As you get older, good nutrition plays an increasingly important role in how well you age. Eating a low-salt, low-fat diet with plenty of fruits, vegetables, and fiber can actually reduce your age-related risks of heart disease, diabetes, stroke, osteoporosis, and other chronic diseases. By eating a wide variety of foods, you can pretty easily get what your body needs, including:

• Protein, which is needed to maintain and rebuild muscles. You can get low-fat, quality protein from poultry, fish, eggs or egg substitutes, soy, and limited amounts of nuts and low-fat meat and dairy.
• Carbohydrate, which is the body's preferred source of energy. There are two main sources of dietary carbohydrates: simple sugars, such as sucrose (the refined white sugar added to sweets and desserts), fructose (the sugar contained in fruit), and lactose (milk sugar); and complex carbohydrates, which come from vegetables and grains. Unlike refined sugars, fruits contain vitamins and fiber, dairy products contain nutrients such as calcium and vitamin D, and complex carbohydrates contain vitamins, minerals, and fiber. Get most of your carbohydrate calories from vegetables, grains, and fruits. And try to replace fat calories with complex carbohydrates in your diet.
• Fat, which also provides energy. To help keep your blood cholesterol levels low, get most of your limited fat intake from the polyunsaturated fats (as in liquid corn oil or soybean oil) and monounsaturated fats (in olive oil, avocados, and nuts). Limit saturated fats (beef, pork, veal, butter, shortening, and cheese). You can do this by eating these foods less often, having smaller servings, choosing less fatty cuts of meat, and by using stronger tasting cheeses so you can use just a little and still get the cheese flavor. Try to avoid the trans fats (hydrogenated fats) found in stick margarine and in many processed foods such as crackers and cookies. Trans fats are now shown on the nutrition facts labels found on most packaged foods.
• Water, to replace water lost through activity. Because your kidneys gradually become less efficient at keeping your body hydrated, make a conscious effort to get six to eight glasses of water a day.