Background/Aims: Inadequate dietary intake of vitamin C results in hypovitaminosis C, i.e. a plasma ascorbate concentration ≤23 µmol/L. The current Australasia recommended dietary intake (RDI) for vitamin C is 45 mg/d which may be insufficient for such individuals. Our aim was to carry out retrospective analysis of two vitamin C supplementation studies to determine whether supplementation with the current RDI is sufficient to restore adequate ascorbate status (≥50 µmol/L) in individuals with hypovitaminosis C.
Methods: Plasma ascorbate data from 70 young adult males, supplemented with 50 or 200 mg/d vitamin C for 4-6 weeks, was pooled and analysed. Hypovitaminosis C individuals were identified based on their plasma ascorbate status being ≤23 µmol/L. Total dietary intake data from 80% of the participants was also analysed.
Results: Participants consuming 50 mg/d vitamin C had plasma concentrations of ~50 µmol/L within four weeks, whereas those with hypovitaminosis C reached only ~30 µmol/L, despite comparable dietary intakes. Participants consuming 200 mg/d vitamin C reached saturating concentrations (>65 µmol/L) within one week, while those with hypovitaminosis C required two weeks to reach saturation. Regression modelling indicated that the participants’ initial ascorbate status and body weight explained ~30% of the variability in the final ascorbate concentration.
Conclusions: Our analysis reveals that vitamin C supplementation with equivalent to the current Australasian RDI is insufficient to achieve adequate plasma ascorbate concentrations in individuals with hypovitaminosis C. This indicates that dietary intakes greater than the RDI are required to meet their health needs.Funding Sources: MBIE, Zespri Intl.