dyer@wivax.UUCP (Stephen Dyer) (12/11/83)
The person who reported on vitamin A toxicity did NOT say that overdoses of vitamin A cause brain tumors. He said that it causes symptoms which may mimic the symptoms of a brain tumor (hence causing doctors treating the patient to waste time looking for something that isn't there.) 25000 IUs of Vitamin A is the largest amount allowed in over-the-counter vitamin pills, since this is already 5 times higher than the Recommended Daily Allowance. There is a margin of safety here before chronic toxicity becomes a possibility (roughly a factor of 5 or 6 for an adult male), but that is completely dependent on the individual's metabolism, age, and how long the vitamin has been given. The FDA limits it to 25000 IU for good reason, given the way some people treat vitamin pills. Incidentally, overdoses of carotenoids (those pigments found in carrots and other vegetables which the body converts to vitamin A) might turn your skin yellow, but they don't seem to cause toxicity. I quote from Goodman and Gilman's "The Pharmacological Basis of Therapeutics" (a gem of a book, by the way, for those who feel comfortable with medical technical writing) page 1587, Sixth Edition, 1980: "Early signs and symptoms of @i(chronic) vitamin A intoxication include irritability, vomiting, loss of appetite, headache, dry and pruritic skin, skin desquamation, and erythematous dermatitis. Fatigue, pain in ankles and feet, myalgia, loss of body hair, papilledema, nystagmus, gingivitis, mouth fissures, and lymph node enlargement have been observed. In addition to hepatosplenomegaly, pathological changes in the liver include hypertrophy of fat-storing cells, fibrosis, scelerosis of central veins, and cirrhosis, with resultant portal hypertension and ascites. --->>>>Intracranial pressure may be increased, and neurological symptoms --->>>>may mimic that of a brain tumor. The diagnosis is usually made following the appearance of tender, deep, hard swellings on the extremeties and occipital region of the head. Hyperostoses in the underlying bone area are easily demonstrated roentgenographically. The activity of alkaline phosphatase in plasma rises because of the increased osteoblastic activity, and a number of cases of hypercalcemia have been reported." (Swallow THAT as you swallow your vitamins!) -- /Steve Dyer decvax!bbncca!sdyer sdyer@bbncca