Warren T. K. Lee

A randomized double-blind controlled calcium supplementation trial, and bone height acquisition in children

There is limited information relating Ca intake to bone and height acquisition among Oriental children who consume little or even no milk. The present controlled study investigated the acquisition of bone mass and height of Chinese children with an initial Ca intake of approximately 567 mg/d who were supplemented to about 800 mg/d. Eighty-four 7-year-old Hong Kong Chinese children underwent an 18-month randomized, double-blind, controlled Ca-supplementation trial. The children were randomized to receive either 300 mg elemental Ca or a placebo tablet daily. Bone mass of the distal one-third radius was measured by single-photon absorptiometry, lumbar spine and femoral neck were determined using dual-energy X-ray absorptiometry. Measurements were repeated 6-monthly. Baseline serum 25-hydroxycholecalciferol concentration and physical activity were also assessed. Baseline Ca intakes of the study group and controls were respectively 571 (SD 326) and 563 (SD 337) mg/d. There were no significant differences in baseline serum 25-hydroxycholecalciferol concentration (P = 0.71) and physical activity (P = 0.36) between the study and control groups. After 18 months the study group had significantly greater increases in lumbar-spinal bone mineral content (20.9 v. 16.34%; P = 0.035), lumbar-spinal area (11.16 v. 8.71%; P = 0.049), and a moderately greater increment in areal bone mineral density of the radius (7.74 v. 6.00%; P = 0.081) when compared with the controls. The results confirm a positive effect of Ca on bone mass of the spine and radius but no effects on femoral-neck and height increase. A longer trial is warranted to confirm a positive Ca effect during childhood that may modify future peak bone mass.

Abnormal peri-pubertal anthropometric measurements and growth pattern in adolescent idiopathic scoliosis : a study of 598 patients

Study Design. A cross-sectional study of anthropometric parameters in adolescent idiopathic scoliosis (AIS). Objective. To compare anthropometric parameters and growth pattern of AIS girls versus normal controls during peri-puberty. Summary of Background Data. Abnormal pattern of growth has been reported in AIS patients. The sequential changes of growth and the correlation with curve severity have not been properly studied. Materials and Methods. Five hundred ninety-eight AIS girls and 307 healthy girls entered the study. Weight, height, body mass index (BMI), arm span, sitting height, and leg length were determined using standard techniques. Height and sitting height were adjusted by using the greatest Cobb angle to correct for spinal deformity (Bjure’s formula). Puberty was graded by Tanner’s staging. Results. AIS girls had significantly shorter height (P = 0.001), corrected height (P = 0.005), arm span (P = 0.022), sitting height (P = 0.005) and leg length (P = 0.004) than the controls at pubertal stage I. From pubertal stages II through V, corrected height (P ≤ 0.033) and arm span (P ≤ 0.038) were significantly longer in the AIS than controls. Corrected sitting height was also longer in AIS from stages II through IV (P ≤ 0.043). Furthermore, BMI of AIS was significantly lower than that of controls from stages II through IV (P ≤ 0.038). In addition, significant correlations of the curve severity versus weight, BMI, and arm span were also found (P ≤ 0.048). Conclusions. Various body segmental lengths were initially significantly shorter in AIS before puberty. However, after the onset of puberty, significantly longer corrected height, arm span, and various body segments were found. And there were significant correlations between anthropometric parameters and the scoliotic curve severity. Results of this large-scale study revealed the presence of abnormal growth in AIS patients during peripubertal development.

Increased prevalence of constipation in pre-school children is attributable to under-consumption of plant foods: A community-based study.

Aim:  To evaluate consumption of foods rich in dietary fibre and its relation to the prevalence of constipation in pre‐school children.

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

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.

Generalized osteopenia in adolescent idiopathic scoliosis--association with abnormal pubertal growth, bone turnover, and calcium intake?

