If apples, pistachios, cocoa and tea don’t show up often in your diet, consider incorporating them into your regular menu.
Thanks to their flavanol content, doing so can mitigate age-related memory loss. That’s according to new research from Columbia University and Brigham and Women’s Hospital, an affiliate of Harvard Medical School.
Here’s what to know about the study, plus the best foods to boost your daily flavanol intake.
What are flavanols?
Flavanols belong to the flavonoid family, a large group of more than 6,000 protective plant compounds found in fruits, vegetables and many other plant foods.
Specifically, you’ll find flavanols in apples, apricots, strawberries, peaches, plums, cocoa powder, dark chocolate, tea, pecans, pistachios and cinnamon.
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It’s thought that flavanols benefit cognitive health by increasing the growth of neurons and blood vessels in the hippocampus, the region of the brain involved in learning and memory. (Neurons are specialized cells in the brain and nervous system which receive and transmit information.)
The U.S. Academy of Nutrition and Dietetics recommends consuming 400 to 600 mg of dietary flavonol, advice that’s largely based on evidence that suggests a flavanols help improve cardiometabolic health – e.g., blood pressure and cholesterol, triglyceride and glucose levels.
Normal cognitive aging
As we age our brain shrinks and there’s a decline in its receptors for neurotransmitters, chemicals that send messages from the brain to other body tissues. The number of synapses, the places where neurons connect and communicate with each other, also decrease.
These age-related changes contribute to minor cognitive deficits in memory, processing speed, attention, reasoning, planning, problem solving and multitasking.
About the new research
The randomized controlled trial, published May 29 in the journal Proceedings of the National Academy of Sciences, set out to determine if flavanols lessen age-related memory decline in healthy older adults.
The study, called COSMOS-Web, assigned 3,562 participants, average age 71, to receive a daily 500 mg cocoa flavanol supplement or a placebo pill for three years. COSMOS stands for COcoa Supplement and Multivitamin Outcomes Study.
At the beginning of the trial all participants completed a survey that assessed the quality of their usual diet.
They also performed a series of web-based cognitive tests designed to detect short-term memory loss from normal aging. Cognitive tests were repeated every year for the duration of the study.
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Overall, memory scores improved only slightly for the group taking flavanol supplements. When the researchers considered diet quality, however, memory scores varied.
After year one of flavanol supplementation, participants with low diet quality scores saw their memory scores increase by 10 per cent compared to the placebo group and 16 per cent compared to their baseline cognitive score.
These improvements, albeit modest, were sustained for the remainder of the study.
Taking flavanol supplements did not improve short-term memory in people who had higher diet quality scores and were already consuming lots of flavanols.
These findings, which build on past studies linking flavanols to healthy brain aging, suggest that a low-flavanol diet might drive age-related memory loss.
They also support the notion that, just as certain nutrients are vital for a developing brain, specific nutrients also strengthen an aging brain.
This trial is notable for its large size and long duration. Study participants were predominately white and highly educated, so the findings may not be applicable to different people.
Eat these foods to get your daily flavanols
You don’t need to rely on a supplement to get 500 mg of flavanols each day.
Doing so is very achievable through diet. Plus, flavanol-rich foods come packed with other protective nutrients and phytochemicals.
Consider that an eight-ounce cup of green tea delivers 332 mg of flavanols; eight ounces of black tea contains 273 mg.
A medium-sized Red Delicious apple has 271 mg of flavanols, one cup of sliced strawberries serves up 236 mg, two plums have 291 mg and a medium-sized peach has 104 mg.
You’ll find 237 mg of flavanols in one-quarter cup of pistachios (49 kernels) and 123 mg in one-quarter cup of pecan halves.
One half-teaspoon of cinnamon contains 105 mg of flavanols and one tablespoon of unsweetened cocoa powder has 75 mg.
Don’t count on dark chocolate to get your daily flavanols, though.
Chocolate with higher percentages of cocoa solids do have higher amounts of flavanols. But even dark chocolate bars with a higher per cent of cocoa solids can have varying levels of flavanols.
That’s because cocoa flavanols are often destroyed by a number of steps in cocoa processing. As a result, the flavanol content of dark chocolate can vary considerably. Sorry to disappoint.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD