Vitamin C Status of US Adults in the 2017–2018 National Health and Nutrition Examination Survey Remains Unchanged Since Last Assessed in 2005–2006

OBJECTIVES: NHANES 2017–2018 serum vitamin C status of the adult (≥20 years) US population was compared with the combined NHANES 2003–2004 and NHANES 2005–2006 surveys. METHODS: Serum vitamin C was measured using HPLC with electrochemical detection. Mean data were stratified by age, sex, race/Hispanic origin, dietary intake, supplement use, smoking, body mass index, and income. Prevalence of deficiency risk (<11.4 mmol/L) was calculated. RESULTS: Overall, there were no significant survey differences in mean serum vitamin C (51.2 vs 54.0 mmol/L; P = 0.087) nor in prevalence of deficiency risk (6.75% vs 6.99%; P = 0.83). The associations between serum vitamin C and the investigated covariates were generally consistent between survey periods. The 60 + y group mean serum vitamin C was 8–12 mmol/L higher than the 20–59 y. Mean serum vitamin C was 9–10 mmol/L lower in men vs women. Mean serum vitamin C in non-Hispanic Whites was higher than Mexican Americans, which was higher than non-Hispanic Blacks. In 2017–2018, non-Hispanic Asians had the highest of all race/Hispanic origin groups (P < 0.0021). Mean serum vitamin C was 22–23 mmol/L higher with vitamin C-containing supplement use and positively associated (Spearman ρ = 0.33; P < 0.0001) with increasing dietary intake. Mean serum vitamin C was 15–17 mmol/L lower in smokers vs non-smokers, 11–12 mmol/L lower in obese vs normal weight, and 8 mmol/L lower in low vs high income. CONCLUSIONS: Overall, the serum vitamin C status of the US adult population was essentially the same since when it was last assessed in the NHANES 2005–2006 survey. FUNDING SOURCES: CDC.