Wednesday, January 16, 2013

Common Cold Remedies - Fact vs. Fiction

It's the middle of winter and you know what that means. Cough and cold season is in full swing for many families and households. There's nothing worse than coming down with a wicked case of the common cold. It can sideline you for a week or more, which is the last thing anyone has time for.

The common cold is most typically caused by the rhinovirus[1]. Symptoms start showing up within 24-48 hours of contracting the virus and include the following:
  • Sore throat
  • Fatigue
  • Low-grade fever
  • Nasal congestion
  • Runny nose
  • Watery eyes
  • Cough
These symptoms last about 7 days for most and can make for a miserable week. It can also have a miserable effect on our nation's pocketbook. In fact, the common cold leads to $25 billion in lost productivity in our society due to absenteeism, reduction in on-the-job productivity, and caregiver absenteeism[2]. With so much at stake many people will do anything to feel better. Many of these efforts involve turning to age old remedies that our parents and grandparents handed down to us. But do these remedies work or do they just make our misery seem less, well, miserable?

I'm here to set the record straight on whether many of these handed down traditions actually work or don't work based on the scientific evidence. To do this, I've consulted one of the most trusted and comprehensive sources of information in the scientific and medical world today—The Cochrane Collaboration—as I did when I wrote my recent article on the flu vaccine - Should I Get A Flu Shot?  The Cochrane Collaboration is known for providing comprehensive reviews without being influenced or biased by any commercial entities, namely the pharmaceutical or medical device companies. That's because they do not accept funding from these commercial industries.

Here's what the reviewers concluded on the various common cold remedies...

"Since vitamin C was isolated in the 1930s it has been proposed for respiratory infections. It became particularly popular in the 1970s when Nobel laureate Linus Pauling concluded from earlier placebo-controlled trials that vitamin C would prevent and alleviate the common cold. Over two dozen new trials were undertaken thereafter. Vitamin C has been widely sold and used as both a preventive and therapeutic agent.

This review is restricted to placebo-controlled trials testing 0.2 g per day or more of vitamin C. Regular ingestion of vitamin C had no effect on common cold incidence in the ordinary population. However, it had a modest but consistent effect in reducing the duration and severity of common cold symptoms. In five trials with participants exposed to short periods of extreme physical stress (marathon runners, skiers, and soldiers on subarctic exercises) vitamin C halved the common cold risk.
Trials of high doses of vitamin C administered therapeutically, starting after the onset of symptoms, showed no consistent effect on either duration or severity of common cold symptoms. However, only a few therapeutic trials have been carried out, and none have examined children, although the effect of prophylactic vitamin C has been greater in children. One large trial with adults reported equivocal benefit from an 8 g therapeutic dose at the onset of symptoms, and two trials using five-day supplementation reported benefit. More trials are necessary to settle the possible role of therapeutic vitamin C, meaning administration immediately after the onset of symptoms.

Authors' conclusions: 
The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine prophylaxis is not justified. Vitamin C could be useful for people exposed to brief periods of severe physical exercise. While the prophylaxis trials have consistently shown that vitamin C reduces the duration and alleviates the symptoms of colds, this was not replicated in the few therapeutic trials that have been carried out. Further therapeutic RCTs (randomized controlled trials) are warranted."

To summarize...
  • Regular supplementation with vitamin C to prevent the common cold in the general population is ineffective.
  • Although regular supplementation of vitamin C did not prevent the chances of acquiring the common cold in the general population, they did alleviate symptoms and reduce the duration of colds by 8% in adults and 13% in children after these individuals contracted the virus. This translates into shortening the duration of the cold by approximately half a day (0.56 days) in adults and just under one day (0.91 days) for children assuming the 7 day average for a case of the common cold.
  • Supplementing with vitamin C to treat the common cold after already contracting the virus is of no use and requires further trials before any conclusions can be made.
  • Vitamin C supplementation in individuals or athletes participating in marathons or other high intensity, prolonged events may reduce the incidence of contracting the common cold by as much as 50%.

