Why is it unwise for the average person to take megavitamin preparations?

Taking megavitamin preparations can be harmful or even fatal and take care to avoid overdosing. The liver can store large amounts of fat soluble vitamins, especially Vitamin A. Therefore, the potential toxicity of fat-soluble vitamin megadoses, including brain and liver damage in extreme cases, is well known. Megadoses of one vitamin can also produce toxic effects and lead to a secondary deficiency of another nutrient.