Bioavailability and vitamin A value of carotenes from red palm oil assessed by an extrinsic isotope reference method
Cha-Sook You PhD, Robert S Parker PhD and Joy E Swanson PhD
http://apjcn.nhri.org.tw/server/APJCN/11%20Suppl%207//S438.pdf
The vitamin A values of red palm oil obtained under these conditions, a mean of 0.17 mg retinol absorbed per mg β-carotene consumed (β-carotene : retinol equivalency of 5.7:1) is higher than that of all other vegetable sources we have evaluated to date.
Our results support the concept that red palm oil is a food product possessing a vitamin A equivalency superior to that of solid foods.
The observed β-carotene : vitamin A equivalency ratio of 5.7:1 (5.7 mg β-carotene yielding 1 mg retinol, assuming that none of the vitamin A was derived from α-carotene) for RPO is substantially higher than those determined for other plant foods using this same approach. For example, raw carrot and spinach, supplying 6 mg β-carotene, gave retinol equivalency ratios averaging approximately 23:1. Using fieldbased interventions in vitamin A marginal populations, de Pee et al. have proposed equivalency ratios of 26:1 for vegetables and 12:1 for some fruits.