Memory restored
When participants in the lowest tertile consumed the supplement, “their flavanol levels went back to normal, and when that happened, their memory was restored,” said Dr. Small.
It appears that there is a sort of ceiling effect to the flavanol benefits. “It seems what you need to do is normalize your flavanol levels; if you go above normal, there was no evidence that your memory keeps on getting better,” said Dr. Small.
The study included only older adults, so it’s unclear what the impact of flavanol supplementation is in younger adults. But cognitive aging “begins its slippery side” in the 40s, said Dr. Small. “If this is truly a nutrient that is taken to prevent that slide from happening, it might be beneficial to start in our 40s.”
He recognized that the effect size is not large but said this is “very dependent” on baseline factors and most study participants had a rather healthy diet. “None of our participants were really highly deficient” in flavanols, he said.
“To see a stronger effect size, we need to do another study where we recruit people who are very low, truly deficient, in flavanols, and then see what happens.”
Showing that flavanols are linked to the hippocampal and not to the prefrontal component of cognitive aging “speaks to the mechanism,” said Dr. Small.
Though the exact mechanism linking flavanols with enhanced memory isn’t clear, there are some clues; for example, research suggests cognitive aging affects the dentate gyrus, a subregion of the hippocampus.
The flavanol supplements were well tolerated. “I can say with close to certainty that this is very safe,” said Dr. Small, adding the flavanols have now been used in numerous studies.
The findings suggest flavanol consumption might be part of future dietary guidelines. “I suspect that once there is sufficient evidence, flavanols will be part of the dietary recommendations for healthy aging,” said Dr. Small.
A word of caution
Heather M. Snyder, PhD, vice president of medical and scientific relations, Alzheimer’s Association, said that though science suggests a balanced diet is good for overall brain health, no single food, beverage, ingredient, vitamin, or supplement has yet been proven to prevent dementia, treat or cure Alzheimer’s, or benefit cognitive function or brain health.
Experts agree the best source of vitamins and other nutrients is from whole foods as part of a balanced diet. “We recognize that, for a variety of reasons, this may not always be possible,” said Dr. Snyder.
However, she noted, dietary supplements are not subject to the same rigorous review and regulation process as medications.
“The Alzheimer’s Association strongly encourages individuals to have conversations with their physicians about all medications and dietary supplements they are currently taking or interested in starting.”
COSMOS is supported by an investigator-initiated grant from Mars Edge, a segment of Mars, company engaged in flavanol research and flavanol-related commercial activities, which included infrastructure support and the donation of study pills and packaging. Small reports receiving an unrestricted research grant from Mars.
A version of this article first appeared on Medscape.com.