The bioavailability of beta-carotene in stir- or deep-fried vegetables in men determined by measuring the serum response to a single ingestion

To evaluate the bioavailability of beta-carotene from plant foods, the seru m beta-carotene response to a single ingestion of various beta-carotene sou rces was determined in 10 healthy men. Tested beta-carotene sources include d stir-fried shredded carrot, stir-fried water convolvulus leaves, deep-fri ed sweet potato ball, purified beta-carotene in a capsule (beadlets) and be adlets with beta-carotene free oriental radish (beadlets + radish). The max imal change in serum beta-carotene concentration occurred at 24 or 32 h pos t ingestion. This response to beadlets was significantly higher than that t o the other four tested beta-carotene sources (P < 0.05). The maximal serum response to beadlets + radish was also significantly higher than that to t he three food beta-carotene sources (P < 0.05). The maximal serum response to sweet potato was significantly higher than that to water convolvulus lea ves (P < 0.05). The bioavailability relative to beta-carotene beadlets was calculated by dividing the maximal change in serum concentration to each te st meal of each subject by his own serum maximal change in response to bead lets. Accordingly, the bioavailability was 65% for beadlets t radish, 33% f or carrots, 26% for water convolvulus leaves and 37% for sweet potatoes. Co ncurrent ingestion of oriental radish reduced the bioavailability of beadle ts to two-thirds of its original value, which partially accounted for the d ifference between the bioavailability of beadlets and natural foods. The re lative bioavailability of beta-carotene from stir-fried and deep-fried vege tables was about one-third to one-fourth that of the purified beta-carotene beadlets. These bioavailabilities are higher than previously reported valu es.