**5. Conclusions**

Our pharmacokinetic study has shown comparable plasma uptake of synthetic and kiwifruit-derived vitamin C and enhanced urinary excretion of kiwifruit-derived vitamin C, although the ~10% increase in total excretion is unlikely to be physiologically significant. Of interest, in our subjects with >50 μmol/L to saturating baseline plasma ascorbate, ~50%–60% of the ingested ascorbate was unaccounted for by urinary excretion, despite complete plasma uptake. This indicates possible tissue uptake even in individuals with supposedly "healthy" or "optimal" plasma ascorbate status.
