The finding stems from work conducted among roughly 1,200 dementia-free patients over the age of 65. All underwent blood tests to assess levels of a key Alzheimer’s-associated protein after providing the study authors with a dietary breakdown dating back more than a year.
“Past research has shown that, in this population, higher levels of the beta amyloid protein appear related to a higher risk for developing Alzheimer’s disease,” said study author Yian Gu, an associate research scientist with the Taub Institute for Research in Alzheimer’s Disease and the Aging Brain at Columbia University in New York City. “So we wanted to try and figure out if what we eat can affect these levels.”
“We considered only the omega-3 nutrient content in [study participants’] diets,” Gu added, “because our previous studies showed that the Mediterranean diet — which is characterized by fish, nuts, vegetables and a lower intake of read meat — was associated with a lower risk for Alzheimer’s. And this time, when we measured beta amyloid levels in their blood — which is representative of what we would find in the brain — we found that the more omega-3 content in the diet, the lower the beta amyloid levels.”
Gu and her colleagues discuss the possibility that seniors could perhaps eat their way to a lower risk for Alzheimer’s in the May 2 online issue of the journal Neurology.
The authors noted that prior research, including their own, has found a possible association between the consumption of certain foods and a lower risk for dementia. Exactly why that would be the case, however, has remained unclear.
To shed some light on the mystery, the team focused on seniors residing in the northern part of Manhattan in New York City. All had undergone neurological and cognitive testing, and only those who were dementia-free were included in the current analysis.
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.”