No increase in risk of hip fracture at high serum retinol concentrations in community-dwelling older Norwegians: the Norwegian Epidemiologic Osteoporosis Studies. Issue 5 (16th September 2015)

• Record Type: Journal Article
• Authors: Holvik, Kristin; Ahmed, Luai A; Forsmo, Siri; Gjesdal, Clara G; Grimnes, Guri; Samuelsen, Sven Ove; Schei, Berit; Blomhoff, Rune; Tell, Grethe S; Meyer, Haakon E
• Is Part Of: American journal of clinical nutrition. Volume 102:Issue 5(2015)
• Page Start: 1289
• Page End: 1296
• Publication Date: 2015-09-16
• Subjects: hip fracture -- vitamin A -- retinol -- elderly -- Norway -- case-cohort; Diet therapy -- Periodicals; Nutrition -- Periodicals; Dietetics -- Periodicals; 613.205
• DOI: 10.3945/ajcn.115.110528
• Languages: English
• ISSNs: 0002-9165

Abstract

ABSTRACT: Background: Norway has the highest hip fracture rates worldwide and a relatively high vitamin A intake. Increased fracture risk at high intakes and serum concentrations of retinol (s-retinol) have been observed in epidemiologic studies. Objective: We aimed to study the association between s-retinol and hip fracture and whether high s-retinol may counteract a preventive effect of vitamin D. Design: We conducted the largest prospective analysis of serum retinol and hip fracture to date in 21, 774 men and women aged 65–79 y (mean age: 72 y) who attended 4 community-based health studies during 1994–2001. Incident hip fractures occurring up to 10.7 y after baseline were retrieved from electronic hospital discharge registers. Retinol determined by high-pressure liquid chromatography with ultraviolet detection in stored serum was available in 1154 incident hip fracture cases with valid body mass index (BMI) data and in a subcohort defined as a sex-stratified random sample ( n = 1418). Cox proportional hazards regression weighted according to the stratified case-cohort design was performed. Results: There was a modest increased risk of hip fracture in the lowest compared with the middle quintile of s-retinol (HR: 1.41; 95% CI: 1.09, 1.82) adjusted for sex and study center. The association was attenuated after adjustment for BMI and serum concentrations of α-tocopherol (HR: 1.16; 95% CI: 0.88, 1.51). We found no increased risk in the upper compared with the middle quintile. No significant interaction between serum concentrations of 25-hydroxyvitamin D and s-retinol on hip fracture was observed ( P = 0.68). Conclusions: We found no evidence of an adverse effect of high serum retinol on hip fracture or any interaction between retinol and 25-hydroxyvitamin D. If anything, there tended to be an increased risk at low retinol concentrations, which was attenuated after control for confounders. We propose that cod liver oil, a commonly used food supplement in Norway, should not be discouraged as a natural source of vitamin D for fracture prevention.