Retinol

Retinol, the most useful form of vitamin A, (along with retinal and retinoic acid) is a fat-soluble, antioxidant vitamin important in vision and bone growth. It is sometimes used in the treatment of severe acne. As can be seen from the structure, this is a compound synthesized from isoprene.

A deficiency of vitamin A is not only disease causing, but it can kill. On the other hand, overdoses of vitamin A are also lethal. The livers of certain animals, especially those adapted to polar environments, often contain amounts of vitamin A that would be toxic to humans. The first documented death due to vitamin A poisoning was Xavier Mertz, a Swiss scientist who died in January 1913 on an Antarctic expedition that had lost its food supplies and fell to eating its sled dogs. Mertz consumed lethal amounts of vitamin A by eating the dogs' livers. The liver of the polar bear also has enough vitamin A to kill a human being.

Deficiency of Vitamin A can cause night-blindness, and pale, dry skin. Vitamin A is found in carrots, spinach, milk and eggs. Vitamin A gets destroyed at about 40 degrees Celsius, hence these foods must be consumed raw in order to avail maximum benefit. George Wald won the 1967 Nobel Prize in Physiology or Medicine for his work with retina pigments, including the role of vitamin A in the retina.

External links:

• http://ods.od.nih.gov/factsheets/cc/vita.html
• Vitamin A information