High blood pressure is associated with increased risk of future fracture, but not vice versa

The association between high blood pressure and fracture showed obvious discrepancies and were mostly between hypertension with future fracture, but rarely between fracture and incident hypertension. The present study aims to investigate the associations of hypertension with future fracture, and fracture with incident hypertension. We included adult participants from the China Health and Nutrition Survey (CHNS) prospective cohort in 1997-2015 (N = 10,227), 2000-2015 (N = 10,547), 2004-2015 (N = 10,909), and 2006-2015 (N = 11,121) (baseline in 1997, 2000, 2004, 2006 respectively and outcome in 2015). Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs. In the analysis of the association between hypertension and future fracture, the adjusted HRs (95% CIs) were 1.34 (0.95-1.90) in 1997-2015, 1.40 (1.04-1.88) in 2000-2015, 1.32 (0.98-1.78) in 2004-2015, and 1.38 (1.01-1.88) in 2006-2015. In the analysis of the association between fracture and incident hypertension, the adjusted HRs (95% CIs) were 1.28 (0.96-1.72) in 1997-2015, 1.18 (0.94-1.49) in 2000-2015, 1.12 (0.89-1.40) in 2004-2015, and 1.09 (0.85-1.38) in 2006-2015. The present study showed that hypertension history was associated with increased risk of future fracture, but not vice versa.

Association between Whole Grain Intake and Chronic Kidney Disease

BACKGROUND

The relationship between whole grain intake and chronic kidney disease (CKD) remains uncertain.

OBJECTIVE

This study aimed to evaluate the association between whole grain intake and risk of CKD in Chinese adults.

METHODS

The present cross-sectional study used data from the China Health and Nutrition Survey conducted in 2009. Whole grain intake was measured using 3 consecutive 24-h dietary recalls and a household food inventory. A multivariable logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for risk of CKD. In addition, a restricted cubic spline was used to investigate the dose‒response relationship between whole grain and risk of CKD.

RESULTS

A total of 6747 participants were included, 728 of whom had CKD. Compared with those in the lowest whole grain intake group, those in the higher grain intake group had an inverse association with risk of CKD (Q2: adjusted OR 0.70, 95% CI: 0.54, 0.89; Q3: adjusted OR 0.54, 95% CI: 0.42, 0.69; and Q4: adjusted OR 0.29, 95% CI: 0.21, 0.41). The association between whole grain intake and CKD seems to be stronger for individuals who were male (P for interaction = 0.008) or smokers (P for interaction = 0.013). In addition, the restricted cubic spline suggested an obvious L-shaped correlation.

CONCLUSIONS

Increased whole grain intake was associated with a decreased risk of CKD in Chinese adults.

Association between triglyceride-glucose index and hypertension: a cohort study based on the China Health and Nutrition Survey (2009-2015)

AIM

Insulin resistance (IR) may participate in the pathogenesis of hypertension by mediating low-grade systemic inflammation. The triglycerides-glucose (TyG) index has recently been suggested as a reliable alternative biochemical marker of IR compared with traditional methods. Herein, we speculated TyG index may also be associated with hypertension.

METHODS

Data of adults were extracted from the China Health and Nutrition Survey (CHNS) in 2009-2015 in this retrospective cohort study. The TyG index was calculated using the formula: TyG = Ln [fasting triglycerides (mg/dL) ×fasting glucose (mg/dL)/2]. Associations between TyG index and hypertension were evaluated by univariate and multivariate logistic regression analyses with odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses of age and gender were also performed. In addition, we assessed the interaction effect between TyG index and body mass index (BMI) on hypertension in participants with different age and gender.

RESULTS

Among 3,413 eligible participants, 1,627 (47.67%) developed hypertension. The average TyG index in hypertension group and non-hypertension group was 8.58 and 8.39 respectively. After adjusting for covariates, we found that compared with participants with TyG index ≤ 8.41 (median value), those who had higher TyG index seemed to have higher odds of hypertension [OR = 1.17, 95%CI: (1.01-1.37)]. Similarly, this association was also discovered in participants who aged ≤ 65 years old [OR = 1.19, 95%CI: (1.01-1.39)] or were female [OR = 1.35, 95%CI: (1.10-1.65)]. Additionally, there was a potential additive interaction effect between obesity and TyG index on hypertension.

CONCLUSION

High TyG index was associated with high odds of hypertension in general population in China, but the causal relationship between them needed further exploration.

Associations between Cholesterol Intake, Food Sources and Cardiovascular Disease in Chinese Residents

Cholesterol is a nutrient commonly found in the human diet. The relationship between dietary cholesterol, its sources, and cardiovascular disease (CVD) is still a topic of debate. This study aimed to investigate the association between dietary cholesterol, its sources, and cardiovascular events in a Chinese population. The present study analyzed data from the China Health and Nutrition Survey (CHNS) cohort between 1991 and 2015. This study analyzed data from 3903 participants who were 40 years of age or older at baseline and had no history of cardiovascular disease, diabetes, or hypertension. During a median follow-up of 14 years, 503 cardiovascular disease events were identified through follow-up questionnaires administered every 2-3 years. The events included fatal and nonfatal coronary heart disease, stroke, heart failure, and other cardiovascular disease deaths. Cox regression was used to estimate risk ratios (HR) for CVD events after adjusting for demographic, socioeconomic, and behavioral factors. It was discovered that sources of dietary cholesterol varied among different subgroups of the population. The top three sources of cholesterol among all participants were eggs, red meat, and seafood, accounting for 57.4%, 28.2%, and 9.0% of total daily cholesterol intake, respectively. The present study found that there was a significant association between total dietary cholesterol intake, and the risk of developing cardiovascular disease (adjusted HR [95% CI]: total cholesterol (highest and lowest quartiles compared) 1.57 [1.17-2.11]). Cholesterol from poultry, seafood, and eggs was also significantly associated with a reduced risk of CVD (adjusted HR [95% CI]: poultry 0.18 [0.04-0.82], seafood 0.11 [0.02-0.54], and eggs 0.16 [0.03-0.73]). After adjusting for daily caloric intake, daily fat intake, and daily saturated fat intake, the previously observed association between red meat cholesterol and cardiovascular events (unadjusted HR [95% CI]: 0.44 [0.35-0.55]) was no longer statistically significant (adjusted HR [95% CI]: 0.21 [0.04-1.01]).

Factors influencing blood pressure variability in postmenopausal women: evidence from the China Health and Nutrition Survey

BACKGROUND

The aim is to identify the factors influencing blood pressure variability in postmenopausal women based on the China Health and Nutrition Survey (CHNS).

MATERIAL AND METHODS

The data on postmenopausal women between 1993 and 2015 were extracted from the CHNS. Group-based trajectory modeling was used to analyze the development track of blood pressure changes, based on which the subjects were separately divided into two groups for systolic blood pressure (SBP) and diastolic blood pressure (DBP). Univariate and multivariate analyzes were performed to analyze the factors influencing SBP and DBP.

