2023-05-29 22:37:09
A large-scale study led by researchers from Columbia y Brigham and Women’s Hospital/Harvard is the first to establish that a diet low in flavanols—nutrients found in certain fruits and vegetables—leads to age-related memory loss.
The study published in «Proceedings of the National Academy of Sciences» found that flavanol intake among older adults is associated with lowest scores in tests designed to detect memory loss due to normal aging and that replacement of these bioactive components of the diet in adults older than 60 years with mild flavanol deficiency improves performance in these tests.
“The improvement among study participants on diets low in flavanols was substantial and raises the possibility of using diets or supplements rich in flavanols to improve cognitive function in older adults,” says Adam Brickman, co-director of the study.
The finding also supports the idea that the aging brain You need specific nutrients for optimal health, just as the developing brain needs specific nutrients to develop properly.
“In this century, as we live longer, research is beginning to reveal that different nutrients are needed to strengthen our aging minds. Our study, which is based on biomarkers of flavanol intake, can serve as a model for other researchers to identify other necessary nutrients,” he says, “says lead study author Scott Small.
The current study is based on more than 15 years of research in Small’s lab, linking age-associated memory loss to changes in the dentate gyrus, a specific area of the hippocampus vital for learning new memories, and showing that flavanols improve the function of this brain region .
Other research, conducted in mice, found that flavanols—particularly a bioactive flavanol substance called epicatechin—improved memory by enhancing the growth of neurons and blood vessels in the hippocampus.
Next, Small’s team tested flavanol supplements in people. A small study confirmed that the decrease in consumption was related to cognitive aging. A second, larger trial showed that flavanols improved memory acting selectively on this brain region and had a greater impact in those who started with a poor-quality diet.
The new study, called COSMOS (COcoa Supplements and Multivitamin Outcomes Study), was designed to test the impact of flavanols in a much larger group and explore whether flavanol deficiency drives cognitive aging in this area of the brain.
More than 3,500 healthy older adults were randomly given a daily flavanol supplement (in pill form) or a placebo for three years. The active supplement contained 500 mg of flavanols, including 80 mg of epicatechins, an amount that adults are advised to get from food.
At baseline, participants filled out a survey assessing the quality of their diet, including foods known to be high in flavanols, and underwent a series of activities to assess the types of short-term memory governed by the hippocampus. The tests were repeated after one, two and three years.
More than a third of the participants also provided urine samples that allowed the researchers to measure a biomarker of dietary flavanol levels before and during the study.
Memory improved only slightly in the entire group taking the daily flavanol supplement, most of whom already ate a healthy diet rich in flavanols.
But by the end of the first year of taking the flavanol supplement, participants who reported eating a poorer diet and having lower baseline flavanol levels saw their memory scores increase by an average of 10.5% compared with placebo and 16% compared to their memory at the start of the study. Annual cognitive tests showed that the improvement observed at one year was sustained for at least two more years.
The results suggest that flavanol deficiency is a determinant of age-related memory loss, as flavanol intake was correlated with memory scores and flavanol supplementation improved memory in flavanol-deficient adults. .
The data is consistent with another recent study, which found that flavanol supplements did not improve memory in a group of people with different flavanol levels. The previous study did not look at the effects of flavanol supplements in people with low and high levels of flavanhim separately.
Flavanols only improved memory processes governed by the hippocampus and did not improve memory mediated by other areas of the brain.
“What both studies show is that flavanols have no effect in people who are not flavanol deficient,” Small says.
It is also possible that the memory tests used in the previous study did not assess memory processes in the area of the hippocampus affected by flavanols. In the new study, the flavanols only improved memory processes governed by the hippocampus and did not improve memory mediated by other areas of the brain.
“We still can’t definitively conclude that a low flavanol dietary intake alone causes poor memory performance, because we didn’t do the opposite experiment: depleting flavanols in non-deficient people,” Small says, adding that an experiment of this type could be considered unethical.
The next step needed to confirm the effect of flavanols on the brain, Small says, is a clinical trial to restore flavanol levels in adults with severe flavanol deficiency.
“Age-related memory decline is thought to occur sooner or later in almost everyone, although there is great variability,” says Small. “If some of this variability is due in part to differences in dietary intake of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they are between 40 and 50 years old.
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