Vitamin C status of Canadian adults: Findings from the 2012/2013 Canadian Health Measures Survey.

BACKGROUND
Although vitamin C is not produced in the body, it is important for many biochemical and physiological functions. Little is known about the current vitamin C status of Canadians. This study describes the correlates of vitamin C status in a nationally representative sample of adults.

DATA AND METHODS
Data are from the 2012/2013 Canadian Health Measures Survey. Plasma vitamin C (L-ascorbic acid) concentrations were measured among a fasting subsample of respondents aged 20 to 79 (n = 1,615). Vitamin C status, prevalence of deficiency (plasma vitamin C < 11 μmol/L), and use of vitamin C-containing supplements were estimated. Multivariate regression models were used to examine associations between vitamin C status and sociodemographic characteristics, smoking, body mass index, supplement use, and consumption of fruit juice and citrus fruit.

RESULTS
The mean plasma vitamin C concentration of adults aged 20 to 79 was 53 μmol/L; fewer than 3% were vitamin C-deficient. Almost 22% took a vitamin C-containing supplement. Concentrations were lower among smokers and people who were obese, and higher among vitamin C supplement users and fruit juice and citrus fruit consumers. Multivariate models showed that supplement use was the strongest and most consistent predictor of vitamin C status; fruit juice and citrus fruit consumption were predictors only among populations with lower vitamin C concentrations (for example, smokers, obese).

INTERPRETATION
Few Canadians were vitamin C-deficient. Smokers and people with a higher BMI were most at risk of lower vitamin C concentrations; concentrations were higher among supplement users and consumers of fruit juice and citrus fruit.