RESULTS

A total of 346 women were eligible for the study. Group-based trajectory modeling showed two different trajectories of blood pressure, including the low-level, slowly developed type and the high-level, rapidly developed, stable type of SBP, as well as the low-level, slowly developed type and the high-level, slowly developed type of DBP. In multivariate analysis, age (odds ratio [OR]: 1.118, 95% confidence interval [CI]: 1.082-1.156), body mass index (BMI) (OR: 2.239, 95%CI: 1.010-4.964), antihypertensive agents (OR: 7.293, 95%CI: 2.191-24.275), hip circumference (OR: 1.069, 95%CI: 1.014-1.128) and marital status (OR: 3.103, 95%CI: 1.028-9.361) were found to be the significant factors influencing SBP; age (OR: 1.067, 95%CI: 1.039-1.096), alcohol consumption (OR: 2.741, 95%CI: 1.169-6.429), antihypertensive agents (OR: 4.577, 95%CI: 1.553-13.492), hip circumference (OR: 1.093, 95%CI: 1.049-1.138), and marital status (OR: 3.615, 95%CI: 1.228-10.644) were the predominant factors influencing DBP.

CONCLUSIONS

In postmenopausal women, age, BMI, antihypertensive agents, hip circumference, and marital status are associated with SBP changes, while age, alcohol consumption, antihypertensive agents, hip circumference, and marital status with DBP variability.

MESH KEYWORDS

postmenopausal women, blood pressure, development track, influencing factors, CHNS.

Association of dietary patterns with general and central obesity among Chinese adults: a longitudinal population-based study

BACKGROUND

Limited evidence exists for the association between dietary patterns and later obesity phenotypes among Chinese adults. This longitudinal study aimed to evaluate associations of dietary patterns with general and central obesity in Chinese adults.

METHODS

Based on the China Health and Nutrition Survey (CHNS) waves 2004 and 2015, the study was conducted on 4207 adult men and women (age range: 18-65 years). Dietary intakes were assessed by three consecutive 24-h dietary recalls, and dietary patterns were identified using exploratory factor analysis. Longitudinal associations of dietary patterns with general and central obesity were evaluated using logistic regression analyses.

RESULTS

The prevalence rates of general and central obesity were 14.2% and 42.1%, respectively. Factor analysis extracted three major dietary patterns: "traditional southern," "modern," and "traditional northern." After adjustment for potential confounders, adults in the highest quartile of the traditional southern dietary group were less likely to develop over 10 years general (odds ratio [OR] = 0.50, 95% confidence interval [95%CI]: 0.39, 0.65) and central (OR = 0.52, 95%CI: 0.43, 0.63) obesity compared to those in the lowest quartile group. The modern dietary pattern was not significantly associated with general and central obesity. Adherence to the traditional northern dietary pattern increased the chance of both general and central obesity (OR = 1.61, 95%CI: 1.23, 2.10; OR = 1.64, 95%CI: 1.36, 1.98) after 10 years.

CONCLUSIONS

Our study provides longitudinal evidence for associations between dietary patterns and later obesity phenotypes among Chinese adults. Our findings may guide the development of evidence-based preventive nutrition interventions to control the obesity epidemic.

Positive association of triglyceride-glucose index with new-onset hypertension among adults: a national cohort study in China

BACKGROUND

Previous studies showed that the triglyceride-glucose (TyG) index was a better predictor of adverse cardiovascular events than triglycerides or fasting blood glucose alone. However, few studies have focused on new-onset hypertension. We aimed to explore the association of TyG index with new-onset hypertension in Chinese adults.

METHODS

A total of 4,600 participants who underwent at least 2 rounds of visits from 2009 to 2015 in the China Health and Nutrition Survey were enrolled in this study. Our outcome of interest was new-onset hypertension. Multivariate Cox hazard regression models and restricted cubic spline were performed to explore the relationship between TyG index and new-onset hypertension.

RESULTS

The mean (standard deviation, SD) age of the study population was 48.1 (13.6) years, and 2058 (44.7%) of the participants were men. The mean (SD) TyG index level was 8.6 (0.7). A total of 1,211 (26.3%) participants developed new-onset hypertension during a median (interquartile range) follow-up duration of 6.0 (2.0-6.1) years. The incidences of new-onset hypertension were 18.1%, 25.3%, 28.5%, and 33.4% by quartiles of TyG index [from quartile 1 (Q1) to Q4], respectively. The Cox model showed that high levels of TyG index were significantly associated with increased risk of new-onset hypertension (adjusted hazard ratio [aHR]: 1.29, 95% confidence interval [CI] 1.07-1.55, Q2; aHR, 1.24, 95% CI 1.03-1.49, Q3; aHR, 1.50, 95% CI 1.22-1.84, Q4) compared with Q1. Consistently, as a continuous variable, for every 1.0 increase in TyG index, there was a 17% increase in the risk of new-onset hypertension (aHR, 1.17; 95% CI 1.04-1.31). The associations were consistent in various subgroups and sensitivity analysis. The dose-response curve indicated a positive, linear association between TyG index and the risk of new-onset hypertension.

CONCLUSIONS

High TyG index was significantly associated with an increased risk of new-onset hypertension among Chinese adults. Our findings suggest that maintaining a relatively low level of TyG index might be effective in the primary prevention of hypertension.

Association of habitually low intake of dietary selenium with new-onset stroke: A retrospective cohort study (2004-2015 China Health and Nutrition Survey)

Background

As an essential trace element in the body, selenium is associated with the development of many diseases. The purpose of this study was to explore the association between dietary selenium intake and new-onset stroke risk in Chinese adults.

Methods

Adults aged ≥18 years in the China Health and Nutrition Survey (CHNS) from 2004 to 2015 were enrolled. Participants were divided into five groups according to the quintile of dietary selenium intake: Q1 (≤ 29.80 μg/day), Q2 (29.80-38.53 μg/day), Q3 (38.53-47.23 μg/day), Q4 (47.23-60.38 μg/day), Q 5(>60.38 μg/day). Cox proportional-hazards model was used to explore the effect of dietary selenium on new-onset stroke. Restricted cubic spline (RCS) was used to visualize the dose-response relationship between dietary selenium and the risk of morbidity.

Results

A total of 11,532 subjects were included, and 271 (2.35%) of them developed stroke during a mean follow-up of 6.78 person-years. Compared with the lowest selenium intake group, the HR and 95%CI of stroke in the participants with selenium intake of Q2, Q3, Q4 and Q5 were: 0.85 (0.59, 1.21), 0.62 (0.42, 0.92), 0.43 (0.28, 0.68), 0.49 (0.30, 0.82), respectively. There was an L-shaped relationship between dietary selenium and stroke (nonlinear P-value = 0.0420). The HR and 95%CI of developing stroke was 0.75 (0.65, 0.87) in participants with selenium intake ≤ 60 μg/day.

