Selenium supplementation for asthma

Association between DASH diet and asthma symptoms among a large sample of adolescents: a cross-sectional study

BACKGROUND

The Dietary Approaches to Stop Hypertension (DASH) diet, which has a lot of emphasis on the consumption of fruits, vegetables, and whole grains, and on the other hand, the consumption of red meat and sodium is limited, due to its anti-inflammatory properties, which can be related to reducing the risk of asthma.

OBJECTIVES

The aim of this study was to determine the relationship between the DASH diet and asthma symptoms among children and adolescents.

METHODS

This cross-sectional study was conducted among7667 children (3414 boys and 4253 girls) aged 6-7 and 13-14 years living in central Iran. Dietary food consumption was assessed using a multiple-choice questionnaire. Logistic regression was used to obtain odds ratios for the association between the DASH-like diet with current asthma and asthma symptoms.

RESULTS

Our findings revealed that higher adherence to a DASH-like diet resulted in lower odds of asthma confirmed by a doctor among the whole population (OR = 0.53; 95%CI: 0.36-0.76) and also in females (OR = 0.47; 95%CI: 0.29-0.78). Moreover, the higher adherence to the DASH-like diet was inversely associated with the chance of wheezing in the past 12 months in all subjects (OR = 0.67; 95%CI: 0.51-0.86) and in boys (OR = 0.57; 95%CI: 0.38-0.85).

CONCLUSION

The findings of the present study showed that following the DASH diet can be associated with the improvement of asthma symptoms in children and adolescents. However, more research is needed to improve dietary recommendations for asthma prevention.

Treadmill exercise with nanoselenium supplementation affects the expression of Irisin/FNDC5 and semaphorin 3A in rats exposed to cigarette smoke extract

In the current study, we investigated the impacts of 6 weeks of aerobic interval training (AIT) with selenium nanoparticles (SeNPs) on muscle, serum, and lung irisin (FNDC5) and Sema3A in rats exposed to cigarette smoke extract (CSE). To this end, 49 male Wistar rats (8 weeks old) were divided into seven groups: control, SeNPs (2.5 mg/kg b.w by oral gavage, 3 days/week, 6 weeks), AIT (49 min/day, 5 days/week for 6 weeks, interval), SeNPs + AIT, CSE (150 µL by IP injection, 1 day/week for 6 weeks), CSE + AIT, and CSE + SeNPs + AIT. The CSE group showed a significant reduction in irisin and Sema3A serum levels, as well as a decrease in FNDC5 and Sema3A gene expression in lung tissue (p < 0.05). A combined treatment (AIT with SeNPs) significantly increased the serum level and the expression of muscle and lung irisin (FNDC5) and Sema3A in CSE received groups (p < 0.05). There was a positive and significant correlation between muscle FNDC5 and lung FNDC5 in the CSE + SeNPs + AIT group (r = 0.92, p = 0.025). In addition, there was a positive and significant correlation between serum Sema3A and lung Sema3A of CSE + SeNPs + AIT group (r = 0.97, p = 0.004). Seemingly, performing aerobic exercises with the antioxidant and anti-inflammatory supplement nano-selenium in the model of lung damage (similar to COPD) can boost myokine irisin and Sema3A, especially in serum and lung tissue. These results displayed the paracrine/endocrine regulatory function of these myokines on other tissues. In other words, these interventions emphasized the creation of crosstalk between skeletal muscles and damaged lung, focusing on its recovery; however, further research is needed.

Serum selenium levels and asthma among seafood processing workers in Greenland

Selenium levels in the Inuit population of Greenland have been declining during the last decades. The association between Selenium and asthma has been investigated previously, but with conflicting results. The objective was to measure human serum Se (s-Se) in Greenlandic seafood processing workers, to compare with levels recorded in previous decades and to establish if s-Se is associated with asthma or lung function. Data, including questionnaire answers, spirometry, skin-prick test and s-Se from 324 seafood processing workers in Greenland were collected during 2016-2017. Mean s-Se values were compared by t-test and one-way ANOVA. Associations between s-Se and asthma, symptoms from the lower airways at work and lung function were assessed using linear regression. The mean s-Se was 96.2 µg/L. S-Se was higher among non-smokers and workers living in settlements. Workers with asthma did not have s-Se levels significantly different from those of non-asthmatics. We found a positive association between s-Se levels and FEV₁ values. Selenium levels appear to continue declining in Greenland, presumably because of a more Westernised lifestyle. The health effects of declining Selenium levels remain unclear. We did not establish an association between s-Se and asthma, but we did record a positive association between s-Se and FEV₁.

