According to a new study eating a diet rich in certain vitamins and omega-3 fatty acids and low in trans fats may be best for brain health.
The study shows that elderly who followed this diet had less of the brain shrinkage linked with Alzheimer's disease and scored better on mental and thinking tests than those with poorer diets. Although previous studies have suggested that a heart-healthy diet is also good for the brain, the new study took a different approach by using blood tests to determine the participant’s diet and nutrient levels.
“The combination of the B vitamins, the antioxidants C and E, plus vitamin D was the most favorable combination of nutrients in the blood for healthy brain aging in our population,” says study author Gene L. Bowman, assistant professor of neurology at the Layton Aging & Alzheimer's Disease Center, Oregon Health & Science University, Portland. B vitamins are found in a variety of foods, such as milk and dairy, whole grain cereals, enriched bread, and peanut butter. Vitamin C is rich in fruits and vegetables, and E is in nuts and oils. Vitamin D is found in the flesh of fatty fish, such as salmon, and in fortified milk. He warned that the worst foods for the brain were a diet high in trans fats. Trans fats are more often found in packaged baked goods and fast foods, including cookies, crackers, and potato chips.
The study is published online in the journal Neurology.
The study looked at 104 people aged average 87. They had very few risk factors known to boost the risk of memory and thinking problems, such as diabetes or high blood pressure Besides the blood tests, the men and women were given memory and thinking skills tests. Forty-two had MRI scans to measure brain volume. Decreased brain volume has been linked with declines in thinking ability associated with Alzheimer's disease. The researchers evaluated how much of the risk of declining mental abilities could be attributed to diet and how much to other factors, such as age or high blood pressure. The team looked at 30 different nutrient biomarkers. Those most consistently linked to brain health were the vitamins, omega-3 fatty acids, and trans fats.
The declines in mental and thinking ability were attributable more to age and other risk factors, but diet did seem to play a role. For the variation found in the tests of mental and thinking abilities, Bowman's team found risk factors such as age explained about 46% of the variation. Diet explained less, about 17%, Bowman says. For the variation in brain volume, diet seems to matter as much as the other risk factors. Diet explained about 37% of the variation, he says. The other risk factors explained about another 40%.
The study was looking just at one point in time, Bowman says, which is a limitation of the study. “We can't say these patterns predict rate of change over time.” Another study limitation is its small size and that the people studied were not diverse, says Heather Snyder, senior associate director of medical and scientific relations for the Alzheimer's Association. She reviewed the study findings. Until more research is done, she says eating a heart-healthy diet - which may also help your brain - is the best advice.
Christy Tangney, associate professor of clinical nutrition at Rush University Medical Center, Chicago, wrote an editorial to accompany the study. She said that as the research progresses, the study results suggest someday it may be possible to slow cognitive declines through diet. Down the road, she says, the researchers might use a blood measure that reflects a typical diet, not just a point in time.
Bowman agrees that the standard advice to eat more fruits and vegetables and fish and avoid trans fats seems wise. Omega-3 fatty acids and vitamin D are found in fish. The B, C, and E vitamins he linked with less brain shrinkage are in fruits and vegetables.
“I think it's timely in that we have other studies showing a connection between, for example, overweight or obesity and dementia risk,” said Dr. Gary Small, director of the UCLA Longevity Center and co-author of “The Alzheimer's Prevention Program” (Workman Publishing, 2011). “You can see there is clearly a connection between what we eat and how well we think as we age.” If confirmed, the findings of the study could allow doctors to determine whether patients with low levels of nutrients should add certain foods to their diet to protect against cognitive decline, Small said.
“There are components of a brain-healthy diet that research points to, including omega-3-rich fish and nuts like walnuts, antioxidant fruits and vegetables, whole grains and avoiding processed foods and dairy products and meats rich in omega-6 fats,” Small said. “If you look at some of the nutrients measured in this study, it certainly is consistent with what we know about a healthy brain diet.”
“The default assumption is that diet is affecting brain aging, but it could also be the case that brain aging is affecting diet,” said Rhoda Au, a dementia and aging researcher at Boston University. Au said that there is also some indication that a very low body weight can hurt cognition, the result of weight loss and lack of nutrition.
But one of the important findings was that it seemed to be foods in combination, rather than individual vitamins, that were helping brain power, and so recommendations for the future would likely focus on foods rather than vitamin supplements. “The take-home message from this study is the concept of a balanced diet, rather than a single source of nutrients,” Au said.
Dr Simon Ridley, head of research at Alzheimer’s Research UK, welcomed the study, although noted that it was a small sample of people and the researchers did not investigate whether these people went on to develop Alzheimer’s. He said, “One strength of this research is that it looked at nutrients in people’s blood, rather than relying on answers to a questionnaire. Although there is no sure-fire way of preventing Alzheimer’s yet, we know that risk factors for heart disease and stroke can also increase the risk of dementia. The best advice at the moment is to eat a balanced diet with plenty of fruit and vegetables, and keep healthy by not smoking, taking regular exercise and keeping blood pressure and cholesterol in check.” “Currently 820,000 people are affected by dementia in the UK and with a rapidly ageing population, those numbers are expected to soar. We urgently need to find ways to prevent dementia if we are to head off a future crisis, and that means it’s vital to invest in research,” he said.
Healthy low-carb diet and time-restricted eating improve weight loss and gut health beyond calorie restriction