Dietary Vitamin A Has Both Chronic and Acute Effects on Vitamin A Indices in Lactating Rats and Their Offspring
Abstract
To further investigate the effect of dietary vitamin A (VA) intake on milk VA concentrations and pup VA status, female rats were fed 2 concentrations of VA 0 ( n = 9) or 50 µ mol/kg diet ( n = 10) during pregnancy and lactation. Plasma retinol concentrations were significantly higher (30–40%) during lactation than before pregnancy or after weaning but were not influenced by dietary VA. In rats fed VA, VA concentrations during lactation were significantly higher in milk (1.5–3 times), mammary tissue (>100%), liver (4 times), pup plasma (20–40%), and pup liver (1.1–6.7 times). In Expt. 2, when VA intake was switched on d 7 of lactation from 0 to 50 µ mol/kg, milk VA concentrations (2.24 ± 0.42 µ mol/L; mean ± SD, n = 6) increased significantly (1.7 times) by d 9 to the same level as in rats administered 50 µ mol/kg (6.04 ± 0.60 µ mol/L; n = 6). When VA was removed from the diet on d 7, concentrations declined significantly (by 50%) and by d 11 were the same as those in rats given 0 µ mol/kg. We conclude that the rapid effect of changes in dietary VA intake are attributable to changes in the delivery of chylomicron VA to mammary tissue and milk. KEY WORDS: • lactation • vitamin A supplementation • vitamin A status • milk vitamin A