There are nutritional and dietary elements that have proven relationships to certain diseases or conditions. For additional information on FDA-approved health claims, refer to nutrition labeling.

This article discusses the following:

1. Calcium and osteoporosis
2. Fiber and cancer
3. Fruits, vegetables, and cancer
4. Fiber and coronary heart disease
5. Fat and cancer
6. Saturated fat, cholesterol, and coronary heart disease
7. Sodium and hypertension
8. Alcohol
9. Nitrates and cancer

1. CALCIUM AND OSTEOPOROSIS:

Calcium is one of the most important minerals for human life. Your body uses it to form and maintain healthy bones and teeth. Calcium also plays a vital role in nerve conduction, muscle contraction, and blood clotting.

Osteoporosis is a disease in which the calcium content of bones is very low. In this disease, calcium and phosphorus, which are normally present in the bones, become reabsorbed back into the body. This process results in brittle, fragile bones that are easily broken.

Getting enough calcium in the diet throughout childhood and puberty is one key to preventing osteoporosis. A person who does not get enough calcium growing up will not have sturdy bones. An older person who consumes a low-calcium diet is also at great risk for osteoporosis.

The recommended dietary allowances (RDA) for calcium are based on age, gender, and hormonal factors. Many foods, such as some vegetables, contain calcium. However, milk and dairy products are some of the best food sources. Calcium may also be obtained by taking supplements.

2. FIBER AND CANCER:

Dietary fiber is found in plant foods, where it occurs in two forms: soluble and insoluble. Soluble fiber attracts water and turns to gel during digestion. This process slows digestion and the rate of nutrient absorption from the stomach and intestine.

Soluble fiber is found in oat bran, barley, nuts, seeds, dried beans and legumes, lentils, peas, and some fruits and vegetables. Insoluble fiber also adds bulk (fiber) to the stool. It is found in wheat bran, vegetables, and whole grains.

A diet high in fiber is thought to reduce the risk of cancers of the rectum and colon.

3. FRUITS, VEGETABLES, AND CANCER:

Eating more fruits and vegetables helps provide a good supply of fiber, vitamin A, vitamin C, beta carotene and other carotenoids, and valuable substances called phytochemicals. Studies have shown that a diet high in these nutrients and fiber can reduce the risk of developing cancers of the stomach, colon rectum, esophagus, larynx, and lung.

Vitamin C and beta carotene, which forms vitamin A, are antioxidants. As such, they protect body cells from oxidation, a process that can lead to cell damage and may play a role in cancer.

In addition to nutrients that are needed for normal metabolism, plant foods also contain phytochemicals, plant chemicals that may affect human health. There are hundreds of phytochemicals, and their exact role in promoting health is still uncertain. However, a growing body of evidence indicates that phytochemicals may help protect against cancer.

To get these benefits, eat more fruits and vegetables that contain vitamins A and C and beta carotene. These include dark-green leafy vegetables such as spinach, kale, collards, and turnip greens. Citrus fruits, such as oranges, grapefruit, and tangerines are also high in antioxidants. Other red, yellow, and orange fruits and vegetables, or their juices are also healthful choices. Note: Juicing removes the fiber.

4. FIBER AND CORONARY HEART DISEASE:

Some fiber, especially soluble fiber, binds to lipids such as cholesterol. The fiber then carries the lipids out of the body through the stool. This lowers the concentration of lipids in the blood and may reduce the risk of coronary heart disease.

5. FAT AND CANCER:

A diet high in fat has been shown to increase the risk of cancers of the breast, colon, and prostate. A high-fat diet does not necessarily cause cancer. Rather, it may promote the development of cancer in people who are exposed to cancer-causing agents.

A diet high in fat may promote cancer by causing the body to secrete more of certain hormones that create a favorable environment for certain types of cancer. Breast cancer is one of these hormone-influenced cancers. High-fat diets also may change the characteristics of the cells to make them more vulnerable to cancer-causing agents.

