Of all the nutritional supplements, straight Vitamin A causes the most concern. Vitamin A toxicity can occur in adults who take in excess of 50000 IV per day for a prolonged period of time. A lower dose may also create toxicity if the patient has liver disease. Signs of Vitamin A toxicity include dry skin, brittle nails, hair loss, gingivitis, anorexia, nausea, fatigue and irritability.
Accidental ingestion of a single large dose of vitamin A by children (100,000 – 300,000 IV) can cause acute toxicity. This may present as headache, vomiting and stupor because of the increase in intracranial pressure ( K.J.Rothman, “Teratogenecity of high Vitamin A intake”. New England Journal of Medicine 333 (1995), (1369 – 1373). A study reported in the January 2, 202, issue of the journal of the American Medical Association indicates that vitamin A can be harmful for normal bone function, leading to an increase in hip fractures.
Women must avoid Vitamin A supplementation during pregnancy. Dosages as low as 5000 – 10000 IU are believed to have caused birth defects.
I never recommend taking straight Vitamin A in supplements. We can meet the need for vitamin A within the body by simply taking beta carotene and the mixed carotenoids. These are very safe and the body is able to turn beta carotene into vitamin A as the need arises without any risk of toxicity.