Closely following a Mediterranean diet can significantly lower the risk of dementia — even in people most genetically vulnerable to Alzheimer’s, according to a 34-year study published Monday in Nature.
Researchers at Mass General Brigham tracked over 5,700 people and found that those who ate a diet rich in vegetables, fruits, nuts, whole grains, legumes, fish and olive oil — and low in alcohol and red/processed meat — had a sharply reduced risk of dementia.
The effect was especially striking in people with two copies of the APOE4 gene, the strongest known genetic risk factor for Alzheimer’s. For them, risk fell by at least 35%.
Lead author Yuxi Liu said people with APOE4 may have distinct metabolic profiles that respond dramatically to healthy nutrients:
“Improving metabolic function through diet might explain, or at least partially explain, the huge fall in dementia risk we saw.”
Neurologist Dr. Richard Isaacson, who was not involved, called the results “stop the presses” findings:
“Genes do not have to be your destiny… If dementia risk can be cut by 35% through diet, imagine the impact when combined with exercise, sleep, and stress management.”
Wider evidence
- A 2023 UK study of 60,000 people linked Mediterranean diet adherence with up to 23% lower dementia risk.
- Another study found people following the Mediterranean or MIND diets had nearly 40% lower odds of Alzheimer’s brain changes at autopsy.
- Even adding one food category, such as vegetables or fruits, reduced amyloid buildup in the brain to the equivalent of being four years younger.
Lifestyle impact
Evidence is mounting that combining diet with exercise, stress reduction and good sleep habits brings the greatest benefit. In one clinical trial, an APOE4 carrier showed reduced amyloid and tau proteins and even growth in hippocampal brain volume after a year of lifestyle changes.
Research threat
The study drew on decades of data and samples from the Nurse’s Health Study and Health Professionals Follow-Up Study, both landmark projects. However, researchers warn their future is at risk after federal funding was cut during the Trump administration’s feud with Harvard. Without support, decades of bio-samples may be discarded.
“It’s like burning the Library of Congress — you just can’t get that back,” said study nurse Martha Dodds.
