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

Effect of Phytochemical-Rich Food Intake on Respiratory and Muscle Function in Middle-Aged Patients with COPD: A Cross-Sectional Study

Background: It is known that the consumption of single phytochemicals improves respiratory function in chronic obstructive pulmonary disease (COPD) patients. Since phytochemicals have a synergistic effect on health, a more comprehensive analysis is needed. The aim of this study was to estimate the intake of phytochemicals using the dietary phytochemical index (DPI) and assess their association with respiratory function, inspiratory muscle strength and function, and peripheral muscle strength. Methods: This study was conducted at the Special Hospital for Pulmonary Diseases in Zagreb (September 2023 to May 2024). The DPI was assessed using three 24 h recalls from 71 COPD patients (66.5 ± 8.4 years; 53.5% men). Anthropometric measurements, respiratory function, inspiratory muscle function and strength, and peripheral muscle strength were assessed during pulmonary rehabilitation following standard protocols. Results: Patients were divided into DPI tertiles with mean values of 7.3 ± 3.0, 16.0 ± 3.0, and 32.2 ± 8.8, respectively. After controlling for confounding factors, a significant association was found between DPI tertiles and FEV1 (p-trend < 0.001), FVC (p-trend = 0.002), FEV1/FVC (p-trend < 0.001), MIP (p-trend = 0.012), and MSUE (p-trend = 0.002). In addition, an inverse association was found between DPI tertiles and diaphragm thickness during inhalation (p-trend = 0.012) and exhalation (p-trend = 0.013). Conclusions: This study suggests that a higher intake of phytochemicals could be beneficial in dietary interventions for COPD therapy. Future prospective studies are needed to confirm these findings.

Does diet quality moderate the long-term effects of discrete but extreme PM2.5 exposure on respiratory symptoms? A study of the Hazelwood coalmine fire

In 2014, a fire at an open cut coalmine in regional Victoria, Australia burned for 6 weeks. Residents of the nearby town of Morwell were exposed to smoke, which included high levels of fine particulate matter (PM2.5). We investigated whether the long-term effects of PM2.5 on respiratory health were moderated by diet quality. A cross-sectional analysis was conducted of data collected 8.5 years after the mine fire from 282 residents of Morwell and 166 residents from the nearby unexposed town of Sale. Primary outcomes were respiratory symptoms. Exposure was coalmine fire-related PM2.5 and diet quality was assessed as Australian Recommended Food Score (ARFS) derived using the Australian Eating Survey (AES). The moderating effect of diet quality on respiratory outcomes associated with PM2.5 was assessed using logistic regression models, adjusting for potential confounders. Diet quality was poor in this sample, with 60% in the lowest category of overall diet quality. Overall diet quality and fruit and vegetable quality significantly attenuated the association between PM2.5 and prevalence of chronic cough and phlegm. Sauce/condiment intake was associated with a greater effect of PM2.5 on COPD prevalence. No other moderating effects were significant. The moderating effects of overall diet quality and vegetable and fruit intake aligned with a priori hypotheses, suggesting potential protective benefits. While more evidence is needed to confirm these findings, improving diets, especially fruit and vegetable intake, may provide some protection against the effects of smoke exposure from fire events.

Dietary patterns and micronutrients in respiratory infections including COVID-19: a narrative review

BACKGROUND

COVID-19 is a pandemic caused by nCoV-2019, a new beta-coronavirus from Wuhan, China, that mainly affects the respiratory system and can be modulated by nutrition.

METHODS

This review aims to summarize the current literature on the association between dietary intake and serum levels of micronutrients, malnutrition, and dietary patterns and respiratory infections, including flu, pneumonia, and acute respiratory syndrome, with a focus on COVID-19. We searched for relevant articles in various databases and selected those that met our inclusion criteria.

RESULTS

Some studies suggest that dietary patterns, malnutrition, and certain nutrients such as vitamins D, E, A, iron, zinc, selenium, magnesium, omega-3 fatty acids, and fiber may have a significant role in preventing respiratory diseases, alleviating symptoms, and lowering mortality rates. However, the evidence is not consistent and conclusive, and more research is needed to clarify the mechanisms and the optimal doses of these dietary components. The impact of omega-3 and fiber on respiratory diseases has been mainly studied in children and adults, respectively, and few studies have examined the effect of dietary components on COVID-19 prevention, with a greater focus on vitamin D.

CONCLUSION

This review highlights the potential of nutrition as a modifiable factor in the prevention and management of respiratory infections and suggests some directions for future research. However, it also acknowledges the limitations of the existing literature, such as the heterogeneity of the study designs, populations, interventions, and outcomes, and the difficulty of isolating the effects of single nutrients from the complex interactions of the whole diet.

Fiber intake and risk of chronic obstructive pulmonary disease: A systematic review and dose response meta-analysis

This systematic review and dose-response meta-analysis examined the risk of chronic obstructive pulmonary disease (COPD) following dietary fiber intake. Relevant articles were retrieved from a variety of databases, including Scopus, Embase, and Medline, until March 2023. Spirometry was the most frequently used method for determining the presence of COPD. Based on the search, there were a total of 213,912 participants across five separate studies. Random effects model was used to combine the data and a dose-response analysis was further conducted. Five distinct cohort studies were identified. Based on highest versus lowest analysis, there was an inverse correlation between the intake of total fiber (RR, 0.72; 95%, CI: 0.64-0.80), cereal fiber (RR: 0.76, 95% CI 0.68, 0.86), and fruit fiber (RR: 0.75, 95% CI: 0.68, 0.83). Although this result was not significant for vegetable fiber (RR, 0.95; 95% CI, 0.84-1.07). Dose-response analysis revealed that daily increase of 10 g of total dietary fiber, cereal fiber, or fruit fiber reduced the risk of COPD by 26%, 21%, and 37%, respectively. The ROBINS-E tool classified all cohort studies as having a moderate risk of bias. Total fiber, cereal fiber, and fruit fiber intake were found to have low credibility using the NutriGrade tool. Additionally, there is a lack of scientific evidence supporting the use of vegetable fiber. Larger, more comprehensive studies are required to confirm these findings.

Dietary fibre in relation to lung function and respiratory symptoms from childhood to adulthood

Background

Epidemiological studies suggest beneficial associations between dietary fibre intake, lung function and chronic respiratory symptoms in adults. Our aim was to investigate the association between dietary fibre intake in childhood and respiratory health up to adulthood.

Methods

The individual fibre intake of 1956 participants from the Swedish population-based birth cohort BAMSE was estimated from 98- and 107-item food frequency questionnaires at ages 8 and 16 years, respectively. At 8, 16 and 24 years, lung function was measured by spirometry. Respiratory symptoms (cough, mucus production, breathing difficulties/wheeze) were assessed by questionnaires, and airway inflammation by exhaled nitric oxide fraction (F_ENO) (≥25 ppb) at 24 years. Longitudinal associations with lung function were analysed by mixed-effects linear regression; associations with respiratory symptoms and airway inflammation were analysed by logistic regression, adjusting for potential confounders.

Results

There were no associations between fibre intake at 8 years, as total and from different sources, spirometry measurements and respiratory symptoms at 24 years. Higher fruit fibre intake tended to be inversely associated with airway inflammation at 24 years (OR 0.70, 95% CI 0.48-1.00), which became non-significant after exclusion of participants with food-related allergic symptoms (OR 0.74, 95% CI 0.49-1.10). No associations between fibre intake at 8 and 16 years as an updated lagged exposure and spirometry measurements up to 24 years were observed.

Conclusion

In this longitudinal study, we observed no consistent association between dietary fibre intake in childhood and lung function or respiratory symptoms up to adulthood. Further research on dietary fibre in relation to respiratory health across the life course is needed.

