Association of dietary antioxidants and waist circumference with pulmonary function and airway obstruction

The Role of Nutrition in the Development and Management of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a prevalent lung condition associated with significant morbidity and mortality. The management of COPD classically involves pulmonary rehabilitation, bronchodilators, and corticosteroids. An aspect of COPD management that is currently lacking in the literature is nutritional management, despite the prevalence of inadequate nutritional status in patients with COPD. In addition, certain nutritional imbalances have been reported to increase the risk of COPD development. This review summarizes the current literature on the role diet and nutrients may play in the risk and management of COPD development.

The Effectiveness of Supplementation with Key Vitamins, Minerals, Antioxidants and Specific Nutritional Supplements in COPD-A Review

Currently, an increasing amount of evidence supports the notion that vitamins C, D and E, carotenoids, and omega-3 fatty acids may protect against the progression of chronic respiratory diseases. Although chronic obstructive pulmonary disease (COPD) primarily affects the lung, it is often accompanied by extrapulmonary manifestations such as weight loss and malnutrition, skeletal muscle dysfunction, and an excess of harmful oxidants, which can lead to a decline in quality of life and possible death. Recently, the role of various vitamins, minerals, and antioxidants in mitigating the effects of environmental pollution and smoking has received significant attention. Therefore, this review evaluates the most relevant and up-to-date evidence on this topic. We conducted a literature review between 15 May 2018 and 15 May 2023, using the electronic database PubMed. Our search keywords included COPD, chronic obstructive pulmonary disease, FEV₁, supplementation: vitamin A, vitamin D, vitamin E, vitamin C, vitamin B, omega-3, minerals, antioxidants, specific nutrient supplementations, clinical trials, and randomized controlled trials (RCTs). We focused on studies that measured the serum levels of vitamins, as these are a more objective measure than patient self-reports. Our findings suggest that the role of appropriate dietary supplements needs to be reconsidered for individuals who are predisposed to or at risk of these conditions.

Pomegranate extract supplementation improves lung function parameters and IL-35 expression in participants with mild and moderate persistent allergic asthma: A randomized, double-blind, placebo-controlled trial

Existing asthma treatments are associated with side effects and limitations, which has led to an interest in alternative and complementary therapies. Given the anti-inflammatory properties of pomegranate, the present study aimed to determine the impact of pomegranate extract supplementation on lung function parameters evaluated through spirometry, high-sensitivity C-reactive protein (hs-CRP), pro-oxidant antioxidant balance, and interleukin 35) (IL-35) in participants with mild and moderate allergic asthma (based on forced expiratory volume in 1 second (FEV1) and clinical symptoms). Participants with mild and moderate allergic asthma (n = 64) were randomly assigned to two groups: the intervention group, which received two pomegranate extract capsules (500 mg/day), or the control group for eight weeks. Also, the physician prescribed similar drugs to the participants in the study. Independent samples T-test and Mann-Whitney U were used to compare the quantitative outcomes between the intervention group and the comparison group. The Wilcoxon test and the paired T-test were applied for within-group comparisons. A p-value <0.05 was considered significant. At the end of the study, the change levels of IL-35 in the intervention group increased significantly compared to the control group. In terms of the lung function parameters, FEV1/ forced vital capacity (FVC) (FEV1/FVC) ratio enhanced significantly in the intervention group compared to the control group. Also, the pomegranate extract significantly improved forced expiratory flow 25-75% (FEF25-75%), FEV1/FVC ratio, and FEV1 in the intervention group. No significant changes in FEV1 values were observed between the two groups at the end of the study. Also, no significant changes were seen in other indicators. It seems that pomegranate extract can improve lung function parameters and IL-35 expression in mild and moderate allergic asthma.

Clinical trial registration

https://www.irct.ir/trial/45612; identifier: IRCT20200205046384N1.

Efficacy of Vitamin C Supplementation on Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis

Background

In recent years, the pleiotropic roles of antioxidants have drawn extensive attention in various diseases. Vitamin C is a well-known antioxidant, and it has been used to treat patients with chronic obstructive pulmonary disease (COPD). This systematic review and meta-analysis aim to demonstrate the impact of vitamin C supplementation in patients with COPD.

Methods

We searched PubMed, Embase, Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure (CNKI), SinoMed, Wanfang, and China Science and Technology Journal Database (cqvip.com) for eligible randomized controlled trials (RCTs) from their respective inception to May 18^th, 2021, by using the searching terms of COPD, vitamin C, and RCTs. A meta-analysis was performed to evaluate the effects of vitamin C on lung function, antioxidant levels, and nutritional conditions in COPD patients by using Review Manager (Version 5.4).

Results

Ten RCTs including 487 participants were eligible for our study. Meta-analysis results showed that vitamin C supplementation (≥400 mg/day) can significantly improve the forced expiratory volume in one second as a percentage (FEV1%) in COPD (SMD:1.08, 95% CI:0.03, 2.12, P=0.04). Moreover, vitamin C supplementation significantly improved the ratio of forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) (WMD:0.66, 95% CI: 0.26, 1.06, P=0.001), vitamin C level in serum (SMD:0.63, 95% CI: 0.02, 1.24, P=0.04) and glutathione (GSH) level in serum (SMD:2.47, 95% CI: 1.06, 3.89, P=0.0006). While no statistically significant difference was observed in body mass index (BMI), fat-free mass index (FFMI), vitamin E level and superoxide dismutase (SOD) level in serum.

Conclusion

Vitamin C supplementation could increase the levels of antioxidation in serum (vitamin C and GSH) and improve lung function (FEV1% and FEV1/FVC), especially in patients treated with vitamin C supplementation greater than 400 mg/day. However, further prospective studies are needed to explore the role of vitamin C in improving nutritional status.

Change in plasma α-tocopherol associations with attenuated pulmonary function decline and with CYP4F2 missense variation

BACKGROUND

Vitamin E (vitE) is hypothesized to attenuate age-related decline in pulmonary function.

OBJECTIVES

We investigated the association between change in plasma vitE (∆vitE) and pulmonary function decline [forced expiratory volume in the first second (FEV1)] and examined genetic and nongenetic factors associated with ∆vitE.

METHODS

We studied 1144 men randomly assigned to vitE in SELECT (Selenium and Vitamin E Cancer Prevention Trial). ∆vitE was the difference between baseline and year 3 vitE concentrations measured with GC-MS. FEV1 was measured longitudinally by spirometry. We genotyped 555 men (vitE-only arm) using the Illumina Expanded Multi-Ethnic Genotyping Array (MEGAex). We used mixed-effects linear regression modeling to examine the ∆vitE-FEV1 association.

RESULTS

Higher ∆vitE was associated with lower baseline α-tocopherol (α-TOH), higher baseline γ-tocopherol, higher baseline free cholesterol, European ancestry (as opposed to African) (all P < 0.05), and the minor allele of a missense variant in cytochrome P450 family 4 subfamily F member 2 (CYP4F2) (rs2108622-T; 2.4 µmol/L higher ∆vitE, SE: 0.8 µmol/L; P = 0.0032). Higher ∆vitE was associated with attenuated FEV1 decline, with stronger effects in adherent participants (≥80% of supplements consumed): a statistically significant ∆vitE × time interaction (P = 0.014) indicated that a 1-unit increase in ∆vitE was associated with a 2.2-mL/y attenuation in FEV1 decline (SE: 0.9 mL/y). The effect size for 1 SD higher ∆vitE (+4 µmol/mmol free-cholesterol-adjusted α-TOH) was roughly one-quarter of the effect of 1 y of aging, but in the opposite direction. The ∆vitE-FEV1 association was similar in never smokers (2.4-mL/y attenuated FEV1 decline, SE: 1.0 mL/y; P = 0.017, n = 364), and current smokers (2.8-mL/y, SE: 1.6 mL/y; P = 0.079, n = 214), but there was little to no effect in former smokers (-0.64-mL/y, SE: 0.9 mL/y; P = 0.45, n = 564).