The Effect of Broccoli Sprout Extract on Seasonal Grass Pollen-Induced Allergic Rhinitis

Patients exposed to pollutants are more likely to suffer from allergic rhinitis and may benefit from antioxidant treatment. Our study determined if patients diagnosed with grass-induced allergic rhinitis could benefit from broccoli sprout extract (BSE) supplementation. In total, 47 patients were confirmed with grass-induced allergic rhinitis and randomized to one of four groups: group 1 (nasal steroid spray + BSE), group 2 (nasal steroid spray + placebo tablet), group 3 (saline nasal spray + BSE) and group 4 (saline nasal spray + placebo tablet). Peak Nasal Inspiratory Flow (PNIF), Total Nasal Symptoms Scores (TNSS) and nasal mucus cytokine levels were analyzed in samples collected before and after the 3-week intervention. Comparing before and after the intervention, PNIF improved significantly when comparing Groups 1 and 2, vs. placebo, at various time points (p ≤ 0.05 at 5, 15, 60 and 240 min) following nasal challenge, while TNSS was only statistically significant at 5 (p = 0.03), 15 (p = 0.057) and 30 (p = 0.05) minutes. There were no statistically significant differences in various cytokine markers before and after the intervention. Combining nasal corticosteroid with BSE led to the most significant improvement in objective measures.

Sex Difference Between Trace Elements and Pulmonary Functions in Children

It has been defined that deficiency of trace elements plays an important role in the progression of asthma. However, the relationship between blood zinc (Zn), selenium (Se), and magnesium (Mg) and pulmonary functions in children remains to be clarified. A cross-sectional study was conducted in Wuxi, China, and a total of 202 healthy children were recruited. The forced vital capacity volume (FVC) and forced expiratory volume in the 1 s (FEV1) were measured. Blood samples were collected, and the levels of blood zinc, selenium, and magnesium were measured by inductively coupled plasma mass spectrometry (ICP-MS). Meanwhile, the concentrations of serum total IgE was also determined. The associations between trace elements and pulmonary functions were analyzed by multiple linear regression models. After stratified by sex, there was a positive association between blood Zn and pulmonary functions in boys. In addition, blood Zn was also negatively associated with serum total IgE concentrations in boys, but not in girls after adjusting for potential confounders. Our findings indicated that zinc deficiency was significantly related to children's pulmonary functions and that screening of trace elements may be a potential solution to decrease the risks of asthma in children.

Selenium Supplementation May Decrease Thyroid Peroxidase Antibody Titer via Reducing Oxidative Stress in Euthyroid Patients with Autoimmune Thyroiditis

OBJECTIVE

Selenium, as an antioxidant, has been implicated in the development of autoimmune thyroiditis (AIT). Many studies showed selenium supplementation could decrease thyroid autoantibodies in patients with AIT. However, the underlying mechanisms have not been well determined. Therefore, we performed a clinical study to investigate the possible mechanism of beneficial effects of selenium treatment on AIT patients.

METHODS

Forty euthyroid patients with AIT were randomized into two groups. Group I was treated with 200 μg/day selenium supplementation, and group II received a placebo over a 3-month period. Thyroid stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), antithyroglobulin antibody (TgAb), malondialdehyde (MDA), total antioxidant capacity (TAC), and superoxide dismutase (SOD) were measured before and 3 months after treatments. Additionally, twenty healthy volunteers also served as a control group for the evaluation of such parameters in basic condition.

