Relationship between long-term calcium intake and bone mineral content of children aged from birth to 5 years

Abstract

This study evaluated Ca intake in Hong Kong Chinese children and examined the association between long-term Ca intake and bone mineral content (BMC) in children. Longitudinal dietary intake from birth to 5 years was obtained in 128 children (sixty-seven boys, sixty-one girls). Ca intakes were evaluated by dietary history and cross-checked with food frequency and 24 h recall. At age 5 years BMC was determined at the one-third distal radius of the right arm using single-photon absorptiometry. The mean Ca intake of 133 children at 5 years was 546 ( SD 325) mg/d. Milk was the chief source of Ca (43·5 %). From birth to 5 years, 90 % of the children had been taking milk regularly. The mean BMC and bone width (BW) of these children were 0·317 ( SD 0·042) g/cm and 0·756 ( SD 0·074) cm respectively. BMC was not correlated with current intakes of Ca, energy and protein but was positively correlated with weight ( r 0·57), height ( r 0·47) and BW ( r 0·66). However, cumulative Ca intake throughout the past 5 years showed significant correlation with BMC ( r 0·235, P = 0·0133). The significant correlation remained even after weight, height, BW, sex. and cumulative intakes of energy and protein were adjusted in multiple regression analysis ( r 0·248, P = 0·0107). Moreover, using principal component analysis, Ca intake during the 2nd year of life had the strongest correlation with BMC at 5 years ( r 0·240, P = 0·02). Ca intake of Hong Kong Chinese children was higher than the RDA of the Food and Agriculture Organization/World Health Organization (1962) and achieved 66% of the current US recommendation (National Research Council, 1989). The increased regular milk consumption reflects a significant change in dietary habits of the younger generation. Children with a habitually higher Ca intake throughout the past 5 years, particularly in the 2nd year, were found to have higher BMC.