Recommended Dietary Allowances defined

Recommended Dietary Allowance (RDA), 17 652 25 784-787 of ascorbic acid, 25 772 defined, 25 784 for vitamins, 25 785t Recommended exposure level (REL), hydrazine, 13 590... 

Reference Intakes (DRIs). In the past, the recommended dietary allowances (RDAs), which are the levels of intake of essential nutrients that are considered to be adequate to meet the known nutritional needs of practically all healthy persons, were the primary reference value for vitamins and other nutrients. The DRIs also include other reference values, such as the estimated average requirement (EAR) and the adequate intake (AI). The RDA, EAR, and AI reference standards define nutritional intake adequacy. Since these recommendations are given for healthy populations in general and not for individuals, special problems, such as premature birth, inherited metabolic disorders, infections, chronic disease, and use of medications, are not covered by the requirements. Separate RDAs have been developed for pregnant and lactating women. Vitamin supplementation may be required by patients with special conditions and for those who do not consume an appropriate diet. 

Research Council defined 1 mg of a-tocopherol as 1 unit of a-TE (mg x 1). The activities as a-TE of other vitamers were (3-tocopherol, mg x 0.5 y-tocopherol, mg xO. 1 8-tocopherol, mg x 0.03 a-tocotrienol, mg x 0.3 and (3-to-cotrienol, mg x 0.05. The activities of y- and 8-tocotrienol were undetectable. The Recommended Dietary Allowances (RDAs) are only based on intake of the 2R-stereoisomeric forms of a-tocopherol (RRR-, RSR-, RRS-, and RSS-tocopherol) from food, fortified food, and vitamin supplements (Food and Nutrition Board, 2000). The 2S-stereoisomeric forms of a-tocopherol and the other tocopherols ((3-, y-, and 5-tocopherol) and tocotrienols are not used to estimate the RDAs. 

The vitamin A content of foods is often given in terms of the international unit (IU). One IU of vitamin A is defined as 0.3 tg of all-trans-retinol. The term retinol equivalent (RE) is used to convert all sources of vitamin A and carotenoids in the diet to a single unit. One RE is by definition 1 pg of all-trans retinol, 12 pg of P-carotene, or 24 pg of other (mixed) provitamin A carotenoids. The recommended dietary allowance for vitamin A ranges from 375 pg RE/day for infants to 1,000 RE/day for adults. 

The polyphenols such as anthocyanidins might have a protective effect on atherosclerosis. This concept suggests that the Recommended Optimal Intake (ROI) is a more important factor for the antioxidation than the Recommended Dietary Allowance (RDA). Now, considering the absence of the appropriate methodology to identify anthocyanidins in the plasma, the analysis of the plasma antioxidant capacity might be a suitable index to define the optimal nutritional intake [95]. 

From Recommended Dietary Allowances, 10th ed. Food and Nutrition Board, National Research Council—National Academy of Sciences, 1989. +The allowances, expressed as average daily intakes over time, are intended to provide for individual variations among most normal persons as they live in the United States under usual environmental stresses. Diets should be based on a variety of common foods in order to provide other nutrients for which human requirements have been less well defined. 

If sufficient scientific evidence is not available to calculate an Estimated Average Requirement, a reference intake called an Adequate Intake (Al) is used instead of a Recommended Dietary Allowance. The Al is a value based on experimentally derived intake levels or approximations of observed mean nutrient intakes by a group (or groups) of healthy people. The Al for children and adults is expected to meet or exceed the amount needed to maintain a defined nutritional state or criterion of adequacy in essentially all members of a specific healthy population LA = linoleic acid LNA = n-linolenic acid DHA = docosahexaenoic acid EPA = eicosapentaenoic acid TRANS-EA = trans fatty acids SAT = saturated fatty acids MONOs = monounsaturated fatty acids. 

The Eood and Nutrition Board of the National Research Council of the National Academy of Sciences publishes information on the quantities of vitamins and minerals that are required in the diet. These are called recommended dietary allowances (RDA) and are defined as "the levels of intake of essential nutrients considered adequate to meet the known nutritional needs of practically all healthy persons." The RDA is determined by obtaining an estimate of the range of normal human needs. The value at the high end of the range is chosen, and an additional safety factor is added. Thus the RDA is by no means a minimum value, but rather a high estimate of daily requirements. It is important to remember that serious physical problems can follow ingestion of megadoses of many minerals or vitamins. 

Vitamins and trace elements are collectively dc.scribed as micronutrients , not because they are of limited importance but because they are required in relatively small amounts. Recommended dietary allowances (RDAs) have been defined for most nutrients and these are used in the make up of artificial diets. 

The Food and Nutrition Board of the U.S. National Academy of Sciences has recently devised a new nomenclature for human nutrient needs [30]. Dietary Reference Intakes (DRI) refer to a set of four nutrient-based reference values, termed the estimated average requirement (EAR), the recommended dietary allowance (RDA), adequate intake (AI), and the tolerable upper intake level (UL). The EAR is defined in the same way as in the CEC and UK recommendations. The RDA is now somewhat more rigorously defined to be the EAR + 2 SD (standard deviations), i.e. equivalent to the RNI and PRI in the UK and CEC systems. 

Recommended dietary allowances (RDA) for the US and Canada were recently revised by the Institute of Medicine (lOM). Owing to the serious, potentially irreversible, effects caused by an excess of vitamin A, guidelines were also established for a tolerable upper intake level (UL), defined as the highest intake of a nutrient that is likely to pose no risk of adverse health effects in nearly all healthy individuals. The 2001 RDA and UL for vitamin A for various life stages are listed in Table 2. 

Folate is a water-soluble vitamin. The recommended daily allowances (RDAs) of folate for the adult man and woman are 20fJ and 101) pg, respectively. The RDA is defined in the Preface. Folate is critically important for growth, and for this reason it is required in increased amounts during pregnancy (400 pg. The need for dietary folate remains elevated after pregnancy and during lactation because of the Irans-... 

The recommended daily allowance (RDA) is the amount of a compound needed daily to maintain good nutrition in most healthy people. RDA values are intended to serve as nutritional goals, not as dietary requirements. They are defined by the Food and Nutrition Board of the National Academy of Sciences... 

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