EXCESSIVE DIETARY-INTAKE OF VITAMIN-A IS ASSOCIATED WITH REDUCED BONE-MINERAL DENSITY AND INCREASED RISK FOR HIP FRACTURE

Background: The highest incidence of osteoporotic fractures is found i n northern Europe, where dietary intake of vitamin A (retinol) is unus ually high. In animals, the most common adverse effect of toxic doses of retinol is spontaneous fracture. Objective: To investigate whether excessive dietary intake of vitamin A is associated with decreased bon e mineral density and increased risk for hip fracture. Design: A cross -sectional study and a nested case-control study. Setting: Two countie s in central Sweden. Participants: For the cross-sectional study, 175 women 28 to 74 years of age were randomly selected. For the nested cas e-control study, 247 women who had a first hip fracture within 2 to 64 months after enrollment and 873 age-matched controls were selected fr om a mammography study cohort of 66 651 women 40 to 76 years of age. M easurements: Retinol intake was estimated from dietary records and a f ood-frequency questionnaire. Bone mineral density was measured with du al-energy x-ray absorptiometry. Hip fracture was identified by using h ospital discharge records and was confirmed by record review. Results: In multivariate analysis, retinol intake was negatively associated wi th bone mineral density. For every l-mg increase in daily intake of re tinol, risk for hip fracture increased by 68% (95% CI, 18% to 140%; P for trend, 0.006). For intake greater than 1.5 mg/d compared with inta ke less than 0.5 mg/d, bone mineral density was reduced by 10% at the femoral neck (P = 0.05), 14% at the lumbar spine (P = 0.001), and 6% f or the total body (P = 0.009) and risk for hip fracture was doubled (o dds ratio, 2.1 [CI, 1.1 to 4.0]). Conclusion: High dietary intake of r etinol seems to be associated with osteoporosis.