Antimicrobial and Anti-Inflammatory Activity of Apple Polyphenol Phloretin on Respiratory Pathogens Associated With Chronic Obstructive Pulmonary Disease

Bacterial infections contribute to accelerated progression and severity of chronic obstructive pulmonary disease (COPD). Apples have been associated with reduced symptoms of COPD and disease development due to their polyphenolic content. We examined if phloretin, an apple polyphenol, could inhibit bacterial growth and inflammation induced by the main pathogens associated with COPD. Phloretin displayed bacteriostatic and anti-biofilm activity against nontypeable Haemophilus influenzae (NTHi), Moraxella catarrhalis, Streptococcus pneumoniae, and to a lesser extent, Pseudomonas aeruginosa. In vitro, phloretin inhibited NTHi adherence to NCI-H292 cells, a respiratory epithelial cell line. Phloretin also exhibited anti-inflammatory activity in COPD pathogen-induced RAW 264.7 macrophages and human bronchial epithelial cells derived from normal and COPD diseased lungs. In mice, NTHi bacterial load and chemokine (C-X-C motif) ligand 1 (CXCL1), a neutrophil chemoattractant, was attenuated by a diet supplemented with phloretin. Our data suggests that phloretin is a promising antimicrobial and anti-inflammatory nutraceutical for reducing bacterial-induced injury in COPD.

Risk factors for chronic cough in adults: A systematic review and meta-analysis

Despite the challenges of diagnosing and managing adult patients with chronic cough, a systematic synthesis of evidence on aetiological risk factor is lacking. We systematically searched PubMed and EMBASE to synthesize the current evidence for longitudinal associations between a wide range of risk factors and chronic cough in the general adult population, following the meta-analysis of observational studies in epidemiology (MOOSE) guidelines. The Newcastle-Ottawa scale was used to assess the quality of the included studies. Fixed-effect meta-analysis was conducted where appropriate. Of 26 eligible articles, 16 domains of risk factors were assessed. There was consistent evidence that asthma (pooled adjusted OR [aOR] = 3.01; 95% CI: 2.33-3.70; I²  = 0%; number of articles [N] = 3) and low education levels/socioeconomic status (SES) (pooled aOR = 1.46; 95% CI: 1.20-1.72; I²  = 0%; N = 3) were associated with an increased risk of chronic cough after adjusting for smoking and other confounders. While continuous smoking was associated with chronic cough (aOR = 1.81; 95% CI: 1.36-2.26; I²  = 57%; N = 3), there was too little evidence to draw conclusions for occupational exposures, outdoor air pollution, early-life exposures, diet, snoring and other chronic conditions, including obesity, chronic obstructive pulmonary disease, gastro-oesophageal reflux disease and chronic pain. Asthma, persistent smoking and lower education/SES were associated with an increased risk of chronic cough. Longitudinal associations between other factors frequently mentioned empirically (i.e., occupational exposures, air pollution and chronic respiratory conditions) need further investigation, ideally with objective and standardized measurement.

Dietary Fibre Intake in Relation to Asthma, Rhinitis and Lung Function Impairment-A Systematic Review of Observational Studies

A high intake of dietary fibre has been associated with a reduced risk of several chronic diseases. This study aimed to review the current evidence on dietary fibre in relation to asthma, rhinitis and lung function impairment. Electronic databases were searched in June 2021 for studies on the association between dietary fibre and asthma, rhinitis, chronic obstructive pulmonary disease (COPD) and lung function. Observational studies with cross-sectional, case–control or prospective designs were included. Studies on animals, case studies and intervention studies were excluded. The quality of the evidence from individual studies was evaluated using the RoB-NObs tool. The World Cancer Research Fund criteria were used to grade the strength of the evidence. Twenty studies were included in this systematic review, of which ten were cohort studies, eight cross-sectional and two case–control studies. Fibre intake during pregnancy or childhood was examined in three studies, while seventeen studies examined the intake during adulthood. There was probable evidence for an inverse association between dietary fibre and COPD and suggestive evidence for a positive association with lung function. However, the evidence regarding asthma and rhinitis was limited and inconsistent. Further research is needed on dietary fibre intake and asthma, rhinitis and lung function among adults and children.

Potentials of Antitussive Traditional Persian Functional Foods for COVID-19 Therapy†

Coronavirus disease 2019 is a worldwide pandemic resulting in a severe acute respiratory syndrome. Remdesivir is the only FDA-approved drug for hospitalized patients older than age 12. It shows the necessity of finding new therapeutic strategies. Functional foods (FFs) could have co-therapeutic and protective effects against COVID-19 infection. Traditional Persian medicine (TPM), one of the safest and most popular schools of medicine for hundreds of years, has recommended potential FF candidates to manage such a global pandemic. To reveal the potential of TPM in terms of antitussive FFs, traditional Persian pharmacopoeia "Qarabadin-e-Salehi" was searched using the keywords "Soaal" and "Sorfeh." Also, a search of MEDLINE, PubMed Central, Google Scholar, and Science Direct was performed for the relevant literature published from the inception up to March 2021. A combination of search terms including "cough, antitussive, antioxidant, anti-inflammation, antiviral, COVID-19, mucoactive, mucolytic, expectorant, and mucoregulatory" was also applied. The potential mechanism of action in SARS-CoV-2 infection was discussed. Twelve TPM FFs were found including Laooqs, Morabbas, a Saviq, a soup, and a syrup. They are combinations of two to seven ingredients. Natural compounds of mentioned formulations have the main pharmacological mechanisms including antiviral, anti-inflammatory, antioxidant, antihistamine, bronchodilator, immunomodulatory, and mucoactive effects as well as central or peripheral antitussive activities. FFs are cost-effective, easily accessible, and safe options for both treatment and prevention of COVID-19. They might have positive psychological effects along with their pharmacological effects and nutritional virtues. They could also manage persistent respiratory discomforts after recovery from COVID-19.

Risk and impact of chronic cough in obese individuals from the general population

BACKGROUND

Obese individuals may be at higher risk of chronic cough. We investigated the risk and impact of chronic cough in obese individuals from the general population.

METHODS

We recorded chronic cough, body mass index (BMI) and other related clinical conditions in 44 554 adults from the Copenhagen General Population Study. Individuals with asthma and/or chronic obstructive pulmonary disease were excluded (n=10 977). BMI was divided into: underweight (BMI <18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²), obese (30.0-34.9 kg/m²) and severely obese (≥35.0 kg/m²).

RESULTS

Among 33 577 adults from the general population, 27 829 (83%) were non-obese and 5748 (17%) were obese. Compared with individuals with normal weight, multivariable adjusted ORs for chronic cough risk were 1.4 (95% CI 1.2 to 1.6) in overweight, 1.9 (95% CI 1.7 to 2.2) in obese and 2.6 (95% CI 2.1 to 3.2) in severely obese individuals. Mediation analyses showed that chronic cough due to obesity was up to 23% mediated by gastro-oesophageal reflux disease (GERD). Other mediators included low vegetable intake with 10% and occupational exposure with 8%. Among obese individuals, those with versus without chronic cough had worse accompanying respiratory symptoms, more often comorbidities including GERD and diabetes, greater healthcare utilisations, lower lung function and higher blood inflammation (all p<0.05).

CONCLUSION

There is dose-response relationship between BMI and chronic cough, and chronic cough risk is twofold to threefold higher in obese individuals from the general population. This increased risk was partly mediated by GERD, low vegetable intake and occupational exposure, supporting that there may be benefit to gain by ameliorating some of these factors in obese individuals with chronic cough.

