Dietary Reference Intakes Applications in Dietary Planning (2003) / Chapter Skim
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6. Special Considerations and Adjustments
6. Special Considerations and Adjustments
Pages 133-146
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From page 133... ...
This chapter also aciciresses factors such as nutrient bioavailability and physiological, lifestyle, and health factors that may alter nutrient requirements and leaci to adjustments in the DRI values when planning clietary intakes for individuals and Croons INTRODUCTION - a-~ -- rIt is well established that biological variability exists among indivicluals with regard to both nutrient requirements and susceptibility to adverse effects from excessive nutrient intakes. These individual differences, when known, in the normal, apparently healthy population have already been considered in establishing the Dietary Reference Intakes (DRIs)
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From page 134... ...
However, there are other identifiable factors that may alter nutrient requirements systematically such that the DRI values may need to be adjusted when planning nutrient intakes for certain individuals or groups. These factors, discussed below, include characteristics of the nutrient source that influence nutrient bioavailability, as well as physiological, health, or lifestyle characteristics of individuals that may require tailoring of requirement estimates.
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From page 135... ...
For example, because about 10 to 30 percent of older adults have recluceci gastric acidity, they may not readily absorb the protein-bounci form of vitamin BE that is found naturally in food sources. To ensure that adequate vitamin BE is absorbed when planning for individuals or groups where the average age is over 50, planners are encouraged to include foods fortified with vitamin BE or a supplement containing vitamin BE since the synthetic form of the vitamin is absorbed effectively even in those with low gastric acid secretion.
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From page 136... ...
Inclivicluals following vegan cliets (exclusively composed of plant foocis) will neeci to either use a vitamin BE supplement or consume fortified foocis containing sufficient amounts of synthetic vitamin Bit.
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From page 137... ...
Because protein intakes of vegetarians are typically lower than intakes of those following omnivorous cliets, the issue of protein quality becomes particularly important. In the past there were no recommencleci intakes for indispensable amino acids, and it was assumed that inclivicluals consuming a mixed cliet (animal and vegetable proteins with a biological value of 75 percent)
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From page 138... ...
for the essential amino acid when total protein intake equals the EAR for protein. c The protein source would not provide recommended amounts of the indispensable amino acid if it were the only source of protein in the diet.
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From page 139... ...
Genetic Variation Rapidly expanding information on the human genome indicates many possible interactions between incliviclual genetic traits and nutrient requirements. Examples of genetic clisorclers requiring nutritional treatment include classical inborn errors of metabolism such as phenylketonuria, lipoprotein lipase deficiency, and vitamin D-clepenclent rickets.
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From page 140... ...
Unusual Body Size or Composition, Energy Expenditure, or Physical Activity By establishing EARs and using the estimated variability of the requirement distribution to set RDAs to include 97 to 98 percent of all individuals in a life stage and gender group, these recommended intakes already account for typical variation in body size or energy expenditure in a specific group. Depending on the function and tissue distribution of the nutrient, such variation may be associated with skeletal mass, lean body mass, body water, or total body mass (IOM, 1997, 2000b)
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From page 141... ...
Body iron losses appear to increase with vigorous exercise, perhaps because of increased gastrointestinal blood losses or because of erythrocyte rupture within the foot cluring running (IOM, 2001~. Consequently, athletes engaged in regular intense exercise may have average requirements for iron that range from 30 to 70 percent above those of normally active inclivicluals.
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From page 142... ...
Dietary iron neecis are lower for women using oral contraceptives clue to recluceci menstrual blood loss. Accordingly, the recommencleci intake for iron is adjusted down to 11.4 mg/day for adolescent girls and clown to 10.9 mg/ciay for premenopausal women using oral contraceptives (IOM, 2001~.
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From page 143... ...
Because vitamin D is not wiclely clistributeci in the food supply (it occurs naturally in liver, fatty fish, and egg yolk, and is routinely acicleci to fluici milk, cirieci skim milk powder, and margarine) , it is easy to envision cliets that would not provide vitamin D in amounts recommencleci for older adults.
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From page 144... ...
Specific nutrient requirements have not been established in relation to levels of alcohol consumption. The importance of assuring adequate intakes of micronutrients in situations of alcohol abuse is emphasized by the greater frequency of nutrient deficiencies in alcoholics, an example of which is the irreversible consequences of the Wernicke-Korsakoff syndrome of severe thiamin deficiency.
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From page 145... ...
For example, patients who are not at nutritional risk, who do not require a nutrition intervention, or who receive a regular cliet, can be treated as a group unless their nutritional status changes. Individual patients with specific nutrition therapy plans can have their dietary intakes planned initially using the RDAs or AIs with appropriate mollifications macle for their specific conditions by a trained health care professional or dietitian.
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From page 146... ...
However, the RDA or AI would be used for other nutrients not known to be affected by the disease process. The DRIs are formulated to meet the neecis of the vast majority of the healthy population within specified life stage and gentler groups.
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