The effect of vitamin A supplementation on serum retinol and retinol binding protein levels

Wald, N.J., Cuckle, H.S., Barlow, R.D., Thompson, P., Nanchahal, K., Blow, R.J., Brown, I., Harling, C.C., McCulloch, W.J., Morgan, J. and Reid, A.R. (1985) The effect of vitamin A supplementation on serum retinol and retinol binding protein levels. Cancer Letters, 29 (2), 203-213. (doi:10.1016/0304-3835(85)90160-0).

Abstract

A randomised double blind controlled trial was conduced to see whether vitamin A supplementation in the form of retinyl palmitate would increase the concentrations of serum retinol and retinol binding protein. A total of 376 people were studied and were allocated to one of 7 regimens covering doses of vitamin A from 0 (placebo) to 36,000 IU daily. Supplementation continued for 6 months and blood samples were collected immediately before the start of supplementation, after 3 months and after 6 months. There was a small but statistically significant increase in serum retinol levels associated with supplementation, but no significant increase in serum retinol binding protein. The extent of the increase in serum retinol was related to the extent of the supplementation. On average, for every 10,000 IU of retinyl palmitate per day, the serum retinol concentration increased by 13 μg/l after 3 months (an increase of 2%) and 12 μg/l after 6 months of supplementation (2% increase). All the regimens used showed no evidence of toxicity other than minor symptomatic and physical changes affecting the skin and mucous membranes.

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Contributors

Author: C.C. Harling

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