Human protein requirements
1980
Palombo, John D. | Blackburn, George L.
Protein is the most important of the cell metabolic components, and is constantly in a dynamic state of synthesis and breakdown. Proteins are synthesized from amino acids in the diet and in tissue protein breakdown. Since protein nitrogen is continuously lost from the body, the supply must be replenished daily. There are 8 essential amino acids which cannot be manufactured in the body; the nutritional value of a food depends on the balance of amino acids it contains, but combinations of foods can also provide this balance. Meat and milk are examples of complete proteins; vegetables and grains tend to have incomplete proteins. Protein quality and quantity are necessary to maintain the nitrogen balance. It is this balance which has been used in the determination of Recommended Dietary Allowances. Daily protein intake varies with age, diet, stress, physical condition and disease. Various studies show that 97% of Americans eat more than the necessary protein requirement, including elderly people who may have poor eating habits. Protein needs must be considered in weight loss diets--the protein/nitrogen content should be analyzed independent of the caloric content. Severe health damage or even death can result.
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