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Ask the Doctors: Can foods rich in flavonoids help reduce blood pressure, improve cognition?

These phytonutrients that give fruits and vegetables their bright colors are associated with a host of health benefits.

Blueberries and blackberries are excellent sources of flavonoids.
Blueberries and blackberries are excellent sources of flavonoids.

Dear Doctors: What are flavonoids? It sounds like if you get enough of them, you’ll have normal blood pressure. Can you get them in regular food?

Answer: Two new studies join a larger body of research that associates flavonoids with a wide range of health benefits.

Flavonoids have anti-inflammatory, antiviral and anti-tumor properties that have been associated with a reduced risk of diseases including cancers, cardiovascular disease and neurodegenerative disorders.

One of the two new studies links the consumption of flavonoid-rich foods to improved blood pressure.

Another study tie the nutrients to less cognitive decline among older adults.

These were observational studies, though, which means they don’t prove cause and effect.

Flavonoids are chemical compounds also called phytonutrients that, beside giving fruits and vegetables their bright colors, are involved in plants’ growth of plants.

The primary dietary sources of flavonoids are fruits, vegetables, some herbs, tea, wine and dark chocolate. Citrus fruits, blueberries, blackberries, cherries, red cabbage, kale, onions, apples, pears, peppers, oregano and parsley are excellent sources.

Flavonoids, which are broken down by the trillions of microbes that live in our gut, are divided into six groups based on their chemical structure. Each offers its own health benefits, which makes it important to eat a varied range of fresh fruit and vegetables.

In the study you heard about, which was published in the American Heart Association journal Hypertension, researchers in Northern Ireland analyzed one year of health and dietary data from 900 study participants and sequenced the genetic composition of bacteria in their guts.

They found that consuming foods rich in flavonoids influenced the composition of the gut microbiome in a way that helped blood pressure. The effect appeared to be especially pronounced in people who ate at least 1 1/2 servings a day of foods rich in flavonoids associated with blue- and red-colored foods, such as blueberries, blackberries and red grapes.

For the other study, in the journal Neurology, Harvard University researchers analyzed 20 years of health and nutritional data from 100,000 women and men and found that people who ate a diet abundant in flavonoids lowered their risk of cognitive decline by as much as 20%. The scientists said they suspect that the antioxidant properties of flavonoids have a protective effect on the blood supply to the brain.

There’s no specific recommendation for how much flavonoids you should get from your diet.

Dr. Eve Glazier and Dr. Elizabeth Ko are internists at UCLA Health.