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Nutrition's Role in Disease Prevention

Evidence is mounting that a healthy diet can help protect you from some diseases. What you eat -- or don't eat -- may help prevent heart disease, cancer, osteoporosis, and type 2 diabetes.

With this in mind, here's how to use your diet to help reduce your risk of disease.

Beat heart disease

To help prevent heart disease, you need to keep your blood cholesterol, blood pressure, and weight under control. Healthy eating habits can help you accomplish this, as well as reduce your risk for stroke.

Experts recommend these general nutrition goals for healthy adults ages 19 and older:

  • Your diet should include foods from all major foods groups, with special emphasis on fruits, vegetables, and grains.

  • Your diet should provide about 20 to 35 percent of daily calories from fat; only 10 percent of these fat calories should come from saturated fat. Trans fat should be 1 percent of daily calories or lower (trans fats are found in hydrogenated/partially hydrogenated vegetable oils).

  • Depending on the amount of calories recommended for your age and activity level, you should aim for 1½ to 2½ cups of a variety of whole, fresh, frozen, canned, or dried fruits and 2½ to 3½ cups of fresh, frozen, or canned vegetables each day.

  • You should aim for at least three servings (equal to three ounces) a day of whole-grain foods.

  • Choose fat-free and low-fat dairy products that are fortified with vitamin D over regular products. You should have three servings of these a day.

  • Your protein should come from lean meats, poultry, fish and legumes with at least two servings of fish each week. Ten to 35 percent of your daily calories should come from protein.

Other nutrition suggestions:

  • Choose fats and oils with two grams or less of saturated fat per tablespoon. These include liquid and tub margarines, canola oil, and olive oil.

  • Limit the foods you eat that are high in calories or low in nutrition, such as soft drinks and candy.

  • Limit the amount of salt you eat each day to 2,300 mg or less of sodium (equivalent to 5.8 grams of salt).

  • Maintain your weight by balancing the number of calories you eat with the number that you use. Multiply the number of pounds you weigh by 15 calories. This represents the number of calories that you use in one day if you are moderately active. If you are mostly sedentary, multiply your weight by 13 instead of 15.

  • Also maintain your weight by getting regular exercise for at least 30 to 60 minutes most days of the week.

  • Limit your alcohol consumption to no more than two drinks a day if you are a man, or one drink a day if you are a woman or a man over the age of 65. One drink is equal to 12 ounces of beer, 4 ounces of wine, and 1½ ounces of 80-proof spirits.

The DASH diet is a specific eating plan developed by the National Heart, Lung, and Blood Institute for lowering high blood pressure, also called hypertension. DASH stands for Dietary Approaches to Stop Hypertension.

This diet is low in sodium, saturated fat, cholesterol, and total fat, as well as red meat, desserts, and sugary beverages. It emphasizes consuming plenty of fruits, vegetables, and low-fat dairy foods. It also includes whole grains, poultry, fish, and nuts. The typical American diet contains about 3,300 mg of sodium; the 2010 Dietary Guidelines Advisory Committee recommends that you eat no more than 2,300 mg a day. The daily sodium intake is 1,500 mg for African-Americans and for people diagnosed with hypertension, diabetes, or chronic kidney disease, as well as people 51 and older. 

Combat cancer

The best diet to help protect you against cancer helps you maintain a healthy weight and includes a variety of foods.

Obesity increases the risk for cancers of the endometrium (the lining of the uterus), colon, kidney, esophagus, and breast (after menopause).

No single food is the perfect one for cancer prevention, but a combination of vitamins, minerals, and phytochemicals (which come from plants) can offer good protection, according to the American Institute for Cancer Research (AICR).

Here are some examples of foods that researchers have identified as being particularly helpful in protecting against cancer:

  • Green leafy vegetables such as spinach, kale, romaine lettuce, and leaf lettuce contain fiber, folate, and a variety of carotenoids, the AICR says. Carotenoids help prevent cancer by acting as antioxidants. The carotenoids in green leafy vegetables can help stop cell growth in cancers of the breast, skin, lung, and stomach. Folate, too, may offer protection against colorectal cancer, breast cancer, and lung cancer.

  • Cruciferous vegetables such as broccoli, cauliflower, cabbage, and brussels sprouts contain substances that have been associated with a lower risk for cancer, according to the AICR. They may help protect against cancers of the breast, endometrium, lung, colon, liver, and cervix.

  • Berries are good sources of vitamin C and fiber, but they also contain ellagic acid, which may help prevent cancers of the skin, bladder, lung, esophagus, and breast, according to the AICR.