Conclusions

The L-shaped negative association between dietary selenium and stroke in Chinese adults which indicated that dietary selenium should be improved to a certain level to prevent stroke.

Intergenerational transmission of parental risky health behaviors in Chinese children: Are there socioeconomic status differences?

Background

Risky health behaviors in childhood, including smoking, alcohol consumption, and having a poor diet, are the major sources of non-communicable diseases in adulthood. This study aimed to examine how parents affect children's risky health behaviors and whether intergenerational transmission differs based on socioeconomic status (SES).

Methods

Data were extracted from the 1991-2015 China Health and Nutrition Survey (CHNS). Smoking (n = 5,946), alcohol consumption (n = 7,821), and sugar-sweetened beverages (SSBs) consumption (n = 3,537) were used as proxies for risky health behaviors in children. A binary choice model for panel data with a random-effect specification was employed to examine whether risky health behaviors can be transmitted from parents to their children. Subsequently, we conducted a seemingly unrelated estimation test (SUEST) to explore the differences in parental transmission between the different SES groups.

Results

We found strong intergenerational persistence of smoking, alcohol drinking, and SSBs drinking behaviors, except for the mothers' smoking behavior. Mothers had a greater influence on children's alcohol drinking and SSBs drinking behaviors than fathers both in urban and rural areas and in different SES groups. The intergenerational transmission of SSBs drinking behavior exhibited a decreasing trend with increasing SES for both urban and rural families. In urban areas, mothers' alcohol drinking behavior has a decreasing trend with increasing education level, occupation, and income; however, in rural areas, the influence of mothers' alcohol drinking behavior occurred in the same direction with increasing education level and occupation type. In rural areas, the influence of fathers' drinking and smoking behaviors on children appears to mostly increase with increasing SES. Meanwhile, the influence of such behaviors among urban fathers would decrease with increasing SES.

Conclusion

Parents' behaviors and SES can influence the initiation of risky health behaviors in their offspring. Thus, to promote healthy behaviors, policymakers can introduce health education programs for parents, particularly for those living in rural areas and with a low SES.

Dietary vitamin E intake and new-onset hypertension

The association between dietary vitamin E intake and the risk of new-onset hypertension remains unknown. We aimed to evaluate the prospective relationship of dietary vitamin E intake with new-onset hypertension in the general Chinese population. A total of 12,177 adults without hypertension at baseline were enrolled from the China Health and Nutrition Survey. Dietary intake was measured by 3 consecutive 24 h dietary recalls at the individual level in combination with a weighing inventory taken over the same 3 days at the household level. The study outcome was new-onset hypertension, defined as a systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg, a diagnosis by a physician, or the use of antihypertensive treatment during follow-up. During a median follow-up duration of 6.1 years, 4269 participants developed new-onset hypertension. Overall, the association between dietary vitamin E intake and new-onset hypertension followed a reverse J-shaped curve (P for nonlinearity <0.001). Accordingly, when dietary vitamin E intake was assessed by quintiles, significantly higher risks of new-onset hypertension were found among participants in the first quintile (<18.75 mg/d: adjusted HR, 1.40; 95% CI, 1.29-1.52) and the fifth quintile (≥40.53 mg/d: adjusted HR, 1.18; 95% CI, 1.09-1.29) compared with those in the second-fourth quintiles (18.75 to <40.53 mg/d). Further adjustments for vitamin A, riboflavin, niacin, vitamin C, zinc, copper, and selenium intake or the intake of vegetables, fruits, legumes, grains, nuts, and vegetable oils did not substantially change the results. In conclusion, there was a reverse J-shaped association between dietary vitamin E intake and new-onset hypertension in general Chinese adults.

The association of energy and macronutrient intake at breakfast and cardiovascular disease in Chinese adults: From a 14-year follow-up cohort study

Background

We aimed to examine the associations between energy and macronutrient intakes at breakfast and the incidence of cardiovascular events among Chinese adults.

Methods

There were 12,937 participants from the China Health and Nutrition Survey who met the study criteria and completed six rounds of questionnaires in 1997, 2000, 2004, 2006, 2009, and 2011. Combined weighing methods with 24-h dietary recall were used to measure dietary intake throughout the day. Intakes of macronutrients at breakfast were calculated using energy provided by nutrients as a percentage of breakfast energy. We calculated hazard ratios using a multivariable Cox frailty model with random intercepts to account for household clustering.

Results

During follow-up, we documented 453 (3.6 per 1,000 person-years) major cardiovascular events, 195 (1.5 per 1,000 person-years) myocardial infarctions, and 293 (2.3 per 1,000 person-years) strokes. In Chinese adults, more breakfast carbohydrates or less proteins intake was associated with the reduced risk of cardiovascular diseases. Especially for women, higher intake of breakfast carbohydrates was associated with a lower risk of major cardiovascular events (quintile 5 vs. quintile 1, HR 0.47 [95%CI 0.30-0.74]; p _trend = 0.0008) and stroke (quintile 5 vs. quintile 1, HR 0.48 [95%CI 0.26-0.88]; p _trend = 0.0006). Higher intake of breakfast proteins was associated with a higher risk of major cardiovascular events (quintile 5 vs. quintile 1, HR 1.77 [95%CI 1.12-2.79]; p _trend = 0.1162), myocardial infarction (quintile 5 vs. quintile 1, HR 2.49 [95%CI 1.21-5.11]; p _trend = 0.2641). There was a significant association between breakfast fat intake and cardiovascular diseases in the adult population, but less significant correlation was found in Chinese men or women. Breakfast fat intake was positively associated with the risk of major cardiovascular events (quintile 5 vs. quintile 1, HR 1.74 [95%CI 1.27-2.36]; p _trend = 0.0070), myocardial infarction (quintile 5 vs. quintile 1, HR 2.03 [95%CI 1.23-3.37]; p _trend = 0.0168), and stroke (quintile 5 vs. quintile 1, HR 1.64 [95%CI 1.12-2.41]; p _trend = 0.0732). There was a significant reduction in major cardiovascular events and stroke when breakfast energy intake was moderated, even if the independence of skipping breakfast.

Conclusion

High carbohydrate intake and low protein and fat intake at breakfast may contribute to cardiovascular health while maintaining a moderate energy intake.

J-shaped association between dietary zinc intake and new-onset hypertension: a nationwide cohort study in China

We aimed to investigate the relationship of dietary zinc intake with new-onset hypertension among Chinese adults. A total of 12,177 participants who were free of hypertension at baseline from the China Health and Nutrition Survey were included. Dietary intake was assessed by three consecutive 24-h dietary recalls combined with a household food inventory. Participants with systolic blood pressure ≽ 140 mmHg or diastolic blood pressure ≽ 90 mmHg or diagnosed by a physician or under antihypertensive treatment during the follow-up were defined as having new-onset hypertension. During a median follow-up duration of 6.1 years, 4269 participants developed new-onset hypertension. Overall, the association between dietary zinc intake and new-onset hypertension followed a J-shape (P for non-linearity < 0.001). The risk of new-onset hypertension significantly decreased with the increment of dietary zinc intake (per mg/day: hazard ratio (HR) 0.93; 95% confidence interval (CI) 0.88-0.98) in participants with zinc intake < 10.9 mg/day, and increased with the increment of zinc intake (per mg/day: HR 1.14; 95% CI 1.11-1.16) in participants with zinc intake ≽ 10.9 mg/day. In conclusion, there was a J-shaped association between dietary zinc intake and new-onset hypertension in general Chinese adults, with an inflection point at about 10.9 mg/day.

