Higher DHA concentrations cut Alzheimer’s disease risk by half.

Docosahexaenoic acid (DHA) is an omega-3 fatty acid found in krill oil and the meat and roe of salmon, flying fish, and pollock. When consumed in the diet (or obtained from dietary supplements), DHA preferentially accumulates in the human brain, where it plays essential roles in normal brain function. Findings from a recent study suggest that higher concentrations of DHA in red blood cells protect against Alzheimer’s disease.

The concentration of omega-3 fatty acids in red blood cells, referred to as the “omega-3 index,” is an indicator of long-term omega-3 exposure, analogous to the HbA1c test for long-term blood glucose concentrations. In general, people who have high blood concentrations – an omega-3 index of about 8 to 12 percent – are far less likely to die from all causes of premature death than those with lower concentrations.

The investigators drew on data collected in the Framingham Offspring Cohort study, an ongoing study of the effects of lifestyle risk factors on cardiovascular, neurological, and other types of disease outcomes across three generations of participants. Their investigation, which involved nearly 1,500 adults (65 years and older) who did not have dementia, examined whether red blood cell concentrations of DHA influenced the participants' Alzheimer’s disease risk, especially those who carried the APOE4 gene, the primary genetic risk factor for the disease. They categorized the DHA concentrations across five levels and tracked the participants' health for seven years.

They found that participants whose red blood cell DHA concentrations were in the top fifth were roughly half as likely to develop Alzheimer’s disease during the follow-up period than those in the lowest fifth. This protective effect of DHA translated to nearly five years of life free of Alzheimer’s disease. Higher DHA concentrations conferred more than seven years of protection for participants with the APOE4 gene, suggesting that promoting DHA intake among this susceptible group could have marked effects on their neurological health.

These findings suggest that higher concentrations of DHA, a type of omega-3 fatty acid, protect against Alzheimer’s disease, especially among carriers of the APOE4 gene. Learn more about the beneficial health effects of omega-3s in this episode featuring Dr. Bill Harris. And for more information about how DHA influences Alzheimer’s disease risk, check out this open-access, peer-reviewed article by Dr. Rhonda Patrick.

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