To reduce fat in the diet, choose lean cuts of beef, lamb, and pork as well as skinless poultry and fish. Baking, broiling, poaching, and steaming are recommended cooking methods. Choose skim or low-fat milk and dairy products, as well as low-fat salad dressings.

6. SATURATED FAT, CHOLESTEROL, AND CORONARY HEART DISEASE:

Eating too much saturated fat is one of the major risk factors for heart disease. A diet high in saturated fat causes cholesterol, a soft, waxy substance, to build up in the arteries. Eventually, the arteries harden and narrow. The result is an increased pressure in the arteries as well as strain on the heart to maintain adequate blood flow throughout the body.

Because of its high calorie content, too much dietary fat also increases the risk of heart disease in that it increases the likelihood that a person will become obese. Obesity is another risk factor for heart disease.

7. SODIUM AND HYPERTENSION:

Sodium is a mineral that helps the body regulate blood pressure. Sodium is also commonly known as salt. It also plays a role in the proper functioning of cell membranes, muscles, and nerves. Sodium concentration in the body is mainly controlled by the kidneys, adrenal glands, and the pituitary gland near the brain.

The balance between dietary intake and kidney excretion through urine determines how much salt you have in your body. Only a small amount of salt is lost through your stools or sweat. The more salt your body holds, the more fluid the body keeps (retains), and vice versa.

Sodium-sensitive individuals may experience high blood pressure from too much sodium in the diet. The American Heart Association has developed specific guidelines for sodium intake. Dietary changes may help control high blood pressure. Salt (sodium) intake may have little effect in persons without high blood pressure, but it may have a profound effect in sodium-sensitive individuals. Blood pressure is often controlled by diuretics that cause sodium excretion in the urine.

8. ALCOHOL:

Alcohol use increases the risk of liver cancer. When combined with smoking, alcohol intake also increases the risk of cancers of the mouth, throat, larynx, and esophagus. In addition, alcohol intake is associated with an increased risk of breast cancer in women.

Alcohol is processed by the liver into energy for the body. Continued and excessive use of alcohol can damage the liver in various ways, including the development of a fatty liver. A fatty liver can lead to cirrhosis of the liver.

Alcohol can damage the lining of the small intestine and stomach, where most nutrients are digested. As a result, alcohol can impair the absorption of essential nutrients. Alcohol also increases the body's need for some nutrients, and interferes with the absorption and storage of other nutrients.

Continued and excessive use of alcohol can result in an increase in blood pressure. Chronic heavy drinking also can cause damage to the heart muscle (cardiomyopathy). In addition, stroke is associated with both chronic heavy drinking and binge drinking.

If you choose to drink alcohol, do so in moderation -- no more than 2 drinks per day for a man, 1 per day for a woman.

9. NITRATES AND CANCER:

Countries in which people eat a lot of salt-cured, smoked, and nitrite-cured foods have a high rate of cancer of the stomach and esophagus. Examples of such foods include bacon, ham, hot dogs, and salt-cured fish.

Eat salted, smoked, or cured foods only on occasion.

RESOURCES:

• The American Cancer Society is an excellent source of information on cancer prevention. www.cancer.org
• The American Dietetic Association provides sound dietary advice on a wide range of topics. www.eatright.org
• The American Heart Association provides dietary guidelines aimed at reducing the risk of heart disease and certain contributors to heart disease, such as high cholesterol, high blood pressure, and obesity. www.americanheart.org
• The National Cancer Institute's CancerNet is a government gateway to the latest, most accurate information on cancer prevention. www.cancer.gov
• The National Heart, Lung, and Blood Institute provides trustworthy information on preventing heart disease and cardiovascular risk factors. www.www.nhlbi.nih.gov/
• The National Osteoporosis Foundation is a good source of information on osteoporosis prevention. www.nof.org

Kushi LH, et al. American Cancer Society guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity. CA Cancer J Clin. 2006;56:254-281.

Lichtenstein AH, et al. AHA Scientific Statement. Diet and lifestyle recommendations revision 2006. A scientific statement from the American Heart Association Nutrition Committee. Circulation. 2006;114:82-96.