The seasonal importance of serum 25-hydroxyvitamin D for bone mineral density in older women.
BackgroundThe impact of season when determining a serum 25-hydroxyvitamin D (S-25OHD) cut-off level for optimal bone health is unknown.ObjectiveTo investigate the relative importance of S-25OHD for bone mineral density (BMD) by season.MethodsA subcohort of 5002 Swedish women (mean age 68 years), randomly selected from a large population-based longitudinal cohort study with repeat dietary and lifes