CONCLUSIONS

Greater response to vitE supplementation was associated with attenuated FEV1 decline. The response to supplementation differed by rs2108622 such that individuals with the C allele, compared with the T allele, may need a higher dietary intake to reach the same plasma vitE concentration.

Visceral adiposity index is associated with lung function impairment: a population-based study

Background

The effects of visceral adiposity on decreased lung function have drawn much attention. Recently, the visceral adiposity index (VAI) has been proposed as a visceral fat distribution and dysfunction marker. However, the relationship between the VAI and lung function has not been investigated. The objective of the study was to analyze the association between the VAI and lung function and evaluate the potential of VAI as a predictor of lung function.

Methods

We collected data from a population-based study of 1786 subjects aged 40 years or older. All subjects completed a questionnaire and underwent anthropometric measurements and laboratory tests. Linear and logistic regression models were developed to assess the association between the VAI and lung function.

Results

The VAI was inversely related to FVC%predicted in men and negatively associated with both FVC%predicted and FEV1%predicted in women. In the linear regression analysis, the decrease in FVC%predicted associated with each 10% increase in the VAI was 1.127% in men and 1.943% in women; the decrease in FEV1%predicted associated with each 10%increase in the VAI was 0.663% in men and 1.738% in women. Further regression analysis revealed that the VAI was positively correlated with FVC and FEV1 impairment in women.

Conclusions

We were the first to show a clear correlation between the VAI and lung function impairment in the Chinese population. The VAI could be a simple and reliable approach in daily practice, and individuals, especially women with a high VAI, should receive additional screening and preventive interventions for respiratory disease.

Dietary total antioxidant capacity significantly interacts with 6-P21 rs2010963 gene polymorphisms in terms of cardio-metabolic risk factors in patients with metabolic syndrome

OBJECTIVE

Gene- nutrient interaction might possibly be involved in the pathogenesis of metabolic syndrome and its components. In the current report, the association between antioxidant potential of the diet with 6P21 rs2010963 gene polymorphism in patients with metabolic syndrome has been evaluated. Two hundred fifty-four patients with metabolic syndrome were enrolled. Total dietary antioxidant capacity (TAC) has been estimated and anthropometric assessments were assessed. Biochemical assays including serum glucose, matrix metalloproteinase-3, liver enzymes and lipid profiles were also assessed. Polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) method was used for determination of 6P21 rs2010963 polymorphism.

RESULTS

Dietary vitamin E score was significantly higher in GC genotype compared with other genotypes (P = 0.035). Patients in CC genotype of 6P21 rs2010963 had significantly higher body mass index (BMI), fasting blood sugar and liver enzymes (P < 0.05). Being in the higher dietary TAC scores was also associated with lower liver enzymes. The interaction between 6P21 rs2010963 and dietary TAC significantly affected BMI, FBS and diastolic blood pressure (P < 0.05). According to our findings the CC genotype of 6P21 rs2010963 could be considered as the possible risk factor for obesity and metabolic disorders among patients with metabolic syndrome.

Waist Circumference and Spirometric Measurements in Chronic Obstructive Pulmonary Disease

Objectives

The aim of this study was to evaluate whether the waist circumference of patients with chronic obstructive pulmonary disease (COPD), had an impact on lung function.

Methods

There were 180 patients with COPD recruited into this prospective cross-sectional study. The age, weight, body mass index and waist circumference (WC) were measured. Spirometry parameters including forced vital capacity (FVC), and forced expiratory volume in the first second (FEV1), were measured and FEV1/FVC calculated.

Results

The mean FEV1/FVC in both normal weight and overweight patients, did not statistically significantly correlate with WC. The COPD assessment test, positively correlated with WC ( p = 0.031). A positive correlation with body mass index ( p < 0.001), smoking ( p = 0.027), and global initiative for chronic obstructive lung disease score ( p = 0.009), were observed to positively associate with WC. WC, age, C-reactive protein, duration of disease, and gender (male), were observed to be statistically significant risk factors for the severity of COPD.

Conclusion

WC was not observed to impact upon lung function in this study but it was a predictive factor for COPD severity in patients.

Spirometric Pulmonary Restriction in Herbicide-Exposed U.S. Vietnam War Veterans

Spirometric restriction in herbicide-exposed U.S. Army Chemical Corps Vietnam War veterans was examined because no published research on this topic in Vietnam War veterans exists. Spirometry was conducted on 468 veterans who served in chemical operations in a 2013 study assessing the association between chronic obstructive pulmonary disease (COPD) and herbicide exposure. Exposure was verified based on blood serum values of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Further, the association between herbicide exposure and spirometry restriction (forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC) ≥ lower limit of normal (LLN) and FVC < LLN) was tested after adjustment for military characteristics, selected anthropometrics, and other predictors using multivariable regression. Spirometric restriction in herbicide sprayers (15.7%, 95% CI: 10.6, 20.9) was almost twice that of nonsprayers (9.91%, 95% CI: 5.9, 13.9) (p = 0.081). While spirometric restriction was not significantly associated with herbicide exposure (adjusted odds ratio (aOR) = 1.64, 95% CI: 0.82, 3.29) despite the greater prevalence of restriction in sprayers versus nonsprayers, spirometric restriction was significantly associated with race/ethnicity (aOR = 3.04, 95% CI: 1.36, 6.79) and waist circumference (aOR = 2.46, 95% CI: 1.25, 4.85). Because restrictive pulmonary disease may result from chemically-induced inflammation or sensitivity, research on chemical exposures and restriction in veterans should continue. Future study should include full pulmonary function testing, targeted research designs, and a wider set of explanatory variables in analysis, such as other determinants of health.

Association between risk factors of metabolic syndrome with lung function

BACKGROUND/OBJECTIVES

Increased evidence suggests that metabolic syndrome (MetS) is correlated with lung function impairment. This study aimed to explore the associations between MetS risk factors and the lung function.

SUBJECTS/METHODS

The cross-sectional study included 6945 participants attending health examination between 2010 and 2012 in Taiwan. MetS was assessed according to the criteria of National Cholesterol Education Program III. Spirometric parameters were measured to define lung function. The relationships were tested using multiple linear regression and logistic regression analyses.

RESULTS

The prevalence of MetS was significantly higher in males (16.2%) than females (3.8%). Although the prevalence of restrictive lung disease (RLD) was comparable between genders (20.7 and 21.0%), males with co-existent MetS had a higher prevalence of RLD than females (27.4 vs. 18.0%). Abdominal obesity, indicated by waist circumference (WC) and weight-to-height ratio (WHtR), was the most significant factor associated with lung function decline. Other components of MetS also showed statistically significant relationships, but very weak, with lung function. There was a trend toward an increased prevalence of RLD with the increasing number of MetS scores in males, independent of age, smoking, and body mass index.

CONCLUSIONS

Abdominal obesity was the key component of MetS associated with mechanical effect on lung function impairment in a prime-age adult population. Although RLD was not associated with increased probability of having MetS, the participants with more MetS scores were at a higher risk of losing lung function.