Association of Dietary Fiber on Asthma, Respiratory Symptoms, and Inflammation in the Adult National Health and Nutrition Examination Survey Population

Rationale: High intake of dietary fiber may have antiinflammatory properties and be protective against respiratory morbidity.Objectives: We examined the relationship between dietary fiber intake and asthma, respiratory symptoms, and inflammation among adults who participated in the 2007 to 2012 NHANES (National Health and Nutrition Examination Survey).Methods: We analyzed data from adults 20 to 79 years of age (n = 13,147) with complete information on fiber intake, total calorie intake, body mass index, smoking status, and poverty level. Fiber intake was categorized into quartiles, with Q1 being lowest quartile of intake and Q4 being the highest quartile. Respiratory morbidities included asthma, wheeze, cough, and phlegm. Self-report questionnaires were used to define asthma, wheeze, cough, and phlegm production. Serum C-reactive protein (CRP) was used as a biomarker of inflammation. Exclusion criteria included current pregnancy and implausible intake of total calories.Results: A total of 69.5% of participants were non-Hispanic white; 54.5% were nonsmokers, and 7.8% had current asthma. After adjusting for covariates, fiber intake was associated with asthma (P = 0.01), with an increased odds of asthma with lower fiber intake (Q1 vs. Q4: odds ratio [OR], 1.4; 95% confidence interval [CI], 1.0-1.8; P = 0.027). There were significant interactions between fiber and sex and fiber and race/ethnicity; stronger associations were seen for women and for non-Hispanic white adults. Low fiber intake (Q1) was associated with increased odds of wheeze (OR, 1.3; 95% CI, 1.0-1.6; P = 0.018), cough (OR, 1.7; 95% CI, 1.2-2.3; P = 0.002), and phlegm (OR, 1.4; 95% CI, 1.1-2.0; P = 0.021) compared with high fiber intake. The odds of having high CRP versus nondetectable CRP were 1.6 times higher in the low-fiber group (Q1) compared with high-fiber group (Q4; OR, 1.6; 95% CI, 1.0-2.5).Conclusions: High-fiber diet may mediate an inflammatory response and decrease odds of having asthma, especially for women and specific racial groups, cough, wheeze, and phlegm production when compared with low-fiber diet.

Phloretin, an Apple Polyphenol, Inhibits Pathogen-Induced Mucin Overproduction

SCOPE

Bacterial infection induces mucus overproduction, contributing to acute exacerbations and lung function decline in chronic respiratory diseases. A diet enriched in apples may provide protection from pulmonary disease development and progression. This study examined whether phloretin, an apple polyphenol, inhibits mucus synthesis and secretion induced by the predominant bacteria associated with chronic respiratory diseases.

METHODS AND RESULTS

The expression of mucus constituent mucin 5AC (MUC5AC) in FVB/NJ mice and NCI-H292 epithelial cells is analyzed. Nontypeable Haemophilus influenzae (NTHi)-infected mice developed increased MUC5AC mRNA, which a diet containing phloretin inhibited. In NCI-H292 cells, NTHi, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa increased MUC5AC mRNA, which phloretin inhibited. Phloretin also diminished NTHi-induced MUC5AC protein secretion. NTHi-induced increased MUC5AC required toll-like receptor 4 (TLR4) and NADH oxidase 4 (NOX4) signaling and subsequent activation of the epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) pathway. Phloretin inhibited NTHi-induced TLR4/NOX4 and EGFR/MAPK signaling, thereby preventing increased MUC5AC mRNA. EGFR activation can also result from increased EGFR ligand synthesis and subsequent ligand activation by matrix metalloproteinases (MMPs). In NCI-H292 cells, NTHi increased EGFR ligand and MMP1 and MMP13 mRNA, which phloretin inhibited.

CONCLUSIONS

In summary, phloretin is a promising therapeutic candidate for preventing bacterial-induced mucus overproduction.

Links Between Inflammatory Bowel Disease and Chronic Obstructive Pulmonary Disease

Inflammatory bowel disease (IBD) and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases of the gastrointestinal and respiratory tracts, respectively. These mucosal tissues bear commonalities in embryology, structure and physiology. Inherent similarities in immune responses at the two sites, as well as overlapping environmental risk factors, help to explain the increase in prevalence of IBD amongst COPD patients. Over the past decade, a tremendous amount of research has been conducted to define the microbiological makeup of the intestine, known as the intestinal microbiota, and determine its contribution to health and disease. Intestinal microbial dysbiosis is now known to be associated with IBD where it impacts upon intestinal epithelial barrier integrity and leads to augmented immune responses and the perpetuation of chronic inflammation. While much less is known about the lung microbiota, like the intestine, it has its own distinct, diverse microflora, with dysbiosis being reported in respiratory disease settings such as COPD. Recent research has begun to delineate the interaction or crosstalk between the lung and the intestine and how this may influence, or be influenced by, the microbiota. It is now known that microbial products and metabolites can be transferred from the intestine to the lung via the bloodstream, providing a mechanism for communication. While recent studies indicate that intestinal microbiota can influence respiratory health, intestinal dysbiosis in COPD has not yet been described although it is anticipated since factors that lead to dysbiosis are similarly associated with COPD. This review will focus on the gut-lung axis in the context of IBD and COPD, highlighting the role of environmental and genetic factors and the impact of microbial dysbiosis on chronic inflammation in the intestinal tract and lung.

Chronic Obstructive Pulmonary Disease: A 2019 Evidence Analysis Center Evidence-Based Practice Guideline

Chronic obstructive pulmonary disease (COPD) is a progressive lung disorder in which patients are at high risk for both pulmonary and systemic complications of their disease. Medical nutrition therapy by a registered dietitian nutritionist can be an integral component of lifestyle treatment targeted at maintaining and improving outcomes, such as lung function, mortality, and quality of life. The Academy of Nutrition and Dietetics (Academy) convened an expert workgroup to conduct a systematic review to update the COPD Evidence-Based Nutrition Practice Guideline. This publication outlines the Academy's Evidence Analysis Library methods used to complete the systematic review and guideline and examines the recommendations and supporting evidence. A total of 14 recommendations were developed based on evidence from eight conclusions. Using the Nutrition Care Process as a framework for practice, recommendations rated as strong included assessing and monitoring and evaluating body weight and medical nutrition therapy by a registered dietitian nutritionist. Weak recommendations included predicting resting and total energy expenditure. All other recommendations were rated as fair. These included individualizing the calorie prescription and macronutrient composition of the diet; assessing and monitoring and evaluating energy intake, serum 25-hydroxyvitamin D levels, and frequency of exacerbations; and determining need for vitamin D supplementation. Fewer than one-third of the systematic review's conclusions could be used to support the recommendations due to conflicting results or limited or no evidence available. The Evidence Analysis Library 2019 COPD Evidence-Based Nutrition Practice Guideline is a valuable resource for registered dietitian nutritionists and other health care professionals caring for those with COPD.

Association of Dietary Fiber and Yogurt Consumption With Lung Cancer Risk: A Pooled Analysis

Importance

Dietary fiber (the main source of prebiotics) and yogurt (a probiotic food) confer various health benefits via modulating the gut microbiota and metabolic pathways. However, their associations with lung cancer risk have not been well investigated.

Objective

To evaluate the individual and joint associations of dietary fiber and yogurt consumption with lung cancer risk and to assess the potential effect modification of the associations by lifestyle and other dietary factors.

Design, Setting, and Participants

This pooled analysis included 10 prospective cohorts involving 1 445 850 adults from studies that were conducted in the United States, Europe, and Asia. Data analyses were performed between November 2017 and February 2019. Using harmonized individual participant data, hazard ratios and 95% confidence intervals for lung cancer risk associated with dietary fiber and yogurt intakes were estimated for each cohort by Cox regression and pooled using random-effects meta-analysis. Participants who had a history of cancer at enrollment or developed any cancer, died, or were lost to follow-up within 2 years after enrollment were excluded.

