Vitamin Update
John N. Udall Jr MD, PhD1
Harry L. Greene MD2
1 Associate Professor of Pediatrics, University of Arizona Health Sciences Center, 1501 North Campbell Avenue, Tucson, AZ 85724; 602-626-4140 (phone) or 602-626-4884 (fax)
2 Bristol Meyers/Squibb, Mead Johnson Nutritional Group, 2400 West Lloyd Expressway, R-20, Evansville, IN 47721; 812-429-8673 (phone) or 812-429-7483 (fax). Formerly: Professor of Pediatrics and Biochemistry, Vanderbilt University Medical Center, Nashville, TN 37232
Pediatricians should be aware of the recommended daily allowances (RDAs) for vitamins. They also should have knowledge of the symptoms and signs of vitamin deficiencies and excesses so as to be able to institute treatment before severe and permanent functional impairment of vital organs occurs. In this article, the RDAs for vitamins will be discussed, followed by an update of fatsoluble and water-soluble vitamins.
Recommended Daily Allowances (Table 1)
In principle, the RDAs are based on various kinds of evidence: 1) nutrient intakes of fully breast-fed infants and of apparently healthy people from their food supply; 2) studies of subjects maintained on diets containing low or deficient levels of a nutrient, followed by correction of the deficit with measured amounts of the nutrient; 3) nutrient balance studies that measure nutrient status in relation to intake; 4) biochemical measurements of tissue saturation or adequacy of molecular function in relation to nutrient intake; 5) epidemiologic observations of nutrient status in populations in relation to intake; and 6) in some cases, extrapolation of data from animal experiments. In practice, there are limited data on which to base the RDAs.1 It should be recognized that all RDAs are somewhat arbitrary and generally on the high side.
