What is protein?
Protein is a molecule composed of amino acids joined together by peptide bonds. Amino acids are made up of the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. Protein is found in the structure of all living organisms. Protein has many roles in the body including enzymatic structures, immunoglobulins, also called antibodies, protein hormones- chemical messengers, and in blood some amino acids help maintain blood acid-base balance. Protein acts as carriers to transport various ions or molecules across cell membranes or in the blood. Proteins are also involved in the formation of implicit and explicit long-term memory.
Of course, athletes are aware protein synthesis is required for new muscle growth, but protein synthesis is also required for the formation of new memories, which may surprise some people.
What are essential amino acids?
Essential amino acids, also called indispensable amino acids, must be supplied in the diet either as free amino acids or as constitutes of protein. Essential amino acids are not made in adequate amounts by the body to supply needs, thus dietary ingestion is required. Essential indispensable amino acids include: Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine, Isoleucine, or Branched Chain Amino Acids. The BCAA's are named so because they have a carbon chain which deviates or branches from the main linear carbon backbone. The BCAA's are metabolized primarily by the peripheral tissues rather than by the liver. BCAA's have been shown to stimulate the motor pathway (the pathway that enhances muscle protein synthesis).
How does protein influence diet-induced thermogenesis?
Of the three macronutrients (carbohydrate, fat, and protein) protein exhibit’s the highest thermic effect (specific dynamic action). The increase in metabolic rate following ingestion of protein is 25-30 percent. The increase in metabolism results from increased oxidation associated with not only digestion of food, but also absorption, transport, metabolism, and storage of energy following eating. The thermic effect of food is also known as diet-induced thermogenesis.
Does protein consumption have a negative impact on the kidneys?
Concerns about level of dietary protein and renal function are often presented in public health guidelines. In addition to the claims that high protein intake causes renal disease, some studies have suggested that renal function may be negatively affected by routine consumption of high protein diets. Although high protein diets cause changes in renal function (i.e., increased GFR) several related endocrine factors may be harmful to individuals with renal disease. There is insufficient evidence to extend these findings to healthy individuals with normal renal function at this time.
Evidence suggests that protein-induced changes in renal function are a normal adaptation of a healthy kidney. More long-term studies are needed to investigate the health kidney and protein consumption. Currently, there is insufficient evidence to warrant public health directives aimed at restricting dietary protein intake in healthy adults for the purpose of preserving renal function.