title: Dietary magnesium and potassium intakes and circulating magnesium are associated with heel bone ultrasound attenuation and osteoporotic fracture risk in the EPIC-Norfolk cohort study.
abstract: BACKGROUND
  In our aging population, maintenance of bone health is critical to reduce the risk of osteoporosis and potentially debilitating consequences of fractures in older individuals. Among modifiable lifestyle and dietary factors, dietary magnesium and potassium intakes are postulated to influence bone quality and osteoporosis, principally via calcium-dependent alteration of bone structure and turnover.
  
  
  OBJECTIVE
  We investigated the influence of dietary magnesium and potassium intakes, as well as circulating magnesium, on bone density status and fracture risk in an adult population in the United Kingdom.
  
  
  METHODS
  A random subset of 4000 individuals from the European Prospective Investigation into Cancer and Nutrition-Norfolk cohort of 25,639 men and women with baseline data was used for bone density cross-sectional analyses and combined with fracture cases (n = 1502) for fracture case-cohort longitudinal analyses (mean follow-up 13.4 y). Relevant biological, lifestyle, and dietary covariates were used in multivariate regression analyses to determine associations between dietary magnesium and potassium intakes and calcaneal broadband ultrasound attenuation (BUA), as well as in Prentice-weighted Cox regression to determine associated risk of fracture. Separate analyses, excluding dietary covariates, investigated associations of BUA and fractures with serum magnesium concentration.
  
  
  RESULTS
  Statistically significant positive trends in calcaneal BUA for women (n = 1360) but not men (n = 968) were apparent across increasing quintiles of magnesium plus potassium (Mg+K) z score intake (P = 0.03) or potassium intake alone (P = 0.04). Reduced hip fracture risk in both men (n = 1958) and women (n = 2755) was evident for individuals in specific Mg+K z score intake quintiles compared with the lowest. Statistically significant trends in fracture risk in men across serum magnesium concentration groups were apparent for spine fractures (P = 0.02) and total hip, spine, and wrist fractures (P = 0.02). None of these individual statistically significant associations remained after adjustment for multiple testing.
  
  
  CONCLUSIONS
  These findings enhance the limited literature studying the association of magnesium and potassium with bone density and demonstrate that further investigation is warranted into the mechanisms involved and the potential protective role against osteoporosis.
authors.affiliation: Department of Population Health and Primary Care, Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, United Kingdom; and.
authors.forename: Richard P G
authors.initials: RP
authors.lastname: Hayhoe
authors.affiliation: Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Strangeways Research Laboratory, Cambridge, United Kingdom.
authors.forename: Marleen A H
authors.identifier: http://orcid.org/0000-0003-4713-907X
authors.initials: MA
authors.lastname: Lentjes
authors.affiliation: Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Strangeways Research Laboratory, Cambridge, United Kingdom.
authors.forename: Robert N
authors.identifier: http://orcid.org/0000-0002-5088-6343
authors.initials: RN
authors.lastname: Luben
authors.affiliation: Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Strangeways Research Laboratory, Cambridge, United Kingdom.
authors.forename: Kay-Tee
authors.identifier: http://orcid.org/0000-0002-8802-2903
authors.initials: KT
authors.lastname: Khaw
authors.affiliation: Department of Population Health and Primary Care, Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, United Kingdom; and a.welch@uea.ac.uk.
authors.forename: Ailsa A
authors.initials: AA
authors.lastname: Welch
mesh_terms: D000368:Aged; D000375:Aging; D015519:Bone Density; D002111:Calcaneus / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D015331:Cohort Studies; D004032:Diet; D005260:Female; D006620:Hip Fractures / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008274:Magnesium / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging / Q000517:prevention & control*; D058866:Osteoporotic Fractures / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D017419:Potassium, Dietary / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D012306:Risk; D014463:Ultrasonography; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D017419:Potassium, Dietary; D008274:Magnesium
keywords: bone density; dietary minerals; epidemiology; fractures; osteoporosis; quantitative ultrasound