Eating a diet high in omega-3 fatty acids — from fish, soy or nuts, for example — may help stave off Alzheimer’s disease, the authors of a new study suggest.
The researchers, from Columbia University Medical Center in New York, looked at 1,219 people over age 65 who were free of dementia. The participants filled out questionnaires about their eating habits for the previous 1.2 years. The researchers focused on the participants’ dietary intake of 10 different nutrients, including saturated fatty acids, omega-3 and omega-6 polyunsaturated fatty acids, monounsaturated fatty acid, vitamin E, vitamin C, beta-carotene, vitamin B12, folate and vitamin D.
The researchers also took blood samples from the participants to test for levels of beta amyloid, a protein found in the amyloid plaques in the brain that are a telltale sign of Alzheimer’s disease. Because beta amyloid is difficult to measure in the brain, however, the researchers looked at blood levels instead, which is thought to be a marker for Alzheimer’s risk.
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They found that the more omega-3s a person consumed, the lower their blood levels of beta amyloid. Most of the omega-3s consumed by study participants came from fish, chicken, margarine, nuts and salad dressing. The study looked at nutrients that came only from food, not supplements.
Consuming 1 gram of omega-3s per day — the equivalent of eating about half a fillet of salmon a week — was associated with 20% to 30% lower blood beta amyloid levels. On average, people in the study weren’t getting this much omega-3s.
Out of all the nutrients studied, only omega-3 consumption was associated with lower beta amyloid levels. The result held even after researchers accounted for the participants’ age, gender, ethnicity and educational background.
“There is no threshold here,” says study author Dr. Nikolaos Scarmeas. “The more omega-3s one eats, the less the beta amyloid levels are. Previous studies have found this association in animals, but not in humans. It’s a good thing we see it in humans.”
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Although the study did not determine why omega-3s are associated with lower beta amyloid levels, the researchers are hopeful their findings will lead to further understanding of how diet can influence Alzheimer’s. “In this study, we were able to relate something that we eat with a very specific mechanism in the body that is very strongly related to Alzheimer’s,” says Scarmeas. “Our next step is to get even closer to the true biology of Alzheimer’s.”
Scarmeas says further research is needed to look at how nutrients directly influence beta amyloid in the brain, possibly using brain imaging to do so.
The study was published online in the journal Neurology.