Disease Prevention

There are three important reasons why following a healthy diet is critical:

1. To maintain health by preventing loss of muscle strength, bone mass, and vitamin deficiency states.
2. To prevent diseases such as heart attacks, strokes, obesity, osteoporosis, and certain cancers.
3. To help control and/or treat diseases such as high blood pressure, diabetes mellitus, and celiac disease.

The body needs carbohydrates, fats, proteins, vitamins, and minerals to maintain healthy organs, bones, muscles, nerves, and to produce hormones and chemicals.

Vitamins and minerals are naturally-occurring substances that are essential for the proper growth and functioning of the body that are necessary (in small amounts) for normal chemical reactions (metabolism) inside the body.



Obesity and heart attacks are major public health problems in the United States and other countries. Therefore, most dietary recommendations are aimed at preventing these two diseases. Obesity is caused by eating more calories than the body burns. Obesity in turn can be a cause of many diseases such as heart disease, diabetes, liver disease, arthritis, high blood pressure, gout, gallstones, and certain cancers. To lose weight or maintain a healthy weight, one needs to eat more low energy-dense foods. Low-energy-dense foods (such as vegetables and fruits) contain few calories per unit volume of food so that one can eat a large volume of it (for example: lettuce) without taking in many calories. One should also eat less of the high energy-dense foods such as fats, egg yolks, fried foods, sweets, and high fat salad dressings. Foods with a high energy density also often have high cholesterol and saturated fat content. One should also eat less of those foods that provide calories but little other nutrients, such as alcohol and many packaged snack foods.

The Dietary Guidelines for Americans, published in 2005 by the United States Department of Agriculture (USDA), contains guidelines for healthy diets based upon review of scientific studies for people above two years of age. These guidelines recommend that a healthy diet should:

• Emphasize fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products
• Include lean meats, poultry, fish, beans, eggs, and nuts
• Be low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars

MyPyramid is an online animated program to help a person customize his/her diet by choosing proper foods and portion sizes based on the individual’s age, sex, and activity level. The key objectives of the MyPyramid Plan are to help a person get the most nutrition (proteins and vitamins and minerals) out of the recommended number of daily calories, and to achieve a balance between food intake and physical activity to maintain a healthy weight. MyPyramid Plan recommendations include:

• Make half your grains whole
• Vary your veggies
• Focus on fruit
• Get your calcium rich foods
• Go lean with protein
• Find your balance between food and physical activity

Vitamins and mineral supplements are important both in preventing deficiency states as well as in preventing diseases. Most diseases resulting from vitamin deficiencies such as scurvy (vitamin C deficiency), blindness (vitamin A deficiency), and beriberi (thiamine deficiency) are found mainly in third world countries and are almost non-existent in the United States. But certain special populations in the United States can develop vitamin or mineral deficiencies, and thus need vitamin supplements. For example:

• Severely malnourished alcoholics can develop nerve damage from thiamine deficiency.
• Elderly individuals lacking sun exposure can develop bone disease from vitamin D deficiency.
• Pernicious anemia is a condition, along with nerve damage, than can result from vitamin B12 deficiency.
• People with celiac sprue can also develop vitamin deficiencies as well as iron deficiency.

For these special populations, vitamin supplements are important to prevent these deficiencies.



Vitamin supplements are not only used to prevent deficiencies but also used to prevent diseases. Certain vitamin supplements (such as folic acid, vitamin B6, and B12) have been used to lower blood levels of homocysteine, which may help prevent heart attacks. Folic acid fortification in cereals and vitamin supplements has been found to decrease the risk of birth defects in women of childbearing age.



Diets low in simple sugars are important in controlling blood glucose levels in diabetes mellitus. When the condition cannot be adequately controlled by diet alone, medications (sometimes including insulin) are required.

• The DASH diet is recommended to lower blood pressure. If dietary measures alone are not sufficient, medications are frequently prescribed by doctors (sometimes in combination) to lower blood pressure.
• A Gluten-Free Diet is the primary treatment for celiac disease (celiac sprue). Since people with celiac sprue may have difficulty absorbing nutrients and vitamins, some people with this condition may also need calcium, iron, and vitamin supplements.
• Therapeutic Lifestyle Changes (TLC)are important treatments for high blood levels of cholesterol, especially the "bad" ( LDL) cholesterol. When TLC are not sufficient, then medications are usually indicated to lower blood lipid levels.