Correspondence

University of Macau, Faculty of Social Sciences, Department of Psychology, Taipa, Macau, China (BJH); Faculty of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China (WC, LL); Sun Yatsen Center for Migrant Health Policy, Guangzhou, China (BJH, WC, LL, JDT); Department of Health Behavior and Society and Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA (CL); University of North Carolina Chapel Hill Project-China, Guangzhou, China (JDT); and University of North Carolina Chapel Hill, Institute of Global Health and Infectious Diseases, Chapel Hill, NC, USA (JDT) 1

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Mathews G, Yang Y. How Africans pursue lowend globalization in Hong Kong and Mainland China. J Curr Chin Aff 2012; 41: 95–120. Bodomo AB. Africans in China: a sociocultural study and its implications on Africa-China relations. New York: Cambria Press; 2012. Haugen H. Chinese exports to Africa: competition, complementarity and cooperation between micro-level actors. Forum Devel Stud 2011; 38: 157–76. Link BG, Phelan JC. Stigma and its public health implications. Lancet 2006; 367: 528–29. Cheng Y. From campus racism to cyber racism: discourse of race and Chinese nationalism. China Q 2011; 207: 561–79. Yip WC-M, Hsiao WC, Chen W, Hu S, Ma J, Maynard A. Early appraisal of China’s huge and complex health-care reforms. Lancet 2012; 379: 833–42.

Vitamin D supplements and bone mineral density The meta-analysis by Ian Reid and colleagues (Jan 11, p 146)1 concluded that treatment with vitamin D did not improve bone mineral density (BMD), although femoral neck BMD was 0·8% greater compared with placebo (13 trials: all women, n=2201). The VICtORy study was not included in their analysis.2 This 12-month placebocontrolled trial, designed to eliminate seasonal effects in 300 older women, found that 1000 IU per day of vitamin D

significantly increased BMD at the total hip compared with placebo (+0·6%, equivalent to +1·2% in 24 months) with no concomitant change in bone turnover markers.2 Supplementary data by region of the hip are presented in the table. The on-going VDOP trial will also determine the effects of vitamin D dose on BMD in 375 older men and women.3 We hypothesise that vitamin D might only improve BMD in individuals with marginally under-mineralised bone, for which higher doses than 400 IU daily might be required. Chapuy and colleagues4 showed a clear fracture risk reduction with vitamin D combined with calcium supplementation. Their study included a population older than 60 years at risk with low vitamin D status,4 whereas more than half the participants in the meta-analysis1 were younger than 60 years. We believe that individuals with poor bone health who are deficient in vitamin D will benefit most from vitamin D supplementation. HM is the principal investigator for the VICtORy study.2 TJA is s the principal investigator for the VDOP study.3 We declare that we have no competing interests.

*Helen Macdonald, Terence J Aspray

400 IU vitamin D3

Femoral neck

+0·5 (0·0 to +0·9)

+0·1 (–0·4 to +0·6)

Greater trochanter

+0·7 (–0·1 to +1·5)

–0·2 (–0·9 to +0·5)

Ward’s triangle

+0·6 (–0·2 to +1·4)

–0·2 (–1·0 to +0·6)

Total hip2

+0·6 (+0·1 to +1·0)

+0·1 (–0·4 to +0·5)

BMD=bone mineral density.

Table: Effect of vitamin D3 on BMD according to region of the hip (VICtORy trial)

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I declare that I have no competing interests.

Colin Robert Dunstan [email protected] University of Sydney, Sydney, NSW 2006, Australia 1

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Reid IR, Bolland MJ, Grey A. Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysis. Lancet 2014; 383: 146–55. Zhai G, Hart DJ, Valdes AM, et al. Natural history and risk factors for bone loss in postmenopausal Caucasian women: a 15-year follow-up population-based study. Osteoporos Int 2008; 19: 1211–17.

[email protected] Musculoskeleal Research, University of Aberdeen, Aberdeen AB25 2ZD, UK (HM); and Musculoskeletal Unit, Freeman Hospital, Newcastle upon Tyne, UK (TJA) 1

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BMD difference from placebo Mean % per year (95% CI ) 1000 IU vitamin D3

assessed by comparing baseline bone density to bone density changes with vitamin D treatment. No consideration was given by the authors to the natural history of bone density in this patient population. One could well expect that the population in this study would show a reduction of about 3% in bone density over the mean 2 years’ duration of treatment if vitamin D was ineffective.2 The fact that there is no significant increase at measured sites, apart from the clinically important femoral neck, is not necessarily a negative finding. Perhaps more remarkable is that there was no significant decrease in bone density at any site in older patients receiving vitamin D.

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Reid IR, Bolland MJ, Grey A. Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysis. Lancet 2014; 383: 146–55. Macdonald HM, Wood AD, Aucott LS, et al. Hip bone loss is attenuated with 1000 IU but not 400 IU daily vitamin D3: a 1-year double-blind RCT in postmenopausal women. J Bone Miner Res 2013; 28: 2202–13. Schoenmakers I, Francis RM, McColl E, et al. Vitamin D supplementation in older people (VDOP): study protocol for a randomised controlled intervention trial with monthly oral dosing with 12,000 IU, 24,000 IU or 48,000 IU of vitamin D3. Trials 2013; 14: 299. Chapuy MC, Arlot ME, Delmas PD, Meunier PJ. Effect of calcium and cholecalciferol treatment for three years on hip fractures in elderly women. BMJ 1994; 308: 1081–82.

The recent article by Ian Reid and colleagues1 contains a basic flaw in interpretation. The population, primarily of post-menopausal women, was

We are intrigued by the meta-analysis by Ian Reid and colleagues1 reporting no beneficial effect of vitamin D supplementation on bone mineral density (BMD). These findings, allying with recent data for maternal vitamin D status and offspring bone development,2 are likely to restrain the prevailing view of vitamin D panacea in the clinical community worldwide. However, there is a need for a balanced view based on representative populations. Reid and colleagues’ meta-analysis1 included mainly white populations with adequate vitamin D status and calcium intake. A mean level of less than 30 nmol/L was noted in only five studies (among 24 included), which is certainly not representative of the world population. We assume that this recruitment bias favoured the high heterogeneity in both femoral neck (I²=67%) and total body BMD (I²=85%) favouring beneficial www.thelancet.com Vol 383 April 12, 2014

Vitamin D supplements and bone mineral density.

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