Interactive effects of adiposity and insulin resistance on the impaired lung function in asthmatic adults: cross-sectional analysis of NHANES data

BACKGROUND

Obesity is considered a risk factor for both asthma and insulin resistance in adults. Insulin resistance (IR) also influences pulmonary function in the non-obese population.

AIM

To investigate the modifying effect of insulin resistance on the predictive role of anthropometric measures in the estimation of impaired lung function among asthmatic adults.

SUBJECTS AND METHODS

A cross-sectional study of 1276 adults extracted from the NHANES 2009-2012 database was performed. Adjusted multiple linear regression was conducted to analyse the contributory role of obesity and IR in predicting lung function among asthmatic adults.

RESULTS

BMI, waist circumference (WC) and waist-to-height ratio (WHtR) showed significantly negative correlations with FVC (r=-0.24, -0.18, -0.39, respectively; p < 0.001), FEV1(r=-0.24, -0.21, -0.40, respectively; p < 0.001) and FEF 25-75% (r=-0.15, -0.18, -0.27, respectively; p < 0.001). Even after adjustment for the covariates (age, gender, smoking history and standing height), BMI and HOMA-IR had significant relationships with FVC (β= -10.3; p < 0.01 and β= -16.0; p < 0.05) and FEV1 (β= -8.7; p < 0.01 and β= -11.7; p < 0.05). BMI could significantly predict the decreased FVC (β= -13.7; p < 0.01) and FEV1 (β= -10.7; p < 0.01) only in the insulin resistant asthmatics.

CONCLUSION

WHtR and IR predict impaired lung function in overweight/obese asthmatic adults independently. IR also modifies the association between excessive adiposity and respiratory function in asthmatic adults.

Potential Micronutrients and Phytochemicals against the Pathogenesis of Chronic Obstructive Pulmonary Disease and Lung Cancer

Lung cancer and chronic obstructive pulmonary disease have shared etiology, including key etiological changes (e.g., DNA damage and epigenetics change) and lung function impairment. Focusing on those shared targets may help in the prevention of both. Certain micronutrients (vitamins and minerals) and phytochemicals (carotenoids and phenols) have potent antioxidant or methyl-donating properties and thus have received considerable interest. We reviewed recent papers probing into the potential of nutrients with respect to lung function preservation and prevention of lung cancer risk, and suggest several hypothetical intervention patterns. Intakes of vitamins (i.e., A, C, D, E, B₁₂), carotenoids, flavonoids, curcumins, resveratrol, magnesium, and omega-3 fatty acids all show protective effects against lung function loss, some mainly by improving average lung function and others through reducing decline rate. Dietary interventions early in life may help lung function reserve over the lifespan. Protective nutrient interventions among smokers are likely to mitigate the effects of cigarettes on lung health. We also discuss their underlying mechanisms and some possible causes for the inconsistent results in observational studies and supplementation trials. The role of the lung microbiome on lung health and its potential utility in identifying protective nutrients are discussed as well. More prospective cohorts and well-designed clinical trials are needed to promote the transition of individualized nutrient interventions into health policy.

Influence of Socioeconomic and Anthropometric Factors on Respiratory Function in Female University Students

The purpose of this study was to evaluate lung function in healthy young female university students and to seek the relation of lung function to socioeconomic and anthropometric indices. The methodology consisted of spirometry tests, anthropometric measures and a questionnaire conducted in November of 2015 among 152 female university students. At first, lung function was analyzed for any relationship with socioeconomic factors and smoking. The results of a multi-factor analysis of variance demonstrate significant differences in the FEV1/FVC ratio depending on the general socioeconomic status. Then, anthropometric and spirometric parameters were tested for correlations. A comparison of underweight, normal weigh, overweight, and obese subjects revealed statistically significant differences for FVC% and FEV1/FVC, with the highest values noted in the subjects of normal weight. Individuals with abdominal obesity had lower FVC% and FEV1% and a higher FEV1/FVC ratio. The findings of our study confirm that both general obesity and abdominal obesity are related to a reduced lung function.

Association of neck circumference and pulmonary function in children

BACKGROUND

Childhood obesity leads to many complications including impaired respiratory function. There are various anthropometric parameters related to obesity.

OBJECTIVE

To investigate the correlation between anthropometric indices and pulmonary function test results in children without asthma.

METHODS

Children without any respiratory disorders were enrolled in this study. Anthropometric measurements, such as height, weight, neck circumference (NC), and waist circumference, were obtained from the enrollees and body mass index was calculated. Afterward, pulmonary function tests were performed using spirometry.

RESULTS

A total of 178 children (106 boys, 59.5%) with a mean age of 9.7 years were included the study. NC was above the 90th percentile in 65 children. Importantly, pulmonary parameters, such as forced expiratory volume during the first second (FEV₁) and the ratio of FEV₁ to forced vital capacity (FVC), were lower in subjects with a large NC. Similarly, waist circumference was above the 90th percentile in 67 children, and FEV₁/FVC was significantly lower in children with a large waist circumference. Moreover, there was a statistically significant negative correlation among FEV₁, FEV₁/FVC, and body mass index SD score. Also, multivariable linear regression analysis showed that an NC above the 90th percentile was associated with lower FEV₁ and FEV₁/FVC values.

CONCLUSION

We identified NC as a novel anthropometric index that is strongly correlated with respiratory functions in children. Therefore, close monitoring of respiratory symptoms, particularly in children with obesity and a large NC, could help with early and prompt determination of respiratory complications of obesity.

The relationship between body fat and respiratory function in young adults

The relationship between adiposity and respiratory function is poorly understood. Most studies investigating this have used indirect measures of body fat and few have assessed how changes in adiposity influence lung function.Body fat measured by bio-electrical impedance analysis, body mass index, waist circumference, spirometry, body plethysmography and transfer factor were measured at ages 32 and 38 years in 361 non-smoking, non-asthmatic participants from a population-based birth cohort.Higher percentage body fat was associated with lower spirometric and plethysmographic lung volumes, but not with airflow obstruction, or transfer factor at 32 years. Changes in adiposity between ages 32 and 38 years were inversely associated with changes in lung volumes. These associations were generally stronger in men than women, but an association between increasing adiposity and lower airway function (forced expiratory volume in 1 s/forced vital capacity) was only found in women. Similar associations were found for body mass index and waist circumference.Higher percentage body fat is associated with lower lung volumes. Direct and indirect measures of adiposity had similar associations with lung function. Adiposity had a greater effect on lung volumes in men than women but was associated with airway function only in women. There was little evidence that adiposity influenced transfer factor.

Associations between antioxidants and all-cause mortality among US adults with obstructive lung function

Chronic obstructive pulmonary disease is characterised by oxidative stress, but little is known about the associations between antioxidant status and all-cause mortality in adults with this disease. The objective of the present study was to examine the prospective associations between concentrations of α- and β-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene, Se, vitamin C and α-tocopherol and all-cause mortality among US adults with obstructive lung function. Data collected from 1492 adults aged 20-79 years with obstructive lung function in the National Health and Nutrition Examination Survey III (1988-94) were used. Through 2006, 629 deaths were identified during a median follow-up period of 14 years. After adjustment for demographic variables, the concentrations of the following antioxidants modelled as continuous variables were found to be inversely associated with all-cause mortality among adults with obstructive lung function: α-carotene (P= 0·037); β-carotene (P= 0·022); cryptoxanthin (P= 0·022); lutein/zeaxanthin (P= 0·004); total carotenoids (P= 0·001); vitamin C (P< 0·001). In maximally adjusted models, only the concentrations of lycopene (P= 0·013) and vitamin C (P= 0·046) were found to be significantly and inversely associated with all-cause mortality. No effect modification by sex was detected, but the association between lutein/zeaxanthin concentrations and all-cause mortality varied by smoking status (P interaction= 0·048). The concentrations of lycopene and vitamin C were inversely associated with all-cause mortality in this cohort of adults with obstructive lung function.

