Zinc status and vitamin A transport in cystic fibrosis.

Zinc status and the retinol transport system were examined in 18 retinol 
supplemented cystic fibrosis (CF) patients and 40 age-matched controls. Plasma vitamin 
A was significantly lower in the CF group as compared to 
the controls and correlated positively with plasma retinol-binding protein (RBP) in 
both the CF and control groups. Plasma zinc of the CF 
group was not significantly lower than controls whereas hair zinc was. 
Plasma zinc was positively correlated with plasma RBP, vitamin A, and 
albumin in the CF group but not in the controls. Plasma 
concentrations of vitamin A, RBP, albumin, and zinc decreased with age 
in the CF group but not in the controls. The data 
support previous suggestions that low plasma vitamin A levels in CF 
are due to defects in the retinol transport system. The zinc 
status of the CF groups as a whole was judged to 
be low-normal however a subgroup of CF patients were in the 
marginal to deficient category. This subgroup also had lower levels of 
plasma vitamin A and RBP. The data suggest that zinc may 
be a contributing factor in the low plasma vitamin A/RBP levels 
of CF patients with marginal or deficient zinc status. 