RESULTS

Totally, 32 patients (group I, n = 18; group II, n = 14) completed the clinical study and were incorporated into the statistics. MDA level was higher and SOD activity and TAC were lower in patients compared to healthy individuals. After 3 months, TPOAb titer significantly decreased within group I (P < 0.001) but did not change within group II (P=0.001). There were also no statistically significant changes in TSH and TgAb titers within the two groups (all P > 0.05). Additionally, decreased MDA level (from 6.8 ± 1.3 nmol/ml to 4.9 ± 0.7 nmol/ml; P < 0.001) and increased TAC (from 10.0 ± 1.9 mmol/l to 12.9 ± 3.1 mmol/l; P=0.003) and SOD activity (from 72.3 ± 10.3 U/ml to 84.3 ± 13.2 U/ml; P=0.007) were simultaneously observed after 3 months' selenium treatment. Moreover, there was a negative correlation between TAC and TgAb/TPOAb and a positive correlation between MDA and TgAb/TPOAb in AIT patients.

CONCLUSIONS

Our findings support the hypothesis that selenium treatment could decrease TPOAb titer via enforcing the defense against oxidative stress in euthyroid patients with AIT, which may be a potential underlying mechanism.

Impact of non-drug therapies on asthma control: A systematic review of the literature

BACKGROUND

Despite growing access to effective therapies, asthma control still needs improvement. Many non-drug factors, such as allergens, air pollutants and stress also affect asthma control and patient quality of life, but an overview of the effectiveness of non-drug interventions on asthma control was lacking.

OBJECTIVES

To identify non-drug interventions likely to improve asthma control.

METHODS

A systematic review of the available literature in Medline and the Cochrane Library was conducted in March 2017, without any time limit. Initial searching identified 884 potentially relevant clinical trial reports, literature reviews and meta-analyses, which were screened for inclusion using criteria of quality, relevance, and reporting outcomes based on asthma control.

RESULTS

Eighty-two publications met the inclusion criteria. In general, the quality of the studies was low. Patient education programmes (22 studies) significantly improved asthma control. Multifaceted interventions (10 studies), which combined patient education programmes with decreasing exposure to indoor allergens and pollutants, significantly improved asthma control based on clinically relevant outcomes. Renovating homes to reduce exposure to allergens and indoor pollutants improved control (two studies). Air filtration systems (five studies) were effective, especially in children exposed to second-hand smoke. Most measures attempting to reduce exposure to dust mites were ineffective (five studies). Dietary interventions (eight studies) were ineffective. Promoting physical activity (five studies) tended to yield positive results, but the results did not attain significance.

CONCLUSION

Twenty-six interventions were effective in asthma control. Simultaneously combining several action plans, each focusing on different aspects of asthma management, seems most likely to be effective.

Interventions for managing asthma in pregnancy

BACKGROUND

Asthma is the most common respiratory disorder complicating pregnancy, and is associated with a range of adverse maternal and perinatal outcomes. There is strong evidence however, that the adequate control of asthma can improve health outcomes for mothers and their babies. Despite known risks of poorly controlled asthma during pregnancy, a large proportion of women have sub-optimal asthma control, due to concerns surrounding risks of pharmacological agents, and uncertainties regarding the effectiveness and safety of different management strategies.

OBJECTIVES

To assess the effects of interventions (pharmacologic and non-pharmacologic) for managing women's asthma in pregnancy on maternal and fetal/infant outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (2 June 2014) and the Cochrane Airways Group's Trials Register (4 June 2014).

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing any intervention used to manage asthma in pregnancy, with placebo, no intervention, or an alternative intervention. We included pharmacological and non-pharmacological interventions (including combined interventions). Cluster-randomised trials were eligible for inclusion (but none were identified). Cross-over trials were not eligible for inclusion.We included multi-armed trials along with two-armed trials. We also included studies published as abstracts only.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial eligibility and quality and extracted data. Data were checked for accuracy.

