PrintToo Little DHA May Shrink Your Brain

Higher intake of fish oil could slow brain aging, according to new research.

It’s normal for the human brain to get smaller with age. But too little of the omega-3 fatty acid docosahexaenoic acid (DHA) may shrink brains more quickly and cause thinking problems, research from the University of California, Los Angeles (UCLA) suggests.

This new cross-sectional study, published in the journal Neurology, has now found that lower levels of red-blood cell DHA levels are associated with smaller brain volumes, as well as vascular-related problems with learning and memory.

“People with lower blood levels of omega-3 fatty acids had lower brain volumes that were equivalent to about two years of structural brain aging,” said study author Zaldy S. Tan, MD, MPH, of the Easton Center for Alzheimer’s Disease Research and the Division of Geriatrics, UCLA, in a press release.

Previously, observational studies have linked getting more fish-derived omega-3 fatty acids DHA and eicosapentanoic acid (EPA) in the diet with reduced risk of cognitive problems with age. These long-chain omega-3 fatty acids, found primarily in fatty fish, are also linked to better cardiovascular health. Acting within the membranes of cells, DHA is also known to be a major structural player when it comes to building a functional brain.

In this elderly community-based cohort, Tan and fellow researchers measured the amount of omega-3s in the red blood cells of 1,575 dementia-free people with an average age of 67. After three months, the participants then underwent MRI scans to measure total brain volume, blood supply to the brain, and mental-functioning tests.

The researchers ranked participants according to the level of omega-3s found within their red blood cells, an indicator, they report, of fatty acid intake over the previous four months. Those in the bottom 25 percent for RBC DHA and EPA levels had lower brain volume and a decreased performance on tests for memory, abstract reasoning, and function in comparison to individuals in the top 75 percent.

Brain scans also showed that those with the lowest omega-3 levels had less blood supply to the brain, which suggests omega-3s contribute to supporting general vascular health in the brain.

Not all studies have found such a benefit for brain from omega-3 fatty acids—particularly in aging, but healthy, populations. One reason for inconsistencies, write the researchers, may be because most diet-related studies rely on food-intake questionnaires to determine total dietary intake. Questionnaires may not accurately reflect what people really consume in their diets. While this study had a large population size and reliable RBC measures, more extensive research with more diverse population groups is warranted.

However, the results are intriguing and suggest that higher intake of DHA from fish or supplementation presents a viable solution to staving off brain aging.

Reference: Tan ZS, Harris WS and AS Beiser. Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging. Neurology 2012; 78:658-64. DOI: 10.1212/WNL.0b013e318249f6a9