Dietary calcium and vitamin D intake in relation to osteoporotic fracture risk.
The etiologic role of dietary calcium and vitamin D intake in primary prevention of osteoporotic fractures is uncertain, despite considerable research efforts. With the aim to examine these associations with an improved precision, we used data from a large population-based prospective cohort study in central Sweden. We estimated nutrient intake from a self-administered food-frequency questionnaire filled in by 60,689 women, aged 40-74 years at baseline during 1987-1990. During follow-up, we observed 3986 women with a fracture at any site and 1535 with a hip fracture. Rate ratio of fractures (RR) and 95% CI were estimated using Cox proportional hazards models. We found no dose-response association between dietary calcium intake and fracture risk. The age-adjusted RR of hip fracture was 1.01 (95% CI 0.96-1.06) per 300 mg calcium/day and the corresponding risk of any osteoporotic fracture was 0.99 (95% CI 0.96-1.03). Furthermore, women with an estimated calcium intake below 400 mg/day and those with a calcium intake higher than 1200 mg/day both had a similar age-adjusted hip fracture risk as those with intermediate calcium intakes: RR 1.07 (95% CI 0.92-1.24) and RR 1.00 (95% CI 0.79-1.27), respectively. Vitamin D intake was not associated with fracture risk. Furthermore, women in the highest quintiles compared to the lowest quintiles of both calcium and vitamin D intake had an age-adjusted RR of 1.02 for all fractures (95% CI 0.88-1.17). Dietary calcium or vitamin D intakes estimated at middle and older age do not seem to be of major importance for the primary prevention of osteoporotic fractures in women.
Michaëlsson
Karl
K
Department of Surgical Sciences, Orthopaedics, University Hospital, SE-751 85 Uppsala, Sweden. Karl.Michaelsson@ortopedi.uu.se
Melhus
Håkan
H
Bellocco
Rino
R
Wolk
Alicja
A
D000328:Adult; D000368:Aged; D002136:Calcium, Dietary / Q000627:therapeutic use*; D016001:Confidence Intervals; D005260:Female; D050723:Fractures, Bone / Q000178:diet therapy / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000178:diet therapy / Q000453:epidemiology / Q000517:prevention & control*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000627:therapeutic use*
D002136:Calcium, Dietary; D014807:Vitamin D