The largest study to date on the effects of eating omega-3 fatty acids confirm that foods high in the fats can preserve memory and cognitive functions only in people without diabetes.
Health experts hold up the Mediterranean diet as likely the best way to eat to stay healthy into old age. High in fruits and vegetables, as well as grains and oils low in saturated fats, the diet is linked to lower risk of heart attacks, stroke, childhood asthma and cancer.
A study from researchers at the University of Alabama at Birmingham and the University of Athens, Greece now shows that people around age 64 who primarily ate a Mediterranean diet, which is high in omega-3 fatty acids, may also have a lower risk of memory loss.
Because there are no pharmaceutical cures or treatments for memory loss or dementia, the researchers say such lifestyle behaviors that can slow or prevent cognitive decline are important strategies for keeping the brain sharp.
The 17,478 African-American and Caucasian men and women were part of the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, and they answered questions about their dietary habits, including how well they stuck to the principles of the Mediterranean diet and avoided red meats and dairy products. The volunteers also agreed to take tests to measure their memory and cognitive abilities over an average of four years.
Seven percent of the study participants developed cognitive impairments during the study period of about four years. Among the healthy participants, those who most consistently ate a Mediterranean diet were 13% less likely to develop memory and thinking problems.
The same benefit did not apply, however, to the 17% of people with diabetes; among those with diabetes, people who followed the Mediterranean diet were 30% more likely to show signs of cognitive impairments during the study than those who didn’t follow the diet. Among non-diabetics, the participants who ate more olive oil, omega-3 fatty acids and avoided red meats, dairy and cheese were 19% less likely to have cognitive problems by the end of the study than those who ate more of these foods. That suggests that diabetes may affect brain function via different routes not influenced by omega-3 fatty acids or other dietary nutrients.
“Diet is an important modifiable activity that could help in preserving cognitive functioning in late life,” said study author Dr. Georgios Tsivgoulis, with the University of Alabama at Birmingham and the University of Athens, Greece in a statement. “However, it is only one of several important lifestyle activities that might play a role in late-life mental functioning. Exercise, avoiding obesity, not smoking cigarettes and taking medications for conditions like diabetes and hypertension are also important.”
The results showed no significant difference in rates of cognitive decline between African-Americans and Caucasians, although the researchers had hypothesized that African-Americans might benefit more from omega-3 fatty acids since they have a higher overall rates of hypertension, obesity, diabetes, and stroke, all of which are risk factors that should put them at greater risk of developing dementia and memory problems.
It’s possible, however, that the scientists did not see any benefits from the Mediterranean diet by race because the effects of dietary habits, such as the fact that certain populations eat fewer fruits and vegetables overall, might override any potential benefits of the Mediterranean diet. Rates of diabetes also tend to be higher in African-American groups, and that could also negate any positive influences the Mediterranean diet had in protecting cognitive functions.
The study is published in Neurology, the medical journal of the American Academy of Neurology.