title: Higher Dietary Acidity is Associated with Lower Bone Mineral Density in Postmenopausal Iranian Women, Independent of Dietary Calcium Intake.
abstract: Findings of studies on the link between dietary acid-base balance and bone mass are relatively mixed. We examined the association between dietary acid-base balance and bone mineral density (BMD) in a sample of Iranian women, hypothesizing that a higher dietary acidity would be inversely associated with BMD, even when dietary calcium intake is adequate. In this cross-sectional study, lumbar spine and femoral neck BMDs of 151 postmenopausal women aged 50-85 years were measured using dual-energy x-ray absorptiometry. Dietary intakes were assessed using a validated food frequency questionnaire. Renal net acid excretion (RNAE), an estimate of acid-base balance, was then calculated indirectly from the diet using the formulae of Remer (based on dietary intakes of protein, phosphorus, potassium, and magnesium; RNAERemer) and Frassetto (based on dietary intakes of protein and potassium; RNAEFrassetto), and was energy adjusted by the residual method. After adjusting for potential confounders, multivariable adjusted means of the lumbar spine BMD of women in the highest tertiles of RNAERemer and RNAEFrassetto were significantly lower than those in the lowest tertiles (for RNAERemer: mean difference -0.084 g/cm2; P=0.007 and for RNAEFrassetto: mean difference -0.088 g/cm2; P=0.004). Similar results were observed in a subgroup analysis of subjects with dietary calcium intake of >800 mg/day. In conclusion, a higher RNAE (i. e. more dietary acidity), which is associated with greater intake of acid-generating foods and lower intake of alkali-generating foods, may be involved in deteriorating the bone health of postmenopausal Iranian women, even in the context of adequate dietary calcium intake.
authors.affiliation: 1 Department of Nutrition Sciences, Varastegan Institute for Medical Sciences, Mashhad, Iran.
authors.forename: Seyedeh-Elaheh
authors.initials: SE
authors.lastname: Shariati-Bafghi
authors.forename: Elaheh
authors.initials: E
authors.lastname: Nosrat-Mirshekarlou
authors.forename: Mohsen
authors.initials: M
authors.lastname: Karamati
authors.forename: Bahram
authors.initials: B
authors.lastname: Rashidkhani
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D005247:Feeding Behavior; D005260:Female; D005502:Food; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008274:Magnesium / Q000008:administration & dosage; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000453:epidemiology / Q000209:etiology; D016226:Phosphorus, Dietary / Q000008:administration & dosage; D017698:Postmenopause; D017419:Potassium, Dietary / Q000008:administration & dosage; D011795:Surveys and Questionnaires
chemical_list: D002136:Calcium, Dietary; D004044:Dietary Proteins; D016226:Phosphorus, Dietary; D017419:Potassium, Dietary; D008274:Magnesium
keywords: Iran; acid-base balance; bone mineral density; calcium; diet; post-menopause