Overweight and obesity may lead to under-diagnosis of airflow limitation: findings from the Copenhagen City Heart Study

BACKGROUND

The prevalence of obesity has increased during the last decades and varies from 10-20% in most European countries to approximately 32% in the United States. However, data on how obesity affects the presence of airflow limitation (AFL) defined as a reduced ratio between forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) are scarce.

METHODS

Data was derived from the third examination of the Copenhagen City Heart Study from 1991 until 1994 (n = 10,135). We examine the impact of different adiposity markers (weight, body mass index (BMI), waist circumference, waist-hip ratio, and abdominal height) on AFL. AFL was defined in four ways: FEV1/FVC ratio < 0.70, FEV1/FVC ratio < lower limit of normal (LLN), FEV1/FVC ratio <0.70 including at least one respiratory symptom, and FEV1/FVC ratio < LLN and FEV1% of predicted < LLN.

RESULTS

All adiposity markers were positively and significantly associated with FEV1/FVC independent of age, sex, height, smoking status, and cumulative tobacco consumption. Among all adiposity markers, BMI was the strongest predictor of FEV1/FVC. FEV1/FVC increased with 0.04 in men and 0.03 in women, as BMI increased with 10 units (kg · m-2). Consequently, diagnosis of AFL was significantly less likely in subjects with BMI ≥ 25 kg · m-2 with odds ratios 0.63 or less compared to subjects with BMI between 18.5-24.9 kg · m-2 when AFL was defined as FEV1/FVC < 0.70.

CONCLUSION

High BMI reduces the probability of AFL. Ultimately, this may result in under-diagnosis and under-treatment of COPD among individuals with overweight and obesity.

Influence of diet and obesity on COPD development and outcomes

The global increase in the prevalence and incidence of obesity has called serious attention to this issue as a major public health concern. Obesity is associated with many chronic diseases, including cardiovascular disease and diabetes, and recently the role of overweight and obesity in lung disease has received new interest. Independently of obesity, diet also plays a role as a risk factor for many chronic diseases, and evidence is accumulating to support a role for diet in the prevention and management of several lung diseases. Chronic obstructive lung disease is the third-leading cause of death globally, and both obesity and diet appear to play roles in its pathophysiology. Obesity has been associated with decreased lung-function measures in population-based studies, with increased prevalence of several lung diseases and with compromised pulmonary function. In contrast, obesity has a protective effect against mortality in severe chronic obstructive pulmonary disease (COPD). Nutrient intake and dietary patterns have also been associated with lung-function measures and the development and progression of COPD. Taken together, this suggests that a focus on obesity and diet should be part of public health campaigns to reduce the burden of lung disease, and could have important implications for clinicians in the management of their patients. Future research should also focus on elucidating these relationships in diverse populations and age-groups, and on understanding the complex interaction between behavior, environment, and genetics in the development and progression of COPD. The goal of this article is to review current evidence regarding the role that obesity and diet play in the development of COPD, and in COPD-related outcomes.

Promotion of lung health: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases

Lung-related research primarily focuses on the etiology and management of diseases. In recent years, interest in primary prevention has grown. However, primary prevention also includes "health promotion" (actions in a population that keep an individual healthy). We encourage more research on population-based (public health) strategies that could not only maximize lung health but also mitigate "normal" age-related declines-not only for spirometry but across multiple measures of lung health. In developing a successful strategy, a "life course" approach is important. Unfortunately, we are unable to achieve the full benefit of this approach until we have better measures of lung health and an improved understanding of the normal trajectory, both over an individual's life span and possibly across generations. We discuss key questions in lung health promotion, with an emphasis on the upper (healthier) end of the distribution of lung functioning and resiliency and briefly summarize the few interventions that have been studied to date. We conclude with suggestions regarding the most promising future research for this important, but largely neglected, area of lung research.

Environmental perturbations: Obesity

Obesity currently affects about one-third of the U.S. population, while another one-third is overweight. The importance of obesity for certain conditions such as heart disease and type 2 diabetes is well appreciated. The effects of obesity on the respiratory system have received less attention and are the subject of this article. Obesity alters the static mechanical properties of the respiratory system leading to a reduction in the functional residual capacity (FRC) and the expiratory reserve volume (ERV). There is substantial variability in the effects of obesity on FRC and ERV, at least some of which is related to the location rather than the total mass of adipose tissue. Obesity also results in airflow obstruction, which is only partially attributable to breathing at low lung volume, and can also promote airway hyperresponsiveness and asthma. Hypoxemia is common is obesity and correlates well with FRC, as well as with measures of abdominal obesity. However, obese subjects are usually eucapnic, indicating that hypoventilation is not a common cause of their hypoxemia. Instead, hypoxemia results from ventilation-perfusion mismatch caused by closure of dependent airways at FRC. Many obese subjects complain of dyspnea either at rest or during exertion, and the dyspnea score also correlates with reductions in FRC and ERV. Weight reduction should be encouraged in any symptomatic obese individual, since virtually all of the respiratory complications of obesity improve with even moderate weight loss.

Improving asthma during pregnancy with dietary antioxidants: the current evidence

The complication of asthma during pregnancy is associated with a number of poor outcomes for the mother and fetus. This may be partially driven by increased oxidative stress induced by the combination of asthma and pregnancy. Asthma is a chronic inflammatory disease of the airways associated with systemic inflammation and oxidative stress, which contributes to worsening asthma symptoms. Pregnancy alone also intensifies oxidative stress through the systemic generation of excess reactive oxidative species (ROS). Antioxidants combat the damaging effects of ROS; yet antioxidant defenses are reduced in asthma. Diet and nutrition have been postulated as potential factors to combat the damaging effects of asthma. In particular, dietary antioxidants may play a role in alleviating the heightened oxidative stress in asthma. Although there are some observational and interventional studies that have shown protective effects of antioxidants in asthma, assessment of antioxidants in pregnancy are limited and there are no antioxidant intervention studies in asthmatic pregnancies on asthma outcomes. The aims of this paper are to (i) review the relationships between oxidative stress and dietary antioxidants in adults with asthma and asthma during pregnancy, and (ii) provide the rationale for which dietary management strategies, specifically increased dietary antioxidants, might positively impact maternal asthma outcomes. Improving asthma control through a holistic antioxidant dietary approach might be valuable in reducing asthma exacerbations and improving asthma management during pregnancy, subsequently impacting perinatal health.

Obesity and asthma: physiological perspective

Obesity induces some pertinent physiological changes which are conducive to either development of asthma or cause of poorly controlled asthma state. Obesity related mechanical stress forces induced by abdominal and thoracic fat generate stiffening of the lungs and diaphragmatic movements to result in reduction of resting lung volumes such as functional residual capacity (FRC). Reduced FRC is primarily an outcome of decreased expiratory reserve volume, which pushes the tidal breathing more towards smaller high resistance airways, and consequentially results in expiratory flow limitation during normal breathing in obesity. Reduced FRC also induces plastic alteration in the small collapsible airways, which may generate smooth muscle contraction resulting in increased small airway resistance, which, however, is not picked up by spirometric lung volumes. There is also a possibility that chronically reduced FRC may generate permanent adaptation in the very small airways; therefore, the airway calibres may not change despite weight reduction. Obesity may also induce bronchodilator reversibility and diurnal lung functional variability. Obesity is also associated with airway hyperresponsiveness; however, the mechanism of this is not clear. Thus, obesity has effects on lung function that can generate respiratory distress similar to asthma and may also exaggerate the effects of preexisting asthma.

