Are high amounts of vitamin A toxic?
Premium Insurance Caps contains beta-carotene, which is a precursor for vitamin A. However, it is not the same thing as fat-soluble vitamin A. Beta-carotene, which is virtually non-toxic (if not altogether non-toxic), is used make vitamin A in the body on an "as needed" basis. The only side effects that have been documented with extremely high doses of beta-carotene are diarrhea and a yellow-to-orange coloration to the hands and feet. These symptoms disappear upon cessation of beta carotene supplementation or lowering of the dose.
Regarding vitamin A toxicity, Dr. Shari Lieberman writes, "... [vitamin A] can, therefore, be toxic in large amounts. In general, a normal healthy adult must take at least 100,000 IU of vitamin A daily for a period of months in order to display any signs of toxicity. Early signs of toxicity are fatigue, nausea, vomiting, headache, vertigo, blurred vision, muscular incoordination, and loss of body hair. Although all of these symptoms are reversible when vitamin A supplementation is stopped, I would not recommend this dose unless you are under professional guidance. Beta-carotene, on the other hand, can be given for long periods of time virtually without risk of toxicity."
Dr. Michael Colgan says this about vitamin A:
"The medical literature contains about 600 cases of vitamin A poisoning. A lot of these cases have been with women given daily prescribed mega-doses of over 330,000 mcg RE (1,000,000 IS) of cis-retinoic acid for skin complains. Such mega-doses are especially dangerous because they build up in your body fat. World expert on the toxicity of nutrients, Dr. John Hathcock of Iowa State University and the Food and Drug Administration, concludes that toxicity of vitamin A does not occur for most people in normal health until they take a dose above 1,000 RE per kilogram bodyweight. That's 70,000 mcg (230,000 IU) for a 70 kg (154 lb) athlete. He does cite some reports of headache, intracranial hypertension, and skin lesions in children and sick individuals at intakes of only 10,000 - 15,000 mcg RE, but none with normal adults. In any case, sensible supplementation [with vitamin A] does not even approach such figures. We have never found an athlete that needed more than 5,000 mcg RE (16,500 IU) [of vitamin A] per day."
Again, we do not use "straight" vitamin A in Premium Insurance Caps (or any of our products), but instead use beta-carotene. 7-14 capsules of Premium Insurance Caps contain 12,500 - 25,000 IU of beta-carotene, which is the suggested Optimal Daily Intake (ODI). This amount, and perhaps even higher amounts, is fine because our body uses beta-carotene selectively to obtain however much vitamin A is needed, and discards what it does not need.