Long-Term Diet Quality and Risk of Diabetes in a National Survey of Chinese Adults

There is little evidence involving the association between diet quality and the risk of diabetes among the Asian populations, especially from the long-term prospective cohort studies in China. This study evaluated the long-term diet quality of Chinese adults by the Chinese diet balance index 2016 (DBI-16) and firstly explored its role in diabetes prevention. A total of 9394 participants from the China health and nutrition survey (2004-2015) prospective cohort were included. Dietary information was selected by three consecutive 24-h dietary recalls, combined with a household food inventory and further calculated as the scores of the DBI-16 components and indicators. Three major indicators, the low bound score (LBS), the high bound score (HBS) and the diet quality distance (DQD), were divided into four level groups, according to the total scores, respectively, including Level 1 (scores below 20%), Level 2 (20-40% of scores), Level 3 (40-60% of scores) and Level 4 (scores above 60%). Diabetes cases were identified through a questionnaire or by testing the overnight fasting blood samples. Cox's proportional hazards models were used to estimate the hazard ratios (HRs) and 95% CIs, while restricted cubic splines (RCS) were applied to explore the potentially non-linear relationships. During a median follow-up of 6.0 years (61,979 persons-years), 657 participants developed diabetes. The LBS and DQD scores were positively associated with diabetes risks, whereas no significant association of the HBS scores with diabetes risks was observed. Compared with those on the lowest level, the adjusted HRs (95%) across the increased levels of diet quality were 2.43 (1.36, 4.37), 3.05 (1.69, 5.53) and 4.90 (2.46, 9.78) for the LBS; 1.06 (0.74, 1.51), 1.30 (0.99, 1.88) and 0.99 (0.39, 2.55) for the HBS; 1.28 (1.01, 1.61) and 2.10 (1.57, 2.82) for the DQD after pooling the participants on Level 1 and 2 as the reference group, due to the few who developed diabetics on Level 1 of the DQD. No significantly non-linear shape was observed for all three indicators. Our findings indicated a significant inverse association between the long-term diet quality assessed by the DBI-16 and diabetes risks, providing evidence for the positive role of healthy diets in diabetes prevention in Asia.

Waist Circumference-Years Construct Analysis and the Incidence of Type 2 Diabetes: China Health and Nutrition Survey, 1997-2015

Background: Few studies have combined the degree and duration of abdominal obesity into a waist circumference-years construct for analysis. The purpose of this study was to investigate the effect of waist circumference-years on the incidence of type 2 diabetes. Methods: A total of 6616 adults from the China Health and Nutrition Survey (CHNS) were enrolled in this study from 1997. The waist circumference-years construct was represented as the sum of the upper and lower area between the waist circumference baseline (men: ≥90 cm, women: ≥85 cm) and the waist circumference line. The correlations in the study were analyzed using logistic regression. Results: The incidence of type 2 diabetes increased with increasing waist circumference-years, with an adjusted risk increase of 38% (95% CI: 31−47%) for each additional 50 waist circumference-years, and this rate was similar across gender and age groups. The area under the curve of waist circumference-years (0.743) was greatest in the receiver operating characteristic curve (ROC) analysis compared to baseline waist circumference (0.731) and the waist-height ratio (0.728) (p < 0.05). Conclusion: The waist circumference-years construct is closely associated with an increased risk of type 2 diabetes and may be a stronger predictor of type 2 diabetes risk than baseline waist circumference or the waist-height ratio.

Characterization of titanium dioxide nanoparticles in confectionary products and estimation of dietary exposure level among the Chinese population

Titanium dioxide (TiO₂) is widely used in the food industry. Recently, European Commission has banned TiO₂ as a food additive, raising public concern about its health risk, especially the nanoparticles (NPs) contained therein. This study aimed to reveal the existence of TiO₂ NPs in food and further estimate the dietary exposure level among Chinese population by characterizing particle size distribution, determining Ti content and micro-distribution in food products, and calculating food consumption from the China Health and Nutrition Survey (CHNS). The results showed that TiO₂ particle size in food additives and chewing gums was 53.5-230.3 nm and 56.8-267.7 nm respectively, where NPs accounted for 34.7% and 55.6% respectively. TiO₂ was firstly in situ presented on the surface of confectionary products with hard shells. The content of TiO₂ ranged from 3.2 to 3409.3 μg/g product. Besides, the mean dietary intake was 71.31 μg/kg_bw/day for TiO₂ and 7.75 μg/kg_bw/day for TiO₂ NPs among Chinese population, affected by people's dietary habits of different regions. Children's exposure levels was the highest due to their love of sweets. More attention should be paid to risk assessment and management of TiO₂ NPs for children in China.

The effects of health insurance and physical exercise participation on life satisfaction of older people in China-Based on CHNS panel data from 2006 to 2015

Background

In China, the problem of aging population has become more and more serious. The factors influencing life satisfaction of older people are becoming a significant issue. This study explores the effects of health insurance and physical exercise on life satisfaction of older people in China.

Method

This study used an unbalanced panel dataset (n = 6,393, T = 4) of older adults aged 60-80 years from the 2006 to 2015 China Health and Nutrition Survey (CHNS). A panel ordered logistic regression model was developed to examine the effects of health insurance and physical exercise on older people' life satisfaction. Mediation tests were used to examine the mediating role of physical exercise in the effect of health insurance on life satisfaction of older people.

Result

Life satisfaction of older people was positively associated with participation in health insurance (OR = 1.439) and physical exercise (OR = 1.033). Participation in government health insurance, urban employee health insurance (UEBMI), new rural cooperative health insurance (NRCMI), and other commercial health insurance all have positive effects on life satisfaction of older people. Physical exercise plays a masking role in the effect of health insurance on life satisfaction of older people.

Conclusion

Participation in health insurance and physical exercise are important means to promote life satisfaction among older people. Physical exercise affects the impact of health insurance on older people's life satisfaction.

The association of grandparental co-residence and dietary knowledge with excess body weight among children aged 7-15 years in China

OBJECTIVES

To investigate the impact of grandparent's co-residence and dietary knowledge on the overweight and obesity risk among school-age children in China.