Ratio of waist circumference to chest circumference is inversely associated with lung function in Chinese children and adolescents

BACKGROUND AND OBJECTIVE

In White children, waist circumference (WC) is positively correlated with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)). Because fat distribution differs among different races, the relationship between WC and lung function in Asian children may differ from that in White children. The present study aimed to examine the effect of WC on ventilatory function in Chinese children.

METHODS

A cross-sectional study was performed on 1572 healthy subjects aged 9-18 years. Height, weight, chest circumference (CC), WC and lung function (FVC, FEV(1), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF)) were measured. To avoid the problem of colinearity, a model that combined CC and WC as the waist-to-chest ratio (WCR) was used. The relative contributions of WCR and body mass index (BMI) to spirometric parameters were determined by linear regression analysis.

RESULTS

WCR was inversely associated with all spirometric parameters. On average, each 0.01 increase in WCR was associated with decreases of 8.14 mL for FVC, 9.36 mL for FEV(1), 6.54% for FEV(1)/FVC, 19.81 mL/s for PEF and 17.25 mL/s for MMEF. BMI was positively associated with all spirometric parameters except FEV(1)/FVC. These results suggest that WC was inversely associated with lung function parameters.

CONCLUSIONS

Inverse associations were identified between WCR, as well as WC, and lung function in a population of Chinese children. The underlying mechanisms need to be further explored.

Central obesity and asthma outcomes in adults diagnosed with asthma

OBJECTIVE

The potential role of central obesity in asthma outcomes has been examined in a few studies. The aim of this study was to examine the relationship between central obesity and asthma outcomes in a group of Iranian asthma patients.

METHODS

One hundred and forty-two outpatients with asthma were studied. Central obesity was defined according to National Institute of Health (NIH) and Asian waist circumference (WC) and waist-to-hip ratio (WHR) cut-offs. Asthma outcomes including asthma control, pulmonary function, and morbidity were evaluated. The association between central obesity and asthma outcomes was studied by linear and logistic regression analyses.

RESULTS

Linear regression analysis showed a significant association of WHR-based central obesity with forced expiratory volume in 1 s (FEV(1)) (β = -9.04; p-value = .044) and forced vital capacity (FVC) (β = -10.52; p-value = .012). Logistic regression analysis showed a significant increased risk of asthma attacks in 3 months with Asian WC-based central obesity [odds ratio (OR) = 6.31, 95% confidence interval (CI): 1.16-34.41]; emergency room (ER) visits with NIH WC-based (OR = 5.15, 95% CI: 1.36-19.55) and Asian WC-based (OR = 18.72, 95% CI: 1.92-182.63) central obesity; and hospitalization in 1 year with NIH WC-based (OR = 5.28, 95% CI: 1.28-21.84) and Asian WC-based (OR = 12.39, 95% CI: 1.29-119.53) central obesity.

CONCLUSIONS

Our study shows that the Asian WC-based central obesity is a better predictor of asthma morbidity. The results of this study emphasize, when studying the relationship between asthma control and obesity, the importance of selecting the proper definitions for asthma control or central obesity and appropriate cutpoints. Further study in this field using other asthma control and quality of life questionnaires is warranted.

Waist circumference and pulmonary function: a systematic review and meta-analysis

BACKGROUND

Studies have reported an impact of central obesity on people's health. The literature is scarce on the effects of waist circumference (WC) on pulmonary function. Our objective was to review the literature on the association between WC and pulmonary function.

METHODS

A systematic review was carried out in the PubMed, CINAHL, Web of Science and Scopus databases. The search included published, in press and online documents up to December 2011. A meta-analysis was carried out to obtain the pooled effect, and a meta-regression was performed to evaluate sources of heterogeneity.

RESULTS

From the 547 studies identified, 10 were included. The meta-analysis revealed an inverse relationship between WC and pulmonary function parameters, indicating that the effect was greater among men (forced expiratory volume in 1 second (FEV1 β = -15.9 (95% confidence interval = -23.2, -8.5); forced vital capacity (FVC) β = -16.6 (95% confidence interval = -21.0, -12.2)) compared with women (FEV1 β = -5.6 (95% confidence interval = -9.1, -2.1); FVC β = -7.0 (95% confidence interval = -9.1, -4.8)). The meta-regression identified sex as the characteristic that most contributed to the heterogeneity (R2 = 54.8% for FEV1 and R2 = 85.7% for FVC).

CONCLUSIONS

There seems to be an inverse relationship between WC and pulmonary function, mainly in men. More population-based studies should be performed, especially among children and adolescents, to confirm these findings.

The Relationship between Metabolic Syndrome and Pulmonary Function

BACKGROUND

Impaired lung function is associated with mortality rate from cardiovascular and all other death causes. There were previous studies on the relationship between lung function impairment and metabolic syndrome, but they are insufficient. This study was conducted on Koreans to analyze each component of metabolic syndrome as well as its variability between sexes.

METHODS

1,370 subjects underwent a health examination at the Eulji General Hospital Health Center. We examined the association between lung function measurement (forced expiratory volume for 1 second [FEV(1)], forced vital capacity [FVC], FEV(1)/FVC) and metabolic syndrome using Student t-test, Pearson partial correlation coefficient, and analysis of covariance for statistical analysis, and we adopted metabolic syndrome defined by American Heart Association/National Heart, Lung, and Blood Institute in Asia.

RESULTS

Men with metabolic syndrome tended to experience lung function impairment. In terms of association to each metabolic syndrome component, metabolic syndrome components in men were associated with pulmonary function impairment and the more metabolic syndrome diagnostic criteria factors the patients had, the more severe their pulmonary function tended to decline. In women, waist circumference, triglyceride and high-density lipoprotein cholesterol were associated with pulmonary function change.

CONCLUSION

In men, all metabolic syndrome components were associated with pulmonary function impairment, and the more metabolic syndrome components men had, the more severe their pulmonary functions decline. In women, components of metabolic syndrome were not associated with pulmonary function impairment.

Candidates for bariatric surgery: morbidly obese patients with pulmonary dysfunction

Obesity is a well-known major risk factor of cardiovascular disease and is associated with various comorbidities. The impact of obesity on pulmonary function remains unclear. Reductions in chest wall compliance and respiratory muscle strength due to a high percent body fat and localized fat distribution contributes to impaired pulmonary function and the occurrence of adverse respiratory symptoms. Dietary modifications and pharmaceutical agents are not effective in the long-term treatment of obesity. Treatment of morbidly obese patients using bariatric surgery has increased each year, especially after the introduction of video laparoscopic techniques. Effective weight loss after bariatric surgery may improve cardiovascular disease risk factors, including diabetes, hypertension, dyslipidemia, atherosclerosis, inflammation, chronic kidney disease, obstructive sleep apnea, and obesity hypoventilation syndrome. Bariatric surgery has also been associated with significantly improved respiratory symptoms and pulmonary function. We currently present a review of principal studies that evaluated the effects of obesity on pulmonary function and the identification of anthropometric factors of obesity that correspond to the reversal of respiratory symptoms and impaired pulmonary function after bariatric surgery.

Serum carotenoid concentrations predict lung function evolution in young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) study

BACKGROUND

A higher dietary intake of carotenoid-rich foods and higher circulating concentrations of carotenoids have been associated with better lung function in cross-sectional studies; however, the longitudinal association between carotenoids and lung function has shown conflicting results.

