March 28, 2005
A diet rich in the heart-healthy fats found in fish like salmon, mackerel, and tuna may be good for the brain, new research reveals. The studies were conducted in mice, a far cry from people, but the findings add to a growing body of evidence that a fish-rich diet may help keep the brain young as we age.
Working with older mice that had been specially bred to develop a brain ailment that resembles Alzheimer's in people, doctors at the Department of Veterans Affairs and the University of California at Los Angeles (UCLA) fed mice a diet rich in DHA, a "good" form of fat called an "omega-3." Increasingly, nutrition experts believe that omega-3s like DHA are key to the health of the heart and blood vessels, including those that nourish the brain.
The researchers fed one group of the mice food that had been fortified with DHA. Another group of mice ate a normal or DHA-depleted diet. After three to five months -- the equivalent of several years in human life -- the high-DHA group had 70 percent less buildup of amyloid in the brain. This sticky protein makes up the plaques, or patches, that are a hallmark of Alzheimer's. Results appeared in the March 23 edition of the Journal of Neuroscience.
"The good news from this study is that we can buy the therapy at a supermarket or drug store," said study leader Greg M. Cole, Ph.D. "DHA has a tremendous safety profile -- essentially no side effects -- and clinical trial evidence supports giving DHA supplements to people at risk for cardiovascular disease."
Oily, coldwater fish, like salmon, halibut, mackerel, sardines, and herring, are particularly rich in DHA and other omega-3s. DHA/omega-3 dietary supplements are also widely available in pharmacies and health-food stores. Other foods high in these "good" fats include almonds, walnuts and many other types of nuts, as well as canola, walnut, soybean and flaxseed oils. Because many of these foods are a rich source of calories, they are best eaten in place of, rather than in addition to, other foods.
Growing Body of Evidence
A similar study by Cole's group published in the scientific journal Neuron last fall showed that DHA protected against damage to the "synaptic" areas where brain cells communicate and enabled mice to perform better on memory tests.
Nutritionists say that many Americans do not get enough omega-3s in their daily diets. In addition, scientists have discovered that the brains of persons with Alzheimer's disease tend to be low in DHA. Population studies also show that people who eat a lot of fish rich in heart-healthy oils also tend to have a lower likelihood of developing Alzheimer's disease.
Supplements containing the fish oils are now being tested in clinical trials in people in the early stages of Alzheimer's to see if they really help slow the disease. Results will likely not be available for several years. In the meantime, it may be a good idea to "eat your fish," just as your grandmother advised.
U.S. Department of Veterans Affairs. Giselle P. Lim, Frdric Calon, Takashi Morihara, et al: "Fish Oil and Beta-Amyloid in the Mouse," Journal of Neuroscience online edition, March 23, 2005.