Subjects completed food questionnaires dating back an average of 1.2 years, with a focus on the consumption of 10 specific nutrients that had been cited by past research as perhaps having an impact on brain health.
The nutrients included saturated fatty acids, omega-3 and omega-6 polyunsaturated fatty acids, mono-unsaturated fatty acids, vitamin E, vitamin C, beta carotene, vitamin B12, folate and vitamin D.
Nutrient intake in the form of food, not supplements, was included in the dietary analysis, the team noted.
The result: Blood testing revealed that, regardless of age, gender, ethnicity and educational background, the more omega-3 fatty acids consumed, the lower the beta amyloid levels found in the blood.
The team observed that omega-3 fatty acids were consumed primarily in the form of fish, poultry, margarine, nuts and salad dressing.
Catherine Roe, an instructor in neurology at the Washington University School of Medicine in St. Louis, hailed the effort as a "great line of inquiry."
"Of course, much more research needs to be done," she cautioned. "It's an association; it's not causal. And this is based on the 'amyloid hypothesis' -- that amyloid levels are in fact associated with Alzheimer's risk -- which is a hypothesis, not a solid fact."
"But at this point ... it does look like people who have abnormal levels of beta amyloid in the cerebral spinal fluid are more likely to develop Alzheimer's disease," Roe said. "We're learning more and more that Alzheimer's disease is not simply a consequence of genes, but that there are probably environmental factors that are important too. So this raises the exciting possibility that you could influence your likelihood of developing Alzheimer's disease by diet."
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