Dietary protein amino acid supplements

Horst, D., Grace, N.D., Conn, H.O., Schiff, E., Schenker, S., Viteri, A., Law, D., Atterbury, C.E. Comparison of dietary protein with an oral branched chain-enriched amino acid supplement in chronic portal-systemic encephalopathy a randomized controlled trial Hepatology 1984 4 279 - 287... 

Maple syrup urine disease is a rare genetic disorder affecting the metabohsm of leucine, isoleucine and valine. Accumulation of these branched-chain amino acids results in severe neurological damage and death. The aim of dietary management is to prevent the accumulation of these amino acids, by the use of a low-protein diet and leucine-, isoleucine-and vahne-free amino acid preparations. Natural protein supplies the necessary leucine, isoleucine and valine, based on a leucine exchange system with additional isoleucine and/ or valine available as single amino acid supplements. 

Retrospective review. Protein recommendations include amino acid supplements. Intakes prescribed based on Ross nutrition support protocol Retrospective review. Dietary survey. Group without protein supplement had inadequate intake of some nutrients and higher Phe levels... 

Since animals tend to concentrate in their own proteins the sulfur amino acids contained in the plants diey eat, such animal products (meat. eggs, and cheese) are valuable sources of the essential sulfur amino acids in human diets. In regions where die diet is composed almost entirely of foods of plant origin, deficiencies of sulfur amino acids may be critical in human nutrition. Frequently, persons in such areas (also voluntary vegetarians) are also likely to suffer from a number of odier dietary insufficiencies unless supplemental sources are used. 

Some creatine products currently on the market are also enriched with other nutrients, including protein, glucose, vitamins, herbal ingredients, and other amino acids. Again, no hard data exists on the effectiveness of taking creatine in combination with other dietary supplements or herbals. 

It may also be necessary to determine the free fatty acid content of oily materials as an index of rancidity, since this will affect palatability. Analyses of amino acids can only be conducted in specialized laboratories and are conducted less frequently. Instead most feed mixers (including commercial feed manufacturers) use procedures such as prediction equations based on the protein content of the sample to predict the content of important amino acids. Tests for minerals are more routine and are offered by most laboratories. Tests for vitamins are offered by certain laboratories but are not very frequent since commercial feed manufacturers often disregard any vitamin contribution from the dietary ingredients and add all the necessary vitamins in the form of a supplement. 

In the first two subjects (Patients 1 and 2), the weight loss may have been partly due to a mild restriction in caloric intake in addition to a dietary zinc restriction. Also, that the synthetic diet based on soy protein may have been limiting in certain amino acids was considered. Because of these considerations, in the second group of subjects we increased the caloric Intake, and in the base-line period of 5 weeks before zinc restriction, we supplemented these two subjects with 30 mg of zinc dally. The weight remained stable during the base-line period but decreased when the zinc was restricted subsequently. 

Dietary protein deficiency, especially a lack of essential amino acids, has a long-term effect on regulatory mechanisms. Tryptophan plays a significant role here. Tryptophan deficiency leads to decreased protein synthesis, which is reversible solely by dietary supplementation of tryptophan even during inanition. The tryptophan effect occurs rapidly following the stimulation of nuclear RNA synthesis. (89) (s. fig. 3.4)... 

The quality of a dietary protein may be increased by supplementing the diet with appropriate amino acids. This concept is illustrated by the study shown in Figure 6.29, which involved supplementation of a wheat-based diet with lysine. The chajtge in the quality of the diet was determined simply by measuring changes in the growth rate... 

The results from the study can be interpreted as follows. Lysine appears to be the first or most limiting amino acid of wheat protein. Maximal grow A occurred with reduced levels of dietary protein where the diet was supplemented with lysine. If lysine was the second most limiting amino add of wheat, the lysine... 

Plant genetic experiments presently being undertaken with corn (maize) and with rice may improve the nutritional properties of these cereals. These may help to close the amino acid nutritional gap, which exists between plant sources of proteins and first class proteins [70]. However, this will still not remove the need for synthetic amino acids for their many other uses (e.g., for chelating agents), as dietary supplements, as building blocks for specialty proteins, and as components of intravenous feeding solutions. All of these... 

Protein turnover is not completely efficient in the reutilization of amino acids. Some are lost by oxidative catabolism, while others are used in synthesis of non-protein metabolites. For this reason, a dietary source of protein is needed to maintain adequate synthesis of protein. During periods of growth, pregnancy, lactation, or recovery from illness, supplemental dietary protein is required. These processes are affected by energy supply and hormonal factors. An overview of amino acid metabolism is presented in Figure 17-1. 

The first can be accomplished by restriction of dietary protein and administration of a-keto analogues of essential amino acids. Arginine supplementation as a precursor of ornithine is essential to the urea cycle. The diversion... 

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