Abstract
Changes in plasma retinol and carotenoids was measured in 17 young males after daily ingestion of grated carrots, carrot juice or spinach leaves for 2 weeks. Regression equations showed that the supply of 3350 and 4750 micrograms carotenes from 78 ml carrot juice (prepared from 185 g carrots) or 91 g grated carrots, respectively were adequate in maintaining plasma retinol at a constant level in subjects with initial plasma retinol of 1.2 mumol/l. Under similar experimental conditions, 280 g boiled spinach leaves providing 12,700 micrograms carotenes were required to maintain plasma retinol at a constant level. Apparent carotene digestibilities of 47 and 81% were obtained with carrot and spinach, respectively.