Serum vitamin C status of people in New South Wales: retrospective analysis of findings at a public referral hospital

Abstract

AbstractObjectivesTo examine the relationship between vitamin C status and demographic factors in New South Wales on the basis of serum vitamin C test results undertaken at the central pathology laboratory in Sydney, and to assess associations with age, gender, social disadvantage, and geographic remoteness.Design, settingRetrospective observational study; analysis of vitamin C test results undertaken at the Royal Prince Alfred Hospital, 1 January 2017 – 31 December 2021.Main outcome measuresVitamin C status (normal, serum concentration ≥ 40 μmol/L; hypovitaminosis C, 12–39 μmol/L; significant deficiency, < 12 μmol/L); associations of vitamin C status with year of testing, age, gender, socio‐economic status (Index of Relative Socio‐Economic Advantage and Disadvantage quintile), and geographic remoteness (Australian Statistical Geography Standard); rate of hypovitaminosis C or significant deficiency test results (relative to findings of normal levels; per 100 000 estimated resident population) by Statistical Area 3.ResultsOf 17 507 vitamin C tests undertaken during 2017–2021, 4573 were excluded (multiple tests for individuals); of 12 934 included results, 6654 were for women (51.5%), 9402 for people living in major cities (73.5%), and 81 for people in remote or very remote areas (0.6%). In multivariable multinomial regression analyses, significant deficiency (relative to normal test results) was more likely for men than women (adjusted odds ratio [aOR], 1.39; 95% confidence interval [CI], 1.27–1.52); the likelihood of hypovitaminosis C (IRSAD quintile 1 v 5, aOR, 1.35; 95% CI, 1.19–1.53) or significant deficiency (aOR, 2.07; 95% CI, 1.79–2.40) generally increased with postcode‐level socio‐economic disadvantage. Several of the population areas with the highest low vitamin C rates were areas of greatest disadvantage in NSW.ConclusionsThe prevalence of vitamin C deficiency among older people and people living in areas of socio‐economic disadvantage indicates that population assessment of vitamin C levels would be appropriate.