September 2, 2004
A diet high in the "good" fats found in fish may be important for keeping memory vital into old age, a new study suggests. The findings add to the growing body of evidence that heart-healthy fats like DHA, found in fish, nuts, and other foods, may protect the brain as well.
The study was conducted in older mice afflicted with a genetic mutation that leads to brain defects similar to those that occur in men and women with advanced Alzheimer's. Some of the mice were fed a diet rich in DHA, a "good" type of fat known as an omega-3 fatty acid that is thought to boost heart and blood vessel health. Others were fed a diet depleted of omega-3 fats.
After five months, the mice that had eaten the fish-oil rich diet performed much better on memory tests than those fed the DHA-depleted diet. The brains of the mice fed the DHA-depleted diet were also riddled with the kinds of damage that occurs in people with Alzheimer's disease.
Though results may be very different in people, scientists are hopeful these findings may lead to effective ways to promote brain health for men and women of all ages. "This is the first proof that our diets affect how our brain cells communicate with each other under the duress of Alzheimer's disease," says study leader Greg Cole, Ph.D., professor of neurology at the David Geffen School of Medicine at the University of California, Los Angeles. "We saw that the diet rich in DHA, or docosahexaenoic acid, dramatically reduces the impact of the Alzheimer's gene in mice."
"Consuming more DHA is something the average person can easily control," adds Dr. Cole. "Anyone can buy DHA in its purified form, fish oil capsules, high-fat fish, or DHA-supplemented eggs."
Oily, coldwater fish, like salmon, halibut, mackerel, sardines, and herring, are particularly rich in DHA and other omega-3s. Fish consume algae rich in DHA, which the human brain absorbs and uses for vital brain functions. 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.
The findings add to a growing body of evidence that DHA and other omega-3 fats, thought to be good for the heart and blood vessels and lower the risk of fatal heart attacks and strokes, may protect the brain as well. A study last year found that a weekly serving of fish and nuts cut the risk of Alzheimer's among nursing home residents by 60 percent. [see the article, "Fish and Nuts May Ward Off Alzheimer's."]
It is not known whether fish and nuts can slow the course of Alzheimer's in those who have the disease. In addition, many other factors besides diet, including genetics and advancing age, play an important role in who gets the illness. But heart-healthy lifestyle factors may help. Keeping blood pressure and cholesterol levels in a normal range, maintaining a healthy weight, not smoking, and getting regular exercise all long promoted for heart and blood vessel health are emerging as factors that may lessen the risk of Alzheimer's as well. What's good for the heart, the evidence increasingly seems to show, is good for the brain.
Greg Cole,Ph.D., et al: Neuron, September 2, 2004. David Geffen School of Medicine, University of California, Los Angeles.