Vitamins human metabolic balance

The balance between excess and insufficient zinc is important. Zinc deficiency occurs in many species of plants and animals, with severe adverse effects on all stages of growth, development, reproduction, and survival. In humans, zinc deficiency is associated with delayed sexual maturation in adolescent males poor growth in children impaired growth of hair, skin, and bones disrupted Vitamin A metabolism and abnormal taste acuity, hormone metabolism, and immune function. Severe zinc deficiency effects in mammals are usually prevented by diets containing >30 mg Zn/kg DW ration. Zinc deficiency effects are reported in aquatic organisms at nominal concentrations between 0.65 and 6.5 pg Zn/L of medium, and in piscine diets at <15 mg Zn/kg FW ration. Avian diets should contain >25 mg Zn/kg DW ration for prevention of zinc deficiency effects, and <178 mg Zn/kg DW for prevention of marginal sublethal effects. 

Vitamins are a group of unrelated chemical substances that are essential in small amounts for the regulation of normal metabolism, growth, and function of the human body. Not all of the vitamins can be synthesized in the body, and therefore, some vitamins must be obtained from an external source, such as a proper well-balanced diet or dietary supplements. 

In the study presented in Reference 15, we focused our attention on spontaneous processes of chiral conversion and peptidization running in aqueous acetonitrile solution of L-Met (Scheme 19.3). We chose this amino acid due to its important functions in the human body. L-Met is a donor of methyl groups in the metabolic processes of methyl group transfer it plays an important role in synthesis of choline and lecithin, promotes normalization of lipid metabolism and hepatic steatosis, and has an anti-atherosclerotic activity. Furthermore, L-Met plays an important role in the activities of the adrenal gland, in particular in the synthesis of adrenaline, and in the processes of inactivation of catecholamines, thereby regulating the catecholamine balance. The existence of a close relationship has also been proven between L-Met, folate transformations, and vitamins B6 and B12 [25]. 

It is unusual for single-nutrient deficiencies to occur under natural conditions, apart from those conditions associated with inborn errors in metabolism or those with unusual ecological circumstances. The latter, for example, may occur when soils are selectively nutrient-deficient, such as for iodine or some other trace minerals, and when access to an external food supply is limited. Consideration of vitamin A in animal and human nutrition, therefore, must be viewed in relation to the balance in diets of other nutrients with which it interacts directly or indirectly. 

Thiamin is the least stored of all the vitamins. The adult human body contains approximately 30 mg. Of the thiamin stored in the body, about 80% is thiamin pyrophosphate, about 10% is thiamin triphosphate, and the remainder is thiamin monophosphate. The liver, kidneys, heart, brain, and skeletal muscles have somewhat higher concentrations than the blood. If the diet is deficient, tissues are depleted of their normal content of the vitamin ini to 2 weeks, so fresh supplies are needed regularly to provide for maintenance of tissue levels. Body tissues take up only as much thiamin as they need with the need increased by metabolic demand (fever, increased muscular activity, pregnancy, and lactation) or by composition of the diet (carbohydrate increases the need for thiamin, while fat and protein spare thiamin). Because thiamin is water soluble, most of the vitamin not required for day-to-day use is excreted in the urine. This means that the body needs a regular supply, and that unneeded intakes are wasted. With a well-balanced diet, approximately 0.1 mg is normally excreted every 24 hours. However, the amount excreted in the urine decreases as the intake becomes inadequate and increases as the intake exceeds body needs because of this, the most widely used biochemical method to assess thiamin status in individuals is the measurement of the vitamin in the urine. 

The kidneys are two fist-sized organs whose primary function is to generate urine for excretion of water and metabolic waste products. The kidneys not only remove accumulated nitrogen products (urea, creatinine, uric acid, and others) but also maintain homeostasis of water and electrolytes (sodium, potassium, chloride, calcium, phosphate, magnesium) and regulate acid-base balance. In addition, human kidneys perform a few endocrine and metabolic functions, such as production of the hormone erythropoietin (a hormone that stimulates blood cell production) and conversion of vitamin D to its active form. Because of the tremendous overcapacity of normal kidney function, a person can live with only a fraction of normal kidney capacity, and the 0.1% of the population who are bom with a single kidney often are not even aware of the missing kidney. 

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