High-quality plant-based diets linked to lower dementia risk

Eating a higher quality plant-based diet is associated with a lower risk of Alzheimer's disease and other related dementias compared to eating a lower quality plant-based diet, according to a study published April 8, 2026, in Neurology®, the medical journal of the American Academy of Neurology. While the study shows an association based on observations, it does not prove that a higher quality plant-based diet causes a lower risk of dementia.

Researchers looked at three plant-based diets. The overall plant-based diet prioritizes eating more plant foods than animal products like meat, milk and eggs, without looking at quality. The healthful plant-based diet prioritizes healthy plant foods like whole grains, fruits, vegetables, vegetable oils, nuts, legumes and tea and coffee. The unhealthful plant-based diet includes less healthy plant foods like refined grains, fruit juices, potatoes and added sugars. Researchers did not look at vegetarian or vegan diets.

"Plant-based diets have been shown to be beneficial in reducing the risk of diseases like diabetes and high blood pressure, but less is known about the risk of Alzheimer's disease and other dementias," said study author Song-Yi Park, PhD, of the University of Hawaii at Manoa's Cancer Center in Honolulu. "Our study found that the quality of a plant-based diet mattered, with a higher quality diet associated with a reduced risk, and a lower quality diet associated with an increased risk."

The study involved 92,849 people with an average age of 59 at the start of the study. It included African American, Japanese American, Latino, Native Hawaiian and white participants. They were followed for an average of 11 years. During that time, 21,478 people developed Alzheimer's disease or another related dementia.