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

**Anitra C. Carr 1,\*, Stephanie M. Bozonet 1 , Juliet M. Pullar <sup>1</sup> , Jeremy W. Simcock <sup>2</sup> and Margreet C. M. Vissers 1**


*Received: 23 July 2013; in revised form: 15 August 2013 / Accepted: 26 August 2013 / Published: 17 September 2013* 

**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.

**Keywords:** ascorbate; ascorbic acid; human; plasma; urine; semen; leukocytes; skeletal muscle
