ArcR modulates biofilm formation in the dental plaque colonizer Streptococcus gordonii.

Biofilm formation and cell-cell sensing by the pioneer dental plaque colonizer Streptococcus gordonii are dependent upon arginine. This study aimed to identify genetic factors linking arginine-dependent responses and biofilm formation in S. gordonii. Isogenic mutants disrupted in genes required for the biosynthesis or catabolism of arginine, or for arginine-dependent gene regulation, were screened for their ability to form biofilms in a static culture model. Biofilm formation by a knockout mutant of arcR, encoding an arginine-dependent regulator of transcription, was reduced to < 50% that of the wild-type whereas other strains were unaffected. Complementation of S. gordonii ∆arcR with a plasmid-borne copy of arcR restored the ability to develop biofilms. By DNA microarray analysis, 25 genes were differentially regulated in S. gordonii ∆arcR compared with wild-type under arginine-replete conditions including eight genes encoding components of phosphotransferase systems for sugar uptake. By contrast, disruption of argR or ahrC genes, which encode paralogous arginine-dependent regulators, each resulted in significant changes in the expression of more than 100 genes. Disruption of a gene encoding a putative extracellular protein that was strongly regulated in S. gordonii ∆arcR had a minor impact on biofilm formation. We hypothesize that genes regulated by ArcR form a critical pathway linking arginine sensing to biofilm formation in S. gordonii. Further elucidation of this pathway may provide new targets for the control of dental plaque formation by inhibiting biofilm formation by a key pioneer colonizer of tooth surfaces.

Summarising published results from spirometric surveys of COPD: the problem of inconsistent definitions.

SETTING: The use of different spirometric definitions for chronic obstructive pulmonary disease (COPD) has made an informative review of the available prevalence surveys impossible. OBJECTIVE: To derive adjustment factors that allow the comparison of studies using different spirometric criteria. METHODS: Pre- and post-bronchodilator one-second forced expiratory volume (FEV1) and forced vital capacity (FVC) values were taken from the Burden of Obstructive Lung Disease (BOLD) survey in 16 centres. Using a post-bronchodilator FEV1/FVC ratio less than the lower limit of normal (LLN) as our reference prevalence, we calculated simple multiplicative adjustments to transform other reported prevalence estimates to reference values. These adjustments were then tested on independent data sets from six further BOLD centres and five centres from the PLATINO study, a Latin American survey on obstructive lung disease. RESULTS: Prevalence estimates based on pre-bronchodilator fixed-ratio measurements were 5-25% higher than reference values, and were strongly positively biased with age and prevalence level. Applying simple adjustments provided prevalence estimates that were almost unbiased and within 5% of the reference values. CONCLUSIONS: Using the BOLD data, we have been able to estimate COPD prevalences based on post-bronchodilator FEV1/FVC < LLN by adjusting estimates based on other common definitions, enabling more meaningful comparisons of published findings.

Tuberculosis control in a socially vulnerable area: a community intervention beyond DOT in a Brazilian favela.

OBJECTIVES: To evaluate the population-based impact of a comprehensive intervention to strengthen tuberculosis (TB) control in Rocinha, the largest urban slum in Rio de Janeiro, Brazil. DESIGN: In July 2003, 40 lay persons were hired and trained as community health workers to supervise treatment, implement educational activities and establish a supportive social network for anti-tuberculosis treatment. Between July 2005 and June 2008, a door-to-door active case finding campaign was conducted. Data were obtained from the Brazilian National Reporting System, which collects information from the TB notification form for every reported case. RESULTS: Between January 2001 and December 2008, 2623 TB cases were reported, 852 before and 1771 after the start of the program. Following the intervention, treatment success rates increased (67.6% vs. 83.2%, P < 0.001) and default rates dropped (17.8% vs. 5.5%, P < 0.001). Compared to the pre-intervention period, the TB case rate declined by an average of 39 cases per 100,000 population per 6 months (P = 0.003) in the post-intervention period, although this may have been due to secular trends already in place at the start of the intervention. Case rates declined from 591/100,000 in 2001 to 496/100,000 in 2008. CONCLUSION: With proper planning and effective community involvement, a successful intervention can lead to high cure rates and may contribute to a decrease in TB notification rates.