METHODS

Data of 790 children aged 7-15 years were retrieved from the China Health and Nutrition Survey (CHNS). Co-residential status was evaluated using household and individual ID. Dietary knowledge was assessed using 17 dietary statements, which was scored by participants. Three principal factors were extracted by factor analysis. Logistic regression analysis was applied to examine the influence of grandparent's co-residence and dietary knowledge on the weight status of the child.

RESULTS

The overweight and obesity incidence of the children increased significantly when they co-reside with two grandparents (OR=1.447, 95CI: 1.001-2.090, p=0.049). Mother's dietary knowledge regarding to protein-related food choices (PT) scored higher was associated with the increased risk (OR=1.270, 95CI: 1.059-1.523, p=0.010). For grandmother's dietary knowledge, the higher score in balanced food consumption (BF) was associated with the decreased overweight and obesity risk (OR=0.456, 95CI: 0.294-0.706, p<0.001). Grandfather's dietary knowledge in BF showed the similar result (OR=0.454, 95CI: 0.271-0.759, p=0.003).

CONCLUSIONS

Living with two grandparents is associated with higher overweight and obesity risk, but grandparents with an adequate knowledge in the balanced food consumption may decrease the risk.

Export Expansion May Increase Adult Illness and Injury: A Quasi-Natural Experiment on China's Accession to the World Trade Organization

Purpose

Exports can boost the economy, but may also cause harm to health through, for example, increased pollution and working hours. Although academic research extensively covers the impact of trade on health, few studies examine the mechanisms through which export expansion affects adult illness or injury within the past 4 weeks (illness/injury).

Method

We utilized China's entry into the World Trade Organization (WTO) as a quasi-natural experiment to investigate the relationship between export expansion and adult illness/injury. We explored the possible mechanisms and the heterogeneity of these associations. Our methodology was based on the analysis of China's Health and Nutrition Survey data, Chinese Customs databases, and China's Statistical Yearbook.

Results

Export expansion, induced by China's accession to the WTO, has a significantly positive effect on adult illness/injury [average effect (AE): 1.83%; 95% CI: 0.38–3.28%]. Our results remain robust following a series of robustness tests. Moreover, the effects of export expansion on adult illness/injury are more pronounced among urban residents (AE: 5.32%; 95% CI: 2.46–8.18%), women (AE: 2.68%; 95% CI: 0.57–4.80%), and higher-income groups (AE: 5.90%; 95% CI: 2.53–9.27%).

Conclusions

We find a statistically significant and positive effect of export expansion on adult illness/injury.

The Association between Dietary Purine Intake and Mortality: Evidence from the CHNS Cohort Study

Objectives: To investigate the association between dietary purine intake and mortality among Chinese adults. Methods: Based on data from the 2004−2015 China Health and Nutrition Survey (CHNS) and the corresponding edition of China Food Composition, the average purine intake per day (mg/day) from 2004 to 2011 was calculated, and the surveyed population was divided into five groups by quintiles. The outcome event and timepoint of concern were defined as death and time, respectively, as reported by family members, recorded until the 2015 survey. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) with 95% confidence intervals (CIs) for death. The possibly nonlinear relationship between purine intake and mortality was examined with restricted cubic splines. Results: We included 17,755 subjects, and the average purine intake among them was 355.07 ± 145.32 mg/day. Purine intake was inversely associated with mortality (Ptrend < 0.001). Compared with the lowest quintiles of purine intake, the highest quintiles (HR = 0.60; 95% CI: 0.46, 0.77) showed a significant association with lower mortality. The negative association with mortality was mainly found in plant-derived purine (Ptrend = 0.001) and, weakly, in animal-derived purine (Ptrend = 0.052). In addition, a U-shaped relationship between purine intake and mortality was observed in males; however, there was no statistically significant dose−response relationship in females. Conclusion: Considering the low-purine-intake levels of the Chinese population, we observed a U-shaped relationship between purine intake and mortality in males, but purine intake may not relate to mortality in females. Future studies should investigate the causal relationship between purine intake and disease burden in China.

U-shaped Association Between Dietary Zinc Intake and New-onset Diabetes: A Nationwide Cohort Study in China

AIMS

We aimed to investigate the relationship of dietary zinc intake with new-onset diabetes among Chinese adults.

MATERIALS AND METHODS

A total of 16 257 participants who were free of diabetes at baseline from the China Health and Nutrition Survey were included. Dietary intake was measured by 3 consecutive 24-hour dietary recalls combined with a household food inventory. Participants with self-reported physician-diagnosed diabetes, or fasting glucose ≥ 7.0 mmol/L, or glycated hemoglobin ≥ 6.5% during the follow-up were defined as having new-onset diabetes.

RESULTS

A total of 1097 participants developed new-onset diabetes during a median follow-up duration of 9.0 years. Overall, the association between dietary zinc intake and new-onset diabetes followed a U-shape (P for nonlinearity < 0.001). The risk of new-onset diabetes was significantly lower in participants with zinc intake < 9.1 mg/day (per mg/day: hazard ratio [HR], 0.73; 95% CI, 0.60-0.88), and higher in those with zinc intake ≥ 9.1 mg/day (per mg/day: HR, 1.10; 95% CI, 1.07-1.13). Consistently, when dietary zinc intake was assessed as deciles, compared with those in deciles 2-8 (8.9 -<12.2 mg/day), the risk of new-onset diabetes was higher for decile 1 (<8.9 mg/day: HR, 1.29; 95% CI, 1.04-1.62), and deciles 9 to 10 (≥12.2 mg/day: HR, 1.62; 95% CI, 1.38-1.90). Similar U-shaped relations were found for plant-derived or animal-derived zinc intake with new-onset diabetes (all P for nonlinearity < 0.001).

CONCLUSIONS

There was a U-shaped association between dietary zinc intake and new-onset diabetes in general Chinese adults, with an inflection point at about 9.1 mg/day.

Dietary Iron Intake and New-Onset Hypertension: A Nationwide Cohort Study from China

OBJECTIVES

The relationship of dietary iron intake with the risk of hypertension remains uncertain. We aimed to investigate the prospective association between dietary iron intake and new-onset hypertension among Chinese adults.

DESIGN

A nationwide cohort study.

SETTING

Using data from seven rounds of the China Health and Nutrition Survey (CHNS) from 1997 to 2015.

PARTICIPANTS

A total of 12,245 participants without hypertension at baseline were included in this study.

EXPOSURES

Dietary intake was measured by three consecutive 24-h dietary recalls combined with a household weighing inventory.

MEASUREMENTS

The study outcome was new-onset hypertension, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg or diagnosed by physician or currently under antihypertensive treatment during the follow-up.

RESULTS

During a median follow-up of 6.1 years, 4,304 (35.1%) participants developed hypertension. Overall, there was a U-shaped association between dietary total iron intake and new-onset hypertension (P for nonlinearity <0.001), with the lowest risk observed at 18.2-<22.1 mg/day (quintile 2-3). Similarly, a U-shaped association between dietary nonheme iron intake and new-onset hypertension was found (P for nonlinearity <0.001), with the lowest risk at 17.4-<21.3 mg/day (quintile 2-3). However, the association between dietary heme iron intake and new-onset hypertension followed a L-shape (P for nonlinearity <0.001), and a significantly lower risk of new-onset hypertension was found in participants with quintile 2-5 of dietary heme iron intake (adjusted HR, 0.75; 95% CI: 0.68, 0.82), compared with those in quintile 1 (<0.25 mg/day).

