Effect Of Calcium Intake On Weight Management In Obese And Overweight Adults

The skyrocketed prevalence of obesity during the past few decades has stimulatedgreat interest in identifying approaches that may contribute to weight reduction or to theprevention of weight gain. Epidemiologic studies showed an inverse relationship betweencalcium intake and body weight, however, there has been no such report in the Chinesepopulation. In addition, intervention studies provided inconsistent results for the beneficialeffect of calcium supplementation on weight management. From this perspective, weinitiated the present study, which can be categorized into two sections as follows:1. A case-control study on the relationship of dietary calcium intake and dairyconsumption with risk of obesityObjectiveThe aim of this study was to assess the relationship of dietary calcium intake and dairyconsumption with risk of obesity in a case-control study design, so as to provide evidencefor further study on feasible interventions for obesity.Methods1) Cases were119obese or overweight female Chinese college students aged18to22y,who were pre-screening volunteers for a weight loss program, recruited from April toOctober,2011. Control subjects were pair matched at1:1ratio by age, gender and bodyheight.2) Anthropometric data, including body height, weight, blood pressure, as well as waist,abdominal, and hip circumference were collected and a food frequency questionnaire (FFQ)was performed with each participant. WHR was calculated as waist circumference (cm)/hipline (cm). Bioelectric impedance analysis (BIA, ZEUS9.9, JAWON) was used todetermine body fat mass (BFM), body fat percentage (BFP), Lean Body Mass (LBM), aswell as visceral fat mass (VFM) and visceral fat area (VFA).3) Subjects in case and control groups were divided into4subgroups via quartiles（P25,P50, and P75）of calcium or dairy consumption. Conditional logistic regression was used toidentify predictive factors related to calcium or dairy intake for obesity. Pearsoncorrelations were performed in the total sample of subjects between body fat percentageand dairy (or calcium) intake. Results1) Significant trend was obtained for calcium intake as protective effects (P＜0.001). The3rd and4th quartiles of calcium intake achieved statistical significance (OR0.19,95%CI0.07–0.50, P＝0.001; OR0.05,95%CI0.07–0.50; P＜0.001, respectively). Quartiles ofdairy consumption did not reach statistical significance (P＝0.07) by noparametric test,however, it seemed to have protective effects for obesity with the3rd and4th quartiles ofdairy consumption (OR0.36,95%CI0.15–0.88; P＝0.02; OR0.16,95%CI0.06–0.41forthe3rd and4th quartiles; P＜0.001, respectively) as protective effects.2) Consumption of dairy, or calcium intake, was proven to be inversely related to BW, BMI,BFM, BFP, VFA, and WHR (P＜0.05). After adjustment for energy intake, calcium intakewas inversely correlated with BW (r＝–0.31), BMI (r＝–0.37), BFM (r＝–0.33), BFP (r＝–0.34), VFA (r＝–0.36), WHR (r＝–0.35)(P＜0.001for all) and with SBP and DBP (r＝–0.19and–0.15, respectively; P＜0.05), whereas dairy consumption was inverselycorrelated with BW (r＝–0.19, P＝0.01), BMI (r＝–0.24, P＝0.001), BFM (r＝–0.24, P＜0.001), BFP (r＝–0.27, P＜0.001), VFA (r＝–0.27, P＜0.001), WHR (r＝–0.29,P＜0.001),and have no significant association with LBM, VFM, SBP and DBP (P＞0.05).Conclusion1) Dietary calcium intake and dairy consumption, which are inversely correlated with BMIand BFP, are important predictive factors for obesity.2) Dairy, as fairly good sources of calcium, is also prove to be predictive factors for obesityand inversely correlated with BMI and BFP.3) Increasing dairy consumption could not only attenuate calcium insufficient status, buthave potential anti-obesity effect.2. Effect of calcium supplementation on weight management in obese and overweightsubjectsObjectiveThe present study aimed to test the hypothesis that calcium supplementation canenhance weight and fat loss during energy restriction, and to evaluate the effect of calciumplus vitamin D supplementation on metabolic profiles in overweight or obese subjects withvery-low habitual calcium consumption.Methods1) Participants were recruited through informational flyers and advertisements posted on campus of colleges and vocational schools in Pudong and Yangpu Districts in Shanghai,China. A pre-screening telephone interview for evaluating habitual calcium intake via foodfrequency questionnaire (FFQ) was conducted with each volunteer, who were evaluated byinclusion and exclusion criteria afterwards for eligibility.2) Subjects were randomly assigned in an open label manner to either the calcium group(n=26) or the control group (n=27). Randomization was computer-generated, andrandomization