Tooth-surface-specific effects of xylitol: randomized trial results.

The Xylitol for Adult Caries Trial was a three-year, double-blind, multi-center, randomized clinical trial that evaluated the effectiveness of xylitol vs. placebo lozenges in the prevention of dental caries in caries-active adults. The purpose of this secondary analysis was to investigate whether xylitol lozenges had a differential effect on cumulative caries increments on different tooth surfaces. Participants (ages 21-80 yrs) with at least one follow-up visit (n = 620) were examined at baseline, 12, 24, and 33 months. Negative binomial and zero-inflated negative binomial regression models were used to estimate incidence rate ratios (IRR) for xylitol's differential effect on cumulative caries increments on root and coronal surfaces and, among coronal surfaces, on smooth (buccal and lingual), occlusal, and proximal surfaces. Participants in the xylitol arm developed 40% fewer root caries lesions (0.23 D2FS/year) than those in the placebo arm (0.38 D2FS/year; IRR = 0.60; 95% CI [0.44, 0.81]; p < .001). There was no statistically significant difference between xylitol and control participants in the incidence of smooth-surface caries (p = .100), occlusal-surface caries (p = .408), or proximal-surface caries (p = .159). Among these caries-active adults, xylitol appears to have a caries-preventive effect on root surfaces (ClinicalTrials.gov NCT00393055).

Restricted spirometry in the Burden of Lung Disease Study.

BACKGROUND: The presence of restrictive lung disease has classically required the measure of total lung capacity to document 'true' restriction, which has limited its detection in large population-based studies. METHODS: We used spirometric data to classify people with restricted spirometry (forced expiratory volume in 1 second [FEV(1)]/forced vital capacity ≥ 0.70 and FEV(1) < 80% predicted) in the Burden of Lung Disease (BOLD) Study and determined the relation between this finding and demographic factors and the presence of chronic diseases, including diabetes mellitus, hypertension and cardiovascular disease. RESULTS: Overall, we found that 11.7% of men (546/4664) and 16.4% of women (836/5098) had restricted spirometry. Prevalence varied widely by site, from a low of 4.2% among males in Sydney, Australia, to a high of 48.7% among females in Manila, The Philippines. Compared to people with normal lung function, those with restricted spirometry had a higher prevalence of diabetes (12.2% vs. 4.6%), heart disease (15.0% vs. 7.7%) and hypertension (38.8% vs. 22.8%). CONCLUSIONS: Restricted spirometry is a common finding in population studies. Additional research is needed to better define and describe the mechanisms that lead to restricted spirometry and potential interventions.

Efficacy of chlorhexidine varnish for the prevention of adult caries: a randomized trial.

The Prevention of Adult Caries Study, an NIDCR-funded multicenter, double-blind, randomized clinical trial, enrolled 983 adults (aged 18-80 yrs) at high risk for developing caries (20 or more intact teeth and 2 or more lesions at screening) to test the efficacy of a chlorhexidine diacetate 10% weight per volume (w/v) dental coating (CHX). We excluded participants for whom the study treatment was contraindicated or whose health might affect outcomes or ability to complete the study. Participants were randomly assigned to receive either the CHX coating (n = 490) or a placebo control (n = 493). Coatings were applied weekly for 4 weeks and a fifth time 6 months later. The primary outcome (total net D(1-2)FS increment) was the sum of weighted counts of changes in tooth surface status over 13 months. We observed no significant difference between the two treatment arms in either the intention-to-treat or per-protocol analyses. Analysis of 3 protocol-specified secondary outcomes produced similar findings. This trial failed to find that 10% (w/v) chlorhexidine diacetate coating was superior to placebo coating for the prevention of new caries (Clinicaltrials.gov registration number NCT00357877).