OBJECTIVE

We examined the longitudinal association between serum carotenoids (β-cryptoxanthin, α-carotene, β-carotene, lutein/zeaxanthin, and lycopene) and the evolution of lung function.

DESIGN

We evaluated our hypothesis in the Coronary Artery Risk Development in Young Adults (CARDIA) prospective cohort study. Spirometry testing was conducted at year 0 (1985-1986) and at follow-up in years 2, 5, 10, and 20; serum carotenoids were assayed at years 0 and 15, and diet was assessed at years 0 and 20.

RESULTS

Year 0 sum of provitamin A carotenoids and β-cryptoxanthin concentrations were associated with maximum forced vital capacity (FVC) (P ≤ 0.01) and forced expiratory volume in 1 s (FEV(1)) (P ≤ 0.05) (maximum across years 0-10) in linear regression models adjusted for age, race, height, study center, amount of physical activity, smoking status, and BMI. Year 0 lutein/zeaxanthin and lycopene were not associated with maximum lung function. Baseline concentrations of lutein/zeaxanthin, lycopene, sum of the 3 provitamin A carotenoids, β-carotene, and β-cryptoxanthin were each inversely associated with a decline from maximum FVC and FEV(1) (P ≤ 0.04). The sum of provitamin A carotenoids and lycopene remained significant after adjustment for dietary intake related to serum carotenoids (P ≤ 0.03). The 15-y change in provitamin A carotenoid and lutein/zeaxanthin concentrations was associated with a slower decline from maximum FVC and FEV(1) (P ≤ 0.04).

CONCLUSION

These findings support an association between serum carotenoid concentrations and a decline in lung function.

Dietary antioxidants and forced expiratory volume in 1 s decline: the Health, Aging and Body Composition study

Increased antioxidant defences are hypothesised to decrease age- and smoking-related decline in lung function. The relationship between dietary antioxidants, smoking and forced expiratory volume in 1 s (FEV(1)) was investigated in community-dwelling older adults in the Health, Aging and Body Composition study. 1,443 participants completed a food frequency questionnaire, self-reported smoking history and had measurements taken of FEV(1) at both baseline and after 4 yrs of follow-up. The association of dietary intake of nutrients and foods with antioxidant properties and rate of FEV(1) decline was investigated using hierarchical linear regression models. In continuing smokers (current smokers at both time-points), higher vitamin C intake and higher intake of fruit and vegetables were associated with an 18 and 24 mL · yr(-1) slower rate of FEV(1) decline compared with a lower intake (p < 0.0001 and p = 0.003, respectively). In quitters (a current smoker at study baseline who had quit during follow-up), higher intake was associated with an attenuated rate of decline for each nutrient studied (p ≤ 0.003 for all models). In nonsmoking participants, there was little or no association of diet and rate of decline in FEV(1). The intake of nutrients with antioxidant properties may modulate lung function decline in older adults exposed to cigarette smoke.

Surgically induced weight loss, including reduction in waist circumference, is associated with improved pulmonary function in obese patients

BACKGROUND

Obesity is associated with impaired pulmonary function. We evaluated the effect of bariatric surgery on pulmonary function among obese patients and identified potential anthropometric factors of obesity corresponding to the reversal of impaired pulmonary function.

METHODS

Pulmonary function and anthropometric factors were studied in 94 obese patients aged 18-65 years with a body mass index >32 kg/m(2). Pulmonary function tests were performed preoperatively and 3 months after bariatric surgery. The measurements included forced vital capacity (FVC), forced expiratory volume in the first second (FEV(1)), total lung capacity, expiratory reserve volume, residual volume, and diffusing capacity of the lung for carbon monoxide. The anthropometric factors included the body weight, body mass index, waist circumference (WC), hip circumference, waist/height ratio, and waist/hip ratio. The changes in anthropometric parameters were analyzed in relation to pulmonary function test results. Multiple linear regression models were applied to identify the factors that influenced pulmonary function after bariatric surgery.

RESULTS

When measured 3 months after surgery, all anthropometric parameters for the 94 patients studied had significantly decreased, and the pulmonary function test parameters had significantly improved. Of the anthropometric parameters, the reduction in body weight, WC, and waist/height ratio correlated significantly with increases in the FEV(1) and FVC. In the multiple linear regression analysis, only the reduction in WC correlated significantly with the reductions in the FEV(1) and FVC.

CONCLUSION

After bariatric surgery, all anthropometric parameters of obesity decreased significantly and the pulmonary function improved. This improvement correlated best with the reduction in the WC and perhaps a decreased intra-abdominal pressure.

An official American Thoracic Society public policy statement: Novel risk factors and the global burden of chronic obstructive pulmonary disease

RATIONALE

Although cigarette smoking is the most important cause of chronic obstructive pulmonary disease (COPD), a substantial proportion of COPD cases cannot be explained by smoking alone.

OBJECTIVES

To evaluate the risk factors for COPD besides personal cigarette smoking.

METHODS

We constituted an ad hoc subcommittee of the American Thoracic Society Environmental and Occupational Health Assembly. An international group of members was invited, based on their scientific expertise in a specific risk factor for COPD. For each risk factor area, the committee reviewed the literature, summarized the evidence, and developed conclusions about the likelihood of it causing COPD. All conclusions were based on unanimous consensus.

MEASUREMENTS AND MAIN RESULTS

The population-attributable fraction for smoking as a cause of COPD ranged from 9.7 to 97.9%, but was less than 80% in most studies, indicating a substantial burden of disease attributable to nonsmoking risk factors. On the basis of our review, we concluded that specific genetic syndromes and occupational exposures were causally related to the development of COPD. Traffic and other outdoor pollution, secondhand smoke, biomass smoke, and dietary factors are associated with COPD, but sufficient criteria for causation were not met. Chronic asthma and tuberculosis are associated with irreversible loss of lung function, but there remains uncertainty about whether there are important phenotypic differences compared with COPD as it is typically encountered in clinical settings.

CONCLUSIONS

In public health terms, a substantive burden of COPD is attributable to risk factors other than smoking. To prevent COPD-related disability and mortality, efforts must focus on prevention and cessation of exposure to smoking and these other, less well-recognized risk factors.

The effects of fatness and fat distribution on respiratory functions

BACKGROUND

Inverse relationships between respiratory function and indices of obesity and fat distribution have been reported, but it remains unclear which measure of obesity shows the strongest relationship with lung function.

AIM

The study assessed the effect of fatness and fat distribution on respiratory function.

SUBJECTS AND METHODS

A sample of 423 males and 509 females aged 40-50 years were examined in the Silesian Centre for Preventive Medicine, DOLMED, in Wrocław in 1995. The strength of influence of height, body mass index (BMI), wait-to-hip ratio (WHR) and abdominal and subscapular skinfolds upon forced vital capacity (FVC) and forced expiratory volume in a 1-s expiration (FEV1) was assessed by multiple regression analysis.

RESULTS

In males, FVC was strongly positively associated with height and BMI, but negatively associated with subscapular and abdominal skinfolds, WHR, and smoking. FEV1 showed a positive relationship with height, BMI and WHR. In females, both FVC and FEV1 showed significant positive associations with height, negative ones with subscapular skinfold, and no association with either WHR or abdominal skinfold. In males, respiratory function is affected to a similar extent by fat in the abdominal region and by fatness of the chest. In females, fatness of the thorax has the strongest relationship with respiratory function.

