Food Sources

Plants synthesize provitamin A carotenoids, which humans convert to retinol. Preformed vitamin A is found in animal foods only. The best sources of vitamin A include liver, yellow and green leafy vegetables, eggs, and whole milk products.

Figure %: Vitamin A Content of Selected Foods


The safe upper limit of vitamin A is 8000 to 10000 IU, or 3000 mcg RE. Supplements of 50,000 to 200,000 IU have been utilized to protect children from developing xerophthalmia for a period of four to six months. Retinoids are used in topical agents for hyperkeratoic disorders, acne, and skin cancer, due to their influence on epithelial cell proliferation. Vitamin A has also been used in cancer prevention. Epidemiological studies have shown an association of total vitamin A to reduced risk of epithelial cancer.