MAIN RESULTS

We included eight trials in this review, involving 1181 women and their babies. Overall we judged two trials to be at low risk of bias, two to be of unclear risk of bias, and four to be at moderate risk of bias.Five trials assessed pharmacological agents, including inhaled corticosteroids (beclomethasone or budesonide), inhaled magnesium sulphate, intravenous theophylline, and inhaled beclomethasone verus oral theophylline. Three trials assessed non-pharmacological interventions, including a fractional exhaled nitric oxide (FENO)-based algorithm versus a clinical guideline-based algorithm to adjust inhaled corticosteroid therapy, a pharmacist-led multi-disciplinary approach to management versus standard care, and progressive muscle relaxation (PMR) versus sham training.The eight included trials were assessed under seven separate comparisons. Pharmacological interventionsPrimary outcomes: one trial suggested that inhaled magnesium sulphate in addition to usual treatment could reduce exacerbation frequency in acute asthma (mean difference (MD) -2.80; 95% confidence interval (CI) -3.21 to -2.39; 60 women). One trial assessing the addition of intravenous theophylline to standard care in acute asthma did not report on exacerbations (65 women). No clear difference was shown in the risk of exacerbations with the use of inhaled beclomethasone in addition to usual treatment for maintenance therapy in one trial (risk ratio (RR) 0.36; 95% CI 0.13 to 1.05; 60 women); a second trial also showed no difference, however data were not clearly reported to allow inclusion in a meta-analysis. No difference was shown when inhaled beclomethasone was compared with oral theophylline for maintenance therapy (RR 0.88; 95% CI 0.59 to 1.33; one trial, 385 women). None of these trials reported on neonatal intensive care admissions.

SECONDARY OUTCOMES

inhaled magnesium sulphate in acute asthma was shown to improve lung function measures (one trial, 60 women); intravenous theophylline in acute asthma was not associated with benefits (one trial, 65 women). No clear differences were seen with the addition of inhaled corticosteroids to routine treatment in three trials (374 women). While inhaled beclomethasone, compared with oral theophylline, significantly reduced treatment discontinuation due to adverse effects in one trial (384 women), no other differences were observed, except for higher treatment adherence with theophylline. Four of the five trials did not report on adverse effects. Non-pharmacological interventionsPrimary outcomes: in one trial, the use of a FENO-based algorithm was shown to significantly reduce asthma exacerbations (RR 0.61; 95% CI 0.41 to 0.90; 220 women); and a trend towards fewer neonatal hospitalisations was observed (RR 0.46; 95% CI 0.21 to 1.02; 214 infants). No exacerbations occurred in one trial assessing pharmacist-led management; this approach did not reduce neonatal intensive care admissions (RR 1.50; 95% CI 0.27 to 8.32; 58 infants). One trial (64 women) assessing PMR did not report on exacerbations or neonatal intensive care admissions.

SECONDARY OUTCOMES

the use of a FENO-based algorithm to adjust therapy led to some improvements in quality of life scores, as well as more frequent use of inhaled corticosteroids and long-acting β-agonists, and less frequent use of short-acting β-agonists (one trial, 220 women). The FENO-based algorithm was associated with fewer infants with recurrent episodes of bronchiolitis in their first year of life, and a trend towards fewer episodes of croup for infants. Pharmacist-led management improved asthma control scores at six months (one trial, 60 women); PMR improved lung function and quality of life measures (one trial, 64 women). No other differences between comparisons were observed.

AUTHORS' CONCLUSIONS

Based on eight included trials, of moderate quality overall, no firm conclusions about optimal interventions for managing asthma in pregnancy can be made. Five trials assessing pharmacological interventions did not provide clear evidence of benefits or harms to support or refute current practice. While inhaled magnesium sulphate for acute asthma was shown to reduce exacerbations, this was in one small trial of unclear quality, and thus this finding should be interpreted with caution. Three trials assessing non-pharmacological interventions provided some support for the use of such strategies, however were not powered to detect differences in important maternal and infant outcomes. While a FENO-based algorithm reduced exacerbations, the effects on perinatal outcomes were less certain, and thus widespread implementation is not yet appropriate. Similarly, though positive effects on asthma control were shown with PMR and pharmacist-led management, the evidence to date is insufficient to draw definitive conclusions.In view of the limited evidence base, further randomised trials are required to determine the most effective and safe interventions for asthma in pregnancy. Future trials must be sufficiently powered, and well-designed, to allow differences in important outcomes for mothers and babies to be detected. The impact on health services requires evaluation. Any further trials assessing pharmacological interventions should assess novel agents or those used in current practice. Encouragingly, at least five trials have been identified as planned or underway.

