The study included more than 3,500 people who were mostly white and around 71 years old. Participants were randomly assigned a daily supplement in pill form containing the recommended amount of 500 milligrams of flavonols, or a placebo pill. Participants completed a survey about the quality of their diets at the beginning of the study and then performed online activities at home to evaluate the short-term memory controlled by the hippocampus part of the brain. The tests were repeated each year and more than a third of participants also supplied urine samples so that researchers could measure dietary flavonol levels.

How flavonols impact memory

While memory scores improved slightly for the group taking the daily flavonol supplement, it was determined that many of the participants were already eating a diet high in flavonols; however, researchers found that participants who reported an unhealthy diet and had lower baselines levels of flavonols saw their memory scores improve by an average 10.5% compared to those who were taking the placebo and 16% compared to their memory at baseline.

Essentially, the supplements do not have an effect on people who don’t have a flavonol deficiency, but they can help reverse memory loss in those who do not consume enough flavonols in their daily diets.

“The improvement among study participants with low-flavonol diets was substantial and raises the possibility of using flavonol-rich diets or supplements to improve cognitive function in older adults,” Adam M. Brickman, PhD, professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons and co-leader of the study, said in a press release about the study.

What to eat (and what not to eat) to get your flavonols

Foods that are naturally high in flavonols include:

• Apples
• Blackberries
• Broad beans
• Cherries
• Grapes
• Pears
• Raspberries
• Cocoa
• Tea leaves

Although flavonols can be extracted from cocoa, eating chocolate is not thought to provide the recommended amount of flavonols as they are destroyed in processing. While it’s generally better to consume vitamins and nutrients through whole foods rather than supplements, you can consult with your doctor to determine whether supplements are right for you.

While researchers cannot definitively conclude whether low dietary intake of flavonols alone causes poor memory performance, they agree the next step is a clinical trial to restore flavonol levels in adults who are deficient.

“Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability,” said the study’s senior author, Dr. Scott A. Small, the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons, in the press release. “If some of this variance is partly due to differences in dietary consumption of flavonols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavonols when they’re in their forties and fifties.”