Quality of spirometry tests performed by 9893 adults in 14 countries: the BOLD Study.

OBJECTIVE: to determine the ability of participants in the Burden of Obstructive Lung Disease (BOLD) study to meet quality goals for spirometry test session quality and to assess factors contributing to good quality. METHODS: Following 2 days of centralized training, spirometry was performed pre- and post-bronchodilator (BD) at 14 international sites, in random population-based samples of persons aged ≥40 years, following a standardized protocol. The quality of each test session was evaluated by the spirometer software and an expert reading center. Descriptive statistics were calculated for key maneuver acceptability variables. A logistic regression model identified the predictors of acceptable quality test sessions. RESULTS: About 96% of test sessions met our quality goals for a low back-extrapolated volume (BEV), time to peak flow (PEFT), and end-of-test volume (EOTV). The mean forced expiratory time (FET) was 10.4 s. Ninety percent of the maneuvers with the highest FVC had a forced expiratory time (FET) > 6.8 s. About 90% of test sessions had FEV(1) and FVC which were repeatable within 150 mL. Test quality was slightly better for post-BD test sessions when compared to pre-BD. Independent predictors of adequate test quality included female sex, younger age, higher education, lack of dyspnea, higher pre-BD FEV(1), less BD responsiveness, and study site. CONCLUSIONS: Quality goals for spirometry tests were met about 90% of the time in these population-based samples of adults from several countries.

CPAP and survival in moderate-to-severe obstructive sleep apnoea syndrome and hypoxaemic COPD.

Obstructive sleep apnoea syndrome (OSAS) often coexists in patients with chronic obstructive pulmonary disease (COPD). The present prospective cohort study tested the effect of OSAS treatment with continuous positive airway pressure (CPAP) on the survival of hypoxaemic COPD patients. It was hypothesised that CPAP treatment would be associated with higher survival in patients with moderate-to-severe OSAS and hypoxaemic COPD receiving long-term oxygen therapy (LTOT). Prospective study participants attended two outpatient advanced lung disease LTOT clinics in São Paulo, Brazil, between January 1996 and July 2006. Of 603 hypoxaemic COPD patients receiving LTOT, 95 were diagnosed with moderate-to-severe OSAS. Of this OSAS group, 61 (64%) patients accepted and were adherent to CPAP treatment, and 34 did not accept or were not adherent and were considered not treated. The 5-yr survival estimate was 71% (95% confidence interval 53-83%) and 26% (12-43%) in the CPAP-treated and nontreated groups, respectively (p<0.01). After adjusting for several confounders, patients treated with CPAP showed a significantly lower risk of death (hazard ratio of death versus nontreated 0.19 (0.08-0.48)). The present study found that CPAP treatment was associated with higher survival in patients with moderate-to-severe OSAS and hypoxaemic COPD receiving LTOT.

Adolescent smokers are at greater risk for current asthma and rhinitis.

BACKGROUND: The association of tobacco smoke with the prevalence of asthma and rhinitis has not been well-characterized in adolescents. METHODS: As part of the International Study of Asthma and Allergies in Childhood (ISAAC), we conducted a cross-sectional survey of 3000 adolescents aged 13-14 years in northern Argentina. Data included questions about asthma and rhinitis symptoms and about parental and personal smoking. Logistic regression and Pearson chi(2) statistics were used to estimate these associations. RESULTS: Over 13% of respondents described themselves as current smokers, and half indicated that at least one parent smoked at home. Active smoking was associated with both asthma (OR 1.83, 95%CI 1.42-2.35) and rhinitis (OR 1.61, 95%CI 1.33-1.92) in unadjusted analysis. These associations persisted after adjusting for parental smoking status, mother's educational level and sex. Boys were significantly less likely than girls to report current asthma or rhinitis. CONCLUSIONS: Active and passive smoking are both risk factors for asthma and rhinitis in adolescents. Assuming that some children with asthma never started smoking due to symptoms, then the true risk could be higher than reported here. These results reinforce the need to develop better strategies for primary and secondary prevention of tobacco exposure in children.