CONCLUSION

Fatness tends to impair respiratory function in both sexes but these effects show a different pattern in males and females. In males, respiratory functions are significantly, and to a similar extant, affected by fatness in the abdominal region, both subcutaneous and visceral, and by fatness on the chest. In females, it is primarily subcutaneous fat on the upper thorax that affects respiratory functions, while visceral and subcutaneous abdominal fatness play little or no role.

Waist circumference associated with pulmonary function in children

In adults abdominal obesity is related to lung dysfunction and waist circumference (WC) predicts pulmonary function. It is not known how WC affects pulmonary function in children. A cross-sectional study of 718 children 6-17 years of age was conducted in a rural community to determine the predictability of WC for pulmonary function in children. Height, weight, WC, and pulmonary function were measured. Multivariate analysis was conducted. WC was positively associated with FVC and FEV(1) and was more strongly associated with FVC than with FEV(1). Increase in WC significantly predicted a reduction in FEV(1)/FVC. After adjustment for sex, age, and height, an increase of 1 cm for WC was associated with an increase of 7 ml of FVC and 4 ml of FEV(1), and with an increase of 4 ml of FVC and 2 ml of FEV(1) with an additional adjustment for weight. Height and weight were not significantly associated with FEV(1)/FVC. WC but not body mass index predicted a decline of FEV(1)/FVC. WC had a larger impact on FVC than FEV(1). WC, but not BMI, was negatively associated with FEV(1)/FVC in children.

Lung function impairment and metabolic syndrome: the critical role of abdominal obesity

RATIONALE

Increased risk for cardiovascular morbidity and mortality has been related to both lung function impairment and metabolic syndrome. Data on the relationship between lung function and metabolic syndrome are sparse.

OBJECTIVES

To investigate risk for lung function impairment according to metabolic syndrome traits.

METHODS

This cross-sectional population-based study included 121,965 men and women examined at the Paris Investigations Préventives et Cliniques Center between 1999 and 2006. The lower limit of normal was used to define lung function impairment (FEV(1) or FVC < lower limit of normal). Metabolic syndrome was assessed according to the American Heart Association/National Heart, Lung, and Blood Institute statement.

MEASUREMENTS AND MAIN RESULTS

We used a logistic regression model and principal component analysis to investigate the differential associations between lung function impairment and specific components of metabolic syndrome. Lung function impairment was associated with metabolic syndrome (prevalence = 15.0%) independently of age, sex, smoking status, alcohol consumption, educational level, body mass index, leisure-time physical activity, and cardiovascular disease history (odds ratio [OR] [95% confidence interval], 1.28 [1.20-1.37] and OR, 1.41 [1.31-1.51] for FEV(1) and FVC, respectively). Three factors were identified from factor analysis: "lipids" (low high-density lipoprotein cholesterol, high triglycerides), "glucose-blood pressure" (high fasting glycemia, high blood pressure), and "abdominal obesity" (large waist circumference). All factors were inversely related to lung function, but abdominal obesity was the strongest predictor of lung function impairment (OR, 1.94 [1.80-2.09] and OR, 2.11 [1.95-2.29], for FEV(1) and FVC, respectively). Similar results were obtained for women and men.

CONCLUSIONS

We found a positive independent relationship between lung function impairment and metabolic syndrome in both sexes, predominantly due to abdominal obesity. Further studies are required to clarify the underlying mechanisms.

Observational studies on the effect of dietary antioxidants on asthma: a meta-analysis

BACKGROUND AND OBJECTIVE

It has been suggested that the rapid increase in asthma prevalence may in part be due to a decrease in the intake of dietary antioxidants, including vitamin C, vitamin E and beta-carotene. Epidemiological studies investigating the association between dietary antioxidant intake and asthma have generated inconsistent results. A meta-analysis was undertaken to examine the association between dietary antioxidant intake and the risk of asthma.

METHODS

The MEDLINE database was searched for observational studies in English-language journals from 1966 to March 2007. Data were extracted using standardized forms. Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random effects model. Ten studies were eligible for inclusion. Seven studies, comprising 13 653 subjects, used asthma or wheeze as their outcome; three studies explored the effect of antioxidant intake on lung function.

RESULTS

A higher dietary intake of antioxidants was not associated with a lower risk of having asthma. The pooled OR for having asthma were 1.06 (95% CI: 0.79-1.43) for subjects with a higher dietary vitamin C intake compared with those with a lower intake; 0.88 (95% CI: 0.61-1.25) for vitamin E; and 1.12 (95% CI: 0.77-1.62) for beta-carotene. There was no significant association between dietary antioxidant intake and lung function except for a positive association between vitamin C intake and an increase in FEV(1) (29.1 mL, 95% CI: -0.4-58.6, P = 0.05).

CONCLUSIONS

This meta-analysis does not support the hypothesis that dietary intake of the antioxidants vitamins C and E and beta-carotene influences the risk of asthma.

Waist circumference is associated with pulmonary function in normal-weight, overweight, and obese subjects

BACKGROUND

Obesity is becoming a serious public health issue and is related to lung dysfunction. Because both weight and height are indicators of body size, body mass index (BMI) may not be an ideal index of obesity in prediction of pulmonary dysfunction.

OBJECTIVE

The objective of the study was to determine the predictability of waist circumference (WC) and BMI for pulmonary function in adults with and without excess body weight.

DESIGN

A cross-sectional study of 1674 adults aged > or = 18 y was conducted in a rural community. Height, weight, WC, and pulmonary function were measured. Multivariate analysis was conducted.

RESULTS

WC was negatively associated with forced vital capacity and forced expiratory volume in 1 s, and the associations were consistent across sex, age, and BMI categories. On average, a 1-cm increase in WC was associated with a 13-mL reduction in forced vital capacity and an 11-mL reduction in forced expiratory volume in 1 s. The association between WC and pulmonary function was consistent in subjects with normal weight, overweight, and obesity. In subjects with normal weight, BMI was positively associated with forced vital capacity and forced expiratory volume in 1 s.

CONCLUSION

WC, but not BMI, is negatively and consistently associated with pulmonary function in normal-weight, overweight, and obese subjects.

Pulmonary function and abdominal adiposity in the general population

BACKGROUND

The prevalence of obesity is increasing, and there is evidence that obesity, in particular abdominal obesity as a marker of insulin resistance, is negatively associated with pulmonary function. The mechanism for this association and the best marker of abdominal adiposity in relation to pulmonary function is not known.

STUDY OBJECTIVE

We assessed the association between pulmonary function and weight, body mass index (BMI), waist circumference, waist/hip ratio, and abdominal height as markers of adiposity and body fat distribution. We used multiple linear regression to analyze the association of pulmonary function (ie, FEV(1) and FVC) [with maneuvers performed in the sitting position] with overall adiposity markers (ie, weight and BMI) and abdominal adiposity markers, stratified by gender, and adjusted for height, age, race, smoking, and other covariates.

SETTING AND PARTICIPANTS

A random sample of individuals (n = 2,153) from the general population living in western New York state, 35 to 79 years of age.

RESULTS

In women, abdominal height and waist circumference were negatively associated with FEV(1) percent predicted, while all five adiposity markers were negatively associated with FVC percent predicted. In men, all overall and abdominal adiposity markers were inversely associated with FEV(1) percent predicted and FVC percent predicted.

CONCLUSION

These results suggest that abdominal adiposity is a better predictor of pulmonary function than weight or BMI, and investigators should consider it when investigating the determinants of pulmonary function.

Lung function and blood levels of copper, selenium, vitamin C and vitamin E in the general population

BACKGROUND

Increased dietary intake of antioxidants has been associated with higher lung function, but few studies have used biological markers of antioxidant intake.

