It’s that time of year. The time when the days are characterized by gray skies, wet slush on the ground, and the sounds of sneezes and coughs. I, myself, am just getting through the last straggling symptoms of my own cold. It seems whenever I am sick, my friends and family are quick to chime in with their two cents about which remedy will make me better the quickest. Chicken noodle soup. Orange juice. Echinacea capsules. Zinc lozenges?
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Most of these I’ve heard time and again, but the suggestion to try zinc was new to me. Hoping for a speedy recovery from my stuffy nose and foggy head, I did a little research. A Cochrane review of 15 randomized trials of zinc as treatment for the common cold was recently published. Based on the included studies, the reviewing authors ultimately concluded that zinc can reduce the length of a cold and the severity of cold symptoms. But while it appears that zinc might help stifle the misery of a stuffy nose and sore throat, its curing abilities are a bit more complicated than simply popping a lozenge in your mouth.
What is zinc? How does it affect colds?
Zinc is a mineral primarily obtained through the foods we consume and is necessary for proper functioning of many of our major organ systems, including our immune system. In addition to promoting strong immunity, zinc appears to stop the replication of the virus responsible for those nasty cold symptoms giving your immune system a chance to fight it off sooner. Seems simple enough, but the effectiveness of zinc in fighting the common cold depends on a lot of factors.
What makes zinc such a complicated remedy?
Based on the clinical trials analyzed in the Cochrane review, zinc must be taken within the first 24 hours of cold symptoms in order for it to impact the virus and cause a benefit. As an over-the-counter remedy, however, it is up to the person with the cold to decide when their symptoms begin. Maybe it’s the development of a sore throat that alerts some people to an oncoming cold, but possibly others don’t recognize a cold until they are totally congested at which time, the window for zinc to have the best effect may have already passed.
Also, the method of delivery matters. Zinc is available as tablets, nasal spray, lozenges, and syrup. The studies in the Cochrane review looked primarily at lozenges and syrups as these are believed to best target the virus where it lives in the nose and sinuses—and target it safely. Despite the direct application of zinc nasal sprays to the nose, they are believed to be less effective, and the FDA warns against their use because they are linked with loss of sense of smell. Yikes!
Further muddying the waters, the zinc products tested in the studies in the Cochrane review contained different formulations of zinc (gluconate, acetate, and sulphate) and different dosages, so it’s not totally clear what form and how much zinc is best to battle a cold. Also, while the studies in the review found consistent findings among participants of all ages, it should be noted that all of the participants with colds were otherwise healthy. Meaning, zinc’s ability to battle a cold needs to be further tested in order to determine if people with other illnesses, like diabetes or asthma, will see improvement as well.
Overall, using zinc as treatment for the common cold can work to improve stuffy nose suffering, but it might take some extra effort and caution to get those results. The difficulty of catching the cold early enough and the time spent finding the best product seems a little exhausting. I think for now I, personally, will stick with my mom’s suggestion to rest and eat a bowl of chicken noodle soup when I have a cold. And this remedy might not be simply derived from old wives’ tales either—poultry, it turns out, is high in zinc.
Ok, I’ll stick with chicken soup. My current version is with sweet potatoes, garlic, and a curry spice mixture containing peppers, turmeric and coriander.
I like the way that you carefully describe the limitations on the way that the data was collected for this study. I think that this helps the public better understand the manner in which such research is conducted and limitations on over-interpretation of the data. I think that it would be very helpful to readers who are average members of the public if you also expanded on how to do “a little research” and how it was that you were able to find your way to a reliable source.
I’m glad you brought up the point about how I found my way to my sources. As a student with a science background, I am sure I have more training and access to resources than people without. Searching the internet is a great starting point, but with so much information (and conflicting information at that), it can be tricky to get the real story. I personally feel that WebMD can be a useful place to start for health-related topics because the information is often presented with less technical language, but I would be sure to check other sources as well. The NIH and CDC websites are also great resources.
Thanks for reading! And your soup recipe sounds delicious!
Great overview! I like how you presented the information and how even with “evidence” from a Cochrane review, real conclusions are still elusive. This is really important as often, the media will pounce on the general conclusions, and then skimp on the actual details.