Exposures

Dietary fiber intake and yogurt consumption measured by validated instruments.

Main Outcomes and Measures

Incident lung cancer, subclassified by histologic type (eg, adenocarcinoma, squamous cell carcinoma, and small cell carcinoma).

Results

The analytic sample included 627 988 men, with a mean (SD) age of 57.9 (9.0) years, and 817 862 women, with a mean (SD) age of 54.8 (9.7) years. During a median follow-up of 8.6 years, 18 822 incident lung cancer cases were documented. Both fiber and yogurt intakes were inversely associated with lung cancer risk after adjustment for status and pack-years of smoking and other lung cancer risk factors: hazard ratio, 0.83 (95% CI, 0.76-0.91) for the highest vs lowest quintile of fiber intake; and hazard ratio, 0.81 (95% CI, 0.76-0.87) for high vs no yogurt consumption. The fiber or yogurt associations with lung cancer were significant in never smokers and were consistently observed across sex, race/ethnicity, and tumor histologic type. When considered jointly, high yogurt consumption with the highest quintile of fiber intake showed more than 30% reduced risk of lung cancer than nonyogurt consumption with the lowest quintile of fiber intake (hazard ratio, 0.67 [95% CI, 0.61-0.73] in total study populations; hazard ratio, 0.69 [95% CI, 0.54-0.89] in never smokers), suggesting potential synergism.

Conclusions and Relevance

Dietary fiber and yogurt consumption was associated with reduced risk of lung cancer after adjusting for known risk factors and among never smokers. Our findings suggest a potential protective role of prebiotics and probiotics against lung carcinogenesis.

Isoflavone Aglycones Attenuate Cigarette Smoke-Induced Emphysema via Suppression of Neutrophilic Inflammation in a COPD Murine Model

Chronic obstructive pulmonary disease (COPD), a lung disease caused by chronic exposure to cigarette smoke, increases the number of inflammatory cells such as macrophages and neutrophils and emphysema. Isoflavone is a polyphenolic compound that exists in soybeans. Daidzein and genistein, two types of isoflavones, have been reported to have anti-inflammatory effects in various organs. We hypothesized that the daidzein-rich soy isoflavone aglycones (DRIAs) attenuate cigarette smoke-induced emphysema in mice. Mice were divided into four groups: the (i) control group, (ii) isoflavone group, (iii) smoking group, and (iv) isoflavone + smoking group. The number of inflammatory cells in the bronchoalveolar lavage fluid (BALF) and the airspace enlargement using the mean linear intercept (MLI) were determined 12 weeks after smoking exposure. Expressions of neutrophilic inflammatory cytokines and chemokines were also examined. In the isoflavone + smoking group, the number of neutrophils in BALF and MLI was significantly less than that in the smoking group. Furthermore, the gene-expressions of TNF-α and CXCL2 (MIP-2) in the isoflavone + smoking group were significantly less than those in the smoking group. Supplementation of the COPD murine model with DRIAs significantly attenuates pathological changes of COPD via suppression of neutrophilic inflammation.

Characteristics of Chinese chronic cough patients

Chronic cough is one of the most common complains for patients seeking medical attention in both general practice and respiratory specialist clinics. Cough variant asthma, eosinophilic bronchitis, upper airway cough syndrome, as well as gastro-esophageal reflux disease are common conditions associated with chronic cough, and cough variant asthma, eosinophilic bronchitis account for a higher proportion of patients with chronic cough in China than in Western countries. An older female predominance has been reported in most Western countries, which may be attributed to a higher cough reflex sensitivity in females, especially those post-menopausal females. However, studies conducted in China showed that patients with chronic cough have a nearly similar gender distribution and most of them are in their late 30s or early 40s, despite the similar gender and age difference in cough reflex sensitivity as Western countries. Environmental and occupational exposures, cigarette smoking, unhealthy lifestyle might play a role in the distinct age and gender distribution of Chinese chronic cough patients, yet further study is needed to clarify it.

Dietary Fiber Intake and Risk of Chronic Obstructive Pulmonary Disease: A Prospective Cohort Study of Men

BACKGROUND

The limited literature suggests that dietary fiber intake from whole grains, fruits, and vegetables is negatively associated with chronic obstructive pulmonary disease (COPD) via fiber's anti-inflammatory properties. Therefore, we investigated the association between total fiber and fiber sources and risk of COPD in the population-based prospective Cohort of Swedish Men (45,058 men, ages 45-79 years) with no history of COPD at baseline.

METHODS

Dietary fiber intake was assessed with a self-administered questionnaire in 1997 and was energy adjusted using the residual method. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (95% CIs) adjusted for potential confounders.

RESULTS

During a mean follow-up of 13.1 years (1998-2012), 1,982 incident cases of COPD were ascertained via linkage to the Swedish health registers. A strong inverse association between total fiber intake (≥36.8 vs. <23.7 g/day) and COPD was observed in current smokers (hazard ratio [HR] = 0.54; 95% confidence interval [CI] = 0.43, 0.67) and ex-smokers (HR = 0.62; 95% CI = 0.50, 0.78) but not in never smokers (HR = 0.93; 95% CI = 0.60, 1.45; P interaction = 0.04). For cereal fiber, HRs for highest versus lowest quintile were 0.62 (95% CI = 0.51, 0.77; P trend < 0.001) in current smokers and 0.66 (95% CI = 0.52, 0.82; P trend < 0.001) in ex-smokers; for fruit fiber, the HR was 0.65 (95% CI = 0.52, 0.81; P trend < 0.001) in current smokers and 0.77 (95% CI = 0.61, 0.98; P trend = 0.17) in ex-smokers; and for vegetable fiber, it was 0.71 (95% CI = 0.57, 0.88; P trend = 0.003) in current smokers and 0.92 (95% CI = 0.71, 1.19; P trend = 0.48) in ex-smokers.

CONCLUSIONS

Our findings indicate that high fiber intake was inversely associated with COPD incidence in men who are current or ex-smokers.

Self-reported intake of fruit and vegetables and risk of chronic obstructive pulmonary disease: A nation-wide twin study

BACKGROUND

Although smoking is the major risk factor for chronic obstructive pulmonary disease (COPD) many patients with obstructive lung function suggesting COPD are never-smokers. Therefore, other lifestyle factors have been suggested as risk factors.

AIMS

i) To examine the association between self-reported intake of fruit and vegetables and risk of COPD and ii) to examine whether the association between these traits are due to underlying genetic factors.

METHODS

12,449 twins, aged 40-80, from the Danish Twin Registry were recruited. The participants completed a questionnaire on medical history and lifestyle factors and participated in clinical examination. COPD was defined according to ATS/ERS recommendations. Multivariate logistic regressions were used to estimate the risk of COPD in individuals with a low intake of fruit and vegetables. Co-twin control analyses were performed to examine whether the association between fruit and vegetables and COPD is explained by genetic factors. Self-reported physician-diagnosed asthmatic individuals were excluded.

RESULTS

Of the 11,458 individuals were included in the analyses, 48% of the participants were males. Mean age was 58.9 (years)±SD 9.6, mean BMI (kg/m²)26.6 ± SD 4.4. A multivariate logistic regression, including sex, age and BMI showed that both smoking, no and heavy drinking and physical inactivity were independent predictors of COPD. There was a significant frequency-pendent association between intake of fruit and vegetables and increased risk of COPD. Conditional logistic regression analyses showed that the association might be controlled by genetic factors.

