Physical activity and the risk of pneumonia in male smokers administered vitamin E and beta-carotene

It has been proposed that moderate exercise may enhance the immune system. We evaluated whether physical activity at work or at leisure is associated with the risk of pneumonia, and whether the antioxidants vitamin E and beta-carotene affect pneumonia risk in physically active people. A cohort of 16 804 male smokers aged 50 - 69 years and working at study entry was drawn from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which examined the effect of vitamin E, 50 mg/day, and beta-carotene, 20 mg/day, on lung and other cancers. Physical activity at work, and the type of leisure-time exercise, were recorded at study entry. We retrieved the first occurrence of hospital-treated pneumonia during a 3-year follow-up from the National Hospital Discharge Register (133 cases). Physical activity at work and at leisure had no association with the risk of pneumonia. In participants with physically loading jobs, neither vitamin E nor beta-carotene affected the risk of pneumonia. In participants carrying out moderate or heavy exercise at leisure, beta-carotene had no effect, but vitamin E reduced the risk of pneumonia by 50% (95% CI: 16-70%). Previously, exercise has been shown to affect diverse laboratory measures of the immune system which are, however, only surrogate markers for the resistance to infections. The lack of association between physical activity and the risk of pneumonia observed in our study emphasizes the problem of drawing conclusions from surrogate end points. The finding that vitamin E reduced the risk of pneumonia in persons carrying out leisure-time exercise warrants further study.Peer reviewe

Zinc Acetate Lozenges May Improve the Recovery Rate of Common Cold Patients : An Individual Patient Data Meta-Analysis

BACKGROUND: A previous meta-analysis of 3 zinc acetate lozenge trials estimated that colds were on average 40% shorter for the zinc groups. However, the duration of colds is a time outcome, and survival analysis may be a more informative approach. The objective of this individual patient data (IPD) meta-analysis was to estimate the effect of zinc acetate lozenges on the rate of recovery from colds. METHODS: We analyzed IPD for 3 randomized placebo-controlled trials in which 80-92 mg/day of elemental zinc were administered as zinc acetate lozenges to 199 common cold patients. We used mixed-effects Cox regression to estimate the effect of zinc. RESULTS: Patients administered zinc lozenges recovered faster by rate ratio 3.1 (95% confidence interval, 2.1-4.7). The effect was not modified by age, sex, race, allergy, smoking, or baseline common cold severity. On the 5th day, 70% of the zinc patients had recovered compared with 27% of the placebo patients. Accordingly, 2.6 times more patients were cured in the zinc group. The difference also corresponds to the number needed to treat of 2.3 on the 5th day. None of the studies observed serious adverse effects of zinc. CONCLUSIONS: The 3-fold increase in the rate of recovery from the common cold is a clinically important effect. The optimal formulation of zinc lozenges and an ideal frequency of their administration should be examined. Given the evidence of efficacy, common cold patients may be instructed to try zinc acetate lozenges within 24 hours of onset of symptoms.Peer reviewe

Vitamin C and infectious diseases

Non peer reviewe

Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma

Retraction: Clinical and Translational Allergy 2012, 2:6BACKGROUND: We previously found a significant benefit of vitamin C supplementation in asthmatic children. PURPOSE: To test whether the effect of vitamin C on asthma is heterogeneous over the participant population. METHODS: Egyptian asthmatic children between 7 and 10 years of age (n = 60) were included in the cross-over trial. They were administered 0.2 grams per day of vitamin C and placebo for separate 6-week periods. The variation in the vitamin C effect on two clinically relevant outcomes was analyzed: the childhood asthma control test (C-ACT), which measures the severity of asthma symptoms (the scale ranges from 0 to 27 points, < 20 points indicating unsatisfactory asthma control), and FEV1. We used linear modeling to examine the variation of the vitamin C effect in the subgroups. RESULTS: The effect of vitamin C on the C-ACT was significantly modified by age and baseline C-ACT levels. In the children aged 7.0-8.2 years with a baseline C-ACT of 18 to 19 points, vitamin C increased the C-ACT score by 4.2 points (95% CI: 3.3-5.3); whereas in the children aged 8.3-10 years who had a baseline C-ACT of 14 to 15 points, vitamin C increased the C-ACT score by only 1.3 points (95% CI: 0.1-2.5). The effect of vitamin C on the FEV1 levels was significantly modified by age and exposure to dampness. In the children aged 7.0-8.2 years with no exposure to dampness, vitamin C increased the FEV1 level by 37% (95% CI: 34-40%), whereas in the children aged 8.3-10 years with exposure to dampness or mold in their bedroom more than one year prior to the study, vitamin C increased the FEV1 level by only 21% (95% CI: 18-25%). CONCLUSIONS: We found strong evidence that the effect of vitamin C on asthmatic children is heterogeneous. Further research is needed to confirm our findings and identify the groups of children who would receive the greatest benefit from vitamin C supplementation.Peer reviewe

