A new study has found that closely following the Mediterranean diet can significantly reduce the risk of dementia, particularly in individuals genetically predisposed to Alzheimer’s disease. Researchers at Mass General Brigham revealed that people carrying two copies of the APOE4 gene — the strongest genetic risk factor for Alzheimer’s — lowered their risk of dementia by at least 35% when adhering to the diet.

Study Findings

The study, published in Nature, followed more than 5,700 people over 34 years. Participants who consumed diets rich in vegetables, fruits, nuts, whole grains, legumes, fish, and olive oil, while minimizing alcohol, red meat, and processed meat, experienced lower dementia risk. The greatest benefit was observed in those with two APOE4 genes. Researchers also found that APOE4 carriers displayed unique metabolic profiles that responded strongly to the nutrients in the Mediterranean diet.

Expert Reactions

Lead author Yuxi Liu noted that improving metabolic function through diet may explain the sharp drop in dementia risk. Neurologist Dr. Richard Isaacson, who was not involved in the study, called the findings groundbreaking. “Hopefully this will change the current dogma that having two copies of the APOE4 is a ‘fait accompli’ for developing Alzheimer’s,” he said, emphasizing that genes “do not have to be your destiny.”

Supporting Evidence

The results build on earlier research. A 2023 UK study of 60,000 people found that those adhering to the Mediterranean diet had up to 23% lower dementia risk. Another study showed that people following Mediterranean and MIND diets were 40% less likely to exhibit Alzheimer’s markers in brain tissue. Even adding one food group, such as vegetables or fruits, lowered amyloid buildup in the brain, effectively making participants biologically “younger.”

Lifestyle and Broader Impact

Experts stress that combining diet with other healthy habits such as regular exercise, stress reduction, quality sleep, and social engagement can further reduce dementia risk. In one case, a patient with two APOE4 genes showed reduced amyloid and tau in his blood and even growth in hippocampal brain volume after adopting lifestyle changes. The Mediterranean diet, emphasizing plant-based foods, olive oil, and fish, remains a cornerstone of these interventions.

Challenges Ahead

Despite these promising findings, future research faces uncertainty. The long-running Nurse’s Health Study and Health Professionals Follow-Up Study, which provided decades of vital data, risk losing their extensive biobank due to halted federal funding. Researchers warn that discarding samples would be a major setback for scientific progress in nutrition and disease prevention.

The study underscores the powerful role diet can play in reducing dementia risk, even among those most genetically vulnerable. While challenges to long-term research remain, the evidence points to the Mediterranean diet as a highly effective tool in protecting brain health and reshaping the future of Alzheimer’s prevention.