"Zinc inhibits rhinoviral replication and has been tested in trials for treatment of the common cold. This review identified 15 randomized controlled trials, enrolling 1360 participants of all age groups, comparing zinc with placebo (no zinc). We found that zinc (lozenges or syrup) is beneficial in reducing the duration and severity of the common cold in healthy people, when taken within 24 hours of onset of symptoms. People taking zinc are also less likely to have persistence of their cold symptoms beyond seven days of treatment. Zinc supplementation for at least five months reduces incidence, school absenteeism and prescription of antibiotics for children with the common cold. People taking zinc lozenges (not syrup or tablet form) are more likely to experience adverse events, including bad taste and nausea. As there are no studies in participants in whom common cold symptoms might be troublesome (for example, those with underlying chronic illness, immunodeficiency, asthma, etc.), the use of zinc currently cannot be recommended for them. Given the variability in the populations studied (no studies from low- or middle-income countries), dose, formulation and duration of zinc used in the included studies, more research is needed to address these variabilities and determine the optimal duration of treatment as well as the dosage and formulations of zinc that will produce clinical benefits without increasing adverse effects, before making a general recommendation for zinc in treatment of the common cold.

Authors' conclusions: 
Zinc administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people. When supplemented for at least five months, it reduces cold incidence, school absenteeism and prescription of antibiotics in children. There is potential for zinc lozenges to produce side effects. In view of this and the differences in study populations, dosages, formulations and duration of treatment, it is difficult to make firm recommendations about the dose, formulation and duration that should be used."

To summarize...
  • Duration and severity of the common cold can be reduced with zinc supplementation if started within 24 hours of symptom onset.
  • Regular supplementation with zinc (at least 5 months) reduces incidence of the common cold in children leading to less school days missed and fewer antibiotics being prescribed. As a side note, the common cold is caused by the rhinovirus and antibiotics are completely useless to treat viruses and, therefore, should not be prescribed or used to treat the common cold under any circumstances.
  • Zinc supplementation in individuals with underlying medical conditions (immunodeficiency, asthma, or other chronic diseases) has not been studied and cannot be recommended to treat the common cold at this time.

"Preparations of the plant Echinacea are widely used in some European countries and in North America for common colds. Echinacea preparations available on the market differ greatly as different types (species) and parts (herb, root, or both) of the plant are used, different manufacturing methods (drying, alcoholic extraction, or pressing out the juice from fresh plants) are used, and sometimes also other herbs are added. We reviewed 16 controlled clinical trials investigating the effectiveness of several different Echinacea preparations for preventing and treating common colds. Two trials investigated whether taking Echinacea preparations for 8 to 12 weeks prevents colds but found no clear effect. The majority of trials investigated whether taking Echinacea preparations after the onset of cold symptoms shortens the duration or decreases the severity of symptoms, compared with placebo. It seems that some preparations based on the herb of Echinacea purpurea might be effective for this purpose in adults, while there is no clear evidence that other preparations are effective or that children benefit. Side effects were infrequent but rashes were reported in one trial in children.

Sixteen trials including a total of 22 comparisons of Echinacea preparations and a control group (19 placebo, 2 no treatment, 1 another herbal preparation) met the inclusion criteria. All trials except one were double-blinded. The majority had reasonable to good methodological quality. Three comparisons investigated prevention; 19 comparisons investigated treatment of colds. A variety of different Echinacea preparations were used. None of the prevention trials showed an effect over placebo. Comparing an Echinacea preparation with placebo as treatment, a significant effect was reported in nine comparisons, a trend in one, and no difference in six. Evidence from more than one trial was available only for preparations based on the aerial parts of Echinacea purpurea (E. purpurea).
Authors' conclusions: 
Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of E. purpurea might be effective for the early treatment of colds in adults but the results are not fully consistent. Beneficial effects of other Echinacea preparations, and Echinacea used for preventative purposes might exist but have not been shown in independently replicated, rigorous RCTs."

To summarize...
  • Consistency of Echinacea products is unpredictable and only one study—using aerial parts of Echinacea purpurea—showed a benefit over placebo in the treatment of the common cold. As a reminder, Echinacea is an over-the-counter herbal product, not subject to any FDA regulations or standards of any kind, and variations in products can be commonplace in the market.
  • No trials showed a benefit in preventing the common cold with the use of Echinacea.

"Many Chinese herbal medicines are used to treat this illness in China. Although we included 17 trials, involving 3212 patients, in this review, the risk of bias was so high that the evidence did not support using any Chinese herbal preparation(s) for the common cold. Well-designed clinical trials are required.

We found17 studies involving 3212 patients. The methods of 15 studies were at high risk of bias. In only two studies was the risk of bias low. Trials used "positive drugs", of which the efficacy was not known, as controls. Different Chinese herbal preparations were tested in nearly all trials. In only one trial was a Chinese herbal preparation tested twice. In seven trials, six herbal preparations were found to be more effective at enhancing recovery than the control preparations. In the other 10 studies, seven herbal preparations were not shown to be significantly different from the control. One study did not describe the difference between the intervention and control groups.
Authors' conclusions: 
Chinese herbal medicines may shorten the symptomatic phase in patients with the common cold. However, the lack of trials of low enough risk of bias, or using a placebo or a drug clearly identified as a control, means that we are uncertain enough to be unable to recommend any kind of Chinese medicinal herbs for the common cold."

