November 6, 2025, Sioux Falls, SD: A new study published in The Journal of Nutrition reveals that higher levels of certain omega-3 fatty acids in the blood — particularly DHA and
ALA — are associated with better cognitive performance over time in middle-aged adults at high risk of developing Alzheimer’s disease (AD).
The research, conducted within the ALFA (Alzheimer and Families) Study, followed 323 cognitively unimpaired participants over three years. By analyzing red blood cell (RBC) concentrations of three omega-3 fatty acids — docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and alpha-linolenic acid (ALA) — researchers discovered that participants with higher DHA levels showed slower cognitive decline, while higher ALA levels were linked to stronger visual processing abilities.
Key Findings
- DHA and global cognition: Participants with higher DHA levels demonstrated a more favorable rate of change in overall cognitive performance, measured using the Preclinical Alzheimer Cognitive Composite (PACC)
- ALA and visual processing: Higher blood levels of plant-derived ALA were linked to improved performance in visual processing tasks.
- EPA not significantly associated: No statistically significant associations were observed between EPA and cognitive performance.
- Consistency across risk groups: The associations between omega-3 status and cognition were similar regardless of sex, APOE-ε4 genotype (a key genetic risk factor for AD), or underlying Alzheimer’s pathology detected through cerebrospinal fluid (CSF) biomarkers.
The ALFA+ cohort, a subset of the larger ALFA project, includes middle-aged individuals (aged 45–74 years) with a family history of Alzheimer’s or other risk factors. All participants were cognitively healthy at baseline but genetically or clinically predisposed to AD.
Researchers measured omega-3 fatty acid levels in red blood cells — a more stable and long-term indicator of dietary intake and metabolism than plasma measurements. Participants underwent a comprehensive battery of cognitive tests at baseline and again three years later, assessing domains such as memory, attention, executive function, language, and visual processing.
The study’s statistical models controlled for several variables, including age, sex, education, physical activity, Mediterranean diet adherence, and APOE-ε4 status. Even after accounting for these factors, DHA emerged as a significant predictor of better cognitive trajectories.
“Our findings reinforce the idea that diet-linked omega-3 fatty acids are important for long-term brain health,” said Dr. Aleix Sala-Vila, Research Scientist at the Fatty Acid Research Institute (FARI) and principal investigator at Hospital del Mar Research Institute and senior researcher in the ALFA project.
“While DHA from fish has long been associated with brain structure and function, our results also point to potential benefits from ALA, a plant-based omega-3 fatty acid, which may be particularly relevant for people with low fish consumption.”
Alzheimer’s disease remains the leading cause of dementia worldwide, with limited options for treatment once symptoms appear. Identifying modifiable lifestyle and nutritional factors that can delay or prevent disease onset has become a major global health priority.
The ALFA study’s focus on individuals in the preclinical phase of Alzheimer’s — those who show no symptoms but carry biological or genetic risk markers — offers critical insight into early preventive strategies.
“These results suggest that maintaining adequate omega-3 fatty acid levels through diet or supplementation may help preserve cognitive function before the onset of Alzheimer’s symptoms,” said Dr. Bill Harris, Founder of OmegaQuant, and President of the Fatty Acid Research Institute (FARI). “Longer and larger studies, including randomized clinical trials, are needed to confirm causality.”
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Study Link: Red blood cell omega-3 status and longitudinal cognition in individuals at risk for Alzheimer’s Disease
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About OmegaQuant:
OmegaQuant is an independent, CLIA-certified lab that offers nutritional status testing to researchers, clinicians and the public. OmegaQuant performs analysis in Sioux Falls, SD, for commercial and academic research collaborators, and for consumers interested in monitoring their nutritional status in both blood and breast milk. Its goal is to offer the highest quality fatty acid analytical services to researchers and to provide simple tests of nutritional status to consumers, with the ultimate purpose of advancing the science and use of certain nutrients to improve health. Internationally, OmegaQuant works with the University of Stirling, based in the Scotland, to help process blood samples from Europe. Learn more @ www.omegaquant.com
About FARI:
FARI was established in 2020 as a non-profit foundation that brings together nutrition scientists and biostatistical experts with strong publication records and expertise in fatty acids to accelerate discovery of the relationship between fatty acids, especially omega-3s, and health. FARI is currently the only organization focused directly on discovering and publishing research evaluating the health effects of individual fatty acids. Learn more @ www.faresinst.org