Effect Of Calcium Fortified Soymilk And Cow Milk On Bone Metabolism In Postmenopausal Women In Shanghai

Objective1.To investigate the BMD status and the risk factors for primary osteoporosis in postmenopausal women in Shanghai.2.To assess the compliance of milk and soymilk and the effect of the supplements containing calcium 250mg/day on BMD,serum biochemical markers and hormones status in postmenopausal women in Shanghai.3.To compare the sensitivity and sensitivity of BMD and serum biochemical markers and hormones measurements.MethodsPart 1 Anthropometric measurements were done and BMD was measured at the lumbar spine and total hip in 478 postmenopausal women aged 45-75 years,using DXA.Participants were excluded if they had any conditions affecting bone metabolism,such as connective tissue disease,gastrointestinal diseases,hepatic disease,hyperthyroidism,hyperparathyroidism,Cushing's syndrome,diabetes mellitus or oral glucocorticoids.Simple questionnaires had been designed to obtain risk factors associated with osteoporosis.Part 2 A total of 141 eligible Chinese women without osteoporosis,aged 45-65(56.34±4.19) and menopausal for more than 2 years,were randomized 250ml/day milk,250 ml/day calcium fortified soymilk,and control groups(no placebo) for 12 months.Participants were excluded if they used to drink cow milk or soymilk daily,had been diagnosed osteoporosis,had any conditions affecting bone metabolism,such as connective tissue disease,gastrointestinal diseases, hepatic disease,hyperthyroidism,hyperparathyroidism,Cushing's syndrome,diabetes mellitus and so on.Women who had taken oral glucocorticoids,as well as any other medications known to affect bone mass,for 3 months prior to recruitment,were also excluded.BMD of the spine and hip were measured using DXA at 0,6 and 12 months.Part 3 Serum E₂,PTH,PINP and 25(OH)D₃ of the 100 eligible women in milk and soymilk groups in part 2 were examined at 0,6 and 12 months.ResultsPart 1 The mean value and standard deviation of BMD was 0.884±0.144g/cm² and 0.829+0.114 g/cm² at the spine and total hip,respectively.The prevalence rate of osteoporosis and low bone density according to WHO criteria in the 478 subjects was 26.36%and 39.96%.Using the stepwise regression model,BMD at spine and hip were dependent variables while height,weight,BMI,BS and answers in the questionnaires were independent variables;BS(B=0.384,P=0.000) and frequency of taking fish or shrimp(B=0.036,P=0.018) were determined to be the most important variable that affected the BMD at spine,while weight(B=0.006,P=0.000), hip fractures happened in parents(B=-0.039,P=0.012) and frequency of taking fish or shrimp(B=0.029,P=0.020) were determined to be the most important variable that affected the BMD at hip.Part 2 The baseline BMD at lumbar spine,the femoral neck,total hip and characteristics of age,height,body weight,body surface area,body mass index,time since menopause,status of physical activities,dietary calcium intake,smoking,drink with caffeine,alcohol consumption,and family medical history,and so on were very similar among the three groups(P＞0.05).There was no significant difference in percent changes of BMD at any sites among the three groups(P＞0.05).On the other hand,the drop of BMD was earlier(6 month,0.76%, P＜0.05) and more significant(1.84%,P＜0.001) for BMD at the total hip in control than the other groups(P＜0.05) in 12 months.Part 3 The baseline status and changes in 6 and 12 months of serum E₂,PTH,PINP and 25(OH)D₃ were very similar between the groups(P＞0.05).Conclusion1.In this study,BMD in postmenopausal women was higher than that in women aged the same years in previous studies.Not the prevalence rate of osteoporosis but low bone density was lower than that established in previous studies in China. BS and weight were the most important factors of body size related to BMD,and hip fractures happened in parents and frequency of taking fish or shrimp were the most important factors of heredity and living customs related to BMD in postmenopausal women in Shanghai.2.Milk and soymilk containing calcium 250mg/day did not suppress BMD decease in postmenopausal women in Shanghai over 12 months.The result may be due to good baseline BMD in subjects,low tested dosages of calcium,short treatment period,or a combination of these factors.Further study is needed to observe the results of a more long-term invention.3.The serum biochemical markers and hormones changed similarly in postmenopausal women in Shanghai who took either milk or soymilk containing calcium 250mg/day over 12 months.Due to different batches of commercial kits, different test time,and variability of serum hormones and biochemical markers of bone turnover(radioimmunoassay methods and ELISA),however,the results could be considered as no more than a reference data.