What Is Protein?
Protein, along with carbohydrate and fat, is an essential nutrient for growth and health in humans. There are thousands of types of proteins in nature, each one consists of a specific combination of amino acids. Some proteins are as small as 2 or 3 amino acids (known as dipeptides and tripeptide) while others contain thousands. Most living things make hundreds of different proteins, each suited for a specific purpose in that species. Protein serves many purposes in living things. Protein is used for growth and maintenance of body structures like muscle, skin, bone, joints, hair, and nails. Other proteins, known as enzymes, are used to support body functions by facilitating vital chemical reactions. Protein is also used to maintain fluid and pH balance, as well as forming vital antibodies, immune factors and blood clotting factors. Finally, certain hormones like insulin and HGH are also made from protein. Virtually all of the proteins used by the body must be manufactured 'from scratch' out of available free amino acids. When required amino acids are not available, the body breaks down muscle and other tissues as a source of last resort, which is a primary reason why athletes and others use protein supplements. Other benefits include support for immune health and low cholesterol diets.
Protein foods are digested in the stomach, where enzymes dismantle them into free amino acids. These aminos are then absorbed in the small intestine. Since only amino acids are absorbed by the body, not the whole protein itself, one important factor that makes one protein source better than another is how quickly and easily the body can break that protein and utilize the free amino acids to build new proteins. This quality is known as the Biological Value or BV of a protein. So the best and most popular protein supplements utilize protein sources with high BVs like whey and casein protein, and egg white protein.
Protein and Amino Acids
In all, humans require 20 different amino acids, some of which can be made by the body and others, known as essential amino acids, which cannot and must therefore come from the diet just like vitamins and minerals. So another way of differentiating protein sources is by comparing the range and amounts of amino acids they contain. The best proteins in this regard are known as 'complete proteins' because they supply the complete range of 20 amino acids. Complete proteins include all animal-source proteins and a few plant sources, primarily hemp and soy. Some amino acids like arginine and glutamine have been termed conditionally essential, meaning supplemental amounts are needed only in certain conditions. These amino acids are among the ones most often used as standalone supplements. See the section on amino acids for more information about the benefits of taking specific amino acids.
Protein supplement powders and bars derive their protein from several sources. Whey protein, derived from milk, is the most popular and the most-efficiently absorbed protein. Egg white protein is a another high-quality protein source that's virtually cholesterol-free. Soy protein is the most popular of the vegetarian protein types, and also provides isoflavones which have antioxidant and hormone balancing properties. Rice proteins are an excellent option for vegetarians who want to avoid soy.
Protein: How Much is Needed?
Recommendations for protein consumption vary among experts but are frequently adjusted based upon individual circumstances and goals. The amount is usually expressed in terms of grams of protein per pound of ideal (not actual) bodyweight, per 24-hour day. A general recommendation for healthy non-athletes is to consume about 0.4 grams of protein per pound, while athletes and bodybuilders - those already in shape looking to build or maintain muscle mass - may need from 0.8 up to 1.5 g of protein per pound of actual body weight.
Using Protein Supplements
Protein supplements are easy to use because they're available in so many forms and varieties. Protein bars and shakes are very popular and provide as much protein as a large serving of meat, but with a tiny fraction of the fat and cholesterol, if any. Protein supplements are available in low carb versions, meal replacement (MRP) versions with added vitamins, ready-to-drink shakes, and weight gainer products.
Side-effects and Cautions:
The main caution with protein supplements pertains to protein-restricted diets, liver or kidney disease or those with allergies to specific types of protein like soy. Do not use protein supplements as your sole source of protein or nutrition. If in doubt, consult your physician or a nutritionist if you have questions about your specific protein requirements or the appropriateness of protein supplements.