To summarize...
  • Chinese herbal medication may be effective in shortening the duration of the common cold, but available trials are heavily influenced and biased by those selling or manufacturing the products themselves leading at best to inconclusive results.

"Garlic is popularly believed to be useful for the common cold. This belief is based on traditional use and some laboratory evidence that garlic has antibacterial and antiviral properties. We looked for studies that investigated the use of garlic for either preventing or treating the common cold. Of the five studies identified, only one fulfilled the criteria for the review. This study of 146 participants found that people who took garlic every day for three months (instead of a placebo) had fewer colds. When participants experienced a cold, the length of illness was similar in both groups (4.63 versus 5.63 days). While this one study was positive, there is a need for large, high-quality randomised controlled trials to support these findings. Possible side effects in this small trial included odour and a skin rash. More information is needed about the possible side effects of garlic.

There is no information from randomised controlled trials about whether taking garlic at the time of a cold reduces either symptom severity or the number of days of illness.

Authors' conclusions: 
There is insufficient clinical trial evidence regarding the effects of garlic in preventing or treating the common cold. A single trial suggested that garlic may prevent occurrences of the common cold but more studies are needed to validate this finding. Claims of effectiveness appear to rely largely on poor-quality evidence."

To summarize...
  • Only one trial showed a benefit of using garlic to prevent the common cold with no significant reduction in duration of the common cold once the illness was contracted. This was also based on poor-quality evidence at best.
  • Adverse effects from taking garlic supplements include rash and odor.

"The common cold has been treated for decades with inhaled steam in the hope this makes the mucus drain away more easily. Also there is laboratory evidence that the cold virus may be sensitive to heat. No large-scale clinical trials have been undertaken to test the clinical efficacy of this age-old therapy. However, steam inhalation continues to be used, as it provides subjective relief of the symptoms of the common cold. This review reports findings from six trials conducted on 387 participants; 215 participants had a naturally-acquired common cold and 172 healthy participants were inoculated with the common cold virus. We combined data from studies reporting the same outcomes. Studies conducted in Europe showed a positive effect whereas those from North America showed no benefit. Reported adverse effects included local discomfort, running of make-up and, in one study, increased nasal resistance. This review found that in some studies inhaling steam helped symptoms; in others it did not. The conclusion is that there is not enough evidence to support steam inhalation for the common cold. None of the studies included children.

Six trials (394 trial participants) were included. Three trials in which patient data could be pooled found benefits of steam for symptom relief for the common cold (odds ratio (OR) 0.31; 95% confidence interval (CI) 0.16 to 0.60). However, results on symptom indices were equivocal. No studies demonstrated an exacerbation of clinical symptom scores. One study conducted in the USA demonstrated worsened nasal resistance, while an earlier Israeli study showed improvement. One study examined viral shedding and antibody titres in nasal washings; there was no change in either between treatment and placebo groups. Minor side effects (including discomfort or irritation of the nose) were reported in some studies.
Authors' conclusions: 
Steam inhalation has not shown any consistent benefits in the treatment of the common cold, hence is not recommended in the routine treatment of common cold symptoms until more double-blind, randomized trials with a standardised treatment modality are conducted."

To summarize...
  • There is no clear cut evidence in any available studies to support using steam humidifiers in the treatment of the common cold. Benefits seen in 3 of the 6 trials were equivocal (questionable in nature, open to more than one interpretation).
  • Some studies showed worsening of symptoms (difficulty in breathing through nasal passages) along with nasal irritation and discomfort.

"Nasal saline sprays or irrigation have been used to treat symptoms of chronic airway infections, and sometimes for acute infections.

This review is limited by the differences in the characteristics of the included studies, including study populations and outcome measures. However, it found little research to support the use of nasal saline for acute upper respiratory tract infections (URTIs). Included studies showed limited benefit for symptoms relief with nasal saline irrigation in adults. Nasal saline is safe and may reduce time off work but may cause minor adverse effects such as dry nose or irritation in less than half of users.