Comparison of spirometry criteria for the diagnosis of COPD: results from the BOLD study.

Published guidelines recommend spirometry to accurately diagnose chronic obstructive pulmonary disease (COPD). However, even spirometry-based COPD prevalence estimates can vary widely. We compared properties of several spirometry-based COPD definitions using data from the international Burden of Obstructive Lung Disease (BOLD)study. 14 sites recruited population-based samples of adults aged > or =40 yrs. Procedures included standardised questionnaires and post-bronchodilator spirometry. 10,001 individuals provided usable data. Use of the lower limit of normal (LLN) forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) ratio reduced the age-related increases in COPD prevalence that are seen among healthy never-smokers when using the fixed ratio criterion (FEV(1)/FVC <0.7) recommended by the Global Initiative for Chronic Obstructive Lung Disease. The added requirement of an FEV(1) either <80% predicted or below the LLN further reduced age-related increases and also led to the least site-to-site variability in prevalence estimates after adjusting for potential confounders. Use of the FEV(1)/FEV(6) ratio in place of the FEV(1)/FVC yielded similar prevalence estimates. Use of the FEV(1)/FVC

Can a normal peak expiratory flow exclude severe chronic obstructive pulmonary disease?

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is underdiagnosed. One barrier to diagnosis is the limited availability of spirometry testing, but in adults at risk for COPD, a normal pre-bronchodilator (pre-BD) peak expiratory flow (PEF) may rule out clinically significant COPD. OBJECTIVE: To identify post-BD airway obstruction using data from 13 708 individuals aged >or=40 years from the PLATINO and BOLD studies. METHODS: We evaluated different cut-off points of pre-BD. The PEF was obtained from a diagnostic-quality spirometer (not a mechanical PEF meter). At least one of the following COPD risk factors was present in 77% of the subjects: chronic respiratory symptoms; exposure to tobacco smoke, biomass smoke or dust in the workplace; or a previous diagnosis of asthma, COPD, emphysema or chronic bronchitis. RESULTS: Although the positive predictive value was low as expected, a pre-BD PEF of >or=70% predicted effectively ruled out Stages III and IV COPD of the Global Initiative for Chronic Obstructive Lung Disease. Among those with at least one risk factor, only 12% would require confirmatory spirometry using this criterion. CONCLUSIONS: Adding PEF measurement to a screening questionnaire may rule out severe to very severe COPD without the need for pre- and post-BD spirometry testing. Confirmation is needed from a study using inexpensive PEF meters or pocket spirometers with a staged screening protocol.

Worldwide burden of COPD in high- and low-income countries. Part I. The burden of obstructive lung disease (BOLD) initiative.

SETTING: Burden of Obstructive Lung Disease (BOLD) Initiative sites worldwide. OBJECTIVE: To measure the prevalence of chronic obstructive pulmonary disease (COPD) and its risk factors, investigate variation in prevalence across countries and develop standardized methods that can be used in industrialized and developing countries. DESIGN: Non-institutionalized adults aged > or =40 years were recruited using population-based sampling plans. Each site targeted a minimum of 600 participants (300 women, 300 men), who filled out questionnaires and performed spirometry before and after administration of 200 mug salbutamol using standardized methods. Random effects meta-analysis models were used to estimate pooled prevalence estimates and risk factor effects and to test for heterogeneity across sites and sex. RESULTS: Data published from 12 sites (n = 8775) showed that the estimated population prevalence of COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] Stage II and higher) was 10.1 +/- SE = 4.8% overall (11.8 +/- 7.9% for men and 8.5 +/- 5.8% for women). Prevalence increased with age and pack-years of smoking, but other less understood risk factors, such as biomass heating and cooking exposures, occupational exposures and tuberculosis, also contribute to the location-specific variations in disease prevalence that BOLD is finding. CONCLUSION: BOLD has estimated the social and economic burden of COPD in 12 countries to date. BOLD and the Proyecto Latinoamericano de Investigación en Obstrucción Pulmonar (the PLATINO study) are developing a growing database of COPD prevalence. Cigarette smoking and age are the most important COPD risk factors, but other risk factors should also be explored.