CONCLUSIONS

This study shows that low intake of fruit and vegetables is associated with an increased risk of COPD and the association might be under influence of genetic factors.

Diet Pattern and Respiratory Morbidity in the Atherosclerosis Risk in Communities Study

RATIONALE

Dietary intake is a potential risk factor for respiratory morbidity in adult populations. Few studies capture the effect of dietary patterns, representative of the combination of nutrients consumed, on self-reported respiratory morbidity in combination with objective measures of lung function.

OBJECTIVES

To evaluate patterns of dietary intake in relation to respiratory morbidity and objective measures of lung function in a U.S.

POPULATION

METHODS

The ARIC (Atherosclerosis Risk in Communities) study investigators enrolled 15,792 participants from four U.S. communities between 1987 and 1989 and collected data using a validated food frequency questionnaire to assess diet. Principal component analysis was applied, and patterns representative of "Western" and "Prudent" diets emerged. We investigated cross-sectional associations between dietary patterns and pulmonary assessments that included asthma and chronic obstructive pulmonary disease (COPD) diagnosis, respiratory symptoms, and lung function. Multivariable Poisson regression models included quintiles of dietary patterns and potential confounders. Interaction of dietary patterns with obesity, sex, and smoking status was assessed in relation to all outcomes.

RESULTS

Higher scores in the "Western" dietary pattern (quintile 5 vs. quintile 1) were associated with higher prevalence of COPD (prevalence ratio [PR], 1.62; 95% confidence ratio [CI], 1.33-1.97), wheeze (PR, 1.37; 95% CI, 1.11-1.69), cough (PR, 1.32; 95% CI, 1.32-1.59), and phlegm (PR, 1.27; 95% CI, 1.05-1.54) and lower percent predicted forced expiratory volume in 1 second (FEV1), percent predicted forced vital capacity (FVC), and FEV1/FVC ratio. Higher scores in the "Prudent" dietary pattern (quintile 5 vs. quintile 1) were associated with lower prevalence of COPD (PR, 0.82; 95% CI, 0.70-0.95) and cough (PR, 0.77; 95% CI, 0.67-0.89) and higher percent predicted FEV1 and FEV1/FVC ratio. The prevalence of asthma was not related to dietary intake.

CONCLUSIONS

A "Western" dietary pattern was associated with respiratory symptoms, lower lung function, and COPD in ARIC participants.

Diet and lifestyle recommendations for the treatment of chronic cough and chronic disease

Chronic cough, possibly due to toxicant exposure, may be improved by using a low-risk nutrition-centred strategy. A 71-year-old man experiencing chronic cough for the past 25 years presented to the Cleveland Clinic. In recent years, the patient's cough had increased in frequency and intensity despite pulmonary interventions. The patient's social history revealed exposures as a foundry worker to dimethylethylamine and triethylamine two known respiratory irritants. The patient was placed on a nutrition programme (nutrient dense, low glycaemic index and anti-inflammatory), encouraged to use a sauna each day and placed on nutraceutical supplementation that supports liver detoxification, digestive health and inflammation reduction. Over the course of approximately 1 year, the patient experienced improvement in his cough despite the discontinuation of formal, intensive pulmonary therapy. The patient also experienced weight loss, lower blood pressure and glycaemic status improvement, as well as decreased fatigue and increased energy.

The Gut-Liver-Lung Axis. Modulation of the Innate Immune Response and Its Possible Role in Chronic Obstructive Pulmonary Disease

Evidence from epidemiological studies suggests that a diet high in fiber is associated with better lung function and reduced risk of chronic obstructive pulmonary disease (COPD). The mechanism for this benefit remains unknown, but, as fiber is not absorbed by the gut, this finding suggests that the gut may play an active role in pathogenic pathways underlying COPD. There is a growing awareness that aberrant activity of the innate immune system, characterized by increased neutrophil and macrophage activation, may contribute to the development or progression of COPD. Innate immunity is modulated in large part by the liver, where hepatic cells function in immune surveillance of the portal circulation, as well as providing a rich source of systemic inflammatory cytokines and immune mediators (notably, IL-6 and C-reactive protein). We believe that the beneficial effect of dietary fiber on lung function is through modulation of innate immunity and subsequent attenuation of the pulmonary response to inflammatory stimuli, most apparent in current or former smokers. We propose that the "gut-liver-lung axis" may play a modifying role in the pathogenesis of COPD. In this review, we summarize lines of evidence that include animal models, large prospective observational studies, and clinical trials, supporting the hypothesis that the gut-liver-lung axis plays an integral part in the pathogenic mechanisms underlying the pathogenesis of COPD.

Chronic cough: an Asian perspective. Part 1: Epidemiology

Asia is one of the most diverse and dynamic continents. Due to recent rapid industrialisation and urbanisation, morbidity patterns are likely to be diverse in Asian populations. Chronic cough is a disease condition resulting from host-environmental interactions, and is associated with a high global epidemiological burden. However, the underlying epidemiology remains unclear, particularly in Asia. We performed a literature search to identify peer-reviewed articles on chronic cough in community-based adult Asian populations that have been published between January 2000 and June 2015. In this review, we aim to examine the epidemiological characteristics and determinants of chronic cough in several geographical areas of Asia.

Whey peptide-based enteral diet attenuated elastase-induced emphysema with increase in short chain fatty acids in mice

Background

Systemic inflammation is present in chronic obstructive pulmonary disease (COPD). A whey peptide-based enteral diet reduce inflammation in patients with COPD, but its effect on COPD development has not been determined. On the other hand, it is known that short chain fatty acids (SCFAs), which are produced by micro-flora in the gut, attenuates bronchial asthma in mice model.

Methods

Mice with elastase-induced emphysema were fed with 1 of 3 diets (control diet, whey peptide-based enteral diet, or standard enteral diet) to determine the effects of whey peptide-based enteral diet on emphysema and on cecal SCFAs.

Results

The whey peptide-based enteral diet group exhibited fewer emphysematous changes; significantly lower total cell counts in bronchoalveolar lavage fluid (BALF); and significantly higher cecal SCFA levels than either the control or standard enteral diet groups. The total cell count was inversely correlated with total cecal SCFA levels in these three diet groups.

Conclusions

The whey peptide-based enteral diet attenuates elastase-induced emphysema through the suppression of inflammation in the lung. This may be related to the increase in cecal SCFA.

A review of the Hispanic paradox: time to spill the beans?

Past epidemiological observations and recent molecular studies suggest that chronic obstructive pulmonary disease (COPD) and lung cancer are closely related diseases, resulting from overlapping genetic susceptibility and exposure to aero-pollutants, primarily cigarette smoke. Statistics from the American Lung Association and American Cancer Society reveal that mortality from COPD and lung cancer are lowest in Hispanic subjects and generally highest in African American subjects, with mortality in non-Hispanic white subjects and Asian subjects in between. This observation, described as the “Hispanic paradox”, persists after adjusting for confounding variables, notably smoking exposure and sociodemographic factors. While differences in genetic predisposition might underlie this observation, differences in diet remain a possible explanation. Such a hypothesis is supported by the observation that a diet high in fruit and vegetables has been shown to confer a protective effect on both COPD and lung cancer. In this article, we hypothesise that a diet rich in legumes may explain, in part, the Hispanic paradox, given the traditionally high consumption of legumes (beans and lentils) by Hispanic subjects. Legumes are very high in fibre and have recently been shown to attenuate systemic inflammation significantly, which has previously been linked to susceptibility to COPD and lung cancer in large prospective studies. A similar protective effect could be attributed to the consumption of soy products (from soybeans) in Asian subjects, for whom a lower incidence of COPD and lung cancer has also been reported. This hypothesis requires confirmation in cohort studies and randomised control trials, where the effects of diet on outcomes can be carefully examined in a prospective study design.

