Can fish oil benefit brain health in older adults? Well, it depends. A new study found that while a specific group of older adults could benefit from regular fish oil use, the general population did not experience the same advantages.

A clinical trial conducted at the Oregon Health & Science University (OHSU) examined the brain health effects of fish oil among older adults and discovered that omega-3 fatty acid use could benefit those with a genetic predisposition to Alzheimer's. However, researchers did not find significant benefits for all older adults in general.

The researchers examined WML (white matter lesion) progression and neuronal integrity breakdown, the factors associated with increased risk of Alzheimer's disease among 102 participants aged 75 or older.

The participants typically had relatively low blood levels of omega-3 fatty acids, which are found in fish oil. To assess the amount of change in white matter lesions in the brain, they underwent magnetic resonance imaging (MRI) of their brains during enrollment and at the end of three years. These participants either took a three-year treatment with 1.65 g of Omega-3 polyunsaturated fatty acids or a soybean oil placebo that tasted and looked similar.

"Our findings showed that over three years, there was not a statistically significant difference between the placebo and the group that took fish oil. I don't think it would be harmful, but I wouldn't say you need to take fish oil to prevent dementia," Lynne Shinto, senior co-author from OHSU, said in a news release.

"Although ω-3 treatment failed to reach a significant reduction in WML progression and neuronal integrity breakdown among all participants at risk for dementia, the findings suggest that APOE*E4 carriers may benefit from ω-3 treatment," the researchers wrote in the study published in the journal Jama Network. APOE*E4 carriers are a known genetic risk factor for late-onset Alzheimer's disease.

The study has certain limitations due to the participants being demographically and geographically homogeneous, limiting the generalizability of the findings. "A future multisite trial will have the ability to enroll a more ethnically, racially, and geographically diverse population and provide an adequate sample size to permit the assessment of clinical benefits, " the researchers wrote.

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