Retinoic Acid and Cod Liver Oil Replenishing Liver Vitamin A Stores in Vitamin A Deficient Rats

Previously we have found that Vitamin A deficiency is associated with abnormal bone growth and development. Our studies indicated that retinoic acid (RA) appeared to be the most effective at correcting the bone pathologies associated with Vitamin A deficiency, restoring osteoblast numbers, compared to the retinyl ester form of Vitamin A found in cod liver oil (CLO). The purpose of this research was to determine which source of Vitamin A, RA or CLO, most effectively replenished Vitamin A liver stores in rats. Twelve male weanling rats were fed a retinol‐adequate (control) diet, while thirty rats were put on a retinol‐deficient diet for 9 weeks. Six rats from the control and six from the deficient group were euthanized at week 9 to verify vitamin A deficient status. The remaining 24 deficient rats were then randomly assigned to one of 4 diets, for 4 weeks: control, RA‐supplemented, CLO‐supplemented, or retinol‐deficient diet. Although the rats were pair‐fed, the vitamin A deficient rats lost weight compared to the control rats. At week 13 the experiment was terminated. The livers were analyzed for retinoid concentrations by HPLC. The results indicated that there was no significant difference between the CLO and RA treatment groups in replenishing stores. Although dietary retinoic acid was effective in partially correcting Vitamin A deficient bone pathologies, it's effectiveness was not dependent upon liver stores.