Previous surveys have shown that people who engage in regular exercise, who keep their brains active and who eat healthy diets high in vitamin E and omega-3 fatty acids tend to preserve their brain function as they get older.
However, so far there has been little definitive research involving randomized trials that demonstrates a cause and effect link between Alzheimer's Disease, nutrients and diet. Many studies of elderly patients, where one group was given dietary supplements and the other a placebos, have generally been inconclusive.
Similarly previous studies have not showed a significant correlation between the nutrients in supplements and brain function abilities like memory, reasoning, language, and cognitive tests.
This article discusses recent research on this topic.
A recent research study, which looked directly at the levels of vitamins and other nutrients in the blood, found significant correlations between healthy diets and better brain function and the size of the parts of the brain associated with Alzheimer's Disease. This offers hope of reducing the risk of developing this disease through healthy diets.
Similarly while it has been shown that regular exercise can prevent the decline in muscle mass as people get older (See:Muscle Loss with Age | If you Don't Use it You Will Lose It!), there has been no link between nutrient intake and brain size.
Recent research has also shown positive signs that diet many be linked to the preservation of brain function and size in the elderly.
The research, recently published in the journal Neurology, demonstrated that subjects with healthier diets that were rich in omega-3 fatty acids and a variety of vitamins had larger brains and better brain function than those with unhealthy diets.
Unlike previous studies that have used questionnaires to compare diets, this study directly measured the levels of vitamins and fatty acids in the blood.
The study involved over 100 healthy elderly people with an average age of 87.
Researchers took blood samples and analyzed them for a variety of nutrients and vitamins, including vitamins B ( folate, B2, B1, B6, B12), C, D and E, carotenoids, saturated fat, cholesterol, omega-3 fatty acids and trans fats.
They then looked for correlations between the levels of these substances and the participants’ performance in various cognitive tests.
The diets of the subjects were not compared, only the levels of the nutrients in the blood MRI scans were used to estimate the size of parts of the brain related to Alzheimer’s.
The team found that
When the researchers considered the known risk factors for Alzheimer's disease - gender age and genetic factors they found that these known risks were responsible for about 46% of the difference in participants' cognitive scores. People who were older and had the APOE4 gene mutation that is a risk factor for Alzheimer's, were more likely to score lower on cognitive tests than younger participants who did not have the genetic mutation. When the research group added in the effect of vitamins and fatty acids in their diets, they found that their nutritional profiles explained another 17% of the variation in cognitive scores.
Older people are known to have poor diets. Omega-3s and vitamin D are found primarily in fish, while vitamins B, C and E are high in fruits and vegetables. Trans fats come largely from packaged, fried, frozen and fast foods, along with baked goods and margarine spreads.
Subjects in the study who had higher levels of vitamins B, C, D and E did not have problems with memory, but did show trouble with attention and visual-spatial tasks, while those with higher levels of carotenoids (found in carrots and dark leafy green vegetables) showed more problems with memory.
For the size of the brain parts measured using MRI, the known Alzheimer's risk factors accounted for about 40% of the difference in cognitive scores between those with normal-size brains and those with smaller brain volumes, while diet explained another 37% of the variance.
Brain size normally shrinks with age, but with Alzheimer's disease, that shrinkage is accelerated - a sign that the condition is getting worse. Diet, plus known risk factors, explained a total of 76% of the variance between the subjects.
For the vitamins, omega-3s, and trans fats, the study found an association between diet and brain health, not cause and effect. The study was also looking just at one point in time and so cannot confirm that these patterns change progressively with time.
Study author Gene Bowman of Oregon Health and Science University said: "These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet."