Calcium requirements for Chinese adults by cross-sectional statistical analyses of calcium balance studies: an individual participant data and aggregate data meta-regression

Abstract

Background Chinese dietary reference intakes for calcium are largely based on foreign studies. We undertook meta-regression to estimate calcium requirements for Chinese adults derived from calcium balance data in Chinese adults. Methods We searched PubMed, Cochrane CENTRAL, and SinoMed from inception to March 5, 2014, by using a structured search strategy. The bibliographies of any relevant papers and journals were also screened for potentially eligible studies. We extracted a standardized data set from studies in Chinese adults that reported calcium balance data. The relationship between calcium intake and output was examined by an individual participant data (IPD) and aggregate data (AD) meta-regression. Results We identified 11 metabolic studies in Chinese adults within 18–60 years of age. One hundred and forty-one IPD (n=35) expressed as mg/d, 127 IPD (n=32) expressed as mg·kg body wt-1·d-1, and 44 AD (n=132) expressed as mg/d were collected. The models predicted a neutral calcium balance (defined as calcium output (Y) equal to calcium intake (C)) at intakes of 460 mg/d (Y=0.60C+183.98) and 8.27 mg·kg body wt-1·d-1 (Y=0.60C+3.33) for IPD, or 409 mg/d (Y=0.66C+139.00) for AD. Calcium requirements at upper intakes were higher than that at lower intakes in all these models. Conclusion Calcium requirement for Chinese adults 18–60 years of age approximately ranges between 400 mg/d and 500 mg/d when consuming traditional plant-based Chinese diets.