History
Ancient Egyptian physicians fed liver to people who could not see at night. In 1913 Elmer McCollum and Marguerite Davis at the University of Wisconsin found a "fat-soluble factor A" in butter and egg yolk needed for growth—the first vitamin A. From the 1930s George Wald showed that the retina's rhodopsin is built from vitamin A, earning the 1967 Nobel Prize. In 1986 Alfred Sommer reported that vitamin A capsules cut child mortality in Indonesia by about 34%, launching global supplementation programs.
What it does and where it is found
Vitamin A forms rhodopsin, the light sensor of the retina, so deficiency causes night blindness and, when severe, xerophthalmia that can blind. It also maintains skin and mucosa and supports immunity. Liver, eggs, milk and eel supply retinol, while carrots, sweet potatoes, spinach and pumpkin supply beta-carotene, converted only as needed and absorbed better with fat. The acne drug isotretinoin and cosmetic retinol are vitamin A derivatives.
Beware of excess
Being fat-soluble, it accumulates. Long-term high retinol intake (adult upper limit 3,000 μg a day) can cause headaches, liver damage and weaker bones, and high doses early in pregnancy risk birth defects, so pregnant women should be careful with liver and retinol supplements. In the 1990s, trials such as CARET found beta-carotene supplements increased lung cancer in smokers. Vegetables in food pose no such risk.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Can eating lots of carrots turn skin orange?
- Yes—carotenemia is harmless and fades when intake drops.
- Does vitamin A improve eyesight?
- It cures night blindness from deficiency but does not sharpen normal vision.
Sources reviewed: 2026-10-26
References
- McCollum, E. V., & Davis, M. (1913). The necessity of certain lipins in the diet during growth. Journal of Biological Chemistry, 15(1), 167–175.
- Sommer, A., et al. (1986). Impact of vitamin A supplementation on childhood mortality. The Lancet, 327(8491), 1169–1173.
- Omenn, G. S., et al. (1996). Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease (CARET). New England Journal of Medicine, 334(18), 1150–1155.