Many continuous variables should be analyzed using the relative scale: a case study of β2-agonists for preventing exercise-induced bronchoconstriction

BACKGROUND: The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochrane systematic review that reported only absolute effects of inhaled β2-agonists on exercise-induced decline in forced-expiratory volumes in 1 s (FEV1). METHODS: From the Cochrane review, we selected placebo-controlled cross-over studies that reported individual participant data (IPD). Reversal in FEV1 decline after exercise was modeled as a mean uniform percentage point (pp) change (absolute effect) or average percent change (relative effect) using either intercept-only or slope-only, respectively, linear mixed-effect models. We also calculated the pooled relative effect estimates using standard random-effects, inverse-variance-weighting meta-analysis using study-level mean effects. RESULTS: Fourteen studies with 187 participants were identified for the IPD analysis. On the absolute scale, β2-agonists decreased the exercise-induced FEV1 decline by 28 pp., and on the relative scale, they decreased the FEV1 decline by 90%. The fit of the statistical model was significantly better with the relative 90% estimate compared with the absolute 28 pp. estimate. Furthermore, the median residuals (5.8 vs. 10.8 pp) were substantially smaller in the relative effect model than in the absolute effect model. Using standard study-level meta-analysis of the same 14 studies, β2-agonists reduced exercise-induced FEV1 decline on the relative scale by a similar amount: 83% or 90%, depending on the method of calculating the relative effect. CONCLUSIONS: Compared with the absolute scale, the relative scale captures more effectively the variation in the effects of β2-agonists on exercise-induced FEV1-declines. The absolute scale has been used in the analysis of FEV1 changes and may have led to sub-optimal statistical analysis in some cases. The choice between the absolute and relative scale should be determined based on biological reasoning and empirical testing to identify the scale that leads to lower heterogeneity.Peer reviewe

Impedance-Matching Hearing in Paleozoic Reptiles: Evidence of Advanced Sensory Perception at an Early Stage of Amniote Evolution

BACKGROUND: Insights into the onset of evolutionary novelties are key to the understanding of amniote origins and diversification. The possession of an impedance-matching tympanic middle ear is characteristic of all terrestrial vertebrates with a sophisticated hearing sense and an adaptively important feature of many modern terrestrial vertebrates. Whereas tympanic ears seem to have evolved multiple times within tetrapods, especially among crown-group members such as frogs, mammals, squamates, turtles, crocodiles, and birds, the presence of true tympanic ears has never been recorded in a Paleozoic amniote, suggesting they evolved fairly recently in amniote history. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we performed a morphological examination and a phylogenetic analysis of poorly known parareptiles from the Middle Permian of the Mezen River Basin in Russia. We recovered a well-supported clade that is characterized by a unique cheek morphology indicative of a tympanum stretching across large parts of the temporal region to an extent not seen in other amniotes, fossil or extant, and a braincase specialized in showing modifications clearly related to an increase in auditory function, unlike the braincase of any other Paleozoic tetrapod. In addition, we estimated the ratio of the tympanum area relative to the stapedial footplate for the basalmost taxon of the clade, which, at 23:1, is in close correspondence to that of modern amniotes capable of efficient impedance-matching hearing. CONCLUSIONS/SIGNIFICANCE: Using modern amniotes as analogues, the possession of an impedance-matching middle ear in these parareptiles suggests unique ecological adaptations potentially related to living in dim-light environments. More importantly, our results demonstrate that already at an early stage of amniote diversification, and prior to the Permo-Triassic extinction event, the complexity of terrestrial vertebrate ecosystems had reached a level that proved advanced sensory perception to be of notable adaptive significance

Vitamin C and the common cold: a retrospective analysis of Chalmers’ review.

In 1975 Thomas Chalmers analyzed the possible effect of vitamin C on the common cold by calculating the average difference in the duration of cold episodes in vitamin C and control groups in seven placebo-controlled studies. He found that episodes were 0.11 +/- 0.24 (SE) days shorter in the vitamin C groups and concluded that there was no valid evidence to indicate that vitamin C is beneficial in the treatment of the common cold. Chalmers' review has been extensively cited in scientific articles and monographs. However, other reviewers have concluded that vitamin C significantly alleviates the symptoms of the common cold. A careful analysis of Chalmers' review reveals serious shortcomings. For example, Chalmers did not consider the amount of vitamin C used in the studies and included in his meta-analysis was a study in which only 0.025-0.05 g/day of vitamin C was administered to the test subjects. For some studies Chalmers used values that are inconsistent with the original published results. Using data from the same studies, we calculated that vitamin C (1-6 g/day) decreased the duration of the cold episodes by 0.93 +/- 0.22 (SE) days; the relative decrease in the episode duration was 21%. The current notion that vitamin C has no effect on the common cold seems to be based in large part on a faulty review written two decades ago

Vitamin E and respiratory tract infections in elderly persons

Non peer reviewe