A randomized steady-state bioavailability study of synthetic versus natural (kiwifruit-derived) vitamin C.
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.
Centre for Free Radical Research, Department of Pathology & Biomedical Science, University of Otago, Christchurch, PO Box 4345, Christchurch 8140, New Zealand. anitra.carr@otago.ac.nz.
Anitra C
AC
Carr
Stephanie M
SM
Bozonet
Juliet M
JM
Pullar
Jeremy W
JW
Simcock
Margreet C M
MC
Vissers
D029042:Actinidia / Q000737:chemistry*; D000293:Adolescent; D000328:Adult; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D001682:Biological Availability; D018592:Cross-Over Studies; D019587:Dietary Supplements; D005638:Fruit / Q000737:chemistry*; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D012661:Semen / Q000378:metabolism; D055815:Young Adult
D000975:Antioxidants; D001205:Ascorbic Acid