DASH for asthma: a pilot study of the DASH diet in not-well-controlled adult asthma

This pilot study aims to provide effect size confidence intervals, clinical trial and intervention feasibility data, and procedural materials for a full-scale randomized controlled trial that will determine the efficacy of Dietary Approaches to Stop Hypertension (DASH) as adjunct therapy to standard care for adults with uncontrolled asthma. The DASH diet encompasses foods (e.g., fresh fruit, vegetables, and nuts) and antioxidant nutrients (e.g., vitamins A, C, E, and zinc) with potential benefits for persons with asthma, but it is unknown whether the whole diet is beneficial. Participants (n = 90) will be randomized to receive usual care alone or combined with a DASH intervention consisting of 8 group and 3 individual sessions during the first 3 months, followed by at least monthly phone consultations for another 3 months. Follow-up assessments will occur at 3 and 6 months. The primary outcome measure is the 7-item Juniper Asthma Control Questionnaire, a validated composite measure of daytime and nocturnal symptoms, activity limitations, rescue medication use, and percentage predicted forced expiratory volume in 1 second. We will explore changes in inflammatory markers important to asthma pathophysiology (e.g., fractional exhaled nitric oxide) and their potential to mediate the intervention effect on disease control. We will also conduct pre-specified subgroup analyses by genotype (e.g., polymorphisms on the glutathione S transferase gene) and phenotype (e.g., atopy, obesity). By evaluating a dietary pattern approach to improving asthma control, this study could advance the evidence base for refining clinical guidelines and public health recommendations regarding the role of dietary modifications in asthma management.

Glutathione redox control of asthma: from molecular mechanisms to therapeutic opportunities

Asthma is a chronic inflammatory disorder of the airways associated with airway hyper-responsiveness and airflow limitation in response to specific triggers. Whereas inflammation is important for tissue regeneration and wound healing, the profound and sustained inflammatory response associated with asthma may result in airway remodeling that involves smooth muscle hypertrophy, epithelial goblet-cell hyperplasia, and permanent deposition of airway extracellular matrix proteins. Although the specific mechanisms responsible for asthma are still being unraveled, free radicals such as reactive oxygen species and reactive nitrogen species are important mediators of airway tissue damage that are increased in subjects with asthma. There is also a growing body of literature implicating disturbances in oxidation/reduction (redox) reactions and impaired antioxidant defenses as a risk factor for asthma development and asthma severity. Ultimately, these redox-related perturbations result in a vicious cycle of airway inflammation and injury that is not always amenable to current asthma therapy, particularly in cases of severe asthma. This review will discuss disruptions of redox signaling and control in asthma with a focus on the thiol, glutathione, and reduced (thiol) form (GSH). First, GSH synthesis, GSH distribution, and GSH function and homeostasis are discussed. We then review the literature related to GSH redox balance in health and asthma, with an emphasis on human studies. Finally, therapeutic opportunities to restore the GSH redox balance in subjects with asthma are discussed.

An integrative review of systematic reviews related to the management of breathlessness in respiratory illnesses

BACKGROUND

Breathlessness is a debilitating and distressing symptom in a wide variety of diseases and still a difficult symptom to manage. An integrative review of systematic reviews of non-pharmacological and pharmacological interventions for breathlessness in non-malignant disease was undertaken to identify the current state of clinical understanding of the management of breathlessness and highlight promising interventions that merit further investigation.

METHODS

Systematic reviews were identified via electronic databases between July 2007 and September 2009. Reviews were included within the study if they reported research on adult participants using either a measure of breathlessness or some other measure of respiratory symptoms.

