Thiamin nutritional requirement

Classic beri-beri, rarely seen in the United States and Europe, except in alcoholism (P4), is endemic in the Far East because of the prevalent diet of decorticated rice (F6). It occurs in two forms wet beri-beri, characterized by edema and cardiovascular symptoms (G6), and dry beri-beri with peripheral neuritis, paralysis, and atrophy of the muscles. Conditions which may predispose to deficiency by increasing thiamine requirements are pregnancy (see section 2.4), and lactation, hyperthyroidism, malignant disease, febrile conditions, increased muscular activity, high carbohydrate diets, and parenteral administration of glucose solutions. A constant supply of thiamine is required for optimal nutrition because storage in the liver and elsewhere is limited. Thiamine is synthesized by bacteria in the intestinal tract of various animals, but this is not a dependable source for man. 

TPP also mediates the oxidative decarboxylation of a-ketoglutaric acid, another intermediate of carboxydrate metabolism in the citric acid cycle. The nutritional requirement for thiamine increases as dietary carbohydrate increases because of a greater demand for TPP. 

Pekovich SR, Martin PR, and Singleton CK (1996) Thiamine pyrophosphate-requiring enzymes are altered during pyrithiamine-induced thiamine deficiency in cultured human lymphoblasts./owmal of Nutrition 126, 1791-8. 

If sporulation is insufficient, the same procedure may be repeated with commeal agar or potato agar, which is sometimes successful. If this fails too, a number of additional tests exist for the identification of dermatophytes, including urea hydrolysis, in vitro hair perforation test, growth on polished rice grains, temperature enhancement or tolerance tests as well as numerous tests for the detection of special nutritional requirements, e.g. thiamine, niacin. 

Acanthamoeha Peptones have been used in the few cases where this organism has been grown. We have no information about its nutritional requirements other than its need for at least one portion of the thiamine molecule. 

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. 

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. 

A Selection of Lower Fungi Showing Relative Nutritional Requirements for Thiamin... 

A further assumption is also often made, namely, that even a mild thiamine deficiency, if it is a real deficiency, will make itself known by outward signs. This, in the author s opinion, is probably far from true. In animal experiments, for example, deficiencies require weeks to develop, and long before an animal shows overt symptoms of deficiency, an analysis of its tissues would show that deficiencies are present and metabolism is being impaired. The importance of considering other evidence about the nutritional state besides overt symptoms is stressed in a recent review by Lowry. 19... 

Pett,55 Director of the Division of Nutrition, Department of National Health and Welfare of Canada, has on the basis of the "best data possible,.. . admittedly not entirely satisfactory," arrived at the following figures for the thiamine requirements of 15 individuals ... 

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. 

From the role of tryptophan in the biosynthesis of nicotinic acid, it is obvious that the nutritional studies on nicotinic acid deficiency must take tryptophan intake into account. Indeed, 60 mg of tryptophan in the diet is as effective as 1 mg of nicotinic acid. Since 70 g of protein yields 720 mg of tryptophan, the intake of such an amount of protein corresponds to 12 mg of nicotinic acid in preventing niacin deficiency. Since the requirements for niacin, like those of thiamine, depend essentially on the caloric intake, it is useful to express the requirements in niacin equivalents per 1000 calories. The optimum requirement is 4.4 mg niacin per 1000 calories. 

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