Differences in the bioavailability of betanin from various dietary sources as estimated by urinary excretion may be significant: betanin of the cactus pear Opuntia sp. fruit showed a considerably greater bioavailability (3.7%) [ 185 ] than that of red beet: 2.7% [ 193 ], 0.7% [ 167 ] or 0.28% [ 175 ].
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