Adopting a plant-rich diet in your late 50s and 60s is linked to a lower risk of cognitive impairment, according to research published Wednesday in the journal Neurology. The study suggests that even late-life dietary changes can offer protective benefits for brain health.
Researchers tracked nearly 93,000 participants with an average age of 59. They found that older adults who reduced their intake of unhealthy foods over a decade saw an 11% lower risk of Alzheimer’s and dementia compared to those whose diets remained unchanged.
“It’s never too late to start eating healthy to lower the risk of Alzheimer’s disease and related dementias,” said senior author Unhee Lim, a professor of population sciences at the University of Hawaii Cancer Center.
Quality matters in plant-based eating
The study highlights a critical distinction: not all plant-based diets are created equal. Participants who shifted toward unhealthy plant-based options—such as refined grains, fruit juices, and foods heavy in added sugars—faced a 25% higher risk of developing dementia over the 10-year period.
Dr. David Katz, a specialist in preventive and lifestyle medicine who was not involved in the research, noted that the findings clarify the necessity of dietary quality. "The findings suggest that both plant-predominant eating and high diet quality help protect brain function as we age," Katz said.
Researchers categorized foods into three tiers for the study. The lowest tier included animal fats, dairy, eggs, and meat. The middle tier consisted of less healthy plant-based items like refined grains and potatoes. The top tier—associated with the highest brain protection—included whole grains, fruits, vegetables, nuts, legumes, and tea or coffee.
Experts warn that relying on ultraprocessed vegan foods can undermine health goals. A diet consisting of frozen vegan waffles, sugary sodas, and refined-flour pasta may be plant-based, but it lacks the nutritional profile required to protect the brain.
Whole fruits are preferred over fruit juices, which researchers noted can trigger rapid blood sugar spikes. Fiber in whole fruit helps regulate the release of fructose into the bloodstream, whereas juice floods the system with sugar.
By tracking diet reports at the start and end of a decade-long period, the study team accounted for a diverse group of participants. The findings provide a clear directive for those looking to protect their cognitive function: prioritize whole, unprocessed plant foods to see the greatest benefit.