sequence was created using SPSS13.0for windows with a1:1allocation.Block randomization was by a computer generated random number list prepared by aninvestigator with no clinical involvement in the trial. The calcium group received calciumplus and vitamin D supplementation (600mg calcium carbonate,125IU vitamin D),administered as the dose of one tablet daily taken after breakfast. In addition, both groupsreceived500kcal/d of caloric deficit for a period of12weeks.3) A2-factor (4level) analysis of variance with repeated measures, controlling for initialbody weight, was performed to evaluate the significance of the differences between groupsfor changes in anthropometric values, including body weight, body fat mass (BFM), bodyfat percentage (BFP), Lean Body Mass (LBM), visceral fat mass (VFM) and visceral fatarea (VFA) at baseline, week4, week8, and at the end of the12-week intervention.Besides, a2-factor (2level) analysis of variance with repeated measures, controlling forinitial body weight, was performed to evaluate the significance of the differences betweengroups for changes in waist, abdominal and hip circumference, waist-to-hip ratio (WHR),and metabolic variables, including blood pressure (BP), fasting plasma glucose (FPG),fasting insulin (FIN), Homa-IR, as well as lipid-lipoprotein profile. Simple Pearsoncorrelations were performed between initial calcium intake and changes in outcomevariables in the total sample of subjects and then repeated with age, gender and initial bodyweight as covariates, so as to indicate the relations between initial calcium intake and thefacilitation of calcium supplementation on weight and fat loss.Results1) A total of43subjects (37females,6males) completed the trial, with an estimateddrop-off rate at18.9%after enrollment.2) Subjects in both groups experienced significant reductions in all anthropometricvariables at the end of the12-week intervention (P＜0.001).3) Subjects in the calcium group lost5.1±2.9kg of body weight, increased by50%(P＝0.045) compared with those in the control group, who experienced3.4±1.9kg of weight loss. A greater trend of augmentation was observed in the calcium group for BFM loss,which was increased by87%(3.4±1.9vs1.8±1.2kg; P＝0.002). Moreover, subjects in thecalcium group also exhibited greater decrease in VFM and VFA (P＜0.01for both)compared with those in the control group. No significant difference was detected inchanges in LBM (P＞0.05).4) Initial calcium intake was found significantly correlated with changes in body weight (r＝－0.38), BMI (r＝－0.36), fat mass (r＝－0.35), visceral fat (r＝－0.36), waistcircumference (r＝－0.40), abdominal circumference (r＝－0.39) and hip circumference (r＝－0.34) after adjustments for age, gender and initial body weight (P＜0.05for all).5. No statistically significant changes was observed in fasting plasma glucose, fastinginsulin, Homa-IR, total cholesterol, triacylglycerol, HDL cholesterol, LDL cholesterol,systolic and diastolic blood pressure from pre-to post-treatment during the short period ofthe study (P＞0.05for all). There was no significant difference for any of the outcomevariables between the calcium and the control group, either (P＞0.05for all).Conclusion1) Significant improvements in anthropometric variables in both groups indicated theeffectiveness of the12-week intervention of energy restriction.2) On the premises of caloric deficit, subjects in the calcium group exhibited greaterweight and fat loss compared with those in the control group, thus supported thehypothesis that calcium supplementation can enhance weight and fat loss during energyrestriction in overweight or obese subjects.3) The present study observed no significant difference for changes in lean body massbetween the two groups after12weeks of intervention, which suggested no beneficialeffect of calcium supplement on preserving fat-free mass during energy restriction.4) Initial calcium intake was found significantly correlated with changes in body weight,BMI, BFM, VFM, as well as with changes in waist, abdominal and hip circumference,indicating those with lower calcium intake are expected to lose more weight and fat on anenergy-restricted diet.5) No significant changes were observed in FPG, FIN, BP and lipid-lipoprotein profileeither from baseline to endpoint or between treatment arms, suggesting these metabolicvariables will not be affected in such a short term.6) The habitual calcium intakes of majority of Chinese population were relatively low.Therefore, it will be of great benefit for them to follow a calcium-rich diet, preferably from dairy sources, to prevent or combat obesity. The recommended dairy intake of300mL/dby the Chinese Nutrition Society should be advocated so as to reach the Acquit Intake (AI).