Does fish oil reduce Alzheimer’s risk? What a new US study says
Research suggests that people with high-risk gene variants derive the most substantial cognitive protection from omega-3s and Mediterranean-style eating patterns.
Does fish oil reduce Alzheimer’s risk? What a new US study says
Recent research indicates that a healthy diet and specific nutritional interventions may significantly lower the risk of Alzheimer's disease, particularly for individuals with a genetic predisposition. While general benefits for all older adults remain unclear, new data suggest that those carrying high-risk gene variants derive the most substantial cognitive protection from omega-3s and Mediterranean-style eating patterns.
The Role of Genetics and Diet
A long-term study conducted by researchers at Mass General Brigham and Harvard Medical School tracked 16,497 women and 9,828 men across the US over three decades. The researchers examined the relationship between cognitive changes and adherence to a Mediterranean diet—characterized by fish, olive oil, legumes, nuts, and fresh vegetables.
The study highlighted a specific benefit for the 420 participants with two copies of the APOE4 gene variant, the gene most closely linked to Alzheimer's risk. These individuals were able to cut their risk of developing dementia by 35% by following a diet rich in leafy greens, fiber, and omega-3s.
The APOE4 variant is common, with about 25% of people carrying one copy, which may double or triple the risk of the disease. However, carrying two copies is rarer, affecting roughly 2% to 3% of the global population and increasing the risk of developing Alzheimer's by more than eightfold. For these "4/4" individuals, the lifetime chance of developing the disease is approximately 60%.
Yuxi Liu, the first author of the study, told Business Insider that these findings were not reported by previous studies nor were they expected.
Supplements vs. Whole Foods
Despite the benefits of omega-3s, researchers caution against relying solely on supplements to replicate the effects of a Mediterranean diet. Experts suggest a synergy
exists within whole meals that supplements cannot match. Puja Agarwal, an assistant nutrition professor at the Rush University Alzheimer's Disease Center, explained that the way the body absorbs nutrients from food differs from supplements due to factors like fiber content and gut interaction.
However, a separate clinical trial at Oregon Health & Science University (OHSU), published in JAMA Network Open, found that fish oil supplements specifically benefited a subset of older adults. The trial enrolled 102 participants aged 75 or older with low blood levels of omega-3 fatty acids and high levels of white matter lesions.
While there was no statistically significant difference between the fish oil group and the placebo group for the general population over three years, APOE4 carriers showed a dramatic reduction
in the breakdown of brain cell integrity as early as one year after treatment.
"The fact that neuronal integrity breakdown was slowed in people randomized to omega-3 treatment who are also at high risk for Alzheimer’s disease is remarkable, and warrants a larger clinical trial in more diverse populations in the future."
Gene Bowman, director of clinical trials at the McCance Center for Brain Health, via news.ohsu.edu
Comparative Diet Patterns and Mortality
Other research drawing from the National Health and Nutrition Examination Survey (NHANES) analyzed over 27,000 participants to determine how different eating patterns affect Alzheimer's mortality. The findings indicated that the alternative-Mediterranean diet (aMED) had the strongest correlation with reduced risk.
| Dietary Pattern | Observed Benefit |
|---|---|
| Alternative-Mediterranean (aMED) | 28% lower risk of Alzheimer's death; 31% lower odds of mild cognitive impairment |
| MIND, Healthy Eating Index, Plant-based | 11% to 19% lower odds of mild cognitive impairment |
The Future of Precision Nutrition
Current research is moving toward "precision medicine," where diets are tailored to a person's specific genetic makeup. A new trial at the University of Cincinnati is currently investigating different types of omega-3 supplements to determine which are most effective at reaching the brain.
Robert McNamara, PhD, of the University of Cincinnati, noted that standard fish oil supplements contain triglyceride-bound DHA (TAG-DHA), which may have limited entry into the central nervous system. His study is comparing TAG-DHA to a different form called lysophosphatidylcholine-bound DHA (LPC-DHA). The trial involves 153 adults between 62 and 80 years old who are experiencing mild cognitive decline.
Researchers will monitor participants for 24 weeks, analyzing cerebrospinal fluid and cognitive assessments to see if LPC-DHA produces greater increases in brain DHA levels and positive changes in neurodegenerative biomarkers.