CONCLUSIONS

The association between dietary iron and new-onset hypertension was nonlinear in Chinese adults, following a U-shape for total or nonheme iron intake, and a L-shape for heme iron intake.

Influence factors for upper respiratory tract infection in Chinese rural children: A cross-sectional study

AIM

The prevalence rate of upper respiratory tract infection (URTI) is high in children. Influencing factors for URTI have been reported in Chinese urban children, but those have not been explored in rural children. In China, children in the rural areas are a disadvantaged group. Therefore, this study aims to explore influencing factors for URTI in Chinese rural children.

METHODS

This is a cross-sectional study based on the 1991-2015 China Health and Nutrition Survey (CHNS). In total, 5,289 children were eligible for the analysis, including 3,684 rural children and 1,605 urban children. The generalized estimating equation was used to determine the influencing factors, and results were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs).

RESULTS

The results showed that rural children aged 7-12 and 13-17 years had lower odds of URTI than those aged 0-1 year, with OR value of 0.17 (95% CI, 0.11-0.27) and 0.12 (95% CI, 0.08-0.19), respectively. Compared with uneducated mothers, those with education level of primary school (OR: 0.59, 95% CI, 0.42-0.84), lower middle school (OR: 0.53, 95% CI, 0.38-0.73), and upper middle school and technical school (OR: 0.62, 95% CI, 0.40-0.95) were associated with the lower odds of URTI in rural children. Children, whose mothers were office workers, had 46% lower odds of URTI than those with farmer mothers (OR: 0.54, 95% CI, 0.34-0.84).

CONCLUSIONS

This study found that mother's education level, children's age, and mother's occupation were significant influencing factors for URTI, which suggested the importance to improve mother's health-related knowledge and working conditions in Chinese rural areas.

The Labor Productivity Consequences of Exposure to Particulate Matters: Evidence from a Chinese National Panel Survey

A growing body of literature has documented the negative impacts of air pollution on labor productivity, especially the effects of fine particulate matter. In this paper, we build on this literature by dissecting two channels of how particulate matter affects labor productivity: decreasing labor supply through damaging the physical functioning of the human body, and decreasing the marginal productivity of labor through damaging the cognitive functioning of the human brain. Using the household panel survey from the China Health and Nutrition Survey (CHNS) spanning 2000 to 2015 and combining that information with remotely sensed data on exposure to particulate matter (PM2.5), namely, the most harmful air pollution, we find a significantly negative effect of PM2.5 (instrumented by thermal inversion) on labor productivity. We also find that workers who are male, without a college degree, and are employed in outdoor occupations are mainly affected by PM2.5 through decreasing working hours, whereas college-educated workers employed in indoor occupations are mainly affected by PM2.5 through decreasing unit wages. We provide suggestive evidence that health impacts are behind our measured labor-productivity losses as we find significantly lower metrics in physical activity and increasing disease prevalence under higher exposure to PM2.5.

Relationship Between Dietary Knowledge, Socioeconomic Status, and Stroke Among Adults Involved in the 2015 China Health and Nutrition Survey

Stroke is a public health threat that requires urgent attention in China. Nutrients have individual significant impacts on the prevalence of stroke. However, little research has been conducted on the impact of dietary knowledge on stroke and whether the impact is potentially heterogeneous under the effect of socioeconomic status. This study used the 2015 Chinese Health and Nutrition Survey to explore the impact of dietary knowledge and socioeconomic factors on populations suffering from stroke. Results indicated that risk of stroke decreased significantly with increasing dietary knowledge score. Additionally, the impact of dietary knowledge scores on the prevalence of stroke has obvious heterogeneity. First, dietary knowledge scores significantly influenced low-income groups and individuals with low educational levels. Second, the risk of stroke in females is more affected by dietary knowledge. Third, for people living in different areas, dietary knowledge determines whether rural populations suffer from stroke.

Higher Dietary Se Intake Is Associated With the Risk of New-Onset Fracture: A National Longitudinal Study for 20 Years

Background: The association between dietary selenium (Se) intake and osteoporosis-related fractures remains inconsistent. We aimed to examine the dose relationship between Se intake and incident fracture among Chinese adults.

Methods: The dietary data were retrieved from the China Health and Nutrition Survey conducted between 1991 and 2011, and 17,150 participants aged above 20 were included. A 3-day, 24-h recall of food intake was performed to assess cumulative average dietary Se intake. The fracture was based on self-report in each survey between 1997 and 2011. The association between Se intake and fracture was tested by Cox regression, and the non-linear association was examined by restricted cubic splines (RCS).

Results: There were 976 fracture cases during a mean of 10.2 years follow-up. In a fully adjusted Cox model, across the quartiles of Se intake, the hazard ratios (HRs) for fracture were 1.07 (95% CI .86–1.33), 1 (reference), 1.25 (95% CI 1.02–1.53), and 1.33 (95% CI 1.07–1.65). RCS showed a parabolic association (P non-linear = 0.037) between Se and fracture for men as well as a U-shape dose-response (P non-linear = 0.04) between Se and fracture for subjects living in highly urbanized areas.

Conclusion: In conclusion, there is a non-linear association between selenium intake and fracture, with higher intake associated with increased risk. The shape of the association varies by gender and urbanization level.

Spatial-Temporal Footprints Assessment and Driving Mechanism of China Household Diet Based on CHNS

Food consumption is closely associated with resource consumption and environmental sustainability. An unreasonable dietary pattern would cause great pressure or damage to resources and the environment. It is particularly important to reduce the negative impact of household food consumption on resources and the environment while simultaneously ensuring people’s nutrient intake and health. This study applied the China Health and Nutrition Survey (CHNS) database to quantitatively study the spatial-temporal analysis of multiple footprints of household food consumption at multiple scales and explored the driving mechanism of the multiple footprints. The results showed that, except land footprint (LF), the other four types of footprints all decreased at varying degrees; the water footprint (WF), carbon footprint (CF), nitrogen footprint (NF) and energy footprint (EF) decreased by 18.24%, 17.82%, 12.03% and 20.36%, respectively, from 2000 to 2011; multiple footprints of food consumption of household in Guizhou was the highest among the 12 provinces involved in the study; this shows that resource consumption (water, energy and land resource) and environmental influences (CO₂ emissions and nitrogen emissions) brought by food consumption of per household in Guizhou are much greater than in other provinces, which has a negative influence on sustainable development; by analyzing the driving factors of multiple footprints, it is shown that nutrient intake, household attributes, educational level and health conditions were significantly correlated to multiple footprints. Among them, nutrient intake has greater impact on the multiple footprints of Chinese household food consumption. By comparing multiple footprints of different dietary patterns, it was found that the current Chinese dietary pattern would cause excessive resource consumption, which would bring more pressure on resources and the environment. Adjusting household living habits would possibly reverse the unsustainable situation, such as reducing the consumption of animal-derived foods and adjusting the dietary pattern of households with a higher educational level and income status. Chinese Dietary Guidelines 2016 has better sustainability; the promotion of this dietary pattern across the country would help China to relieve the pressure on resources and environment from the consumer side, promoting the realization of sustainable development.

