Heart Disease. By now, every American surely knows the roll call of foods that affect your heart, for better and for worse. Good for the ticker: monounsaturated fats like olive oil and the omega-3 fatty acids found in such cold-water fish as salmon and herring and in flaxseed and walnuts. Harmful: too much red meat and full-fat dairy, because of their saturated fat content, and margarine and baked goods, because of the trans fats they contain.
But expunging troublesome foods from your daily fare can be surprisingly difficult. "Although many supermarket products have removed the trans fats, they're hardly history. Restaurants, especially, continue to use them," cautions Robert Eckel, former president of the American Heart Association and a professor at the University of Colorado–Denver. Some food manufacturers, moreover, have simply swapped out their trans fats for saturated fat, which is equally problematic, Eckel says. Saturated fat should total no more than 7 percent of daily energy intake—about 16 grams for the average 2,000-calorie diet.
Research points to another potential heart danger: high-fructose corn syrup, commonly found in soda. The decades-long, 88,000-woman Nurses' Health Study found that, even controlling for weight and other unhealthful habits, drinking one 12-ounce can of regular soda daily boosts a woman's risk of later having a heart attack by 24 percent; two or more servings raise the risk by 35 percent.
Hypertension. Lowering high blood pressure before it contributes to the development of heart disease is vital for people in midlife. It can be accomplished with an eating plan known as the DASH (Dietary Approaches to Stop Hypertension) diet. "The DASH diet has the same effect as taking a blood-pressure-lowering medication," Eckel says. The plan is rich in fruits and vegetables (eight to 10 servings a day for someone on a 2,000-calorie diet), grains (six to eight servings daily, with most being whole grains), and low-fat protein sources. And it's low in saturated fats and added sugars. DASH also limits sodium to 2,300 mg a day or to an even lower 1,500 mg—just two thirds of a teaspoon.
Insulin Resistance. Research has repeatedly demonstrated that type 2 diabetes and insulin resistance (a precursor to the disease in which the body begins to respond less well to the hormone that clears glucose from the bloodstream) can often be prevented or postponed with a healthful diet, exercise, and weight loss. That three-part combination, in fact, actually has been shown to be more effective than medication. An eating plan aimed at minimizing the risk of insulin resistance does not have to be complex.
"I coach people to mentally divide their lunch and dinner plate into thirds, with one third protein, one third nonstarchy vegetables, and the final third a starch like brown rice, whole-wheat pasta, potatoes, or corn," says Nora Saul, a dietitian and diabetes educator at Harvard's Joslin Diabetes Center in Boston. It's also a good idea to get serious about cutting back on sugar and white flour, both of which have a high glycemic index and can spike blood glucose levels.
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 3 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), according to the Arthritis Foundation.