important implications for healthcare.

“This study adds to the growing body of literature, which shows how important nutrition is in both the prevention of heart disease and cancer,” Bilchik told Healthline.

“Further studies need to be done to explain why there’s more benefit in smokers and drinkers. The anti-inflammatory theory proposed by the authors is important, but needs to be further explored,” he said.