Thiamin vitamin nutritional requirement

From a nutritional standpoint, it is significant that five of the B-complex vitamins (riboflavin, nicotinamide, thiamine, vitamin Be, and pantothenic acid) have been shown to be constituents of the coenzymes. The nutritional requirement of these vitamins is explained on the basis of their coenzyme function. In all cases the coenzyme form appears to be the sole bound form of the vitamin, and this then becomes the only metabolically active form for these particular vitamins. 

The role of pantothenic acid in human nutrition has not been established. It is of wide natural occurrence, as the name implies. Metabol-ically, pantothenic acid seems to have some special role in the adrenals, and this may be a link with acetylation mechanisms in the synthesis of steroids (Hughes, 1953). The burning feet" syndrome encountered in prisoners of war and other malnourished groups has been specifically treated with pantothenic acid (Gopalan, 1946). The figures given by Williams et al. (1950) for B vitamins in different foods and tissues can be considered to show a ratio of pantothenic acid to thiamine, riboflavin, and niacin at an amount about half that of the niacin, but ten times the thiamine. No precise requirement can be stated. 

MINERAL AND VITAMIN SUPPLEMENTS. There is considerable controversy among nutritionists and pediatricians regarding the amounts and types of nutrient supplements that are required by infants, since breast-fed infants have long been given little or no supplementation. Furthermore, the need for supplementation depends upon a variety of factors such as (1) status of the infant at birth, since preterm or low birth weight infants have higher nutritional requirements to attain the rates of growth and development of normal infants (2) type of milk or formula used (3) affliction of the infant with diarrhea, fever, infection, and/or other stresses and (4) age at which supplemental foods are introduced. It is noteworthy that even breast milk is low in iron, copper, fluoride, vitamins A, D, and E, and biotin, folacin, niacin, thiamin, and vitamin B-6. Furthermore, diluted evaporated milk is notably inferior to breast milk with respect to the contents of iron, zinc, vitamin A, vitamin E, and vitamin C. Therefore, the need for nutrient supplements should be evaluated by a health professional who is familiar with the diet and the overall health status of the infant. 

Nonfat dry milk—This product is prepared by removing water from pasteurized skim milk. Federal standards of Identity require that It contain not more than 5% by weight of moisture and not more than 1.5% by weight of milkfat unless Indicated. Except for small losses of ascorbic acid, thiamin, vitamin B-12, and biotin, the processing has no appreciable effect on the nutritive value of the milk. Due to Its low moisture content. It can be kept for long periods. 

The combined dehydrogenation and decarboxylation of pyruvate to the acetyl group of acetyl-CoA (Fig. 16-2) requires the sequential action of three different enzymes and five different coenzymes or prosthetic groups—thiamine pyrophosphate (TPP), flavin adenine dinucleotide (FAD), coenzyme A (CoA, sometimes denoted CoA-SH, to emphasize the role of the —SH group), nicotinamide adenine dinucleotide (NAD), and lipoate. Four different vitamins required in human nutrition are vital components of this system thiamine (in TPP), riboflavin (in FAD), niacin (in NAD), and pantothenate (in CoA). We have already described the roles of FAD and NAD as electron carriers (Chapter 13), and we have encountered TPP as the coenzyme of pyruvate decarboxylase (see Fig. 14-13). 

Parenteral nutrition was used to support a patient requiring autologous blood stem-cell transplantation, but vitamins were excluded (the reason was not identified). After about 28 days, the patient suddenly developed severe metabolic acidosis, heart failure, and deep coma. Thiamine was immediately infused, with rapid improvement. 

D. This patient has exhibited symptoms of beri beri heart disease, which is a result of a nutritional deficiency in vitamin Bj (thiamine). The active form of the vitamin, thiamine pyrophosphate, is a required cofactor for a-ketoglutarate dehydrogenase. 

Thiamine hydrochloride is structurally similar to thiamine pyrophosphate (TPP). TPP is a coenzyme universally present in all living systems. It catalyzes several biochemical reactions in natural systems. It was originally discovered as a required nutritional factor (vitamin) in humans by its link with the disease beriberi. Beriberi is a disease of the peripheral nervous system caused by a deficiency of Vitamin in the diet. Symptoms include pain and paralysis of the extremities, emaciation, and swelling of the body. The disease is most common in Asia. 

Caster, W.O., and Meadows, J.S., 1980. The three thiamin requirements of the rat. International Journal for Vitamin and Nutrition Research. 50 125-130. 

NOTE WELL The Food and Drug Administration requires that fortified foods or foods that are labeled or advertised with a claim to their nutrition be labeled to show content, in terms of percent Recommended Daily Allowance, of protein, vitamin A, vitamin C, thiamin, riboflavin, niacin, calcium, and iron. Also, serving size and quantities per serving must be stated for calories, fat, protein, and carbohydrate. 

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