Vitamin and mineral supplements are being widely used by physically active people because of all the performance-enhancing claims made by supplement manufacturers. It is estimated that 40-50 percent of athletes use some form of vitamin/mineral supplements. Some doses range from amounts similar to the Recommended Dietary Allowances (RDA) up to levels many times the RDA. Supplements are useful under a variety of conditions, such as if an individual

has an existing vitamin or mineral deficiency;
has poor nutrient intake and/or dietary habits; or
is exposed to extreme environmental conditions, such as altitude.

Often, laxatives are prescribed in conjunction with some medical treatments and may cause decreased absorption of vitamins, loss of minerals and elec-trolytes, or inhibition of glucose uptake. Therefore, any patient on laxatives should be carefully monitored, and supplementary nutritives should be administered as necessary.

Taking a general multivitamin supplement appears to be without measurable performance enhancing effects in healthy, well-nourished, physically active personnel. Similarly, no improvements in muscle strength or endurance have been noted in strength athletes, such as body builders, who tend to use megadoses of vitamin and mineral supplements. The indiscriminate use of high-potency vitamins and minerals is of growing concern since excessive amounts of vitamins and/or minerals can be harmful and may result in nutrient imbalances. Excessive intake of some vitamin and mineral supplements can result in adverse-and possibly toxic-side effects.

WATER
Water is often called the "forgotten nutrient." Water is needed to replace body fluids lost primarily in urine and sweat. A person can survive weeks without food but only days without water. Water makes up 70 percent of body weight and is found in every cell in the body. It is the medium through which nutrients are transported from the digestive tract to the cells where they are needed. Water is also the medium through which the by-products of cell metabolism are removed.

Water also serves as the medium in which the chemical processes of life take place. It is normally taken into the body in beverages, soups, and in the form of solid foods. Fluid needs are increased with sweating, vomiting, diarrhea, high-protein diets, and in hot environments. An insufficient intake may cause dehydration, evidenced by loss of weight, increased body temperature, and dizziness.

GUIDE TO GOOD EATING
LEARNING OBJECTIVE: Recall the elements of the USDA Food Guide Pyramid and recommended dietary guidelines.

Calculating a therapeutic diet can be complicated and is best left to dietitians. It is now common practice for dietitians or dietary kitchens to select foods for diets using the food groups outlined in figure 9-2, the Food Guide Pyramid. These foods are classified according to their nutritional value and the number of servings that should be eaten each day.

THE FOOD GUIDE PYRAMID
The Food Guide Pyramid emphasizes foods from the five food groups shown in the sections of the pyramid. Each of these groups provides some, but not all, of the nutrients we require. For good health we need them all. For everyday living, the simplest and most practical plan is to follow those same guidelines, selecting from the various food groups the type and amount of food recommended.

DIETARY GUIDELINES
The food pyramid graphically communicates the message of the Dietary Guidelines for Americans. Diets should be built upon a base of complex carbohydrates and less fats. The placement of the food groups starting at the base of the pyramid conveys the current recommendations. These recommendations are as follows:

Eat more grains, vegetables, and fruits

Eat moderate amounts of lean meats and dairy foods

Use sweets, fats, and oils sparingly

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Figure 9-2.-Food Guide Pyramid.

Generally accepted guidelines suggest that you eat a diet that is high in complex carbohydrates and low in protein and fat. Your diet should consist of at least five combined servings of fruits and vegetables each day. Avoid fat when possible. Eat at regular intervals when possible, and avoid snacking late at night. For detailed information on nutrition, consult Navy Nutrition and Weight Control Guide, NAVPERS 15602; and the Fat, Cholesterol and Calorie List for General Messes, NAVSUP 580.