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Randomized Controlled Trial
. 2013 Sep 17;5(9):3684-95.
doi: 10.3390/nu5093684.

A Randomized Steady-State Bioavailability Study of Synthetic Versus Natural (Kiwifruit-Derived) Vitamin C

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Free PMC article
Randomized Controlled Trial

A Randomized Steady-State Bioavailability Study of Synthetic Versus Natural (Kiwifruit-Derived) Vitamin C

Anitra C Carr et al. Nutrients. .
Free PMC article

Abstract

Whether vitamin C from wholefoods has equivalent bioavailability to a purified supplement remains unclear. We have previously showed that kiwifruit provided significantly higher serum and tissue ascorbate levels than synthetic vitamin C in a genetically vitamin C-deficient mouse model, suggesting a synergistic activity of the whole fruit. To determine if these results are translatable to humans, we carried out a randomized human study comparing the bioavailability of vitamin C from kiwifruit with that of a vitamin C tablet of equivalent dosage. Thirty-six young non-smoking adult males were randomized to receive either half a gold kiwifruit (Actinidia Chinensis var. Hort 16A) per day or a comparable vitamin C dose (50 mg) in a chewable tablet for six weeks. Ascorbate was monitored weekly in fasting venous blood and in urine, semen, leukocytes, and skeletal muscle (vastus lateralis) pre- and post-intervention. Dietary intake of vitamin C was monitored using seven day food and beverage records. Participant ascorbate levels increased in plasma (P < 0.001), urine (P < 0.05), mononuclear cells (P < 0.01), neutrophils (P < 0.01) and muscle tissue (P < 0.001) post intervention. There were no significant differences in vitamin C bioavailability between the two intervention groups in any of the fluid, cell or tissue samples tested. Overall, our study showed comparable bioavailability of synthetic and kiwifruit-derived vitamin C.

Figures

Figure 1
Figure 1
Parallel groups study design. * Weekly plasma samples; ** urine, semen and leukocyte samples; *** urine, semen, leukocyte and skeletal muscle samples.
Figure 2
Figure 2
Plasma ascorbate concentrations in vitamin C group (50 mg/day, ●) and kiwifruit group (0.5/day, ○). Data represent mean ± SEM. Two way analysis of variance with Fisher pairwise multiple comparison procedure indicated a significant increase in plasma ascorbate from one week post-intervention (week 6) onwards, but no significant difference between the two interventions.

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