Several simple diet and lifestyle changes can dramatically lower the risk of developing Alzheimer`s disease, according to nutrition researcher Dr. Neal Barnard, founder and president of the Physicians Committee for Responsible Medicine. Alzheimer's, which affects about 5 million Americans, is the sixth leading cause of death in the United States. Speaking at a fundraising event Saturday in Amagansett, N.Y., Barnard cited research by the Chicago Health and Aging Project which showed a heart-healthy diet rich in fruits, vegetables, and vitamins E and B could eliminate Alzheimer’s risk by up to 50 percent. Barnard, author of Power Foods for the Brain, recommended eliminating saturated fats and transfats, citing research that shows a link between diets with a daily intake of 25.5 grams of fat and a higher risk of Alzheimer’s. Other guidelines include a Mediterranean diet rich in vegetables, fruits, beans, pulses and whole grains, along with a handful of nuts or seeds for vitamin E. Barnard also suggested avoiding metals such as iron and copper in multivitamins. Barnard said the lifestyle changes were also effective with people with genetic risk factors for Alzheimer's. ''Genes are not destiny,'' he said. Barnard also recommended establishing a regimen of aerobic exercise of at least 40 minutes of brisk walking three times a week. Physicians Committee for Responsible Medicine is a nonprofit organization that promotes preventive medicine and good nutrition.