Nutrient Needs for Catch-Up Growth in Low-Birthweight Infants.

Growth restriction among low-birthweight (LBW) infants occurs prenatally as well as postnatally. Regardless of when and how the growth restriction occurs, growth-restricted infants have the potential for catch-up growth. Catch-up growth has decidedly beneficial effects on later cognition. It also may have adverse effects on cardiovascular and metabolic health. Although the benefits for later cognition are well documented in a number of studies, growth-restricted LBW infants often do not experience catch-up growth and therefore do not enjoy its benefits. One reason is that for catch-up growth to occur, extraordinarily high protein intakes are required. Nutrient intakes have been estimated with the use of the factorial method based on the assumption that catch-up growth comprises essentially a restoration of lean body mass, with restoration of fat mass optional. The basic (no catch-up) nutritional needs of growth-restricted LBW infants are altered to a modest degree, with energy needs increased and protein needs decreased. With catch-up, however, protein needs are increased sharply. Since energy needs are only modestly increased, the protein/energy ratio of requirements is appreciably increased. The high protein needs are difficult to meet with the usual feedings for LBW infants unless special measures are taken to increase protein intakes and to increase the protein/energy ratio. Without the necessary protein intake, catch-up growth is not possible or will be delayed, which may compromise the realization of the long-term benefits on cognition.