... Basile-Filho A, Beaumier L, El-Khoury AE, et al. Twenty fourhour L-[ 1- 13C] tyrosine and L-[3, 3- 2H2] phenylalanine oraltracer studies at generous, intermediate, and low phenylala-nine ... manifest, and “catch-up” growth occurs when adequate zinc supple-ments are administered.14Randomized, double-blind, controlled studies in youngformula-fed infants, older infants and toddlers, and ... directcause -and- effect relationship in humans. However, a signif-icant effect of zinc supplementation on food intake hasbeen observed in a double-blind, controlled study.25Trace Elements 89TABLE 6-4 ...