L-dehydroascorbic acid can substitute l-ascorbic acid as dietary vitamin C source in guinea pigs

Abstract

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 (0.25mg/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.

Keywords: Ascorbate recycling; Bioavailability; Guinea pig; Human; Mouse; Rat; Vitamin C.

Graphical abstract

Fig. 1

Stability of drinking solutions and water intake. In A, the stability of ascorbate and DHA, respectively, are presented over time. The solutions were freshly made and kept in drinking bottles in the animal facility. Concentrations were normalized to that of the initial preparation. B shows the daily water intake within each group. Data is presented as mean±SEM. *=p≤0.05; **=p≤0.01; ***=p≤0.001 by one-way ANOVA with Bonferroni correction for multiple comparisons.

Fig. 2

Tissue vitamin C levels. Vitamin C levels in plasma (A), liver (B), spleen (C), kidney (D), adrenal glands (E), cortex (F), cerebellum (G), lung (H), heart (I), and skeletal muscle (J). Vitamin C levels are depicted as ascorbate (gray bar part), oxidized vitamin C (DHA) (white bar part), and total vitamin C (total bar height). N.D.=Not depicted. Statistics are present in Table 2. Data is presented as mean±SEM.

Fig. 3

Recycling capacity in liver, intestine and erythrocytes of guinea pig, rat and mouse. Liver or intestinal homogenate or isolated erythrocytes were incubated with 100 µmol/L dehydroascorbic acid for 20 min and the accumulation of ascorbate was expressed as % of initial concentration. Erythrocytes from rats and mice did not contain any initial ascorbate, nor did they accumulate any following incubation. Data were compared by Kruskal–Wallis multiple comparison test for non-parametric data.