Harnessing stakeholder perspectives to improve the care of osteoporosis after a fracture.

UNLABELLED: This study used in-depth interviews and focus groups to evaluate osteoporosis care after a fracture. Patients (eligible women aged 67 who sustained a clinical fracture(s)), clinicians, and staff stated that an outreach program facilitated osteoporosis care management, but more-tailored education and support and increased participation of orthopedic specialists appear necessary. INTRODUCTION: Osteoporosis treatment reduces fracture risk, but screening and treatment are underutilized, even after a fracture has occurred. This study evaluated key stakeholder perspectives about the care of osteoporosis after a fracture. METHODS: Participants were from a nonprofit health maintenance organization in the United States: eligible women members aged 67 or older who sustained a clinical fracture(s) (n = 10), quality and other health care managers (n = 20), primary care providers (n = 9), and orthopedic clinicians and staff (n = 28); total n = 67. In-depth interviews and focus groups elicited participant perspectives on an outreach program to patients and clinicians and other facilitators and barriers to care. Interviews and focus group sessions were transcribed and content-analyzed. RESULTS: Patients, clinicians, and staff stated that outreach facilitated osteoporosis care management, but important patient barriers remained. Patient knowledge gaps and fatalism were common. Providers stated that management needed to begin earlier, and longer-term patient support was necessary to address adherence. Orthopedic clinicians and staff expressed lack of confidence in their osteoporosis management but willingness to encourage treatment. CONCLUSIONS: Although an outreach program assisted with the management of osteoporosis after a fracture, more-tailored education and support and increased participation of orthopedic specialists appear necessary to maximize osteoporosis management.

Risk factors for the development of bronchiolitis obliterans in children with bronchiolitis.

BACKGROUND: Bronchiolitis obliterans (BO) is an uncommon and severe form of chronic obstructive lung disease in children that results from an insult to the lower respiratory tract. METHODS: A case-control study of children under the age of 3 years was performed in 109 cases and 99 controls to determine risk factors for the development of BO. Participants were evaluated by immunofluorescence viral tests, pulmonary function tests, and questions to assess tobacco and other exposures. RESULTS: Bronchiolitis due to adenovirus (odds ratio (OR) 49, 95% confidence interval (CI) 12 to 199) and the need for mechanical ventilation (OR 11, 95% CI 2.6 to 45) were strongly and independently associated with an increased risk for BO. Factors not associated with post-infectious BO included age of the child, sex, and environmental tobacco exposure (either in utero or during infancy). CONCLUSIONS: Adenovirus infection and need for mechanical ventilation are significant risk factors for developing BO in children. Further research is needed to determine why these risk factors are so strong and how they may contribute to the development of the disease.

Caesarean section delivery and the risk of allergic disorders in childhood.

