VITAMIN REQUIREMENTS FOR TERM INFANTS - CONSIDERATIONS FOR INFANT FORMULAS

Objective. To provide the informed health professional with an up to d ate evaluation of the current thinking regarding requirements for vita mins in infant feeds. Establishing criteria por adequacy. Vitamin adeq uacy in the neonate is currently defined in terms of circulating level s of a vitamin or of the activity of a vitamin dependent enzyme in the erythrocytes. Although these measurements have their value there is a need to develop biochemical, physiological or clinical markers of wel l defined specific function. For some vitamins there is a risk of dele terious effects of very high intakes: risk of toxicity needs to be tak en into consideration when making recommendations for inclusion in inf ant formulae. Breast milk as the 'gold standard'. Breast milk concentr ations of vitamins have been used as the criteria of adequate intake b y neonates. This may not always be justified. Greater consideration ne eds to be given to differences in bioavailability of vitamins from bre ast milk compared with formula feeds, of the influence of season, and of stage of lactation, on the stated composition. Experimental approac hes. Animal studies have provided limited information regarding effect s of different levels of intakes on current status indices in the neon atal period. There are few reports of randomized controlled studies in to the effects of different levels of vitamins and these rely heavily on biochemical criteria of adequacy. Recent developments. The inclusio n of beta-carotene into formula feeds for premature babies is an issue of current interest. What is the justification for this? Are there po tential benefits for the term infant? Riboflavin deficiency in the per iod around weaning may affect the normal structural and functional dev elopment of the gastrointestinal tract; some of these effects may be p ermanent. Research to be done. A greater understanding of the absorpti on and metabolism of vitamins during infancy is required in order to h elp establish dietary requirements. The relative bioavailability of vi tamins in human milk and formulae needs to be investigated. Criteria f or vitamin adequacy should be extended to include measures of function . Information regarding the conversion factor from tryptophan to niaci n in infancy would allow us to set niacin requirements with greater co nfidence. There is a particular lack of information about concentratio ns of biotin and pantothenic acid in breast milk and the relative bioc hemical status of infants receiving breast milk and formulae. Benefits of including beta-carotene into infant formulae need to be evaluated. The role of individual micronutrients in the structural and functiona l development of the gastrointestinal tract should be explored.