Protein Requirements
For Muscle Growth and Health

Protein, one of the macro-nutrients, is the basic structure of all living cells. It is used in making hormones, blood plasma transport systems, and enzymes. It is crucial for proper central nervous system (CNS) function.

Proteins are made up of amino acids, and there are two types: complete and incomplete. Of the 20 amino acids that have been identified, nine are considered essential because they cannot be manufactured by your body. They must come from the food you eat.

The essential amino acids are . . .

• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine

Foods that contain all nine essential amino acids in sufficient quantity to sustain life are called complete.

The Protein Efficiency Ratio (PER) is a measurement of its completeness. It is rated according to various indexes. The most common being the Biological Value, or BV. The higher the BV the more readily it is absorbed by the body. Eggs have a BV of 100, the highest. Whey’s value is close to 100, while beans have a BV of 49.

(Ratings greater than 100 refer to the chemical score of an amino acid pattern in a reference product to a test product and not the BV.)

The non-essential amino acids are . . .

• Alanine
• Arginine
• Aspartic Acid
• Cysteine
• Glycine
• Glutamic Acid (Glutamine)
• Ornithine
• Taurine
• Proline
• Serine
• Tyrosine

Our bodies are able to manufacture the non-essential amino acids from the by-products of carbohydrate metabolism.

Protein is synthesized in all our body tissues, the liver and muscles being the most active. Our bodies synthesize about 300 grams per day even though the average daily intake is only 70 grams.

Meat, fish, milk, cheese, and eggs contain all nine essential amino acids.

Vegetables, grains, seeds, and nuts do not contain all nine essential amino acids by themselves. But combinations of incomplete amino acid foods can supply all the essential ones, e.g. beans with rice or peanut butter on wheat bread. Therefore, knowledgeable vegetarians can get all the required amino acids by combining incomplete amino acid foods.

Digestion begins in the stomach but is primary in the small intestine and then metabolized by your liver for the building of tissue. That which is not utilized for tissue can be used as an energy source, providing four calories per gram.

Fasting causes your body to use protein as an energy source, even to the point of breaking down vital tissues such as organs and muscle. Internal ramifications of deficiencies can be muscle wasting, weak ligaments, and cellular dysfunction.

On the other hand, excess amounts not utilized for tissue repair and growth, or as an energy source, are converted to body fat and stored.

How much is enough?

Your individual requirements depend on you and your daily activities. Tissue growth due to injury, growth, weight training, or pregnancy influences daily requirements.

The United States Department of Agriculture's Recommended Daily Allowance (RDA), for an adult, on average, is approximately .36 grams per pound of body weight per day (or .8 grams per kg of body weight) as a minimum requirement. As a general rule, during intense weight training, up to one gram per pound of body weight may be consumed.

Protein metabolism produces nitrogen, which creates a workload for your kidneys and liver to eliminate the excess. It is important to adequately hydrate when consuming increased levels, since dehydration can occur if your kidneys do not get enough water to dilute the nitrogen.

Returm from Protien Requirements to Nutrition