Top Tips for Choosing Healthier Proteins

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Protein is an essential nutrient that yields approximately 4 calories per gram. Its energy is liberated for:

1. Building and repairing body tissues
2. Forming enzymes, hormones, antibodies, and hemoglobin
3. Transporting fats and other nutrients through the blood
4. Maintaining the acid-base balance in tissue fluids
5. Supplying energy for muscular work when there is a shortage of carbohydrates and fat.

Proteins are complex chemical structures containing carbon, oxygen, hydrogen, and nitrogen. These elements are combined into chains of different structures called amino acids. The proteins of all living tissue consist of 20 different amino acids. Two other rare amino acids have been identified but are found in very few proteins. Nine of the amino acids are considered essential because the body cannot manufacture them and they can be obtained only through the diet.

Complete proteins contain all of the essential amino acids. A high-quality protein is a complete protein that has all of the essential amino acids in amounts proportional to the bodys needs for them. Meat, fish, poultry, and dairy products are high-quality proteins. Incomplete proteins do not contain the amino acids in the proportions the body needs.

Plant sources of protein are usually incomplete. This is important, particularly for vegetarians, because protein synthesis is regulated by the all-or-none principle. The body cannot make partial proteins, only complete ones. Therefore, if an amino acid from a protein source is in short supply, protein synthesis will stop as soon as that amino acid is used up. Vegetarians can obtain complete proteins by consuming complementary proteins from mixing and matching foods. For example, food A may be missing three essential amino acids that are contained in food B. Food B may be missing some essential amino acids that are found in food A. Together, they have all of the essential amino acids.

Legumes, such as kidney and lima beans, black-eyed peas, garden peas, lentils, and soybeans, are excellent sources of proteins. Although their protein is not quite the caliber of meat protein, they are rich in other healthy nutrients such as B vitamins, and they are low in fat.

Daily protein requirements vary according to age. Infants require about 2.2 grams of protein per kilogram of body weight to support growth. Adolescents require 1.0 gram per kilogram. Adults need 0.8 gram per kilogram.

The typical U. S. diet contains more than adequate protein. Consuming more than 15 percent of the total calories in the form of protein seems to have no advantage. One of the major problems associated with excessive protein intake is that it usually is accomplished by increasing the consumption of animal products, which also are high in saturated fat. The increased consumption could displace fiber in the diet, and the two together can lead to a host of immediate and long-term problems.

The average daily consumption of protein by adults in the United States is about 16 percent of total calories well above the requirement. For example, a 154-pound person requires 56 grams of protein each day. If this person is consuming 2,500 kcals/day with a typical protein intake of 15 percent, this person actually is consuming 94 grams of protein.

Many people¡ªcompetitors and noncompetitors alike who are striving to develop strength and power take amino acid supplements to build larger and more powerful muscles. Selected amino acids do not build larger muscles. Only exercise can do that. Nevertheless, these and other unfounded notions proliferate among uninformed participants who are constantly attempting to enhance their performance with substances that might give them an edge beyond what they achieve through training.

Current evidence indicates that long-distance, endurance-type athletes and weightlifters and bodybuilders have the greatest need for protein 1.5 to 1.6 grams of protein for every kilogram of body weight. Even if this proves to be correct, protein supplements are not necessary, as most athletes consume more than this amount from their food intake.

Active people tend to get more vitamins in their diet than sedentary people do because active people consume more calories than their less active counterparts. If you are concerned about not getting enough vitamins in your diet but are unwilling to make appropriate dietary changes, a one-a-day brand supplemented by extra C and E should suffice.

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