Vitamin C Status of US Adults Assessed as Part of the National Health and Nutrition Examination Survey Remained Unchanged between 2003–2006 and 2017–2018

Abstract

Abstract Background We compared serum vitamin C (VIC) status of the adult (≥20 y) US population in the National Health and Nutrition Examination Survey (NHANES) 2017–2018 with combined data from 2003–2004 and 2005–2006. Methods VIC was measured using HPLC with electrochemical detection. Mean data were stratified by age, sex, race/Hispanic origin, income, body mass index, dietary intake, supplement use, and smoking status. Prevalence of VIC deficiency (<11.4 μmol/L) was calculated. Results In NHANES 2017–2018, the mean VIC was 8 μmol/L higher in people ≥60 y compared with those 20–59 y of age, 10 μmol/L lower in men vs women, 8 μmol/L lower in low vs high income, 11 μmol/L lower in obese vs healthy weight, and 15 μmol/L lower in smokers vs nonsmokers. Differences in mean VIC across race/Hispanic origin groups ranged from 2 to 7 μmol/L. Mean VIC was 27 μmol/L higher with vitamin C-containing supplement use and positively associated (Spearman ρ = 0.33; P < 0.0001) with increasing dietary intake. The associations between mean VIC and the investigated covariates were generally consistent and the prevalence of deficiency was not significantly different between survey periods (6.8% vs 7.0%; P = 0.83). However, a few subgroups had double the risk. We found no significant survey differences in mean VIC (51.2 vs 54.0 μmol/L; P = 0.09). Conclusions Overall VIC status of the US adult population has remained stable since last assessed in the NHANES 2005–2006 survey. Vitamin C deficiency remained high for those with low dietary intake and who smoke.