Zinc and muscle growth during recovery from malnutrition - abstract

ABSTRACT

During recovery from severe malnutrition, muscle gain is slow relative to overall weight gain. We postulated that this might be due to an inadequate supply of zinc. We therefore compared nitrogen (N) balance and protein synthesis rates (as estimates of muscle gain) during early, mid and late recovery in children fed 3 different levels of dietary zinc (Low Zn gp.n = 4; Moderate Zn gp.n = 4; High Zn gp.n = 3). N intake was similar in the 3 Zn groups throughout recovery. N net absorption and N retention were also similar in early recovery. Later, both increased in the moderate and high Zn groups only so also did the N retention /g wt gained. By late recovery, they were each significantly higher in the high Zn gp than in the low Zn gp. Thus, Zn supplementation of the relatively low Zn recovery diet resulted in synthesis of tissue richer in N - and therefore, by implication, having a higher proportion of muscle. Protein synthesis rates were calculated from the 15N enrichments of urinary urea and ammonia at plateau, obtained during a constant nasogastric infusion of 15N labeled glycine. Overall, the results using the 2 different end products were not different. However, there was a difference among the Zn gps in the 15N ammonia enrichments. From these values, protein synthesis rates were significantly higher than in the high Zn gp than in the low Zn gp by late recovery (table included). These data are consistent with the N balance data in that they indicate increased muscle protein metabolism with Zn supplementation (AU)