Memory problems. Alas, there's no magic bullet that will guarantee protection from dementia. But researchers are finding that a Mediterranean diet—similar to a conventional healthful diet but with an emphasis on fish and olive oil—seems to lower the odds of developing cognitive problems. Scientists at Columbia University followed more than 1,300 people for up to 16 years; those most closely adhering to this diet developed Alzheimer's at half the rate of those who didn't. One caveat: Alcohol (particularly in the form of wine), one element of the Mediterranean diet that has been suggested as a memory function enhancer, has not been proven as such, says Gary J. Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York.
Joint disease. Although age is a risk factor for arthritis, the breakdown of cartilage in the joints is not inevitable. Minimizing weight gain goes a long way toward avoiding this problem, because every extra pound translates to three pounds of pressure on the knees while walking. It is also a good idea to limit foods that encourage inflammation in the body, particularly omega-6 fatty acids (found in corn and soybean oils and many snack and fried foods), the Arthritis Foundation says.
Cancer. Some 45 percent of colon cancers, 38 percent of breast cancers, and 69 percent of esophageal cancers would never occur if Americans ate better, controlled their weight, and stepped up their exercise, estimates the American Institute for Cancer Research. "It's not just cancers of the digestive tract. What you eat and what you weigh affect certain other cancer types as well," says Alice Bender, AICR's nutrition communications manager. The organization recommends limiting red meat to 18 (cooked) ounces per week and loading up on plant-based foods, which are high in the phytochemicals and antioxidants known to inhibit cancer cell growth in lab animals. Those with the deepest colors—like purple grapes, blueberries, and leafy green vegetables—have the most beneficial compounds. One recent study, for example, showed that eating foods with the antioxidant sulforaphane, found in broccoli and kale, reduces the amount of a bacteria linked to stomach cancer.
At least for now, people should plan on getting as many as possible of their healthful nutrients from food rather than supplements. "Numerous studies on supplements—of vitamin C, lycopene, beta-carotene, and even fiber—have all proved disappointing," Bender says. Another reason to swap that cookie for a carrot.