Dietary patterns and pulmonary function in Korean women: findings from the Korea National Health and Nutrition Examination Survey 2007-2011

In the present study, we evaluated the association between dietary patterns and pulmonary functions in Korean women older than 40 years. This study analyzed the data from the Korea National Health and Nutrition Examination Survey IV and V (2007-2010). In total, 7615 women were included in the analysis. Using principal component analysis, two dietary patterns were identified, namely a balanced diet pattern (vegetables, fish, meat, seaweed, and mushrooms) and a refined diet (snacks, bread, milk, dairy products, and fast food). The refined diet pattern was positively associated with energy from fat but negatively associated with vitamin A, β-carotene, niacin, and fiber. After adjusting for potential confounders, the refined diet pattern was negatively associated with levels of predicted forced vital capacity (odds ratio (OR): 0.84, 95% confidence intervals (CIs): 0.70, 0.99) and predicted forced expiratory volume in 1 second (OR: 0.79, 95% CIs: 0.66, 0.93). In conclusion, the refined diet pattern was associated with decreased pulmonary function in Korean women. This information may be useful toward the development of nutritional guidelines for improving pulmonary function in Korean women.

Suppressed anti-oxidant capacity due to a cellulose-free diet declines further by cigarette smoke in mice

Dietary fiber, maintaining the gut environment, contributes to better lung function among smokers. This study was aimed to investigate the role of dietary fiber on the anti-oxidant capacity and gut environment during exposure to cigarette smoke. The anti-oxidant capacity as well as caecal levels of organic acids and population of micro-flora in the gut was measured after 4 months' exposure to cigarette smoke in mice (C57BL/6NcrSlc) fed with a cellulose-free diet. Animals were divided into control diet (AIN-93G)/non-smoke, cellulose-free diet/non-smoke, control diet/smoke, and cellulose-free diet/smoke groups. The anti-oxidant capacity in plasma was significantly suppressed by the cellulose-free diet in the non-smoke exposed mice. The suppression in the anti-oxidant capacity further declined following exposure to cigarette smoke. Both these changes in the anti-oxidant capacity were accompanied with changes in some organic acids levels in caecal contents. The anti-oxidant activity was significantly inversely correlated to succinic acid / acetic acid levels balance in caecal contents. In conclusion the cellulose-free diet suppressed the anti-oxidant capacity in mice, and the suppression further decreased by exposure to cigarette smoke. These changes in the anti-oxidant capacity may be related with changes in the gut environment.

Genistein attenuated allergic airway inflammation by modulating the transcription factors T-bet, GATA-3 and STAT-6 in a murine model of asthma

BACKGROUND

Genistein, a flavonoid in legumes and some herbal medicines, has various biological actions. Previous studies have shown that genistein decreased airway inflammation in allergic asthma. However, studies on how genistein affects immunoreactions in asthma are very limited.

OBJECTIVE

It was the aim of this study to investigate the effect of genistein on T helper 1 (Th1)/Th2 cytokines in a murine asthma model and to explore its underlying mechanisms.

METHODS

The asthma model was set up both in vivo and in vitro: the mice were divided into four groups in vivo, i.e. control group, ovalbumin-sensitized (OVA) group, Gen20 group (20 mg/kg genistein) and Gen40 group (40 mg/kg genistein), and into three groups in vitro, i.e. control group, OVA group, genistein group. Changes in lung histology were observed and concentrations of interleukin-4, interleukin-5 and interferon-γ in bronchoalveolar lavage fluid and serum were measured by enzyme-linked immunosorbent assay. The mRNA expression of GATA binding protein 3 (GATA-3), signal transducer and activator of transcription 6 (STAT-6) and T-box transcription factor (T-bet) in the lungs and CD4+ T cells of each group were detected by real-time PCR and the corresponding proteins were detected by Western blot.

RESULTS

The results showed that genistein attenuated OVA-induced airway inflammation, decreased Th2-type cytokines and increased Th1-type cytokines. Additionally, our data suggested that genistein may modulate the Th1/Th2 reaction by inhibiting GATA-3 and STAT-6 production while increasing T-bet production.

CONCLUSION

Genistein may modulate the immunomodulatory actions caused by Th1/Th2 cytokines in asthma, at least partially, by the down-regulation of GATA-3 and STAT-6 and the up-regulation of T-bet.

Oxidative stress in asthma

Asthma is a chronic inflammatory lung disease that results in airflow limitation, hyperreactivity, and airway remodeling. There is strong evidence that an imbalance between the reducing and oxidizing systems favoring a more oxidative state is present in asthma. Endogenous and exogenous reactive oxygen species, such as superoxide anion, hydroxyl radical, hypohalite radical, and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide, peroxynitrite, and nitrite, play a major role in the airway inflammation and are determinants of asthma severity. Asthma is also associated with decreased antioxidant defenses, such as superoxide dismutase, catalase, and glutathione. In this review, we will summarize the current knowledge and discuss the current and future strategies for the modulation of oxidative stress in asthma.

A systematic review of the role of vitamin insufficiencies and supplementation in COPD

BACKGROUND

Pulmonary inflammation, oxidants-antioxidants imbalance, as well as innate and adaptive immunity have been proposed as playing a key role in the development of COPD. The role of vitamins, as assessed either by food frequency questionnaires or measured in serum levels, have been reported to improve pulmonary function, reduce exacerbations and improve symptoms. Vitamin supplements have therefore been proposed to be a potentially useful additive to COPD therapy.

METHODS

A systematic literature review was performed on the association of vitamins and COPD. The role of vitamin supplements in COPD was then evaluated.

CONCLUSIONS

The results of this review showed that various vitamins (vitamin C, D, E, A, beta and alpha carotene) are associated with improvement in features of COPD such as symptoms, exacerbations and pulmonary function. High vitamin intake would probably reduce the annual decline of FEV1. There were no studies that showed benefit from vitamin supplementation in improved symptoms, decreased hospitalization or pulmonary function.

Prospective study of dietary fiber and risk of chronic obstructive pulmonary disease among US women and men

Little is known about the relation between dietary fiber intake and the incidence of respiratory diseases, especially chronic obstructive pulmonary disease (COPD). The authors investigated this issue among 111,580 US women and men (Nurses' Health Study and Health Professionals Follow-up Study), with 832 cases of newly diagnosed COPD being reported between 1984 and 2000. The cumulative average intake of total fiber and of fiber from specific sources (cereal, fruit, and vegetables) was calculated from food frequency questionnaires and a food composition database and divided into quintiles. After adjustment for 11 factors (age, sex, smoking, energy intake, body mass index, US region, physician visits, physical activity, diabetes, and intakes of omega-3 and cured meat), total dietary fiber intake was negatively associated with risk of newly diagnosed COPD (for highest vs. lowest intake, relative risk = 0.67, 95% confidence interval: 0.50, 0.90; P(trend) = 0.03). For specific fiber sources (cereal, fruit, and vegetables), only cereal fiber was significantly associated with newly diagnosed COPD independently of other fiber sources (for highest vs. lowest intake, relative risk = 0.77, 95% confidence interval: 0.59, 0.99; P(trend) = 0.04). These data suggest that a diet high in fiber, and possibly specifically cereal fiber, may reduce risk of developing COPD.

Do vegetables and fruits reduce the risk of chronic obstructive pulmonary disease? A case-control study in Japan

OBJECTIVE

To investigate the relationship between vegetable and fruit consumption and the risk of chronic obstructive pulmonary disease (COPD), a case-control study was conducted in central Japan in 2006.