RESULTS

In total 219 systematic reviews were identified and 153 included within the final review, of these 59 addressed non-pharmacological interventions and 94 addressed pharmacological interventions. The reviews covered in excess of 2000 trials. The majority of systematic reviews were conducted on interventions for asthma and COPD, and mainly focussed upon a small number of pharmacological interventions such as corticosteroids and bronchodilators, including beta-agonists. In contrast, other conditions involving breathlessness have received little or no attention and studies continue to focus upon pharmacological approaches. Moreover, although there are a number of non-pharmacological studies that have shown some promise, particularly for COPD, their conclusions are limited by a lack of good quality evidence from RCTs, small sample sizes and limited replication.

CONCLUSIONS

More research should focus in the future on the management of breathlessness in respiratory diseases other than asthma and COPD. In addition, pharmacological treatments do not completely manage breathlessness and have an added burden of side effects. It is therefore important to focus more research on promising non-pharmacological interventions.

The roles of phytochemicals in bronchial asthma

Despite gaps in our knowledge of how phytochemicals interfere with cellular functions, several natural plant products are utilized to prevent or treat a wide range of diseases. Identification of an agent with therapeutic potential requires multiple steps involving in vitro studies, efficacy and toxicity studies in animal models, and then human clinical trials. This review provides a brief introduction on natural products that may help to treat and/or prevent bronchial asthma and describes our current understanding of their molecular mechanisms based on various in vitro, in vivo, and clinical studies. We focus on the anti-inflammatory and anti-vascular actions of the plant products and other roles beyond the anti-oxidative effects.

Differences in associations between markers of antioxidative defense and asthma are sex specific

BACKGROUND

Lungs are exposed to high levels of oxygen, air pollutants, and smoke, all of which stimulate the production of reactive oxygen species (ROS). In addition, inflammatory cells produce ROS, and thus there may be increased demand for antioxidants, including antioxidant enzymes, in inflammatory lung diseases such as asthma. Sex-specific differences have been noted for asthma, which in postpubertal subjects is predominantly found in females. These sex-specific differences may be associated with differences on the molecular level as well.

OBJECTIVE

The aim of this cross-sectional study was to examine associations between markers of antioxidative defense and asthma, and to investigate whether these associations were different between women and men.

METHODS

Based on the European Community Respiratory Health Survey protocol, subjects were enrolled in a study of asthma risk factors. The multicenter study was conducted in 5 west Danish counties between 2003 and 2006, and the subjects were recruited as a case-enriched random sample of 10,000 Danish inhabitants aged 20 to 44 years selected by their civil registration number. Participants were identified by positive answers to asthma questions on a screening questionnaire, random sampling, or both. Serum selenium concentrations and antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase [GPX], glutathione reductase [GR], and glucose-6-phosphate dehydrogenase [G6PD]) in erythrocytes were measured. Asthma was defined as either current asthma symptoms with bronchial hyperresponsiveness (BHR) or a continuous asthma score based on 8 questions.

RESULTS

A total of 1191 mostly white women and men (mean [SD] age, 34.0 [7.1] and 35.1 [7.1] years, respectively) were enrolled in the study. Current asthma symptoms were present in 29.9% (200/670) of women and 22.5% (117/521) of men, with women reporting more positive answers (51.1% vs 40.9%, respectively; P < 0.01) to asthma questions. Serum selenium concentrations were measured in 1151 subjects (640 women, 511 men), and antioxidant enzyme activities were measured in 295 subjects (161 women, 134 men). Women had higher enzyme activities of most antioxidant enzymes (GPX, P = 0.006; GR, P < 0.001; and G6PD, P = 0.009) than did men. Although the serum selenium concentration was inversely associated with asthma in both sexes, there was a female preponderance, with 3.5% lower serum selenium in subjects with current asthma symptoms with BHR (n = 77) compared with controls (n = 287). GR activity was associated with asthma in men, with 5.7% higher enzyme activity in subjects with current asthma symptoms with BHR (n = 14) compared with controls (n = 77). However, a significant interaction with gender was observed for analyses of GR (P = 0.02), but not for analyses of selenium.

