Hj. Powers et al., DOES VITAMIN-C INTAKE INFLUENCE THE RATE OF TYROSINE CATABOLISM IN PREMATURE BABIES, Annals of nutrition & metabolism, 38(3), 1994, pp. 166-173
A study was conducted to investigate the relationship between vitamin
C intake and the rate of tyrosine catabolism in premature babies. A C-
13 tyrosine breath test was developed for the measurement of tyrosine
catabolism. Premature babies were randomly allocated to receive a dail
y intake of vitamin C which ranged from 8 to 100 mg/kg body weight, fo
r 5 days. Tyrosine catabolism was measured at the beginning and the en
d of this period. Daily intakes of vitamin C of 20 mg/kg or more elici
ted a greater increase in tyrosine catabolism over 5 days than 8 mg/kg
/day. The magnitude of the difference, in terms of percentage of tyros
ine metabolised, was, however, small and of doubtful biological signif
icance. Vitamin C intakes above 20 mg/kg/day had no further measurable
effect on the catabolism of tyrosine.