The aim of the present study was to investigate the biochemical changes in serum and liver retinol,
serum nitric oxide (NO), total protein, serum protein electrophoresis, albumin, blood hemoglobin,
glucose -6- phosphate dehydrogenises (G6PD), and antioxidant enzymes activities: glutathione
peroxidase activity (GSH-PX), glutathione reductase (GR ase), activity reduced glutathione (GSH),
superoxide dismutase activity (t-SOD) and catalase (CAT) in experimental under the effect of
administration of ordinary, double, toxic doses of vitamin A in rats. In order to achieve this aim 80 male
Sprague-Dawely rat 3-6 weeks old weighting 120-250 grams were used in the experimental
investigation of this study. The animals were divided into 4 groups each 20 rats that were orally
supplemented with retinol palmitate (2500, 5000, 10000 IU/Kg/day) and the fourth group served as
control. The result of the present study showed a significant association between vitamin A
supplementation and low level of liver and serum retinol, low nitric oxide level, high G6PD level, high
catalase activity, low super oxide dismutase activity, low glutathione reductase and peroxidase activity,
low reduced glutathione level. These parameters may all be regarded as risk factors for exposure to high
doses of vitamin A. Vitamin A can potentially promote liver damage. When you consume large amounts
of vitamin A, your body stores the excess vitamin within your liver. After a very high dose or long-term
consumption of moderately high doses vitamin A can form toxic accumulations in your liver, leading to
liver swelling and damage. In addition, the toxicity can cause skin peeling, kidney damage.