BACKGROUND: The composition of the intestinal flora in young children, if unfavourable, may increase the susceptibility to allergic disorders. Beneficial intestinal microbes originate from the maternal vaginal tract and thus are more likely to be transferred during vaginal births than during Caesarean sections (C-sections). OBJECTIVE: To determine whether children born by C-section have a different risk of allergic disorders compared with those delivered vaginally. We also tested the hypothesis that the risk of allergic disorders is highest for children born after 'repeat C-sections'. METHODS: A retrospective cohort study of 8,953 children aged 3-10 years. Children diagnosed with allergic rhinoconjunctivitis (AR), asthma, atopic dermatitis (AD), or food allergies were identified from the Kaiser Permanente Northwest Region electronic records. The children's sex, birth weight, birth order, postnatal exposure to antibiotics as well as the mothers' age, ethnicity, education, marital status, smoking status during pregnancy, and use of asthma or hayfever medications were identified through the mothers' medical records or through the Oregon Birth Registry. RESULTS: The risk of being diagnosed with AR was significantly higher in the children born by C-section than in those delivered vaginally: adjusted odds ratio (OR)=1.37%, 95% confidence interval (CI)=1.14-1.63. Delivery by C-section was also associated with the subsequent diagnosis of asthma (OR=1.24%, 95% CI=1.01-1.53); this association was gender specific, with a positive association restricted to girls (OR for asthma in girls: OR=1.53%, 95% CI=1.11-2.10; in boys: OR=1.08%, 95% CI=0.81-1.43). There was no significant association between mode of delivery and AD. If children born in a 'repeat C-section' were considered separately the risk of being diagnosed with AR increased further (OR=1.78%, 95% CI=1.34-2.37). The same increase was noted for asthma in girls (OR=1.83%, 95% CI=1.13-2.97) but not in boys. CONCLUSION: Caesarean sections may be associated with an increased risk of developing AR in childhood.

Effect of lifestyle modifications on blood pressure by race, sex, hypertension status, and age.

Recommendations for control of high blood pressure (BP) emphasize lifestyle modification, including weight loss, reduced sodium intake, increased physical activity, and limited alcohol consumption. The Dietary Approaches to Stop Hypertension (DASH) dietary pattern also lowers BP. The PREMIER randomized trial tested multicomponent lifestyle interventions on BP in demographic and clinical subgroups. Participants with above-optimal BP through stage 1 hypertension were randomized to an Advice Only group or one of two behavioural interventions that implement established recommendations (Est) or established recommendations plus DASH diet (Est plus DASH). The primary outcome was change in systolic BP at 6 months. The study population was 810 individuals with an average age of 50 years, 62% women, 34% African American (AA), 95% overweight/obese, and 38% hypertensive. Participants in all the three groups made lifestyle changes. Mean net reductions in systolic (S) BP in the Est intervention were 1.2 mmHg in AA women, 6.0 in AA men, 4.5 in non-AA women, and 4.2 in non-AA men. The mean effects of the Est Plus DASH intervention were 2.1, 4.6, 4.2, and 5.7 mmHg in the four race-sex subgroups, respectively. BP changes were consistently greater in hypertensives than in nonhypertensives, although interaction tests were nonsignificant. The Est intervention caused statistically significant BP reductions in individuals over and under age 50. The Est Plus DASH intervention lowered BP in both age groups, and significantly more so in older individuals. In conclusion, diverse groups of people can adopt multiple lifestyle changes that can lead to improved BP control and reduced CVD risk.

Comparing office-based and ambulatory blood pressure monitoring in clinical trials.

Ambulatory blood pressure monitoring (ABPM) is commonly used in clinical trials. Yet, its ability to detect blood pressure (BP) change in comparison to multiple office-based measurements has received limited attention. We recorded ambulatory and five daily pairs of random zero (RZ) BPs pre- and post-intervention on 321 adult participants in the multicentre Dietary Approaches to Stop Hypertension trial. Treatment effect estimates measured by ambulatory monitoring were similar to those measured by RZ and did not differ significantly for waking vs 24-h ambulatory measurements. For systolic BP, the standard deviations of change in mean 24-h ambulatory BP (8.0 mmHg among hypertensives and 6.0 mmHg among nonhypertensives) were comparable to or lower than the corresponding standard deviations of change in RZ-BP based on five daily readings (8.9 and 5.9 mmHg). The standard deviations of change for mean waking ambulatory BP (8.7 and 6.7 mmHg) were comparable to those obtained using three to four daily RZ readings. Results for diastolic BP were qualitatively similar. Ambulatory monitoring was more efficient (ie, a smaller sample size could detect a given BP change) than three to four sets of daily RZ readings and required fewer clinic visits. The average of 33 ambulatory BP readings during the waking hours had an efficiency comparable to that from the mean of four daily pairs of RZ-BPs. Participants readily accepted the ABPM devices, and their use requires less staff training. ABPM provides a useful alternative to RZ-BP measurements in clinical trials.

