No increase in risk of hip fracture at high serum retinol concentrations in community-dwelling older Norwegians: The Norwegian Epidemiologic Osteoporosis Studies

Kristin Holvik, Luai A. Ahmed, Siri Forsmo, Clara G. Gjesdal, Guri Grimnes, Sven Ove Samuelsen, Berit Schei, Rune Blomhoff, Grethe S. Tell, Haakon E. Meyer

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

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 a-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.

Original languageEnglish
Pages (from-to)1289-1296
Number of pages8
JournalAmerican Journal of Clinical Nutrition
Volume102
Issue number5
DOIs
Publication statusPublished - Nov 1 2015

Keywords

  • Casecohort
  • Elderly
  • Hip fracture
  • Norway
  • Retinol
  • Vitamin A

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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