Sunday, April 13, 2014
Oral Zinc for the Common Cold
The Cochrane study below is properly cautious but it seems that zinc does do some good. The result when zinc was used to prevent colds among children was particularly impressive
By Rashmi Ranjan Das, MD, FCCP1; Meenu Singh, MD, FCCP2
Is oral zinc associated with a shorter duration, decreased severity, and reduced incidence of the common cold compared with placebo ?
When initiated within 24 hours of symptom onset, oral zinc is associated with a shorter duration of the common cold in healthy people. However, there is no association between oral zinc and symptom severity, and the prevalence of adverse effects with zinc lozenges is high.
Given the high heterogeneity of data, these results should be interpreted with caution. Used prophylactically, oral zinc is associated with a reduced cold incidence in children. Prophylactic use has not been studied in adults.
Human rhinoviruses attach to nasal epithelium via the intracellular adhesion molecule 1 (ICAM-1). 1 Zinc ion blocks the ICAM-1 receptor, thereby exerting an antiviral effect. 2 This JAMA Clinical Evidence Synopsis summarizes an updated Cochrane Collaboration review 3 comparing outcomes between zinc vs placebo for reducing the duration, severity, and incidence of the common cold.
Summary of Findings
The mean supplementation duration was 7 days in therapeutic trials and 6 months in prophylactic trials.
Treatment started within 24 hours of symptom onset in 14 trials, and within 48 hours in 2 trials. The mean duration of cold symptoms was 6.75 days in the lozenge group and 7.5 days in the placebo group (mean difference, −1.04 [95% CI, −2.02 to −0.05). The mean duration was 5.1 days in the syrup group and 5.9 days in the placebo group (mean difference, −0.63 [95% CI, −0.84 to −0.43]).
There was no difference in the symptom severity score between the 2 groups. The overall mean score (of 10 symptoms each measured on a 0-3 scale, 3 = worst) was 2.52 in the lozenge group and 4.17 in the placebo group (mean difference, −1.55 [95% CI, −3.62 to 0.52]), and 0.25 in the syrup group and 0.55 in the placebo group (mean difference, −0.27 [95% CI, −1.51 to 0.97; Table).
Zinc lozenges were associated with a higher incidence of adverse events compared with placebo (46.5% for lozenges vs 36.4% for placebo; number needed to harm [NNH], 10). The most common adverse events included bad taste (29.2% for zinc vs 16.4% for placebo; NNH, 8) and nausea (22.3% for zinc vs 10.6% for placebo; NNH, 8).
Prophylactic use of zinc syrup or tablets at onset of cold season was studied only in children. Cold incidence was 38.2% in the zinc group and 61.8% in the placebo group (2 trials, 761 total children; number needed to treat [NNT], 4; Table).
Zinc was associated with shorter duration of the common cold, but not reduced severity. The prevalence of adverse effects associated with zinc lozenges is high. In the prophylactic trials, zinc was associated with a reduced cold incidence for children, but no data on prophylactic use are available for adults.
After the publication of this updated Cochrane review, a randomized clinical trial using zinc bisglycinate tablets for 3 months prophylactically in children was published. 4 The primary outcome was incidence of cold symptoms. The results were as follows: 1 symptom (84% for zinc vs 82% for placebo), 2 symptoms (38% for zinc vs 54% for placebo), and 3 symptoms (12% for zinc vs 26% for placebo). When the 2-cold symptom result was included in our analyses, our conclusions were unchanged.
The release of ionic zinc varies across formulations. Thus, the dose of zinc associated with improved outcomes varied across the included trials. A higher incidence of bad taste with zinc lozenges might have compromised blinding. No trials were conducted among high-risk participants with chronic illness, immunodeficiency, or asthma. Results may not be generalizable to these populations.
Because of a significant potential for publication bias and high heterogeneity among the lozenge trials, results should be viewed with caution. The prophylactic data in children included only 2 studies and there was a high degree of data heterogeneity.
Comparison of Findings With Current Guidelines
Our findings are consistent with 2012 American Family Physician Guidelines and with the 2013 dietary supplement fact sheet of the National Institutes of Health. Both support use of zinc supplementation within 24 hours of onset of the common cold.
Areas in Need of Future Study
Future trials should focus on patients with underlying comorbidities (chronic illness, asthma, immunodeficiency) and comparisons between syrup, tablet, or both formulations. Further information on the association of zinc dose with toxicity is needed.
JAMA. 2014;311(14):1440-1441. doi:10.1001/jama.2014.1404.
Homeopathic treatments 'no better than a placebo': Study of alternative medicine on 68 conditions found 'no evidence it was effective'
Homeopathy is no more effective than a placebo, a national medical agency has concluded in a hard-hitting report. Australia’s National Health and Medical Research Council (NHMRC) analysed research into the effectiveness of alternative medicines on 68 health conditions and found ‘there is no reliable evidence that homeopathy is effective’ on any of them.
The review, conducted by a working committee of medical experts, said homeopathy had no impact on a range of conditions including asthma, arthritis, sleep disturbances, cold and flu, chronic fatigue syndrome, eczema, cholera, burns, malaria and heroin addiction.
The authors of the report said: ‘No good-quality, well-designed studies with enough participants for a meaningful result reported either that homeopathy caused greater health improvements than a substance with no effect on the health condition [placebo], or that homeopathy caused health improvements equal to those of another treatment.’
They went on to dismiss anecdotal support for the effectiveness of homeopathy, and urged health professionals to take account of scientific evidence when informing patients.
‘It is not possible to tell whether a health treatment is effective or not simply by considering individuals’ experiences or healthcare practitioners’ beliefs,’ they said.
Homeopathy is a complementary medicine, the central principle of which is that ‘like cures like’ – that a substance that causes certain symptoms can also help to remove them in tiny doses.
In England there are several NHS homeopathic hospitals and some GP practices offer the treatment but it is not widely available.
The report prompted medical professionals to call for governments to stop legitimising homeopathy.
Professor John Dwyer, an immunologist and emeritus professor of medicine at the University of New South Wales, told Guardian Australia the report was long overdue and said homeopathic treatments should now be ‘put away’ once and for all.
He said: ‘Obviously we understand the placebo effect. We know that many people have illnesses that are short lived by its very nature and their bodies will cure them, so it’s very easy for people to fall in trap that because they did A, B follows.’ He added he did not think it ethical to prescribe a placebo.
Dr Richard Choong, Western Australia president of the Australian Medical Association, also welcomed the report and said his organisation has long held there is no evidence to support homeopathy.
‘Homeopathy is not a science. It is not based in science,’ he said. ‘In a lot of cases it can be considered dangerous and can risk people’s lives,’ said Dr Choong.
Submissions from homeopathy interest groups and the public were among the studies assessed by the NHMRC, but did not alter the conclusions of the Council, in some cases due to the poor quality of the studies submitted.
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