Proteins are the building blocks that grow and repair your body. Proteins are needed not only for muscle but also for hair, skin and internal organs. Some proteins travel around your body in the blood as hormones, enzymes and red blood cells. Protein is unique because it is the only food source of nitrogen, which is essential to all plant and animal life.

Proteins are made up of chains of amino acids. For each protein, there are specific amino acids in a specific amount, and they are joined in a unique order. This is what makes a chicken different from cheese or a fingernail different from a strand of hair. There are 22 amino acids. Eight of these are called the essential amino acids because they cannot be made by the body and must be provided by the diet.

What does it do?

Antibodies, which are made of protein, help you resist disease and infection.
Each day, your body loses protein in the form of hair, skin and nails. You also use up protein in all the activities of running and maintaining your body.
If you eat protein daily, it is supplied to your body tissue to replenish any loss and repair any injury.
For growing infants, children and teens, protein, along with sufficient calories, is necessary for growth of the entire body.
Pregnant and breast-feeding women need adequate protein for the fetus, for supporting maternal tissue, and for the production of breast milk after delivery.
If you have a cut, undergo surgery, or have an injury or illness, you need protein to recover and to rebuild your body.

Where do you get it?

Protein foods are classified in two ways: complete and incomplete. Complete proteins, which come from animal sources such as chicken, fish, dairy and soybeans, contain all the essential amino acids that help build your muscle and body tissue. Incomplete proteins, found in plant foods, such as grains, seeds, nuts, beans and vegetables, provide a varying but limited array of amino acids. A greater variety and amount of incomplete proteins must be consumed to cover all the amino acids needed for protein building.

We can compensate for the amino acid deficiencies in an incomplete protein by combining it with another protein, thus providing all the building blocks for protein creation. This is the concept of complementary proteins, in which proteins with opposite strengths and weaknesses complement each other.

For example, many cereals are low in an amino acid called lysine, but high in methionine and cystine. Lima beans, soybeans and kidney beans are high in lysine but low in methionine and cystine. Many cultures, including Mexican and Indian cultures, have limited animal protein sources but eat combinations of incomplete foods.

Examples of appropriate combinations include:

rice and beans
cereal and milk
beans and corn
bread and cheese

Recent research indicates that such combinations need not be eaten at the same meal. If they are consumed over the period of a day, the necessary building of muscle and body tissue will occur. Vegetarians thrive on non-animal protein diets because of our body's ability to do this.

Use the following chart to help select foods that are good sources of protein.

Food	Grams of Protein
6 oz. canned tuna	40
4 oz. chicken breast	35
3 oz. beef*	26
3 oz. turkey	25
3 oz. salmon	23
8 oz. (1 cup) garbanzo beans	15
8 oz. (1 cup) milk	8
8 oz. (1 cup) yogurt	10
4 oz. (1/2 cup) tofu	10
4 oz. (1/2 cup) cottage cheese	14
1 egg	6
1 oz. cheddar cheese	87
8 oz.(1 cup) pasta	5

*A 3 ounce serving of beef (or chicken) is about the size of a deck of cards.

How much do we need?

Your protein needs are determined by your age, sex, weight and whether you are pregnant, lactating or in intense sports training. The accompanying chart indicates the recommended daily amounts for different types of people.

You may calculate the amount of protein you need daily by multiplying your weight in pounds by the number that corresponds to your situation, as shown here. This will give you the recommended grams of protein per pound of body weight per day that is appropriate for people of your sex, age and/or activity level.

Sedentary adult	weight x 0.4
Adult recreational exerciser	weight x 0.5-0.75
Adult competitive athlete	weight x 0.6-0.9
Adult who is building muscle mass	weight x 0.7-0.9
Dieting athlete	weight x 0.7-1.0
Growing teen-age athlete	weight x 0.9-1.0

Using this formula, you can calculate that a 140-pound sedentary female, for example, would need 56 grams of protein (140 x 0.4) per day. A 170-pound male would need 127.5 grams (170 x 0.5-0.75).

The amount of protein needed by athletes is the subject of active research. Currently, the American Dietetic Association recommends that athletes consume 1.5 grams of protein per kilogram of body weight, or about twice the Recommended Daily Allowance (RDA).

How to increase your protein intake

Here are five ways to increase protein in your diet if you need more than you are currently getting.

Increase your meat serving at lunch or dinner by just one ounce to add seven more grams to your daily protein intake.
Make a high-protein breakfast drink by blending a cup of yogurt or silken tofu, a cup of milk and your favorite fruit. Bananas and strawberries work well. You may want to add ice.
Add shredded cheese, cottage cheese or garbanzo beans to a tossed salad at dinner.
Add a little protein to your snacks. Put peanut butter on apples, drink milk with cookies, or use cheese cubes to make a kabob with grapes, pineapple and cherries.
Mix protein into foods. For example, you can make an eggnog of egg substitutes, milk and sweetener, stir nonfat dried powdered milk powder into hot cereal or mashed potatoes, or add powdered egg whites to applesauce.