Screen-detected disordered eating and related traits in a large population sample of females in mainland China: China Health and Nutrition Survey

OBJECTIVE

We describe the prevalence and sociodemographic factors associated with screen-detected disordered eating and related traits in a population-based sample of women in China. We also explored prevalence trends over time.

METHOD

A total of 4,218 females aged 12-50 were sampled from 15 provinces as part of the China Health and Nutrition Survey (CHNS) in 2015. The SCOFF questionnaire screened for disordered eating and the selected questions from the Eating Disorders Examination-Questionnaire measured dietary restraint, shape concerns, and weight concerns. Body mass index (BMI) was measured and sociodemographic factors captured urban/rural residence, age, ethnicity, income, education, marital status, and occupational status. We calculated the prevalence of screen-detected disordered eating and related traits broadly and across several dimensions and compared prevalence estimates to 2009 and 2011 reports.

RESULTS

We detected 296 individuals who screened positive for disordered eating on the SCOFF (prevalence = 7.04%). Positive screens were associated with urban residence (p = .002) and higher education levels (p < .001). Scores on restraint, shape concerns, and weight concerns were all higher for individuals in urban versus village locations (all p's < .001), and with higher BMI (p < .001) for shape and weight concerns. The prevalence of screen-detected disordered eating increased numerically across 2009, 2011, and 2015.

DISCUSSION

The prevalence of screen-detected disordered eating in mainland China was comparable to other populations worldwide obtained from a recent meta-analysis. The distribution of disordered eating and related traits varied by several sociodemographic factors, which include age, BMI, urban/rural residence, education, and income, suggesting important directions for case detection and intervention in China.

Secular trends of hypertension prevalence based on 2017 ACC/AHA and 2018 Chinese hypertension guidelines: Results from CHNS data (1991-2015)

This study aimed to assess the impact of the 2017 American College of Cardiology and American Heart Association (ACC/AHA) guideline and the 2018 Chinese hypertension guidelines on the different secular trends for hypertension prevalence. A total of 82 665 eligible individuals aged ≥20 years were selected from nine cross-sectional study periods (1991-2015) from the China Health and Nutrition Survey (CHNS). Over the 24-year period, the long-term trend for the prevalence of the 2017 ACC/AHA-defined age-adjusted hypertension showed an increase from 32.2% (95% confidence interval (CI): 31.0%-33.3%) in 1991 to 60.0% (95% CI: 58.6%-61.3%) in 2015 (Ptrend  < 0.001). According to the 2018 Chinese guideline for hypertension, the weighted hypertension prevalence increased from 10.0% (95% CI: 9.4%-10.5%) in 1991 to 28.7% (95% CI: 27.9%-29.6%) in 2015 (Ptrend  < 0.001). However, slopes of increasing prevalence of hypertension were significantly greater according to the 2017 ACC/AHA guideline than that based on Joint National Committee (JNC 7) report (β = 1.00% vs β = 0.67% per year, respectively, P = 0.041). Based on the 2017 ACC/AHA definition, the prevalence of stage 1 hypertension and elevated blood pressure significantly increase from 22.3% and 6.9% in 1991 to 31.2% and 10.1% in 2015 (all P < 0.05), respectively. The secular trend for the prevalence of hypertension according to the 2017 ACC/AHA guideline showed a greater rate of increase compared with the prevalence based on the 2018 Chinese hypertension guidelines. Public health initiatives should focus on the current status of hypertension in China because of the possible high prevalence of hypertension and concomitant vascular risks.

Using the Machine Learning Method to Study the Environmental Footprints Embodied in Chinese Diet

The food system profoundly affects the sustainable development of the environment and resources. Numerous studies have shown that the food consumption patterns of Chinese residents will bring certain pressure to the environment. Food consumption patterns have individual differences. Therefore, reducing the pressure of food consumption patterns on the environment requires the precise positioning of people with high consumption tendencies. Based on the related concepts of the machine learning method, this paper designs an identification method of the population with a high environmental footprint by using a decision tree as the core and realizes the automatic identification of a large number of users. By using the microdata provided by CHNS(the China Health and Nutrition Survey), we study the relationship between residents’ dietary intake and environmental resource consumption. First, we find that the impact of residents’ food system on the environment shows a certain logistic normal distribution trend. Then, through the decision tree algorithm, we find that four demographic characteristics of gender, income level, education level, and region have the greatest impact on residents’ environmental footprint, where the consumption trends of different characteristics are also significantly different. At the same time, we also use the decision tree to identify the population characteristics with high consumption tendency. This method can effectively improve the identification coverage and accuracy rate and promotes the improvement of residents’ food consumption patterns.

Association of leisure sedentary time with common chronic disease risk factors: A longitudinal study of China Health and Nutrition Surveys

BACKGROUND

Although the common risk factors were identified and controlled for many years, the overall prevalence of chronic diseases continued to increase in China.

OBJECTIVE

We presumed the leisure sedentariness as a latent but pivotal factor of chronic diseases, and examined its distribution and changing trend, analysed its interaction effects on common risk factors, which could provide a new perspective for the prevention and management.

METHODS

A total of 5013 participants were screened out from China Health and Nutrition Survey. Random-effects ordered logistic models were used for ordinal dependent variables, and fixed-effects or random-effects logit models were used for binary dependent variables.

RESULTS

From 2004 to 2011, the prevalence of high leisure sedentary time (LSED) increased by 58.58%. Members of the high LSED group were likely to choose fast food, salty snacks, soft drinks and more likely to smoke or drink alcohol compared with those of the low LSED group. However, they preferred walking, sports and body building more than those of the low LSED group.

CONCLUSIONS

For the unhealthy dietary, tobacco and alcohol consumption, more targeted introduction and guidance related to sedentary time should be promoted. Meanwhile, the appeal for physical exercise as well as adequate facilities should be initiated.

