Sulfur amino acids, dietary, effect

Since dietary cereals are low in sulfur-containing amino acids, they produce an alkaline urine which favors the retention of bone minerals. In post-menopausal women, there appears to be some interaction between the diet and the effect produced by estrogens on bone mineral content (28). 

Much of the toxicological interest in cyanide relating to mammals has focused on its rapid lethal action. However, its most widely distributed toxicologic problems are due to its toxicity from dietary, industrial, and environmental factors (Way 1981, 1984 Gee 1987 Marrs and Ballantyne 1987 Eisler 1991). Chronic exposure to cyanide is correlated with specific human diseases Nigerian nutritional neuropathy, Leber s optical atrophy, retrobulbar neuritis, pernicious anemia, tobacco amblyopia, cretinism, and ataxic tropical neuropathy (Towill etal. 1978 Way 1981 Sprine etal. 1982 Beminger et al. 1989 Ukhun and Dibie 1989). The effects of chronic cyanide intoxication are confounded by various nutritional factors, such as dietary deficiencies of sulfur-containing amino acids, proteins, and water-soluble vitamins (Way 1981). 

Excessive heat can cause destruction of amino acid residues. The amino acid most susceptible to direct heat destruction is cystine. Although not an essential amino acid, cystine does have a sparing effect on the dietary requirement for methionine. As a result, cystine destruction can be nutritionally important. In addition, many vegetable proteins are limiting in the sulfur amino acids. Cystine destruction would be particularly harmful for these proteins. 

The mechanism by which dietary protein induces an increase in urinary calcium is not clear, The effect has been attributed, in part, to the catabolism of sulfur-containing amino acids to yield sulfate. Elevated levels of plasma sulfate can form a complex with calcium. The complex passes into the renal tubule, where it is poorly reabsorbed, resulting in its excrehon in the urine. The mechanism by which phosphate reverses the hypercalciuric effect of protein is also not dear. 

Nutrients have a profound effect upon the production and actions of cytokines. Protein-energy malnutrition, dietary (n-3 polyunsaturated fatty acids, and vitamin E suppress the production of specific cytokines. The synthesis of acute-phase proteins and glutathione is dependent on the adequacy of dietary sulfur-containing amino acids. The consequences of the modulatory effects of previous and concurrent nutrient intake on cytokine biology are the depletion of resources and damage to the host, which ranges from mild and temporary to severe, chronic, or lethal. 

Kato N, Mochizuki S, Kawai K, et al. 1982a. Effect of dietary level of sulfur-containing amino acids on liver drug-metabolizing enzymes, serum cholesterol and urinary ascorbic acid in rats fed PCB. J Nutr 112 848-854. 

Among sheep with dietary insufficiencies, the minerals copper and zinc, when supplemented to the diet, have been shown to be important to wool fiber growth. Their effectiveness is attributed to the important roles these minerals play in sulfur amino acid metabolism copper serves to catalyze the oxidation of cysteine to cystine during fiber synthesis [109]. Zinc is required for cell division to occur, and it also appears to play a role in protein metabolism [110]. 

The chemical and functional characteristics of proteins in Brazil nnt have not yet been fully explored and little information is available on the health effects of Brazil nut by-products. For example, the cake produced from Brazil nut oil extraction industries, which might be used as functional food ingredients, sources of nutraceutical extracts or dietary protein due to its high content of sulfur-containing amino acids, requires further research. 

The recommended daily dietary doses of copper are 0.4-0.7 mg for children under 1 year, 0.7-2.0 mg for children aged 1 to 10 years, 1.5-2.5 mg for adolescents and 1.5-3.0 mg for adults. Resorption of copper and its retention in the body depend on the chemical form in which this element is present in the diet. Experiments on laboratory animals have shown a higher utilisation of copper in the form of neutral and anionic complexes contained in plant material than in the form of copper sulfate. Availability of copper increases the presence of proteins and amino acids in the diet. Also, carboxylic and hydroxycarboxylic acids stimulate resorption of copper. In contrast, higher doses of ascorbic acid, fructose, molybdenum, sulfur compounds and zinc significantly reduce the resorption of copper. Ascorbic acid reduces cupric compounds to slightly soluble cuprous compounds. The effect of phytic acid and dietary fibre on copper resorption is, in comparison with the effect of these components in zinc, less pronounced. 

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