Vitamin C deficiency globally affects several hundred million people and has been associated with increased
morbidity and mortality in numerous studies. In this study, bioavailability of the oxidized form of
vitamin C (L-dehydroascorbic acid or DHA)—commonly found in vitamin C containing food products
prone to oxidation—was studied. Our aim was to compare tissue accumulation of vitamin C in guinea pigs
receiving different oral doses of either ascorbate or DHA. In all tissues tested (plasma, liver, spleen, lung,
adrenal glands, kidney, muscle, heart, and brain), only sporadic differences in vitamin C accumulation
from ascorbate or DHA were observed except for the lowest dose of DHA (0.25 mg/ml in the drinking
water), where approximately half of the tissues had slightly yet significantly less vitamin C accumulation
than from the ascorbate source. As these results contradicted data from rats, we continued to explore the
ability to recycle DHA in blood, liver and intestine in guinea pigs, rats and mice. These investigations
revealed that guinea pigs have similar recycling capacity in red blood cells as observed in humans, while
rats and mice do not have near the same ability to reduce DHA in erythrocytes. In liver and intestinal
homogenates, guinea pigs also showed a significantly higher ability to recycle DHA compared to rats and
mice. These data demonstrate that DHA in guinea pigs—as in humans—is almost as effective as ascorbate
as vitamin C source when it comes to taking up and storing vitamin C and further suggest that the guinea
pig is superior to other rodents in modeling human vitamin C homeostasis.