Vitamin A Facts

Vitamin A is needed for normal vision, immunity, growth and reproduction. It keeps the mucous linings of he respiratory, urinary, and intestinal tracts healthy to prevent bacteria and viruses from entering. Vitamin A in animal foods is already formed (preformed vitamin A). Vitamin A in colorful fruits and vegetables is in a form that can be converted to Vitamin A (provitamin A). Carotenoids, like beta-carotene, are examples of provitamin A.

The RDAs for healthy adults are 900 micrograms (mcg)/day for males and 700 mcg/day for females. The RDAs are listed in International Units (IU) on food and supplement labels. Adult men require 3000 IU/day and women need 2310 IU/day. There is no RDA for provitamin A. The upper tolerable intake level (UL) for vitamin A is set at 3,000 mcg/ day (or 10,000 IU) for all adults. The UL applies to supplements.

In most cases, excess vitamin A is taken in the form of supplements. High storage levels of vitamin A can lead to problems with the liver, nervous system, bones and to birth defects. It is impossible to get excess provitamin A from plants. A high intake of provitamin A can turn the skin yellow, but it is not dangerous.

Inadequate Vitamin A is associated with impaired immunity and resulting infections. Vitamin A deficiency is uncommon in developed countries. In the US, vitamin A deficiency is most often associated with strict dietary restrictions and excess alcohol intake.

Pre-formed Vitamin A is found in the fat of milk and eggs and in liver. Provitamin A is found in dark green and bright orange vegetables and fruits like spinach, sweet potatoes carrots, cantaloupe, apricots, and others. Deeper colors are associated with higher levels.