[Health situation of and health service provided for adult migrants--a survey conducted during school admittance examinations]. / Gesundheitliche Lage und Gesundheitsversorgung von erwachsenen Migranten--ein Survey bei der Schuleingangsuntersuchung.

BACKGROUND: In spite of the increasing numbers of migrants in Germany, only few epidemiological studies have been carried out to investigate the health status of ethnic minorities in Germany. Results from national and international studies on the health of immigrants are inconsistent showing either increased or decreased morbidity in relation to native inhabitants. A survey was undertaken to study the self-reported health status, help-seeking behaviour, and health care utilization among immigrants and Germans. METHODS: 565 adults (276 immigrants and 289 Germans, 97% parents) in Bielefeld, Germany, were interviewed while they accompanied children who attended the pre-school medical examinations. In the analysis descriptive statistics and logistic regression models were used. RESULTS: The self-reported general health status of the study population was good for Germans and immigrants. Germans utilized health care facilities and preventive programmes (e. g. screening programmes) more frequently than immigrants. Furthermore, Germans reported higher levels of satisfaction with health care and a higher level of knowledge about several diseases as compared to immigrants. Logistic regression models indicate that neither migration itself (OR = 0.7, 95% CI = 0.4 - 1.1) nor socio-economic factors (OR for low vs. high social level = 1.2, 95% CI = 0.6 - 2.4) were significantly associated with physical diseases among the study population. CONCLUSIONS: We found no indications that immigrants are less healthy compared to Germans. Further investigations are needed to clarify the differences in patterns of health care utilisation and participation in preventive programmes among Germans and ethnic minorities.

Dietary vitamin C intake is inversely related to cough and wheeze in young smokers.

We aimed to investigate whether dietary vitamin C intake, an important antioxidant, is inversely related to self-reported respiratory symptoms in young adults of a community. A random sample of 4300 subjects, aged 20-44 years, living in Bergen, Norway, received a postal questionnaire on respiratory symptoms; 80% responded. Vitamin C intake (mg per week) was estimated from a food-frequency questionnaire asking how often the subject, during the last year, had consumed units of orange juice, oranges, potatoes, carrots and tomatoes. Significant differences in the intake of vitamin C were observed across smoking categories with current smokers having the lowest intake, while there was no variation by gender, age or occupational dust exposure. Dietary vitamin C intake was in univariate analyses inversely related to "morning cough", "chronic cough", "wheeze" and "wheeze ever". After adjusting for gender, age, body mass index, "occupational exposure" pack-years as well as having and stratified on smoking habits in multiple logistic regression analyses, the relationship between dietary vitamin C intake and "cough" and "wheeze" tended to be associated to smoking. The odds ratio (OR) for "morning cough" was 0.68 (95% CI: 0.35-0.95), "chronic cough" OR 0.69 (95% CI: 0.47-1.04) and "wheeze ever" OR 0.75 (95% CI: 0.56-1.01) in current-smokers with dietary vitamin C intake in the upper (> or =395 mg/ week) vs. the lower (<209 mg/week) tertile. The OR for "wheeze" was 0.56 (95% CI: 0.35-0.88) in ex-smokers. The magnitude ofthese effects remained after excluding subjects with supplementary vitamin C intake (n=199) from the statistical analyses. Among young Norwegian adults, having a low prevalence of asthma and high prevalences of smoking-related respiratory symptoms, dietary vitamin C intake may act as an antioxidant and thereby reduce cough and wheeze in smokers having high oxidant stress.