A diet that includes abundant amounts of plant foods can help you live longer. The reasons why are many, but a new study puts the spotlight on flavonoids, a specific type of antioxidant found in plant foods. People who regularly eat foods high in flavonoids appear to have a lower risk of dying from cancer, heart disease or any cause.

Flavonoids are found in nearly all fruits and vegetables, as well as nuts, seeds, tea, red wine, dark chocolate and some spices. Studies have found them to be beneficial to bone health and the regulation of blood sugar and blood pressure, and they are also known for their antioxidant and anti-inflammatory properties.

There are many types of flavonoids, so consuming different plant-based foods and beverages ensures that your diet includes a variety of these compounds.

Researchers at Edith Cowman University and the University of Western Australia studied the diets of over 56,000 Danish people, average age of 52, for more than 23 years using information collected through the Danish Diet, Cancer, and Health study for relationships between deaths from cancer, heart disease or all causes.

People who ate the most flavonoid-containing foods were less likely to die from heart disease, cancer or any cause when compared to those who ate the least amount of flavonoid-rich foods. It is likely that the participants’ main sources of flavonoids were tea, chocolate, wine, apples and pears.

Interestingly, this protective effect was strongest for those who were cigarette smokers and those who drank more than two standard servings of alcohol a day. However, eating a flavonoid-rich diet does not undo the damaging effects to the body caused by smoking or excessive consumption of alcohol.

Even among people who eat a high-flavonoid diet, smokers and people who drink too much are at a higher risk of early death. Quitting smoking and reducing alcohol intake are far more beneficial to health than eating more flavonoid-containing foods. But encouraging such people to eat more foods high in flavonoids might reduce, but not eliminate, their increased risk of chronic disease.

Eating about 500 milligrams of total flavonoids a day seemed to create the lowest risk of death from cancer or heart disease.

How do flavonoids work? The exact mechanisms are not yet fully understood, but previous studies have shown that they improve the function of blood vessels and reduce inflammation. This could explain their association with a lower risk of cancer and heart disease, but there is likely more to it than that.

There are many types of flavonoids, so consuming a variety of plant-based foods and beverages ensures that your diet includes many different flavonoids. Getting in 500 milligrams a day of various flavonoids is as easy as eating an apple, an orange, a cup of blueberries, a cup of broccoli and drinking a cup of tea in a day.

The study is published in Nature Communications.