An interaction between zinc and vitamin A in pregnant and fetal rats

A possible interaction between zinc and vitamin A metabolism was studied in pregnant rats. Rats were depleted of vitamin A by feeding retinoic acid during growth. At mating, they were fed diets containing 100, 9, or 0.5 microgram/g zinc and were given orally 400, 8, or 0 microgram/kg body weight/day of retinyl palmitate. Low intake of zinc, but not of vitamin A, caused maternal body weight gain, placental weight, and fetal weight all to be low. The number of implantation sites affected and the proportion of fetuses malformed were dependent on intake of both zinc and vitamin A, and there was a significant interaction between these nutrients in regard to both of these parameters. In maternal as well as in fetal animals, plasma and liver zinc concentrations were low in groups fed low levels of zinc, but not in those given low vitamin A. Liver vitamin A values were affected by vitamin A intake but not by dietary zinc concentration. However, plasma vitamin A concentration in both maternal and fetal animals was significantly reduced by low intake of either zinc or vitamin A. There was a significant interaction between these two nutrients in regard to plasma vitamin A. These data indicate an interaction between zinc and vitamin A metabolism possibly at the level of vitamin A mobilization from the liver.