Association Of Soy Products And Isoflavones With Coal-burning Fluorosis

Objective: Soy isoflavones have antioxidant effects,and oxidative stress is one of the most important mechanisms of coal-burning fluorosis.Therefore,the aim of this study was to understand the soy products and soy isoflavone intake of local residents,and compare and analyze the soy products and soy isoflavones and soy isoflavones in vivo from the perspective of nutrition.The relationship between the metabolites(glycitein,genistein,daidzein,dihydrodaidzein,equol,and o-desmethylangolensin)and patients with coal-burning fluorosis provides a reference for multi-angle and multiple measures to control coal-burning fluorosis quality of life of residents in fluorosis areas.Methods: A cross-sectional study was conducted and a random cluster sampling method were used to recruit 896 residents aged 18-75 years in coal-burning fluorosis areas in Zhijin County,Bijie City,Guizhou Province.The questionnaire used a face-to-face inquiry to collect general information,factors closely related to coal-fired fluorosis,and previous medical history.In addition,a 75-item food frequency questionnaire(FFQ)was used to investigate the dietary habits of the subjects in the past year.Ion-selective electrode method was used to detect the urinary fluoride content in the study subjects.High performance liquid chromatography(HPLC)was used to determine the urine soy isoflavones(daidzein,genistein,glycitein and its metabolite dihydrodaidzein,equol,o-desmethylangolensin).Soy product intake,soy isoflavone intake and urinary soy isoflavone were categorized into Quartiles(Q1-Q4).The lowest quartile(Q1)served as the reference group.Univariate and multifactor logistic regression were used to analysis the association of dietary soy products,soy isoflavones,and isoflavones subclasses(daidzein,genistein,glycitein and its metabolites dihydrodaidzein,equol,o-desmethylangolensin)with coal-burning fluorosis,and to calculate the odds ratios(ORs)with 95% confidence intervals(CIs).Results: 1.The relationship between soy products and coal-burning fluorosis.A comparative analysis of the intake of various soy products revealed that there were differences between soymilk,tofu and stinky tofu among non-fluorine poisonedpatients and coal-burning fluorosis patients(P <0.05).After adjustment for gender,age,marital status,monthly household income per capita,education level,smoking,drinking,tea,stove improvement,fuel type,baked food,corn and dried pepper intake,total energy,calcium intake,corn intake,dried chili intake the highest quartile of tofu and stinky tofu in soy were statistically significant compared to the first quartile.Compared with the lowest quartile of uptakes,the ORs and 95% CI for fluorosis risk in the Q2 to Q4,were 0.75(0.47,1.20),0.66(0.41,1.06)and 0.58(0.36,0.92)for tofu,0.81(0.50,1.31),0.63(0.39,1.02)and 0.57(0.35,0.92)for stinky tofu.Combining soy and its products as soy protein analysis,after multi-factor correction,the ORs and 95% CI of the second to fourth quantiles of soy protein were 1.03(0.64,1.66)and 0.64(0.40,1.01),0.69(0.43,1.10),respectively.2.The relationship between dietary soy isoflavones and coal-burning fluorosis.Dietary soy isoflavones in the second to fourth quartiles of ORs and 95% CI of coal-burning fluorosis were 0.93(0.58,1.49),0.84(0.53,1.35),and 0.61(0.38,0.97),respectively.Both daidzein and genistein have the same trend.As the intake increases,the ORs value gradually decreases.3.The relationship between urinary isoflavones and coal-burning fluorosis.Examining the exposure of soy isoflavones in the body,it was found that the higher isoflavone subclass in urine were associated with lower risk of coal-burning fluorosis.The adjusted OR and 95% CI in the highest quartile of isoflavone subclass in urine compared with the lowest were 0.27(0.16,0.46)for dihydrodaidzein,0.33(0.19,0.56)for daidzein,0.43(0.25,0.72)for glycitein,0.42(0.25,0.69)for equol,0.62(0.37,1.04)for genistein,and 0.59(0.36,1.00)for o-desmethylangolensin.Conclusion: Soy and its products have a protective effect on coal-burning fluorosis.The greater the dietary intake of isoflavones were associated with the lower the risk of coal-burning fluorosis.The urine soy isoflavone results are consistent with dietary results.This protective effect may be related to the phytochemical of soy isoflavones in soy.