Dietary vitamin C is positively associated with heel bone density but not with fracture risk in men and women in the EPIC-Norfolk study

Abstract

Previous epidemiological studies have reported positive associations between vitamin C and bone density(1-3), possibly due to the role of vitamin C in bone collagen formation and maintenance as well as in bone remodelling(4-6). However, to date, there have been limited studies in UK populations, particularly in men, and in relation to fracture risk. The present study aimed to investigate potential associations between dietary vitamin C intake and heel bone ultrasound and fracture risk in a UK population of men and women. A representative sample of 2777 men and women aged 42-81 years from the EPIC-Norfolk study (25,000 men and women)(7) were included in this case-cohort analysis. All participants gave informed consent and the study was approved by the Norwich District Health Authority ethics committee. Vitamin C intake was estimated from 7-day diet diaries. Heel bone density was measured using broadband ultrasound attenuation (BUA) and velocity of sound (VOS), and fracture incidence (all, hip, spine and wrist) was ascertained over 11 years follow-up. Multiple regression of BUA and VOS as well as hazard ratios (HRs) of fracture risk were plotted against quintiles of vitamin C intake, after adjustment for age, family history of osteoporosis (BUA and VOS only), body mass index (BMI), smoking and physical activity in all participants, and additionally for menopausal status and HRT in women. All analyses were performed using STATA (version 11, STATA Corp, USA). Mean (SD) age was 63 years (9 years) in both genders and mean (SD) vitamin C intake was 91 mg/d (54 mg/d) in men and 94 mg/d (52 mg/d) in women. BUA increased significantly by 0.84% across all quintiles of vitamin C intake in women and VOS by 0.12% in men, after adjustment for potential confounding factors (P-trend