Subject recommended dietary allowance

Recommended dietary allowances for vitamins have proved to be useful guidelines however it has to be appreciated that these guidelines are not more than estimates made from experiments on only a limited number of subjects. These recommended dietary allowances also need periodic reevaluation. While vitamin deficiencies due to inadequate intakes are encountered in developing countries, few cases are seen in the Western world apart from patients with an increased risk for deficiencies such as diabetics or alcoholics. On the contrary, the widely held belief that vitamins promote better health is deceptive and may lead to overdose disorders. 

The normative lithium requirement of humans is assessed at < 100 tg per day, as all German test subjects of both genders took in between < 100 and > 3500 tg Li per day without showing deficiency symptoms, even at the lowest intake amounts (Anke etal. 1995, 1997b). However, deficiency symptoms may occur in dialysis patients, in kidney failure and in parenteral nutrition. Based on intake data in different countries, Schrauzer (2002) suggested a provisional recommended dietary allowance (RDA) of 1 mg Li per day for a 70-kg adult. Compared with the above intake data, therapeutic effectiveness in the treatment of manic-depressive disorders is achieved at doses of 140 to 280 mg Li per day - about 100 to 300 times higher than RDA (Schou... 

It is sometimes difficult to calculate the RE because, in order to determine the actual content of vitamin A in food products, meals, or daily food allowance, it is necessary to first determine the content of retinol, P-carotene, and other carotenoids, and only then calculate the RE. Currently, recommended dietary allowances (RDA) are being proposed to ensure that there are appropriate quantities of individual vitamins in the diet to cover the organism s demand. The recommended doses are subject to modification and take into consideration changing life conditions and dietary patterns. In addition, increasing knowledge of human nutrition makes it necessary to update them from time to time (Russell, 1997). 

LRNI, Lower Reference Nutrient Intake RNI, Reference Nutrient Intake Al, Adequate Intake RDA, Recommended Dietary Allowance. Sources UK Department of Health (1991) Dietary Reference Values for Food Energy and Nutrients for the United Kingdom, Report on Health and Social Subjects No. 41. London HMSO. USA Food and Nutrition Board, Institute of Medicine (2000) Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and Carotenoids. Washington, DC National Academy Press. WHO/FAO WHO/FAO (2002) Human Vitamin and Mineral Requirements. Report of a Joint FAO/WHO Expert Consultation, Bangkok, Thailand. Rome WHO/ FAO. 

The dimension of standard error is such that many subjects are not reaching the Recommended Dietary Daily Allowance (RDA) and consequently they need to increase the vitamins, intake either with food or supplements. On the other hand, many subjects take a very high amount of vitamins with the food. In these last cases a further intake through supplements could generate the condition of a pro-oxidant effect. 

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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