CONCLUSIONS

In this study of asthma risk factors, women had higher levels of enzyme activities than did men in a randomly selected Danish population, and sex-specific differences were found in the associations between markers of antioxidative defense and asthma.

Common respiratory diseases

The self-medication phenomenon in upper respiratory tract infections, rhinosinusitis, asthma, and chronic obstructive pulmonary disease are significant and will continue to increase. Current level of evidence is poor because of the small number of good quality studies, small sample size, short duration, and variation in the composition of the herbal interventions or therapies. The current review points to several potential therapies that could be effective either alone, or as adjuncts to conventional therapies.

Asthma in childhood

Management decisions for pediatric asthma (in patients younger than 12 years of age) based on extrapolation from available evidence in adolescents and adults (age 12 years and older) is common but rarely appropriate. This article addresses the disparity in response between the two age groups, presents the available pediatric evidence, and highlights the important areas in which further research is required. Evidence-based recommendations for acute and interval management of pediatric asthma are provided.

Bovine milk in human nutrition--a review

Milk and milk products are nutritious food items containing numerous essential nutrients, but in the western societies the consumption of milk has decreased partly due to claimed negative health effects. The content of oleic acid, conjugated linoleic acid, omega-3 fatty acids, short- and medium chain fatty acids, vitamins, minerals and bioactive compounds may promote positive health effects. Full-fat milk has been shown to increase the mean gastric emptying time compared to half-skimmed milk, thereby increasing the gastrointestinal transit time. Also the low pH in fermented milk may delay the gastric emptying. Hence, it may be suggested that ingesting full-fat milk or fermented milk might be favourable for glycaemic (and appetite?) regulation. For some persons milk proteins, fat and milk sugar may be of health concern. The interaction between carbohydrates (both natural milk sugar and added sugar) and protein in milk exposed to heat may give products, whose effects on health should be further studied, and the increasing use of sweetened milk products should be questioned. The concentration in milk of several nutrients can be manipulated through feeding regimes. There is no evidence that moderate intake of milk fat gives increased risk of diseases.

Selenium deficiency alters epithelial cell morphology and responses to influenza

It is unknown whether nutritional deficiencies affect the morphology and function of structural cells, such as epithelial cells, and modify the susceptibility to viral infections. We developed an in vitro system of differentiated human bronchial epithelial cells (BEC) grown either under selenium-adequate (Se+) or selenium-deficient (Se-) conditions, to determine whether selenium deficiency impairs host defense responses at the level of the epithelium. Se- BECs had normal SOD activity, but decreased activity of the selenium-dependent enzyme GPX1. Interestingly, catalase activity was also decreased in Se- BECs. Both Se- and Se+ BECs differentiated into a mucociliary epithelium; however, Se- BEC demonstrated increased mucus production and increased Muc5AC mRNA levels. This effect was also seen in Se+ BEC treated with 3-aminotriazole, an inhibitor of catalase activity, suggesting an association between catalase activity and mucus production. Both Se- and Se+ were infected with influenza A/Bangkok/1/79 and examined 24 h postinfection. Influenza-induced IL-6 production was greater while influenza-induced IP-10 production was lower in Se- BECs. In addition, influenza-induced apoptosis was greater in Se- BEC as compared to the Se+ BECs. These data demonstrate that selenium deficiency has a significant impact on the morphology and influenza-induced host defense responses in human airway epithelial cells.

Randomised, double blind, placebo-controlled trial of selenium supplementation in adult asthma

BACKGROUND

Epidemiological evidence from observational studies has suggested that blood levels and dietary intake of selenium of adults with asthma are lower than those of controls. The only previous trial of selenium supplementation in adults with asthma found no objective evidence of benefit but involved only 24 participants.

METHODS

A randomised, double blind, placebo-controlled trial of selenium supplementation was performed in adults with asthma in London, UK, the majority of whom (75%) reported inhaled steroid use at baseline. 197 participants were randomised to receive either a high-selenium yeast preparation (100 microg daily, n=99) or placebo (yeast only, n=98) for 24 weeks. The primary outcome was asthma-related quality of life (QoL) score. Secondary outcomes included lung function, asthma symptom scores, peak flow and bronchodilator usage. Linear regression was used to analyse the change in outcome between the two treatment arms by "intention to treat".

