THE EFFECTS OF SOLUBLE CORN FIBRE AND CALCIUM SUPPLEMENTATION ON BONE HEALTH INDICES IN CHILDREN AGED 9 TO 11 YEARS OLD - A DOUBLE-BLIND RANDOMISED CONTROLLED TRIAL

Abstract

Background: During rapid growth, optimal calcium intake is important to achieve (PBM). Failure to achieve PBM leads to increased risk of osteoporosis, an important public health problem. However, Malaysian children consume only 30-50% of their calcium requirement thus alternative strategies need to be explored to bridge the gap between requirement and intake. Short-term studies have demonstrated that consumption of soluble corn fibre (SCF) is associated with an increase in the gastrointestinal absorption of calcium in children. However, the long-term impact on bone accrual is unknown. Thus, this double-blinded, randomised, parallel design study aimed to investigate the long-term effect of SCF and calcium on bone mineral density (BMD) and bone mineral content (BMC) of preadolescent children (PREBONE-Kids study). Methods: A total of 243 children aged 9 to 11 years old were recruited from 3 national primary schools around Brickfields and Bangsar, Kuala Lumpur. The participants were randomised into 4 groups to receive 600 mg calcium alone (Ca), 12 g SCF alone (SCF), 600 mg calcium + 12 g SCF (SCF+Ca) and placebo for 12 months. The supplements were in form of fruit-flavoured powder in sachets which was mixed in 200 ml of cold water to make a drink. The parameters assessed at baseline, 6 months and 12 months were BMD and BMC measured using dual-energy X-ray absorptiometry, serum bone turnover markers (CTX1, P1NP, BAP, OC), calcium intake using diet history and physical activity using Children Physical Activity Questionnaire (cPAQ). Serum 25- hydroxyvitamin D (25-OHD) levels and intact parathyroid hormone (iPTH) was measured at baseline using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and direct chemiluminometric technology respectively. Gastrointestinal symptoms were evaluated on monthly basis using a short questionnaire. Changes in participants weight, height and Tanner staging was recorded every 6 months. Participants were provided with the supplements during recess in their schools from Monday to Friday. On the weekends and school holidays, the participants consumed the supplements at home. The participants returned the empty sachets of supplements consumed over the weekend and school holidays to the researchers on a weekly basis. Compliance to the treatment intervention was calculated as a percentage of the actual number of sachets of supplements consumed each day compared to the expected consumption. Results: Participants were 10.1 ± 1.0 years, predominantly of Malay ethnicity and pre-pubertal. The mean calcium intake was 349 ± 180 mg/day and mean serum 25-OHD levels was 43.9 ± 14.5 nmol/L. A total of 201 participants completed the study with a final retention rate of 82.7%. Participants achieved mean intervention compliance of 78.7%. At 6 months post-intervention, the participants receiving calcium supplementation had a significantly higher increase in total body BMD (Ca : 0.014 ± 0.003 g/cm2 , p=0.002; SCF+Ca : 0.019 ± 0.003 g/cm2 , p<0.001) compared to the SCF (0.004 ± 0.002 g/cm2, p=1.000) and placebo (0.002 ± 0.003 g/cm2, p=1.000). At 12-month, only participants in the Ca and SCF+Ca groups had significant within group increases in total body BMD however there was no difference between groups. From baseline to 6 months, only SCF+Ca had a significant increase in total body BMC(27.14 ± 6.10 g, p=0.001). At 12 months, there was a significant increase in total body BMC in the SCF+Ca (40.28 ± 9.03 g, p=0.001) and SCF (27.34 ± 7.93 g, p=0.037). However, comparison between groups showed no difference in the amount of total body BMC gained between the 4 groups at 12 months. There was no significant effect of SCF and calcium on the lumbar spine BMD, lumbar spine BMC and serum bone turnover markers at 12 months. SCF conferred small benefit in total body BMC of study participants at 12 months over calcium alone. Conclusion: In summary, calcium supplementation with and without SCF improved total body BMD and total body BMC accrual in pre-adolescent children with habitual low calcium intake. The addition of SCF in the diets of this population did confer a small benefit to total body BMC. The general lack of response to SCF may be due to genetic variation, differences in gut microbiota makeup and the dietary pattern of study participants. Further work is needed to fully understand the mechanism and health benefits of prebiotics in this study population. Keywords: Soluble corn fibre, preadolescent children, calcium, bone mineral density, bone mineral content