You can do something about those “senior moments” where you forget a name or the place you put your keys. And if you are in your forties, you can probably do even more.

Your diet is one of the biggest contributors to age-related memory loss. A diet deficient in flavanols — nutrients found in certain fruits and vegetables — has been found to be linked to memory problems. The good news is these types of memory issues are reversible. A study led by researchers at Columbia and Harvard's Brigham and Women’s Hospital found that when older adults overcame their flavanol deficiency, either by eating more of certain fruits and veggies or taking a supplement, their memory scores improved.

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

The results strongly suggest that flavanol deficiency is a driver of age-related memory loss. People with low flavanol consumption had a 16 percent increase in their memory scores after a year of taking the flavanol supplement.

“In this century, as we are living longer, research is starting to reveal that different nutrients are needed to fortify our aging minds. Our study, which relies on biomarkers of flavanol consumption, can be used as a template by other researchers to identify additional, necessary nutrients,” the study's senior author, Scott Small, Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons, explained in a statement.

The study builds on more than 15 years of research linking age-related memory loss to changes in a specific area within the brain’s hippocampus — a region vital for learning new memories — by Small’s lab. Their has work found that flavanols improved function in a particular part of this brain region, the dentate gyrus.

Earlier research in mice showed that epicatechin, a substance in flavanols, enhanced the growth of neurons and blood vessels and in the hippocampus, thus improving memory. Other earlier work tested flavanol supplements in people. One study confirmed that the dentate gyrus is linked to cognitive aging. A second, larger trial showed that flavanols improved memory by acting selectively on this brain region and had the most impact on those starting out with a diet deficient in flavanols.

The current study tested the impact of flavanols in a much larger group of people. A collaboration of researchers affiliated with Columbia University, Harvard University and University of Reading in the United Kingdom explored whether flavanol deficiency drives cognitive aging in this area of the brain.

More than 3,500 healthy older adults were randomly assigned to receive a daily supplement of 500 mg of cocoa flavanols per day (in pill form) or placebo pill for three years. The active supplement contained an amount that adults are advised to get from food: 500 mg of flavanols, including 80 mg epicatechins.

All the participants completed a survey that assessed the quality of their diet, including foods known to be high in flavanols, at the study’s start. At one point each year for the next three years participants performed a series of web-based activities in their own homes to assess the types of memory controlled by the hippocampus. The tests of short-term memory were repeated for all three years.

Urine samples made it possible for researchers to more precisely measure flavanol levels of over a third of the participants, using a method developed by study co-authors at Reading University. It also helped researchers make sure that participants were sticking to their assigned regimen and to determine if flavanol levels corresponded to performance on the cognitive tests.

“Age-related memory decline is thought to occur sooner or later in nearly everyone…If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they’re in their 40s and 50s.”

Participants’ flavanol levels varied moderately, but none were seriously deficient.

Taking flavanols made a big difference among those participants who were somewhat deficient, however. Participants taking flavanols, who had lower levels of flavanols at the start, saw their memory scores increase by an average of 10.5 percent by the end of the first year of flavanol supplementation. And when compared to their memory scores at baseline, scores in this group increased by 16 percent.

Annual testing showed this improvement observed at one year was sustained for at least two more years.

The results strongly suggest that flavanol deficiency is a driver of age-related memory loss. Flavanol consumption was positively correlated with memory scores, and flavanol supplements improved memory in flavanol-deficient adults. Adults with adequate flavanol levels did not enjoy a bigger memory boost from taking a flavanol supplement however.

The study did not prove that low dietary intake of flavanols alone causes poor memory performance. Such an experiment — depleting flavanol in people who are not deficient to see if their memories suffered — Small explained, might well be considered unethical.

Confirming flavanols’ effect on the brain in a clinical trial is the next step. “Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability,” said Small. “If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they’re in their 40s and 50s.”

The study is published in PNAS, Proceedings of the National Academy of Science.