Determine the Occurrence of vitamin A
In the vegetable kingdom, vitamin A probably occurs in the form of its provitamins which belong to the group of carotenes. Carrots, spinach, lettuce, celery leaves,mangoes, papaya and dried apricots are especially rich in carotenes and carotene isomers. In the human beings and animals, you should know, the provitamins (carotenes) are converted into vitamin A in the intestinal mucosa.
The most important provitamin is β-carotene. Other important sources of preformed vitamin A are the fish-liver oils (like codfish, Salmon, tunny fish and whale), butter, milk, egg yolk and animal liver.