title: Urbanization of black South African women may increase risk of low bone mass due to low vitamin D status, low calcium intake, and high bone turnover.
abstract: Globally, rural to urban migration is accompanied by changes in dietary patterns and lifestyle that have serious health implications, including development of low bone mass. We hypothesized that serum 25 (OH) vitamin D3 (25[OH]D3) levels will be lower, bone turnover higher, and nutrition inadequate in urban postmenopausal black women, increasing risk for low bone mass. We aimed to assess the prevalence of risk factors for low bone mass in 1261 black women from rural and urban areas in the North West Province of South Africa (Prospective Urban and Rural Epidemiology-South Africa project). Fasting blood samples were taken; and participants were interviewed to complete questionnaires on self-reported diseases, fractures, and dietary intakes. Bone health markers were assessed in a subgroup of 658 women older than 45 years. Specific lifestyle risk factors identified were inactivity, smoking, injectable progestin contraception use, and high alcohol consumption. Dietary risk factors identified were low calcium and high animal protein, phosphorous, and sodium intakes. The 25(OH)D3 and C-terminal telopeptide (CTX) levels were significantly higher in the rural vs the urban women older than 50 years. Parathyroid hormone (PTH) levels increased with age in both groups. The 25(OH)D levels were inversely correlated with CTX and PTH in rural women. In urban women, PTH and CTX were correlated while dietary calcium was inversely correlated with CTX and PTH with 25(OH)D3. The combination of low dietary calcium (<230 mg/d), marginally insufficient 25(OH)D3 status, and raised PTH may result in increased bone resorption. Further research is required to assess bone health and fracture risk in black African women.
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. m.c.kruger@massey.ac.nz
authors.forename: Marlena C
authors.initials: MC
authors.lastname: Kruger
authors.forename: Iolanthé M
authors.initials: IM
authors.lastname: Kruger
authors.forename: Edelweiss
authors.initials: E
authors.lastname: Wentzel-Viljoen
authors.forename: Annamarie
authors.initials: A
authors.lastname: Kruger
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D044383:Black People; D001842:Bone and Bones / Q000378:metabolism*; D002112:Calcifediol / Q000097:blood; D002118:Calcium / Q000172:deficiency*; D002136:Calcium, Dietary / Q000008:administration & dosage; D024042:Collagen Type I / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008019:Life Style / Q000208:ethnology; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D015995:Prevalence; D012307:Risk Factors; D012423:Rural Health; D012720:Severity of Illness Index; D013019:South Africa / Q000453:epidemiology; D014504:Urban Health; D014808:Vitamin D Deficiency / Q000208:ethnology / Q000209:etiology*
chemical_list: D015415:Biomarkers; D002136:Calcium, Dietary; D024042:Collagen Type I; C470125:PTH protein, human; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D002112:Calcifediol; D002118:Calcium