A new meta-analysis published in The Journal of Prevention of Alzheimer’s Disease finds that adults who closely follow plant-based diets—particularly those centered on whole, minimally processed plant foods—have a significantly lower risk of developing cognitive impairment and dementia.
The research was conducted by scientists from Tzu Chi University, National Taiwan University, National Yang Ming Chiao Tung University, and National Cheng Kung University. Investigators reviewed prospective cohort studies published through December 2025, focusing on adults age 20 and older who had no cognitive impairment at the start of the studies.
In total, seven studies involving 221,380 participants and 5,668 cases of incident cognitive impairment or dementia were included. The findings show that individuals with the highest adherence to plant-based diets had a 26% lower risk of developing cognitive impairment or dementia compared to those with the lowest adherence.
Researchers evaluated different types of plant-based dietary patterns. Higher scores on overall plant-based diet indices and healthful plant-based diet indices—patterns emphasizing fruits, vegetables, whole grains, legumes and nuts—were linked to lower dementia risk. In contrast, higher adherence to unhealthful plant-based diet indices, which include refined carbohydrates, sweets, sugar-sweetened beverages and trans fats, was associated with an increased risk.
The authors note that while the results point to a meaningful association, there was significant variation between studies and the data are based on observational research. As such, they caution that randomized controlled trials are needed to determine whether plant-based diets directly reduce dementia risk.
Still, the findings add to a growing body of evidence suggesting that diet quality, rather than simply eliminating animal products, plays a key role in long-term brain health.