RESULTS

There was a 48% increase in plasma selenium between baseline and end of trial in the active treatment group but no change in the placebo group. While the QoL score improved more in the active treatment group than in the placebo group, the difference in change in score between the two groups was not significant (-0.05 (95% CI -0.19 to 0.09); p=0.47). Selenium supplementation was not associated with any significant improvement in secondary outcomes compared with placebo.

CONCLUSIONS

Selenium supplementation had no clinical benefit in adults with asthma, the majority of whom were taking inhaled steroids.

The increase in the prevalence of asthma and allergy: food for thought

Since about 1960, the prevalence of asthma and allergic disease has increased sufficiently to become a major public-health concern. Concurrently, there have been marked changes in our diet, and it has been proposed that these changes have contributed to the increase in the prevalence of asthma and allergy. In this article, these hypotheses about diet are described, together with the postulated mechanisms and the evidence for and against, leading to the most recent evidence indicating that maternal diet during pregnancy might be particularly important in the development of childhood asthma.

Low maternal vitamin E intake during pregnancy is associated with asthma in 5-year-old children

RATIONALE

We have previously reported an association between reduced maternal vitamin E intake during pregnancy and wheezing in 2-yr-old children.

OBJECTIVES

To assess whether maternal nutrient intake during pregnancy is associated with asthma-related outcomes in children aged 5 yr.

METHODS

A longitudinal cohort study of 1,861 children born to women recruited during pregnancy and followed up at 5 yr.

MEASUREMENTS

Maternal nutrient status was assessed by a food frequency questionnaire and plasma levels. Respiratory and food frequency questionnaires were completed at 5 yr and children were invited for measurement of spirometry and skin-prick testing.

MAIN RESULTS

Symptom and food frequency questionnaire data were available for 1,253 and 1,120 children, respectively; 700 children were skin prick tested, and FEV(1) was measured in 478 and exhaled nitric oxide in 167 children. In 5-yr-old children, maternal vitamin E intake during pregnancy was negatively associated with wheeze in previous year (odds ratio per intake quintile, 0.82; 95% confidence interval, 0.71-0.95), asthma ever (0.84, 0.72-0.98), asthma and wheeze in previous year (0.79, 0.65-0.95), and persistent wheezing (0.77, 0.63-0.93). Maternal plasma alpha-tocopherol during pregnancy was positively associated with post-bronchodilator FEV(1) at 5 yr, with a 7-ml (95% confidence interval, 0-14; p = 0.04) increase in FEV(1) per microg/ml alpha-tocopherol. Maternal zinc intake during pregnancy was negatively associated with asthma ever (0.83, 0.71-0.78) and active asthma (0.72, 0.59-0.89). There were no associations between children's nutrient intake and respiratory outcomes.

CONCLUSION

Maternal intake of foods containing vitamin E and zinc during pregnancy is associated with differences in the risks of developing childhood wheeze and asthma.

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Biology of diesel exhaust effects on respiratory function

In recent decades, clinicians and scientists have witnessed a significant increase in the prevalence of allergic rhinitis and asthma. The factors underlying this phenomenon are clearly complex; however, this rapid increase in the burden of atopic disease has undeniably occurred in parallel with rapid industrialization and urbanization in many parts of the world. Consequently, more people are exposed to air pollutants than at any point in human history. Worldwide, increases in allergic respiratory disease have mainly been observed in urban communities. Epidemiologic and clinical investigations have suggested a strong link between particulate air pollution and detrimental health effects, including cardiopulmonary morbidity and mortality. The purpose of this review is to provide an evidence-based summary of the health effects of air pollutants on asthma, focusing on diesel exhaust particles (DEPs) as a model particulate air pollutant. An overview of observational and experimental studies linking DEPs and asthma will be provided, followed by consideration of the mechanisms underlying DEP-induced inflammation and a brief discussion of future research and clinical directions.