Availability of beta-carotene from high-beta tomato hybrids to vitamin A-deficient rats & utilization of beta-carotene in the presence of other carotenoids
Premachandra, B.R.; Vasantharajan, V.N.; Cama, H.R.
Indian Journal of Experimental Biology 16(4): 473-477
1978
ISSN/ISBN: 0019-5189 PMID: 680854 Document Number: 130594
Tomato strains where lycopene (vitamin A inactive) is replaced by .beta.-carotene (vitamin A potent) were cultivated and their pro-vitamin A potency was established by body bioassay trials. Such high-.beta.-carotene tomatoes gave rise to 4 .times. the liver stores of vitamin A compared to the common red tomatoes. These bioassay trials revealed that .beta.-carotene in the tomatoes is as freely available as the synthetic all-trans .beta.-carotene administered in oil. The presence of lycopene did not affect the conversion of .beta.-carotene to vitamin A. It facilitated the absorption of .beta.-carotene protecting it against the oxidative degradative conditions prevailing in the intestine. Independent of the amount of .beta.-carotene ingested, a constant percentage of the ingested dose of lycopene is excreted. The extent of lycopene exeretion depended on the amount present. Prolonged vitamin A deficiency affected the intestinal conversion of .beta.-carotene to vitamin A. The validity of study of absorption of .beta.-carotene based on the extent of its excretion was questioned.