Table 1.

Summary of human clinical studies comparing plasma vitamin C concentrations between gender groups.

Study/Year	Sample size	Age group	Health status	Result
Birlouez-Aragon et al. (2001)	2,584	>60 years	Healthy	Males 31.6 μmol/L vs. females 40.3 μmol/L, p = 0.001
Hampl et al. (2004)	15,769	12–74 years	Healthy	Females exhibited a higher mean serum vitamin C concentration at every age group.
Schleicher et al. (2009)	7,277	>6 years	Healthy	Females reported higher mean serum vitamin C concentration at every age group, particularly in those of 60 years.
Pearson et al. (2017)	404	50 years	Healthy	45.1% of females and 28.7% of males presented with adequate vitamin C
Ness et al. (1996)	1,018	40–59 years	Healthy	Fasting plasma vitamin C levels were significantly higher in women
Fain et al. (2003)	184	>18 years	Hospitalized	Hospitalized males presented with significantly lower mean serum vitamin C concentrations.
Travica et al. (2019)	80	>18 years	Healthy	Females slightly higher concentrations (p = 0.46), adequate plasma levels = 47 females (70%) vs. 20 males (30%)