Why can people consume large amounts of foods with beta-carotene without any ill effects but cannot consume large amounts of foods with active vitamin A without risk of serious toxic effects?

Answer 1

The liver converts beta-carotene into active vitamin A. The diet must supply 12 micrograms of beta-carotene to produce 1 microgram of active vitamin A, and this conversion is not efficient enough to result in a toxic level of active vitamin A. The only sign of excess beta-carotene intake is a bright yellow color of the skin due to a buildup of beta-carotene in the fat beneath the skin.
Certain animal foods, such as liver, contain very high levels of active vitamin A. When these foods are ingested, all of the vitamin A is sent directly into the body and its fat tissues. The amount of active vitamin A can quickly reach toxic levels that can cause digestive upset as well as possible damage to the liver.