OBJECTIVE

This study aimed to determine if antioxidant status, as measured by blood levels, influences lung function.

DESIGN

Using a random subsample of 479 participants, aged 18-65 y old, from a larger cross-sectional observational study, the association of forced expiratory volume in 1 s (FEV1) with plasma copper, vitamin C, vitamin E and serum selenium was assessed.

RESULTS

An s.d. increase in blood copper level was associated with a difference in FEV1 of -48 ml (95% confidence intervals: -95, -2 ml, P = 0.04), vitamin C +49 ml (+4, +94, P = 0.03), vitamin E -15 ml (-62, +32, P = 0.53) and selenium +52 ml (+7, +96, P = 0.02). The sizes of association were not appreciably altered in a mutually adjusted model.

CONCLUSIONS

Higher levels of serum vitamin C and selenium appear to be associated with higher FEV1. The association between higher serum copper and lower FEV1 requires further study in view of the ubiquitous exposure to this mineral.

Body fat distribution, body composition, and respiratory function in elderly men

BACKGROUND

Most population studies have reported weak or nonsignificant associations between body mass index (BMI; in kg/m2) and lung function.

OBJECTIVE

This study focused on the distinct effects of fat distribution and body composition on lung function and examined these relations in elderly men.

DESIGN

The study was a cross-sectional evaluation of 2744 men aged 60-79 y who were free of cardiovascular disease and cancer and were drawn from general practices in 24 British towns. Anthropometric and body-composition [including fat mass (FM), fat-free mass (FFM), and percentage body fat (%BF) evaluated with bioelectric impedance] measurements were made, and lung function was examined by using spirometry.

RESULTS

Height-standardized forced expiratory volume in 1 s (FEV1) was diminished only in lean (BMI < 22.5) and obese (BMI > or = 30) men, but forced vital capacity (FVC) tended to decrease with increasing BMI (P < 0.01). All other measures of adiposity [ie, waist circumference (WC), waist-hip ratio (WHR), FM, and %BF] were significantly and inversely related to FEV1 and FVC after adjustment for confounders, including age and cigarette smoking (all: P < 0.05). This was seen both in nonobese (BMI < 30) and obese men. FFM was positively associated with FEV1 (P = 0.03) and to a lesser extent with FVC. Higher BMI and FFM were both associated with reduced odds of a low FEV1-FVC ratio (ie, <70%).

CONCLUSION

Total body fat and central adiposity are inversely associated with lung function, but increased FFM reflecting increases in muscle mass is associated with increased lung function and lower odds of low FEV1:FVC in the elderly.

Socioeconomic deprivation and waist circumference in men and women: The Scottish MONICA surveys 1989 ?1995

Socioeconomic deprivation and waist circumference were measured in three Scottish MONICA cross-sectional surveys of 2233 men and 2516 women aged 25-64 years in 1989-1995. Means of waist circumference, waist/hip ratio (WHR) and body mass index (BMI) increased with level of deprivation (measured by the Carstairs index) more significantly in women than in men, and more significantly in non-smokers than in current-smokers. Their obesity cases defined by conventional cut-points showed similar patterns of relation to deprivation. There appeared to be more obviously consistent and significant increases in the prevalence of large waist circumference with deprivation for both sexes than in the prevalence of WHR and BMI above the 90th centile. Also there was a more significant trend of increase in waist circumference over time than there was in WHR and BMI for both sexes. Residual case-control analysis, controlling for height, showed a 'dose-response' relationship between deprivation and waist circumference. Compared to the most affluent (the first tertile of the Carstairs score), odds ratio for men in the middle group (the second tertile) adjusted for age, survey year and smoking status was 1.37 (95%CI 1.10-1.70) and in the most deprived (the third tertile) 1.46 (1.17-1.82); and for women 1.22 (0.99-1.50) and 1.81 (1.47-2.23). The study suggests that large waist circumference, increasingly prevalent, is directly related to socioeconomic deprivation, and greater attention should be paid to increasing girth in the socially deprived.

Vegetable, fruit, and cereal intake and risk of idiopathic pulmonary fibrosis in Japan

AIMS

There has been little interest in the role of nutrition in prevention of idiopathic pulmonary fibrosis (IPF). We investigated the relationship between dietary intake of vegetables, fruit, cereals, antioxidants, and fiber and the risk of IPF in Japan.

METHODS

Included were 104 cases aged 40 years or over who were within 2 years of the diagnosis in accordance with the most recent criteria. Controls aged 40 years or over comprised 56 hospitalized patients diagnosed as having acute bacterial pneumonia and 4 outpatients with common cold. Information on dietary factors was collected using a validated self-administered diet history questionnaire. Adjustment was made for age, sex, region, pack-years of smoking, employment status, occupational exposure, saturated fatty acid intake, and body mass index.

RESULTS

Consumption of fruit in the second and third quartiles was associated with a statistically significant reduced risk of IPF. Although not statistically significant, a beneficial association between soluble fiber intake and IPF was found. No statistically significant dose-response relationship was observed between intake of green and yellow vegetables, other vegetables, cereals, beta-carotene, vitamins C and E, or insoluble fiber and the risk of IPF.

CONCLUSION

Our findings suggest that fruit intake may confer protection against the development of IPF.

Dietary fiber and reduced cough with phlegm: a cohort study in Singapore

Smoking is the major risk factor for chronic respiratory symptoms, but dietary factors may also play a role. Most studies of diet and lung disease have been cross-sectional and conducted in populations with a Western-style diet. We analyzed the relation between dietary intake at baseline and new onset of cough with phlegm in a population-based cohort of 63,257 middle-aged Chinese men and women initiated in Singapore between 1993 and 1998. Beginning in 1999, we ascertained respiratory symptoms by telephone interview and have identified 571 incident cases of cough with phlegm among the 49,140 cohort members with completed follow-up. Nonstarch polysaccharides, a major component of dietary fiber, total fruit, and soy isoflavones had the strongest associations. Odds ratios comparing highest and lowest quartiles after adjustment for age, sex, dialect group, total energy intake, and smoking were 0.61 (95% confidence interval [CI]: 0.47, 0.78; p for trend < 0.001) for nonstarch polysaccharides, 0.67 (95% CI: 0.52, 0.87; p for trend = 0.006) for fruit, and 0.67 (95% CI: 0.53, 0.86; p for trend = 0.001) for soy isoflavones. These data suggest that a diet high in fiber from fruit and, possibly, soyfoods may reduce the incidence of chronic respiratory symptoms. Associated nutrients, such as flavonoids, may contribute to this association.

Abdominal obesity and respiratory function in men and women in the EPIC-Norfolk Study, United Kingdom

Poor respiratory function and obesity are associated with all-cause and cardiovascular disease mortality. Obese persons may also have impaired lung function, but the mechanism is unclear. The authors investigated the relation between abdominal pattern of obesity and respiratory function in the European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk) cohort in Norfolk, United Kingdom. This analysis included 9,674 men and 11,876 women aged 45-79 years with no known preexisting serious illness who had complete anthropometric and respiratory function measures obtained at a health visit between 1993 and 1997. Waist:hip ratio was used to assess abdominal obesity, and forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), obtained by spirometry, were used to assess respiratory function. Both FEV1 and FVC were linearly and inversely related across the entire range of waist:hip ratio in both men and women. This relation persisted after adjustment for age, body mass index, cigarette smoking, social class, physical activity index, prevalent bronchitis/emphysema, and prevalent asthma. The association remained significant among nonobese nonsmokers without preexisting respiratory disease. In the general adult population, abdominal fat deposition may play a role in the impairment of respiratory function among the abdominally obese.