METHODS

A total of 278 referred patients with COPD diagnosed within the past four years and 340 community-based controls undertook spirometric measurements of respiratory function. A structured questionnaire was administered face-to-face to obtain information on demographics, lifestyle and habitual food consumption.

RESULTS

The mean vegetable and fruit intakes of cases (155.62 (SD 88.84) and 248.32 (SD 188.17) g/day) were significantly lower (p<0.01) than controls (199.14 (SD 121.41) and 304.09 (SD 253.72) g/day). A substantial reduction in COPD risk was found by increasing daily total vegetable intake, p for trend=0.037. The prevalence of breathlessness also decreased with vegetable consumption, the adjusted odds ratio being 0.49 (95% CI 0.27-0.88) for the highest versus lowest quartile of intake. However, the effects of fruit consumption were not significant. Among the nutrients contained in vegetables and fruits, vitamin A was particularly significant (p=0.008) with an estimated 52% reduction in COPD risk at the highest level of intake.

CONCLUSION

The study provided evidence of an inverse association between vegetable consumption and the risk of COPD for Japanese adults.

Soy consumption and risk of COPD and respiratory symptoms: a case-control study in Japan

BACKGROUND

To investigate the relationship between soy consumption, COPD risk and the prevalence of respiratory symptoms, a case-control study was conducted in Japan.

METHODS

A total of 278 eligible patients (244 men and 34 women), aged 50-75 years with COPD diagnosed within the past four years, were referred by respiratory physicians, while 340 controls (272 men and 68 women) were recruited from the community. All participants underwent spirometric measurements of respiratory function. Information on demographics, lifestyle characteristics and habitual food consumption was obtained using a structured questionnaire.

RESULTS

Total soy consumption was positively correlated with observed lung function measures. The mean soy intake was significantly higher among controls (59.98, SD 50.23 g/day) than cases (44.84, SD 28.5 g/day). A significant reduction in COPD risk was evident for highest versus lowest quartile of daily intake of total soybean products, with adjusted odds ratio (OR) 0.392, 95% CI 0.194-0.793, p for trend 0.001. Similar decreases in COPD risk were associated with frequent and higher intake of soy foods such as tofu and bean sprouts, whereas respiratory symptoms were inversely associated with high consumption of soy foods, especially for breathlessness (OR 0.989, 95% CI 0.982-0.996).

CONCLUSION

Increasing soy consumption was associated with a decreased risk of COPD and breathlessness.

Clinical cough V: complementary and alternative medicine: therapy of cough

We review the actions of complementary and alternative medicines (CAMs) in the treatment of cough and of the conditions associated with it; in particular asthma and upper respiratory tract infections. These therapies may work (1) peripherally, at the sites in the airways and lungs at which cough is being activated, (2) in the brainstem, where the neural "cough center" is situated, or (3) at the cerebral cortex, where cough can be initiated, suppressed or modified by conscious or unconscious controls. Of the large number of trials of CAMs against cough, most are inadequate in design. It may be difficult to randomize selection. Blinding is often impossible both for the patient and the therapist, and adequate placebo controls may be difficult to devise. The patient can usually identify the "active" treatment by the taste or smell of a medicine, or from the approach and apparatus being used. Pure chemicals can be extracted from many of the herbs used as antitussives, and can be shown to be effective in randomized, blind, and controlled trials, but it does not follow that the herb itself, used in the recommended formula and shown to be antitussive, acts by this agency unless a placebo effect is ruled out. A few herbs are identified where the evidence points to a true antitussive action. Of nonherbal treatments, the few positive results are usually outweighed by the larger number of negative ones. Thus, in general, CAMs for cough are welcomed enthusiastically by the patient but lack sound evidence for their efficacy. Antitussive chemicals can be extracted from many herbs, but it is no more than a reasonable hypothesis that the herb itself acts through this pathway.

(Xeno)estrogen regulation of food allergy

Food allergy and other types of allergies are becoming epidemic in both the developed and developing countries. A large amount of information is available in literature that (xeno)estrogens can regulate the immune response in general, and the development of allergy in particular; however, the effect of (xeno)estrogens on food allergy is basically unknown. With increasing use of xenobiotics worldwide, chemicals with estrogenic activity have been accumulating in our environment. This review has summarized the current literature relating to the topic (xeno)estrogen regulation of food allergy. The effect of (xeno)estrogens on enterocytes, proteases for protein hydrolysis, dendritic cells and T-regulatory cells in the gastrointestinal tract has been discussed. Finally, considering the current confusion in literature regarding the effect of phytoestrogen genistein on the immune system, a brief discussion has been included for its effect on T(H)1-T(H)2 polarization, and possibly food allergy in its relation to windows of exposure. Sufficient evidences exist to support the notion that (xeno)estrogens can regulate food allergy, with the developmental periods more sensitive. Further clinical and animal studies are needed to determine the causal relationship between the exposure of (xeno)estrogens and incidence of food allergy, and the underlying mechanisms.

Dietary fiber, lung function, and chronic obstructive pulmonary disease in the atherosclerosis risk in communities study

Recent data suggest beneficial effects of fiber intake on chronic respiratory symptoms in adults that are independent of antioxidant vitamin intake, but little is known about fiber consumption in relation to lung function and chronic obstructive pulmonary disease (COPD). The authors investigated the association of fiber intake with lung function and COPD in 11,897 US men and women from the Atherosclerosis Risk in Communities study (1987-1989). After control for potential confounders, positive associations were found between lung function and fiber intake from all sources as well as from cereal or fruit alone. Compared with those in the lowest quintile, participants in the highest quintile of total fiber intake had a 60.2-ml higher forced expiratory volume in 1 second (FEV(1)) (p for trend < 0.001), 55.2-ml higher forced vital capacity (FVC) (p = 0.001), 0.4% higher FEV(1)/FVC ratio (p = 0.040), 1.8% higher percent predicted FEV(1) (p < 0.001), and 1.4% higher percent predicted FVC (p = 0.001). Adjusted odds ratios of COPD for the highest versus lowest quintiles of intake were 0.85 (p = 0.044) for total fiber, 0.83 (p = 0.021) for cereal fiber, and 0.72 (p = 0.005) for fruit fiber. This study provides the first known evidence that dietary fiber is independently associated with better lung function and reduced prevalence of COPD.

A mechanism of benefit of soy genistein in asthma: inhibition of eosinophil p38-dependent leukotriene synthesis

BACKGROUND

Dietary intake of the soy isoflavone genistein is associated with reduced severity of asthma, but the mechanisms responsible for this effect are unknown.

OBJECTIVE

To determine whether genistein blocks eosinophil leukotriene C(4) (LTC(4)) synthesis and to evaluate the mechanism of this effect, and to assess the impact of a 4-week period of soy isoflavone dietary supplementation on indices of eosinophilic inflammation in asthma patients.

METHODS

Human peripheral blood eosinophils were stimulated in the absence and presence of genistein, and LTC(4) synthesis was measured. 5-lipoxygenase (5-LO) nuclear membrane translocation was assessed by confocal immunofluorescence microscopy. Mitogen-activated protein (MAP) kinase activation was determined by immunoblot. Human subjects with mild-to-moderate persistent asthma and minimal or no soy intake were given a soy isoflavone supplement (100 mg/day) for 4 weeks. The fraction of exhaled nitric oxide (FE(NO)) and ex vivo eosinophil LTC(4) production were assessed before and after the soy isoflavone treatment period.

RESULTS

Genistein inhibited eosinophil LTC(4) synthesis (IC(50) 80 nm), blocked phosphorylation of p38 MAP kinase and its downstream target MAPKAP-2, and reduced translocation of 5-LO to the nuclear membrane. In patients with asthma, following 4 weeks of dietary soy isoflavone supplementation, ex vivo eosinophil LTC(4) synthesis decreased by 33% (N=11, P=0.02) and FE(NO) decreased by 18% (N=13, P=0.03).