Study Design. A cross-sectional study in girls with adolescent idiopathic scoliosis (AIS) and healthy counterparts of similar age. Objectives. To study the association of bone mass with anthropometric parameters, bone turnover, and calcium intake in 621 girls with AIS, aged 11–6-years, and compare the results with 300 healthy girls of similar age. Summary of Background Data. Generalized low bone mass has been documented in AIS, yet the cause of low bone mineral density in AIS is unknown. Methods. Corrected height and arm span, bone mineral density and bone mineral content of proximal femur, lumbar spine, and distal tibia, and bone turnover markers (bone alkaline phosphatase [bALP] and deoxypyridinoline) were evaluated. Results. From age 13 years and older, the AIS group had longer anthropometric parameters (P < 0.05), generalized lower bone mass (P < 0.035), and 38.6% higher in bALP (P < 0.004) when compared with controls. A stronger inverse correlation between bALP and bone mass was noted in the AIS group. The bALP was positively correlated with bone area of tibia (P = 0.013) in the AIS group only. Deoxypyridonine of the AIS group was not different from the controls until age 15 years. The mean calcium intake of the AIS group was very low (only 361 mg/day), and calcium intake was significantly associated with bone mass in the AIS group. Low bone mass in AIS could be explained by faster anthropometric bone growth, higher bone turnover, and lower calcium intake in multiple regression analysis. Conclusions. Results from the current study showed that an abnormally faster growth rate and higher bone turnover in the patient with AIS might lead to increased bone dimensions. Calcium intake in patients with AIS was very low and likely to be insufficient for normal bone mineralization. Therefore, low bone mass in AIS may result from abnormal bone mineralization qualitatively and quantitatively and, thus, fails to catch up with increased bone growth during the peripubertal period.

Bone mineral content of two populations of Chinese children with different calcium intakes

Bone mineral content (BMC) of 5-year-old Chinese children (115 children in Jiangmen, China and 128 children in Hong Kong) was evaluated by single-photon absorptiometry at the distal 1/3 radius. The mean (S.D.) calcium intakes of children of Jiangmen and Hong Kong were 244 (46) and 542 (332) mg/day, respectively. The mean BMC, weight and height of Jiangmen children were significantly less than Hong Kong children by 14%, 10% and 4%, respectively (P < 0.001). Multiple regression analysis showed that 62% of the variance in BMC was explained by bone width (BW), weight and regional location (P < 0.0001). A regional difference in BMC of 0.0303 g/cm (P < 0.0001) still remained after adjusting for BW and weight by multiple regression analysis. When comparing sub-groups of children in the two regions with comparable low current calcium intake at 5 years, the BMC of Jiangmen children was still significantly lower than Hong Kong children even when potential confounders were adjusted (P < 0.003). The study suggests that the regional discrepancy in BMC might be explained by long-term habitual calcium intake and physical activity.

Determinants of axial and peripheral bone mass in Chinese adolescents

OBJECTIVE To determine the relation of puberty, physical activity, physical fitness, and calcium intake with bone mineral content (BMC) of the distal radius, and on bone mineral density (BMD) of the L2 to L4 vertebrae in a group of healthy Chinese adolescents. DESIGN Cross sectional survey. SUBJECTS A group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged 12 to 13 years enrolled in the first year of the Tii Junior High School in Shatin, Hong Kong. Ninety four of the pupils enrolled were in the physical education major class (PE), and the other 85 were in the art major class (ARTS). MAIN OUTCOME MEASURES Correlation of BMC of the distal radius and BMD of the L2 to L4 vertebrae with level of physical activity, physical fitness (isometric and isokinetic), muscle strength of the upper and lower limb, and calcium intake. RESULTS BMC of the distal radius and BMD of the L2 to L4 vertebrae were significantly positively correlated. Univariate and regression analysis showed that age, pubertal staging, physical fitness, and muscle strength were significantly associated with bone mass in a positive way. Calcium intake and type of sport practised did not exert a significant influence on BMC of the distal radius and BMD of the L2 to L4 vertebrae in boys. The results for the BMD of the L2 to L4 vertebrae were similar in girls and boys; however, in girls, the BMC of the distal radius had a negative correlation with calcium intake. Physical fitness was a significant positive predictor of BMD of the L2 to L4 vertebrae. CONCLUSIONS Among Chinese adolescents bone mass was positively influenced by certain measures of physical fitness as well as by age, weight, and pubertal stage.

