A megadose of a vitamin with intake of 20 to 600 times the RDA is actually a misnomer because at these levels, the vitamin is functioning as a drug rather than a nutrient.

Question

Quizplus · Accepted Answer

Megadoses are sometimes advocated, but this practice is dangerous, and it should be supervised by a healthcare provider to ensure that toxicities do not occur. By definition, a megadose is more than 10 times the RDA. A well-established principle of pharmacologic therapy is that all substances are potentially toxic at large enough doses. Taking more than the Institute of Medicine's upper limit means that risks likely outweigh benefits.

A Megadose of a Vitamin with Intake of 20 to 600