Association between Three Low-Carbohydrate Diet Scores and Lipid Metabolism among Chinese Adults

This study investigated the blood lipid levels of 5921 Chinese adults aged >18 years using data from the China Health and Nutrition Survey 2009. Diet information was collected through 3 day, 24 h recalls by trained professionals. The low-carbohydrate diet (LCD) score was determined according to the percentage of energy obtained from carbohydrate, protein, and fat consumption. Dyslipidemia was defined when one or more of the following abnormal lipid levels were observed: high cholesterol levels, high triglyceride levels, and low high-density lipoprotein cholesterol levels. Multivariate adjusted odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated using logistic regression models. After adjusting the confounding variables, in males, the OR of hypercholesterolemia was 1.87 (95% CI, 1.23–2.85; p for trend = 0.0017) and the OR of hypertriglyceridemia was 1.47 (95% CI, 1.04–2.06; p for trend = 0.0336), on comparing the highest and lowest quartiles of the LCD score. The animal-based LCD score showed a similar trend. The OR of hypercholesterolemia was 2.15 (95% CI, 1.41–3.29; p for trend = 0.0006) and the OR of hypertriglyceridemia was 1.51 (95% CI, 1.09–2.10; p for trend = 0.0156). However, there was no significant difference between plant-based LCD scores and dyslipidemia. In females, lipid profiles did not differ much among the quartiles of LCD scores—only the animal-based LCD score was statistically significant with hypercholesterolemia. The OR of hypercholesterolemia was 1.64 (95% CI, 1.06–2.55), on comparing the highest and lowest quartiles of the LCD score. In conclusion, a higher LCD score, indicating lower carbohydrate intake and higher fat intake, especially animal-based fat, was significantly associated with higher odds of hypercholesterolemia and hypertriglyceridemia in Chinese males. Future studies investigating the potential mechanisms by which macronutrient types and sex hormones affect lipid metabolism are required.

Plain Water Intake and Association With the Risk of Overweight in the Chinese Adult Population: China Health and Nutrition Survey 2006-2011

Background

The prevalence of overweight is increasing dramatically worldwide. The aim of our study was to investigate the association of plain water intake (PWI) with the risk of new-onset overweight risk among Chinese adults.

Methods

A total of 3,200 adults aged 18–65 who were free of overweight at baseline were enrolled from China Health and Nutrition Survey (CHNS) cohort study in 2006–2011. The risk of new-onset overweight with different amounts of PWI per day was analyzed in this 5-year cohort. A multiple logistic regression model was used to assess the association of PWI and the risk of new-onset overweight and adjust for potential confounders. Moreover, dose-response models were developed to estimate the linear relationship.

Results

During 5 years of follow-up, 1,018 incident cases were identified. Our analysis indicated an inverse association of more than 4 cups of PWI per day and the risk of new-onset overweight among normal weight individuals. Compared with participants who drank 2 to 3 cups PWI, the adjusted odds ratios (OR) of overweight were 0.741 (95% confidence interval [CI], 0.599–0.916) in participants who drank 4 to 5 cups PWI, and 0.547 (95% CI, 0.435–0.687) in participants who drank more than 6 cups PWI. The dose-response analysis showed that every cup of PWI was associated with a 6.5% and 8.4% decrease in the risk of new-onset overweight among men and women, respectively. The interactions of PWI and covariates on the risk of overweight were not found.

Conclusion

Drinking more than 4 cups (≈1 liter) per day of plain water is associated with decrease in the risk of new-onset overweight among normal-weight individuals.

[The relationship between smoking and hyperuricemia in Chinese residents]

Objective: To explore the relationship between smoking and hyperuricemia in Chinese residents. Methods: Based on data from the China Health and Nutrition Survey (CHNS), residents with blood samples provided in the 2009 round (including information of socio-demographic factors, lifestyle behaviors, medical history, and laboratory examinations etc.) were selected as the participants in the current analysis. Unconditional logistic regression models were utilized to compute the ORs and corresponding 95%CIs for assessing the relationship between smoking and hyperuricemia. Results: Among the 8 785 subjects, 1 435 had hyperuricemia with a prevalence rate of 16.3%, consisting of 886 men and 549 women with prevalence rates of 21.6% (886/4 110) and 11.7% (549/4 675) , respectively. Compared with never smokers, the adjusted OR (95%CI) for hyperuricemia was 0.83 (0.70-0.98) among current smokers, 0.77 (0.63-0.94) among current smokers with 20-39 years of smoking, and 0.79 (0.65-0.97) among current smokers with 11-20 cigarettes per day. When stratified by gender and compared with non-smoker, the adjusted OR (95%CI) for hyperuricemia among current smokers compared with never smokers was 0.83 (0.70-0.98) among men, while no significant association was found in female current smokers (OR=0.73, 95%CI: 0.42-1.26, P=0.260). Conclusion: In Chinese residents, there is an inverse association between smoking and hyperuricemia prevalence, and this association may be related to duration and intensity of smoking among current smokers. The findings need to be validated in large prospective cohort studies.

The income body weight gradients in the developing economy of China

Existing theories predict the income gradient of individual body weight to change sign from positive to negative in process of economic development. However, there are only few empirical studies which test this hypothesis. This paper adds to the literature on that topic by investigating the case of China. Using individual and community data from 1991 to 2009 waves of the China Health and Nutrition Survey regression analyses suggest that after controlling for important confounding factors (1) higher income is positively related to future growth of individuals' BMI in less developed areas (i.e. BMI growth is 0.7-1.5 percentage points higher when comparing the richest with the poorest individuals), but negatively related to BMI growth in more developed areas (i.e. BMI growth is 0.8-1.6 percentage points lower for the richest individuals), and (2) that concentrations of overweight are "trickling down" to lower income ranks as regions become more developed. Moreover, the reversal of the income gradient appears to happen at earlier stages of development for females.

Prevalence of metabolic syndrome and its influencing factors among the Chinese adults: the China Health and Nutrition Survey in 2009

OBJECTIVE

We aimed to estimate the up-to-date prevalence of metabolic syndrome (MS) and its influencing factors among the Chinese adults.

METHODS

Data were obtained from the China Health and Nutrition Survey conducted in 2009, which was a cross-sectional and partially nationally representative study including a total of 7488 Chinese adults (age ≥18 years).

RESULTS

The overall age-standardized prevalence estimates of the MS were 21.3% (95%confidence interval (CI): 20.4%-22.2%), 18.2% (95%CI: 17.3%-19.1%) and 10.5% (95%CI: 9.8%-11.2%) based on definitions of revised NCEP ATPIII, IDF and CDS criteria, respectively. Individuals who were women (compared to men: odds ratio [OR]=1.37, 95% CI=1.16-1.61), 40 years or older (compared to less than 40 years old: OR=2.82, 95%CI=2.37-3.34 for 40-59 years; OR=4.41, 95%CI=3.68-5.29 for 60 years or older), overweight/obese (compared to normal weight: OR=4.32, 95%CI=3.77-4.95 for overweight; OR=11.24, 95%CI=9.53-13.26 for obese), and living in urban area (compared to living in rural area: OR=1.27, 95%CI=1.12-1.43) were more likely to have a higher prevalence estimate of MS. In addition, frequency of alcohol consumption and cigarette intake were also found to be significantly associated with probability of MS.

CONCLUSIONS

Our results suggest an urgent need to develop national strategies for the prevention, detection, treatment and control of obesity and MS in China.