Natural plant compounds known as polyphenols, found in berries, tea, cocoa, coffee, and extra virgin olive oil, may positively influence biological processes linked to Alzheimer’s disease and other disorders characterized by the gradual loss of nerve cells, according to a review by researchers at Semmelweis University. The analysis, published in Nutrients, suggests that these bioactive compounds may contribute to healthy brain aging.
Researchers at Semmelweis University reviewed the findings of hundreds of previous laboratory, animal, population-based, and clinical studies. The studies reviewed suggest that polyphenols may support nerve cell function through their antioxidant and anti-inflammatory properties while helping counteract harmful processes associated with brain aging.
Nature’s Hidden Bioactive Compounds
Bioactive compounds, including polyphenols, are naturally occurring substances found in plants, animals, and microorganisms. Although they are not considered essential nutrients like vitamins or minerals, their biological activity may help support normal bodily functions and overall health
Particular attention has been paid to the Mediterranean diet, which is rich in vegetables, fruits, legumes, whole grains, fish, and olive oil, as well as the MIND diet, which is based on Mediterranean dietary principles. The MIND diet was specifically developed to support brain health by emphasizing leafy green vegetables and berries while limiting the consumption of red meat, butter, cheese, sweets, and fried and fast foods
Among the compounds frequently examined in the reviewed studies were EGCG, one of the main antioxidants found in green tea; the pigments responsible for the color of berries; flavanols found in cocoa; and curcumin, the compound that gives turmeric its characteristic yellow color. These compounds are commonly found in plant-based diets, including the Mediterranean diet.
“Polyphenols are not miracle cures, but research suggests they may be promising tools for supporting healthy brain aging. The focus, however, should not be on dietary supplements but on a varied diet rich in plant-based foods,” said Dr. Mónika Fekete, Assistant Professor at the Institute of Preventive Medicine and Public Health of Semmelweis University and senior author of the study.
A substantial proportion of polyphenols is not absorbed directly. Instead, they are transformed by bacteria living in the gut into compounds that may influence inflammatory processes, cellular energy metabolism, and, through these mechanisms, nervous system function. Because the composition of the gut microbiome varies considerably from person to person, the same foods may not produce identical biological effects in everyone
“This may help explain why the same diet does not affect everyone in the same way. In the future, personalized nutrition could help us better understand who is most likely to benefit from a polyphenol-rich diet,” said Dr. Noémi Mózes, Assistant Professor at the Institute of Preventive Medicine and Public Health of Semmelweis University and first author of the study.
According to the World Health Organization (WHO), more than 55 million people worldwide are living with dementia, and that number is expected to rise in the coming decades. Dementia is one of the most significant health challenges associated with aging, which is why growing attention is being paid to lifestyle factors – including diet – that may help maintain brain health and reduce the risk of cognitive decline
The researchers emphasize that despite encouraging findings from human studies, there is currently insufficient evidence to recommend any single food or nutrient as a stand-alone strategy for preventing dementia.
According to the authors, healthy brain aging depends not on any one “superfood” but on long-term eating habits. In other words, there is currently no miracle diet that can prevent Alzheimer’s disease. However, existing evidence suggests that regularly eating more vegetables, fruits, berries, fiber-rich foods, fish, and nuts while limiting highly processed foods may help support healthy brain aging and preserve cognitive function over time.
Robert Cseszregi
Photo: Bálint Barta – Semmelweis University and dr. Noémi Mózes
Cover: iStock by /tbralnina
