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David G. Meyers, MD
Kansas City, Kan

Pierre A. Maloley, PharmD; David Weeks, PharmD
Omaha, Neb

Arch Intern Med. 1997;157(15):1777.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

Schulz expressed concern about our statement that, when women of childbearing potential, persons with liver disease, and heavy consumers of alcohol are excluded, vitamin A is safe in dosages of up to 100 000 IU/d.¹ We respond to Schulz with the following points.

First, to our knowledge, no reports are available that have prospectively evaluated the safety of vitamin A doses in excess of 100 000 IU/d. Therefore, we cannot say with absolute certainty that megadoses of vitamin A are safe.

Second, yet, others² who have extensively reviewed the epidemiologic literature have noted that long-term vitamin A toxic effects are rare at doses less than 100 000 IU/d. Importantly, not only dose, but also duration and pre-existing comorbidity, influence the occurrence of toxic reactions to vitamin A.

Third, for the above reasons, toxic effects have been observed at doses as low as 4000 IU/d.³ But, toxic effects . . . [Full Text PDF of this Article]

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