Diets low in flavanols may induce age-related memory loss. The corresponding study was published in PNAS.
"The identification of nutrients critical for the proper development of an infant's nervous system was a crowning achievement of 20th century nutrition science," said the study's senior author, Scott Small, MD, the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons, in a press release.
"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."
For the study, the researchers recruited over 3,500 healthy older adults, and randomly assigned them to receive either a flavanol supplement pill containing 500 mg of coca flavonols or a placebo pill for three years.
To begin, the participants completed a survey assessing their diet quality, including foods high in flavanols. They also undertook assessments of their short-term memory at the beginning of the study and once per year for the three-year study period. Over a third of participants additionally provided a urine sample for more accurate measurements of their dietary flavanol levels.
In the end, the researchers found that flavonol supplements increased memory among those in the lowest tertiles of dietary flavonol consumption, although they did not produce significant effects among those in the higher tertiles. They further found that improvements in memory were sustained for at least three years.
The researchers noted that their findings mean that while flavonol supplements may not affect those who are not deficient in flavanols, they may help people who have a deficiency. They noted that to understand flavanols’ effect on the brain, researchers should next conduct a clinical trial aimed at increasing flavanol levels among those with severe flavanol deficiency.
"Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability," said Dr. 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."