Sammendrag
The increased oxidative stress associated with ageing influences the formation and survival of bone forming and bone resorbing cells. Vitamin E, of which α-tocopherol is the most abundant form in human tissues, is a plant-derived lipid soluble substance with potent antioxidant properties. The relation between vitamin E concentrations in blood and risk of hip fracture has not previously been investigated in a population-based study. We aimed to study the association between α-tocopherol levels in serum and risk of hip fractures in elderly men and women in Norway, the population with the world’s highest hip fracture incidence.
In the Norwegian Epidemiologic Osteoporosis Studies (NOREPOS), we performed a case-cohort analysis in 21,774 men and women aged 65-79 years (mean 72 y) who underwent baseline examinations in four population-based health studies during 1994-2001. Data on incident hip fractures occurring up to 10.7 years of follow-up were retrieved from electronic patient administrative systems. Frozen serum samples from baseline were analyzed in participants who suffered a hip fracture during follow-up (n=1179; 307 men and 872 women) and in sex-stratified random samples from baseline (n=1447, including 89 of those who later suffered a hip fracture). α-tocopherol in serum was determined by high pressure liquid chromatography (HPLC)-fluorescence detection. Cox proportional hazards regression adapted for the case-cohort design was performed with adjustment for age, sex, and study center.
Median (25, 75-percentile) serum α-tocopherol concentration was 30.0 (22.6, 38.3) µmol/l. A linear inverse relation between serum α-tocopherol levels and hip fracture was observed, with hazard ratio (HR) 1.12 (95% CI 1.04-1.20) per 10 µmol/l lower serum α-tocopherol. HR of hip fracture in the lowest (=38.3 µmol/l) quartile of serum α-tocopherol was 1.53 (95% CI 1.18-1.97). The trend was linear across quartiles (p
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