*3.1. Direct Induction of DNA Damage*

We evaluated DNA damage, *i.e.*, SBs and oxidized bases, just after incubating HeLa cells with different concentrations of vitamin C for 30 min or 6 h, using the comet assay with and without FPG. Treatment with different concentrations of vitamin C (5–200 μM) did not cause or decrease SBs or base oxidation in HeLa cells (Figure 1A,B).

**Figure 1.** Effect of different concentrations of vitamin C on DNA integrity (SBs and net formamidopyrimidine DNA glycosylase (FPG)-sensitive sites) of HeLa cells treated for 30 min (**A**) and 6 h (**B**) and measured using the comet assay. Bars: SD calculated from the results of 3 independent experiments. No significant effects were seen.
