Eating colourful fruits and vegetables may lower dementia risk by up to 20%

February 18, 2022

Eating brightly coloured fruit and vegetables on a daily basis may reduce the risk of developing dementia by as much as 20%, according to results of a new study.

Foods such as strawberries, oranges, peppers and apples have a protective effect on the brain due to high levels of flavonoids, a naturally occurring compound.

Scientists at Harvard University studied the diets of more than 77,000 middle-aged men and women over 20 years, asking them how often they ate particular foods containing flavonoids.

The participants were asked to report their levels of cognitive decline twice during the study by answering seven questions about their memory and cognitive function. They answered questions such as: “Do you have more trouble than usual remembering recent events?” and “Do you have more trouble than usual remembering a short list of items?”

Researchers found that the people who ate the most flavonoid-rich foods (around 600 milligrams per day), had a 20% less risk of cognitive decline than those eating 150mg each day. 

The researchers also looked at individual flavonoids. Flavones, found in some spices and yellow or orange fruits and vegetables, had the strongest protective qualities, and were associated with a 38% reduction in risk of cognitive decline, which is the equivalent of being three to four years younger in age. 

Study author Walter Willett, MD, DrPH, of Harvard University said: “There is mounting evidence suggesting flavonoids are powerhouses when it comes to preventing your thinking skills from declining as you get older.

“Our results are exciting because they show that making simple changes to your diet could help prevent cognitive decline.”

What are flavonoids and why are they important to brain health?

Flavonoids are polyphenols – powerful antioxidants which occur naturally in plants. There are several different types, including: flavonols, flavones, flavanones, flavan-3-ols, anthocyanins, polymeric flavonoids, and proanthocyanidins.

They are thought to help the brain by boosting blood flow, which delivers more oxygen and nutrients, such as glucose, to the brain. This helps give more energy to neurons, the cells which run our brains. 

The people in the study who did the best over time ate at least half a serving per day of foods like orange juice, oranges, peppers, celery, grapefruits, grapefruit juice, apples and pears.

Dr Willett said: “While it is possible other phytochemicals are at work here, a colorful diet rich in flavonoids—and specifically flavones and anthocyanins—seems to be a good bet for promoting long-term brain health. And it’s never too late to start, because we saw those protective relationships whether people were consuming the flavonoids in their diet 20 years ago, or if they started incorporating them more recently.”

What foods are high in flavonoids?

It’s not only fruit and vegetables that contain flavonoids – some drinks such as tea and red wine, as well as dark chocolate also contain high levels.

Some foods are higher in flavonoids than others, but to keep it simple, opt for foods which have the most intense colour, such as blueberries, oranges and spinach.

  • Apples
  • Blackberries
  • Blueberries
  • Broccoli
  • Celery
  • Cherries
  • Citrus fruit e.g. limes and lemons
  • Dark chocolate
  • Grapefruit
  • Kale
  • Onions
  • Oranges
  • Parsley
  • Pears
  • Peppers
  • Red cabbage
  • Red wine
  • Spinach
  • Strawberries
  • Tea – especially green tea

How to eat well for good brain health

It’s important to maintain a balanced, varied and healthy diet to keep your brain in good shape as you get older. That includes eating flavonoid-rich foods. 

Take a look at our guide to nutrition to find out what the best foods are for optimum brain health.