Heart disease. By now every American surely knows which foods affect your heart. 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. Still, troublesome foods can be hard to limit. "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. Plus, some food manufacturers have swapped their trans fats for equally problematic saturated fat, Eckel says. Sat fat should total no more than 7 percent of daily energy intake—about 16 grams for the average, 2,000-calorie diet.
Recent research points to another potential heart danger: high-fructose corn syrup, commonly found in soda. The decades-long, 88,000-women Nurse's Health Study found that, even controlling for weight and other unhealthy 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. "We don't know exactly why this is, but fructose does increase uric acid and triglycerides in the blood, which are known contributors to hypertension and heart disease," says study coauthor Teresa Fung, associate professor of nutrition at Simmons College in Boston.
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 DASH-Sodium version, which subtracts salt, works as well as up to two medications. 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. The biggest difference from standard healthful eating advice is DASH's focus on lowering sodium, which can damage artery walls in people sensitive to the nutrient. The diet limits sodium to 2,300 mg a day, while DASH-Sodium slashes it to 1,500 mg—just two thirds of a teaspoon. It's not enough to go easier on the salt shaker; the National Institutes of Health recommends looking for low- or no-salt labels, limiting salty foods like bacon and sauerkraut, and rinsing canned foods. (Here's a sample menu of a DASH eating plan.)
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 combination, in fact, actually has proved 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 in 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 can spike blood glucose levels.