THE BIOAVAILABILITY TO HUMANS OF ASCORBIC-ACID FROM ORANGES, ORANGE JUICE AND COOKED BROCCOLI IS SIMILAR TO THAT OF SYNTHETIC ASCORBIC-ACID

The relative bioavailability of ascorbic acid from several sources was compared in 68 male nonsmokers. Subjects underwent two 8-wk ascorbic acid depletion-repletion cycles. In repletion, subjects were randomize d to receive 108 mg/d ascorbic acid as tablets with or without iron, a s orange segments or juice, or as raw or cooked broccoli with a crosso ver within each major treatment group (e.g., cooked to raw broccoli) f or the second repletion. Relative ascorbic acid bioavailability was es timated based on the slope obtained from linear regression of plasma a scorbic acid on time during each repletion. In the first repletion, sl opes for all groups were similar except for the group consuming raw br occoli (20% lower response, P < 0.01). Second repletion responses were attenuated, but were similar to the first repletion. Ascorbic acid in gested as cooked broccoli, orange juice or fruit, or in synthetic form seems to be equally bioavailable. The lower relative bioavailability of ascorbic acid from raw broccoli is unlikely to be of practical impo rtance in mixed diets.