| Chronic kidney disease(CKD)has become an important public health issue in the world,which has attracted wide public attention.As a high risk population of CKD,middle-aged and elderly people are in urgent need of research to analyze their disease status and risk factors.Studies have shown that metals in the environment can be absorbed by the human through a variety of ways,thus affecting the human kidney function,but the combined effects of various metals and their dietary sources are unclear.Objective:In this study,we investigated the effects on internal by assessing the dietary exposure to various metals in middle-aged and elderly people.Then we analyzed whether renal function was in association with single and multiple metals exposure.This study provided theoretical basis for the prevention and control of CKD.Methods:This study is based on the "135 Cohort" carried out in Suzhou Industrial Park.A total of 1368 residents aged 45 years and older were included in the study in 2015,and followed for four years between 2015 and 2019.Plasma samples were collected from the subjects at baseline and after follow-up.Inductively coupled plasma-mass spectrometry(ICP-MS)and inductively coupled plasma(ICP)were used to measure the concentrations of 11 metals in baseline plasma,including calcium,magnesium,iron,zinc,chromium,copper,selenium,lead,cadmium,sodium and potassium.Serum creatinine concentrations at baseline and after follow-up were detected and estimated glomerular filtration rate(eGFR)was calculated as an indicator of renal function.Rapid renal decline(defined as annual eGFR decline ≥5 mL/min/1.73 m2)or incident eGFR<60 mL/min/1.73 m2 were used to define renal impairment.In the first part of the study,the daily intakes of cereal,meat,fish,vegetables,fruits,and soy products were calculated.We also measured the dietary intake of metals.Then linear regressions were used to analyze the association between dietary exposure to metals and internal exposure in the total population.The factor analysis was used to type the metal dietary exposure patterns,and linear models were constructed to analyze the relationship between the internal exposure of metals and the intake of various foods under each dietary pattern,so as to screen out the dietary patterns and food types related to the internal exposure.In the second part of the study,the Mann-Whitney U test was used to investigate the differences in plasma concentrations of 11 metals between different eGFR groups,and the linear regression model was used to evaluate the relationships between baseline plasma metal levels and annual eGFR changes.Then,principal component analysis(PCA)was used to construct multiple metals exposure patterns.Linear and logistic regressions were used to analyze the effects of different metals exposure patterns on renal function.Results:1.Dietary exposure of metals and associations between internal and external exposureDiet assessment showed that the total exposure of metal elements in the study population was in the order of potassium>calcium>sodium>magnesium>selenium>iron>zinc>copper>chromium=lead>cadmium from high to low.The main food sources of potassium,iron,lead and cadmium are cereals and vegetables.Linear regression analysis showed that dietary exposure to cadmium increased internal exposure to cadmium(P<0.05),while dietary exposure to copper increased internal exposure to copper(P<0.05).No statistically significant results were found for other elements.Factor analysis was used to obtain two dietary patterns:the fruit-vegetable-fish dietary pattern with vegetables,fruits and fish as the main sources of exposure and the staple food dietary pattern with staple food as the main sources of exposure.To investigate the association between dietary exposure to metals and internal exposure under different patterns,the results showed that dietary intake of potassium through staple food,meat and fruit can lead to increased internal exposure to potassium in the study population who preferred the fruit-vegetable-fish dietary pattern.Sodium ingested through fish and soy products can lead increased internal exposure to sodium.Internal exposure to selenium increases through intake of staple foods,meat,fish,fruits and vegetables.However,in the study population preferred to the staple food dietary pattern,the intake of potassium,sodium,zinc and cadmium through staple food,meat and fruit can lead to the corresponding increase in internal exposure.The intake of potassium and sodium through vegetables resulted in increased exposure to the corresponding metals,while the intake of magnesium and zinc through fish and fruits resulted in increased exposure to the corresponding metals.Chromium ingested through meat can cause increased internal exposure to chromium.2.Study on the correlation between exposure to multiple metals and renal functionIn this study.408 patients had rapid renal function decline and 189 had incident eGFR<60 mL/min/1.73 m2.The results of Mann-Whitnev U test showed that the concentrations of chromium,sodium and potassium in plasma of the rapidly declining renal function group were higher than those of the control group,while the concentrations of copper,selenium,iron and calcium were lower than those of the control group.The plasma concentrations of chromium and potassium in eGFR<60 mL/min/1.73 m2 group were higher than those in control group,while the concentrations of selenium and iron were lower than those in control group(P<0.05).The linear regression model analysis showed that the plasma cadmium,zinc,sodium and potassium were positively associated with the annual eGFR decrease,while the plasma copper,selenium,iron and calcium were negatively associated with the annual eGFR decrease(P<0.05).Four principal components(PC)were obtained by PCA,representing four metal exposure models,namely,PC1(calcium,copper,magnesium)exposure model,PC2(iron,chromium)exposure model,PC3(sodium,potassium)exposure model and PC4(lead,cadmium)exposure model.In the PC2 exposure model,the average annual eGFR increment of the highest quartile array was 1.54(1.04-2.03)higher than that of the lowest quartile array,while in the PC3 and PC4 exposure models,The average annual eGFR reduction of the highest quartile array was 2.02(1.53-2.51)and 1.60(1.10-2.09)higher than that of the lowest quartile array,respectively.With the increase of PC2 scores,the average annual eGFR tended to increase,while with the increase of PC3 and PC4 scores,the average annual eGFR tended to decrease.Further logistic regression analysis showed that participants with the highest PC2 quartile had a lower risk of rapid renal decline or new eGFR<60 mL/min/1.73 m2 events,and PC3 and PC4 scores were positively correlated with the risk of renal impairment(P<0.05).Conclusion:In Chinese middle-aged and elderly population,the intake of potassium and sodium through meat,fish and soy products can lead the increase of internal exposure of corresponding metals,and the intake of chromium through meat can lead the increase of internal exposure of chromium.These metals are positively associated with decreased renal function,which increases the risk of renal impairment.In addition,renal function injury was positively correlated with plasma chromium and potassium,but negatively correlated with plasma selenium and iron.Combined exposure to multiple metals has a potential joint effect.Iron&chromium exposure patterns are negatively associated with renal injury and can reduce the risk of renal injury,while sodium&potassium and lead&cadmium exposure patterns are positively associated with renal injury and can increase the risk of renal injury. |
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