Recommended dietary allowance thiamin

Vitamins are chemically unrelated organic compounds that cannot be synthesized by humans and, therefore, must must be supplied by the diet. Nine vitamins (folic acid, cobalamin, ascorbic acid, pyridoxine, thiamine, niacin, riboflavin, biotin, and pantothenic acid) are classified as water-soluble, whereas four vitamins (vitamins A, D, K, and E) are termed fat-soluble (Figure 28.1). Vitamins are required to perform specific cellular functions, for example, many of the water-soluble vitamins are precursors of coenzymes for the enzymes of intermediary metabolism. In contrast to the water-soluble vitamins, only one fat soluble vitamin (vitamin K) has a coenzyme function. These vitamins are released, absorbed, and transported with the fat of the diet. They are not readily excreted in the urine, and significant quantities are stored in Die liver and adipose tissue. In fact, consumption of vitamins A and D in exoess of the recommended dietary allowances can lead to accumulation of toxic quantities of these compounds. 

Tree nuts can be good dietary sources (>10% of recommended dietary allowances [RDA] or adequate intake [Al]) of most vitamins except vitamins A and cobalamin (B,2). At suggested consumption level (1.5 ounces or 42.5g/day), acorn and pine nuts are excellent sources of folate and vitamin K (Table 2.7). In case of thiamin (Bj), niacin (B3), and pyridoxine (Bg), tree nuts offer alternative sources of these vitamins when more abundant animal sources are not available or are not consumed. 

National Academy of Sciences (1980) Recommended dietary allowances, ninth revised edition. National Academy of Sciences, Washington, DC Nava C (1971) Allergic reaction to vitamin Bi2- Med Lav 62 285-291 Neal RA, Sauberhch HE (1973) Thiamin. In Modem nutrition in health and disease, 5th edn. Lea Febiger, Philadelphia... 

The nutritional status for thiamine supported by current recommended dietary allowance for thiamine serves as a background to understanding animal assays of thiamine. 

It is principally known for its high vitamin C content, being one of the most important natural sources for this vitamin (Muller et al. 2010 Vendramini and Trugo 2000). The consumption of three fruit units per day satisfies the vitamin C recommended dietary allowance for an adult. In addition, it presents amounts of thiamine, riboflavin, niacin, proteins, and mineral salts, mainly iron, calcium, and phosphorous (Mezquita and Vigoa 2000). Mezadri et al. (2008) observed that contents in total... 

In dogs, the niacin requirement appears to be about ten times that of thiamine.In rats, niacin is an essential nutrient only when the tryptophan content of the diet is low, and under these circumstances requirement is about ten times the thiamine need. The recommended dietary allowances for niacin in this country are ten times the thiamine allowances (Table 1). In view of the above data, these allowances should provide a fair margin of safety. 

Thiamine requirements must be related in any logical standard to the calorie requirements, but there is no general agreement on how much thiamine is needed per 1000 calories. Experimental evidence has given values ranging from a low of 0.13 mg. per 1000 calories (Holt, 1944) up to 0.44 mg. per 1000 calories (Alexander et al., 1946). The Canadian Dietary Standard uses 0.33 to 0.35 mg. per 1000 calories, and the U.S. Recommended Dietary Allowances uses 0.5 mg. per 1000 calories. 

National Research Council, Food and Nutrition Board, and Institute of Medicine (1998) Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B-6, folate, vitamin B-12, pantothenic add, biotin, and choline. In Recommended Dietary Allowances., pp. 374-389. Washington, DC. National Academy Press. 

The body s need for most vitamins is relatively low. The amounts needed to ensure the normal physiological function of humans is dependent on many factors such as age, sex, health status, lifestyle, eating habits and work-related activity. Many countries have recommendations for the daily intake of vitamins, which are continually revised in accordance with contemporary scientihc knowledge and dietary guidelines. Presently, Recommended Daily Allowances (RDAs) are set in the EU (upper number) and United States (lower number) as follows vitamin A (800/900 xg), vitamin D (5/15 xg), vitamin E (12/15 mg), vitamin K (75/120 xg), thiamine (1.1/1.2 mg), riboflavin (1.4/1.3 mg), niacin (16/16 mg), pantothenic acid (6/5 mg), vitamin Bg (1.4/1.3 mg), biotin (50/30 xg), folacin (200/400 (xg), vitamin Bj2 (2.5/2.4 xg) and vitamin C (80/90 mg). 

PORK AS A FOOD. Pork is an important food and a rich source of many essential nutrients. An average 3.5 oz (99.4 g) serving of cooked pork ham provides 37 g of protein (that s 2/ 3 of the recommended daily allowance of protein) and 8.8 g of fat, along with being an excellent source of minerals and vitamins. Its high-quality protein contains all the essential amino acids needed to build, maintain, and repair body tissues. Pork is rich in iron, and the iron is readily used in the formation and maintenance of red blood cells. Also, pork is a major dietary source of the B vitamins, especially thiamin, riboflavin, and niacin. Also pork is about 98% digestible. 

In general, the recommended allowances are based (1) on assessments of the effects of varying levels of dietary thiamin on the occurrence of clinical signs of deficiency, (2) on the excretion of thiamin or its metabolites, and (3) on erythrocyte transketolase activity. Most studies have been conducted on subjects fed diets with ratios of carbohydrate and fatsimilar to those commonly consumed in the United States. There is evidence that dietary fat spares thiamin to some extent... 

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