Three RCTs (618 participants) were included. Most results showed no difference between nasal saline treatment and control. However, there was limited evidence of benefit with nasal saline irrigation in adults. One study showed a mean difference of 0.3 day (out of eight days) for symptom resolution, but this was not significant. Nasal saline irrigation was associated with less time off work in one study. Minor discomfort was not uncommon and 40% of babies did not tolerate nasal saline drops.
Authors' conclusions: 
Included trials were too small and had too high a risk of bias to be confident about the possible benefits of nasal saline irrigation in acute URTIs. Future trials should involve much larger numbers of participants and be rigorously designed and controlled."

To summarize...
  • Saline nasal sprays have limited, at best, use in treating symptoms of the common cold. This was seen in adults only.
  • A large number (40%) of children (babies) experienced minor discomfort from using saline products and did not tolerate them very well.
  • Available studies contained a high risk of bias and were small in scale.

Advice From The Plant-Based Pharmacist For Preventing and Treating The Common Cold

As with any illness or disease, I encourage others to use the most effective, safest, and least costly methods to achieve optimal health. This does not change with my advice on the common cold.

The best approach I've found in preventing and treating the common cold involves doing the little things right every single day. These include the following:

1) Eating a whole foods, plant-based diet
2) Engaging in 3-5 hours of moderate exercise per week
3) Avoiding animal-based (meat, dairy, and eggs) and processed foods (refined flours, added sugars, artificial sweeteners, all vegetable oils, etc.)

Nutrition does play a role in preventing illnesses like the common cold and flu. A recent study showed the incidence of upper respiratory infections was reduced by 31% in women who consumed greater than 200 mg/day of vitamin C in their diet compared to those who consumed less than 100 mg/day[3]. Kiwi is an excellent source of vitamin C, and a recent study showed how the consumption of more kiwi in the diet reduced the severity and duration of cold symptoms[4]. This was attributed to the rise in plasma levels of vitamin C, folate, and carotenoids found in individuals eating the kiwi fruit. Other fruits and vegetables with high levels of vitamin C include peppers (bell and chili), guavas, dark leafy greens (kale, mustard greens, etc.), cruciferous vegetables (broccoli, cauliflower, brussels sprouts), papayas, oranges, and strawberries. These same foods also have high levels of antioxidants and phytonutrients such as the carotenoids and/or folate to help the body boost its immune system.

Moderate-intensity exercise is also an important factor in preventing the common cold. However, regular, rigorous exercise actually increases both the incidence and severity of upper respiratory illnesses[6]. This is why marathon runners or ironman triathletes are more at risk for developing upper respiratory tract infections. Their bodies are under extreme amounts of physical stress which diminishes the ability of their immune systems to fight off would be viruses and bacteria. However, a little bit of exercise goes a long ways. Engaging in as little as 45 minutes of moderate exercise 5 days a week has been shown to decrease the incidence of URTIs in individuals[5].

The bottom line is when you take care of your body, your body will take care of you. Eat healthy and exercise every single day. You'll be thanking yourself a hundred times over. There's not a day goes by I don't thank my body for taking care of me. Since adopting a plant-based lifestyle over 4 years ago, I've caught a cold only one time. It lasted a total of 3 days and consisted of nasal congestion, runny nose, and watery eyes. That's it. I didn't take any supplements, medications, or chinese medicinal herbs, and, yet, the symptoms lasted only 72 hours. That's 4 full days less than the typical cold lasts. I simply listened to my body. I rested as much as I could, cut back on my total food intake (due to reduced appetite), and drank plenty of fluids. Oh... and I kept a large box of Kleenex handy too :)

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by Dustin Rudolph, PharmD
Clinical Pharmacist

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1 Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician. 2007 Feb 15;75(4):515-20. Review.

2 Bramley TJ, Lerner D, Sames M. Productivity losses related to the common cold. J Occup Environ Med. 2002 Sep;44(9):822-9.

3 Fondell E, Bälter O, Rothman KJ, Bälter K. Dietary intake and supplement use of vitamins C and E and upper respiratory tract infection. J Am Coll Nutr. 2011 Aug;30(4):248-58.

4 Hunter DC, Skinner MA, Wolber FM, et al. Consumption of gold kiwifruit reduces severity and duration of selected upper respiratory tract infection symptoms and increases plasma vitamin C concentration in healthy older adults. Br J Nutr. 2012 Oct;108(7):1235-45. Epub 2011 Dec 15.
5 Chubak J, McTiernan A, Sorensen B, et al. Moderate-intensity exercise reduces the incidence of colds among postmenopausal women. Am J Med. 2006 Nov;119(11):937-42.
6 Weidner TG, Sevier TL. Sport, Exercise, and the Common Cold. J Athl Train. 1996 Apr;31(2):154-9.

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