CONCLUSION

At physiologically relevant concentrations, genistein inhibits eosinophil LTC(4) synthesis in vitro, probably by blocking p38- and MAPKAP-2-dependent activation of 5-LO. In asthma patients, dietary soy isoflavone supplementation reduces eosinophil LTC(4) synthesis and eosinophilic airway inflammation. These results support a potential role for soy isoflavones in the treatment of asthma.

Gene-air pollution interactions in asthma

Genetic and environmental factors interact to cause asthma. However, genetic studies have generally ignored environmental factors and environmental studies have generally ignored genetics. Thus, there are few examples from the literature of specific gene-environment interactions in relation to asthma. The clearest examples of genetic interactions for inhaled pollutants exist for endotoxin, environmental tobacco smoke, and ozone. Endotoxin-genetic interactions in asthma are the focus of two other manuscripts from this conference, so this review focuses on environmental tobacco smoke and ozone. In the sparse literature, there is evidence for the role of specific genes involved in oxidative stress, notably GSTM1 and TNF, in the respiratory responses to ozone and environmental tobacco smoke. There are few data on genes involved in innate immune pathways, which are crucial in response to endotoxin and may play a role in response to ozone and environmental tobacco smoke. Genes involved in oxidative stress may interact with both air pollutants and diet in relation to asthma phenotypes. Future directions to advance the field include whole genome association studies, better assessment of exposure and phenotypes, and consideration of joint interactions with diet and other co-factors that influence individual susceptibility.

Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men

BACKGROUND

Many foods are associated with chronic obstructive pulmonary disease (COPD) symptoms or lung function. Because foods are consumed together and nutrients may interact, dietary patterns are an alternative way of characterising diet. A study was undertaken to assess the relation between dietary patterns and newly diagnosed COPD in men.

METHODS

Data were collected from a large prospective cohort of US men (Health Professionals Follow-up Study). Using principal component analysis, two dietary patterns were identified: a prudent pattern (high intake of fruits, vegetables, fish and whole grain products) and a Western pattern (high intake of refined grains, cured and red meats, desserts and French fries). Dietary patterns were categorised into quintiles and Cox proportional hazards models were adjusted for age, smoking, pack-years, (pack-years)(2), race/ethnicity, physician visits, US region, body mass index, physical activity, multivitamin use and energy intake.

RESULTS

Between 1986 and 1998, 111 self-reported cases of newly diagnosed COPD were identified among 42,917 men. The prudent pattern was inversely associated with the risk of newly diagnosed COPD (RR for highest vs lowest quintile 0.50 (95% CI 0.25 to 0.98), p for trend = 0.02), and the Western pattern was positively associated with the risk of newly diagnosed COPD (RR for highest vs lowest quintile 4.56 (95% CI 1.95 to 10.69), p for trend <0.001).

CONCLUSIONS

In men, a diet rich in fruits, vegetables and fish may reduce the risk of COPD whereas a diet rich in refined grains, cured and red meats, desserts and French fries may increase the risk of COPD.

Low dietary nutrient intakes and respiratory health in adolescents

BACKGROUND

Epidemiologic studies have indicated that a diet rich in fruit, antioxidants, and n-3 fatty acids may contribute to optimal respiratory health. We investigated whether low dietary nutrient intakes were associated with lower pulmonary function and higher reporting of respiratory symptoms in adolescents.

METHODS

We examined the association of dietary factors (fruit, vegetables, vitamins C and E, beta-carotene, retinol, n-3 fatty acids) with respiratory health in a cohort of 2,112 twelfth-grade students in 13 communities in the United States and Canada during the 1998 to 1999 school year. We assessed the associations between dietary factors and pulmonary function with linear mixed models, and respiratory symptoms with logistic regression using a generalized estimating equation adjusted for individual and group-level covariates.

RESULTS

Low dietary fruit intake was associated with lower FEV(1) (- 1.3% of predicted; 95% confidence interval [CI], - 2.4 to - 0.2% of predicted), and increased odds of chronic bronchitic symptoms (odds ratio [OR], 1.36; 95% CI, 1.03 to 1.73) compared with higher intake. Low dietary n-3 fatty acids intake was associated with increased odds of chronic bronchitic symptoms (OR, 1.37; 95% confidence interval [CI], 1.05 to 1.81), wheeze (OR, 1.34; 95% CI, 1.06 to 1.69), and asthma (OR, 1.68; 95% CI, 1.18 to 2.39) compared with higher intake. Smokers with lower dietary vitamin C intake had higher ORs of respiratory symptoms compared with smokers who had higher intake.

CONCLUSIONS

Adolescents with the lowest dietary intakes of antioxidant and antiinflammatory micronutrients had lower pulmonary function and increased respiratory symptoms, especially among smokers, suggesting that adequate dietary intake may promote respiratory health and lessen the effects of oxidative stress.

Soy consumption and mortality in Hong Kong: proxy-reported case-control study of all older adult deaths in 1998

OBJECTIVES

This study investigates the relation between soy consumption and mortality in a population-based case-control study in Hong Kong of all adult deaths in 1998.

METHODS

Multivariable logistic regression was used to assess the effect of soy on all-cause and cause-specific mortality in 21,494 deceased cases and 10,968 living controls who were ethnic Chinese aged 60 or above, using proxy reports collected from the person registering the death. Dietary habits were obtained from proxies in both cases and controls, based on a 7-item questionnaire.

RESULTS

The adjusted odds ratios for all-cause mortality for soy consumption 4 or more times a week compared with less than once a month were 0.77 (95% CI: 0.62, 0.95) for men and 0.66 (0.54, 0.81) for women. Mortality from lung cancer (males P = 0.02, females P = 0.02), colorectal cancer (males P = 0.07, females P < 0.001), stomach cancer (males P = 0.04, females P = 0.03), female breast cancer (P = 0.02) and ischemic heart disease (males P < 0.001, females P = 0.002) was inversely associated with soy consumption.

CONCLUSIONS

Our study suggests that maintaining traditional levels of soy consumption could be protective for some chronic diseases in China.

Vapor, dust, and smoke exposure in relation to adult-onset asthma and chronic respiratory symptoms: the Singapore Chinese Health Study

Occupational factors contribute to a significant fraction of respiratory disease and symptoms. The authors evaluated the role of occupational exposures in asthma, chronic bronchitis, and respiratory symptoms in the Singapore Chinese Health Study, a population-based cohort of adults aged 45-74 years at enrollment in 1993-1998. Information on occupations and occupational exposures was collected at enrollment for 52,325 subjects for whom respiratory outcomes were obtained via follow-up interviews in 1999-2004. Exposure to dusts from cotton, wood, metal, minerals, and/or asbestos was associated with nonchronic cough and/or phlegm (odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.08, 1.30), chronic bronchitis (OR = 1.26, 95% CI: 1.01, 1.57), and adult-onset asthma (OR = 1.14, 95% CI: 1.00, 1.30). Cotton dust was the major contributor to respiratory symptoms. Vapor exposure from chemical solvents, dyes, cooling oils, paints, wood preservatives, and/or pesticides was associated with nonchronic cough or phlegm (OR = 1.14, 95% CI: 1.03, 1.27), chronic dry cough (OR = 1.55, 95% CI: 1.19, 2.01), and adult-onset asthma (OR = 1.34, 95% CI: 1.15, 1.56). Chemical solvents, cooling oils, and pesticides were the major contributors to respiratory symptoms. These data support the role of occupational exposures in the etiology of respiratory illness in a population-based cohort in Singapore with a low prevalence of atopic illness.