To help protect against cancer, your diet should include five to 13 servings of vegetables and fruits each day, according to the American Cancer Society (ACS) and the USDA.

Here are some ways to add fruits and vegetables to your daily fare:

  • Make sure vegetables and fruits are a part of every meal, and serve them as snacks.

  • Limit the amount of fried vegetables you eat; prepare vegetables in healthier ways, such as steaming or microwaving. Or eat them raw.

  • If you want to drink fruit or vegetable juice, make sure it's 100 percent juice. Other types of fruit beverages contain only small amounts of juice.

Besides fruits and vegetables, a healthy diet should include whole grains. Whole grains are rich in fiber, vitamins, minerals, and a wide range of phytochemicals that may lower the risk for cancer, the AICR says.

You should choose whole grains over processed or refined grains and sugars. When buying rice, bread, pasta, and cereal, look for varieties that are made from whole grains. The 2010 Dietary Guidelines Advisory Committee recommends that you eat 3 to 4 ounces of whole grains a day. Limit the amount of refined carbohydrates you eat. This includes pastries and desserts, sweetened cereals, and soft drinks, according to the ACS.

When selecting sources of protein, choose fish, poultry, or beans instead of beef, pork, or lamb. When eating red meat, buy lean cuts and serve smaller portions. Bake, broil, or poach meats instead of frying or grilling. This reduces the fat content.

Another food that may help protect against cancer is green tea. Both black tea and green tea contain polyphenols and flavonoids, which are antioxidants, according to the AICR. One type of flavonoid, catechins, seems particularly promising in its protective effect. Green tea contains about three times the amount of catechins that black tea has. Green tea may help protect against cancer of the colon, liver, breast, and prostate.

Fight osteoporosis

The best step you can take against osteoporosis: Eat plenty of low-fat foods that are rich in calcium and fortified with vitamin D such as skim milk, low-fat yogurt, and low-fat cheese, as well as broccoli.

Other steps you can take: Use calcium-fortified foods such as orange juice and breakfast cereals. Add soy foods, such as tofu and tempeh, to your diet. Besides being a good calcium source, soy foods have been shown to increase bone density. If you drink soymilk, buy brands that are calcium fortified.

Also, reduce your consumption of carbonated beverages. Studies show the phosphorus they contain may leech calcium from bones. Not all carbonated beverages contain phosphorus, however. If “phosphoric acid” is not listed on the label, then the beverage will not affect your calcium levels.

Here are the recommended calcium intakes: Children ages 1 to 3 should get 700 mg of calcium each day; children ages 4 to 8 should get 1,000 mg; and children 9 to 12 should get 1,300 mg. Teens should consume 1,300 mg each day. Adults ages 19 to 50 should consume 1,000 mg each day; adults 50 and older should get 1,200 mg.

You should also make sure you get enough vitamin D in your diet and through exposure to sunlight, according to the National Osteoporosis Foundation (NOF). As we age, we are less able to make vitamin D through our skin. That's why food sources of vitamin D become even more important in older adults. Good sources of vitamin D include fortified dairy products, egg yolks, ocean fish, and liver. Most multivitamins and calcium supplements contain vitamin D.

Adults under 70 and children who get minimal sun exposure should get 600 international units each day. People over 70 who get minimal sun exposure should get 800 IU a day. Don't take more than 800 IU a day unless your doctor prescribes it, because too much vitamin D may be harmful, the NOF says.

Decrease your risk for type 2 diabetes

The best way to help prevent type 2 diabetes: Maintain a healthy weight by eating a balanced, low-fat diet. Obesity is a strong risk factor for developing type 2 diabetes.

Another strong risk factor for developing type 2 diabetes is having prediabetes, a condition in which your blood sugar is above normal, but not high enough to be diagnosed as diabetes. A person with prediabetes is at risk for developing type 2 diabetes within 10 years, and also is at higher risk for heart attack or stroke, according to the National Diabetes Education Program (NDEP).

Losing 5 to 7 percent of your weight if you are overweight can reduce your risk, according to the NDEP.

Other steps you can take to reduce your risk, according to the American Diabetes Association: Reduce your fat intake to less than 30 percent of your calories and your intake of saturated fat to less than 10 percent of your calories. Eat more high-fiber foods, such as oatmeal, beans, legumes, fresh fruits, and fresh vegetables.

Get regular exercise, which help you with weight management, as well as reduce your risk. The USDA recommends 30 to 60 minutes of brisk walking or some other moderate exercise most days of the week to maintain your weight. To lose weight, 60 to 90 minutes a day may be needed.