Protein and Diet

Protein is essential for certain functions in your body. Protein provides support to almost all of your body tissues, helps build enzymes and hormones, aids in maintaining acid-base balance, helps transport nutrients throughout your body and helps ensure a proper immune response. Protein can also provide you with energy in the absence of carbohydrates. To ensure that your body contains enough protein, you must consume adequate amounts of protein in your diet.

Amino Acids

Proteins are composed of individual units called amino acids. Joan Salge Blake explains in her book "Nutrition and You" that proteins human bodies use have 20 amino acids; of these amino acids, nine are essential and 11 are nonessential. Essential amino acids are those your body cannot make and thus must be obtained from your diet. Nonessential amino acids are the ones your body is able to synthesize, so it is not necessary to consume them through the food you eat. The order in which the amino acids come together determine what type of protein is made.

The total number of amino acids and the essential and nonessential amino acid ratio differ among sources. One reason is that certain conditions prevent some people from synthesizing amino acids. Those amino acids, which are nonessential for most people, become essential for those individuals.

Types of Protein

Proteins are separated into two types based on their amino acid profile. Proteins that provide all of the essential amino acids and some of the nonessential ones are called complete proteins. Proteins that are missing or low in one or more of the essential amino acids are called incomplete proteins. Most animal sources of protein are complete proteins, whereas most vegetable sources of protein are incomplete proteins.

Protein Recommendations

You can determine your protein needs in two ways. The first way to calculate protein needs is by calorie intake. Protein, which provides 4 calories per gram, should constitute 10 to 35 percent of your daily calories. If you consume 2,000 calories per day, your protein needs vary from 50 to 175 g per day.

Another way to calculate protein needs is by body weight. You should consume 0.8 g of protein for every kg of body weight. If you weigh 150 lbs., or 68.2 kg, you should consume approximately 55 g of protein daily.

Protein Choices

When choosing protein sources, it is important to remember that not all protein is nutritionally equal. While animal sources of protein may provide all of the essential amino acids, choosing the wrong types can contribute to your cholesterol and saturated fat intake. Better complete protein choices are fish and poultry without the skin. Choose lean cuts of red meat and remove any excess fat.

Incomplete proteins are good sources of protein because they provide vitamins, minerals and fiber without providing excess calories or saturated fat. When choosing incomplete proteins, it is important to vary your choices to ensure that you are obtaining all of the essential amino acids. Good incomplete protein sources include nuts, seeds, beans and whole grains.