Adjusting Bone Mass for Differences in Projected Bone Area and Other Confounding Variables: An Allometric Perspective

The traditional method of assessing bone mineral density (BMD; given by bone mineral content [BMC] divided by projected bone area [Ap], BMD = BMC/Ap) has come under strong criticism by various authors. Their criticism being that the projected bone “area” (Ap) will systematically underestimate the skeletal bone “volume” of taller subjects. To reduce the confounding effects of bone size, an alternative ratio has been proposed called bone mineral apparent density [BMAD = BMC/(Ap)3/2]. However, bone size is not the only confounding variable associated with BMC. Others include age, sex, body size, and maturation. To assess the dimensional relationship between BMC and projected bone area, independent of other confounding variables, we proposed and fitted a proportional allometric model to the BMC data of the L2‐L4 vertebrae from a previously published study. The projected bone area exponents were greater than unity for both boys (1.43) and girls (1.02), but only the boys fitted exponent was not different from that predicted by geometric similarity (1.5). Based on these exponents, it is not clear whether bone mass acquisition increases in proportion to the projected bone area (Ap) or an estimate of projected bone volume (Ap)3/2. However, by adopting the proposed methods, the analysis will automatically adjust BMC for differences in projected bone size and other confounding variables for the particular population being studied. Hence, the necessity to speculate as to the theoretical value of the exponent of Ap, although interesting, becomes redundant.

Axial and peripheral bone mineral acquisition: a 3-year longitudinal study in Chinese adolescents

Abstract We performed a 3-year longitudinal study of a group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged from 12 to 16 years to determine the effects of puberty, physical activity, physical fitness, and calcium intake on the acquisition of bone mass. At yearly intervals for 3 consecutive years we recorded nutrition, calcium intake and anthropometric measurements, and assessed pubertal status according to Tanner. Bone mass of the lumbar spine was determined by dual-energy X-ray absorptiometry and radial bone mass by single-photon absorptiometry. Physical fitness and level of physical activity were assessed and muscle strength and power determined by isokinetic testing. Peripheral bone mass correlated with axial skeleton bone mass. Age, pubertal staging, physical fitness and muscle strength were significantly associated with bone mass increments on cross-sectional univariate and regression analysis. Longitudinal regression analysis showed that the most important factor affecting bone mass accretion in adolescents in both sexes was their pubertal stage. In boys, bone mass increment throughout the study was greater in children who were already in the advanced pubertal stages on entering the study than in those who started puberty in year 2 or 3 of the study. The percentage change in bone mineral content of the forearm and in bone mineral density of the lumbar spine was greater than 25% in the advanced pubertal group as compared to around 20% in the less mature group. For girls, the reverse was true. The increment of bone mass during the study period was significantly greater in those who presented in the earlier pubertal stages than in those who were at the more advanced stage of puberty on entry into the study. There was no significant effect of calcium intake and physical activities on the bone mass accretion. Conclusion In Chinese adolescents, bone mineral accretion at adolescence is not influenced by exercise, level of physical fitness and calcium intake. In both sexes, and especially in girls, to optimally increase bone mass, regular physical exercise programmes should be instituted well before the onset of puberty rather than at or after it. Once puberty starts, these interventions may have no or only limited effect.

Growth and nutrition of Hong Kong children aged 0–7 years

Objective: To study the early dietary practices in relation to growth of Hong Kong children from birth to 7 years.