I totally agree with you that the media can be quick to latch onto general conclusions and statistics, often leaving out the rest of the information. There’s almost always more to the story when it comes to research. Marisa did a great job discussing that in her post earlier this week, too.
Thanks for reading!
A great, well-organized post. Terrific use of the Cochrane review and explaining the limitations of the data. I’m with you, I’ll keep sipping homemade chicken soup when I have a cold, or better yet, when I feel those initial symptoms.
Thanks!
And yes, seems that chicken noodle soup might provide more than comfort, but the sooner the better!
I always find myself skeptical of remedies claiming to shorten the life of a cold, and you do a great job outlining the scope of the study as well as the limitations and liabilities. Did the reviewing authors calculate how much shorter or how less severe the cold would be with any quantitative numbers? those would be useful here, too.
Also, in case you didn’t read the comments on the other posts, I’ll link here to my previous comment on section headers and accessibility interests.
I agree that hard numbers are useful. The authors of the review did provide some data about the reduction in cold length and symptom severity, however the methods and results of each study they included varied. It’s important to recognize that when studying something like symptom severity, there isn’t a hard and fast measurement that’s typically used. Different measurement tools will provide different information. In addition, determining how serious a symptom is often relies on self-reporting from each person with a cold which can be inconsistent. I think with a review of many different studies, it’s not always feasible that the results be pooled to provide one set of data.
Also, I’m new to the world of blogging, so thanks for the information about formatting posts!
Great post! Informative AND easy/fun to read, so it will appeal to the average person. I like that you presented the facts along with the limitations, so even unseasoned readers can get to the bottom of the data–we simply just aren’t sure what will help the common cold. Good work!
Thanks for reading!
Interesting post! I liked the approach you took to critically evaluating published scientific evidence, while still making it easy to understand and enjoyable to read. You mentioned that most of the people under study were generally healthy and that an important next step would be to determine if zinc has any benefits for those with asthma, diabetes, etc. I was wondering if you found anything concerning the age of study participants, as this could be important for children and the elderly, who may have a harder time getting over colds than healthy adults.
As far as age-specific results, the review noted that the participants in the 15 studies covered a wide variety of ages, so it seems the results may be fairly consistent. I agree that if the benefit of zinc can further be proven that it could be important for children and older adults in the battle against the common cold. However, children and older adults are typically immunocompromised to some degree, and with the current research based only on “healthy” participants further studies on zinc will definitely need to look into differences in age and health status to be more certain of the results. Thanks for the comments!
You share some very interesting info, Ashley! It is a bit buried, however. I would have liked to learn earlier in my reading that timing, delivery, and formula can make or break the zinc effect. An editor once told me that I should go back after writing any article and see if I can cut the lead paragraph(s)! Sometimes, the beginning turns out to be for our own benefit, to warm us up to what we’re writing.
So I think you could have gotten to your analysis quicker AND still eased the reader in with anecdote. I like your conclusion, though: I never knew poultry had zinc.
Thanks for the feedback, I will keep it in mind for my future posts!
Good to know – I’ll have to pay more attention to the onset of symptoms. Also did not know that poultry was a good zinc source!
Thanks for commenting!
I usually pop a zinc tablet when I first get that tingling in my nose and throat which heralds the onset of a cold, it generally staves it off at least for 2-3 days or so, gives me time to wrap up deadlines before I collapse.
There is a caveat to ingesting zinc as a supplement though. I mentioned this remedy to my GP a while back and he told me that he was working with a team in Cambridge investigating cadmium levels in zinc supplements. I haven’t seen the data yet, but there would be a suspicion that cadmium would likely be a contaminant in any zinc product, which may be a bad thing depending on actual concentration.
After digging into this notion of zinc helping fight off a cold, I am interested to find out more as well. You bring up an excellent point that additives need to be studied just as much as the main ingredients before we can truly determine what is safe and effective and what is not. Thanks for the comments!
I seriously thought that zinc supplements were a snake oil remedy, but I’ve always sworn by chicken soup (a garlic, lemon, cinnamon recipe). Now I’m left wondering if I should dose myself up with both.
I did as well. It was interesting to discover all of the details about when, how, and why zinc might work as a remedy. Thanks for reading!
How come this blog don’t have a Twitter account?
Do you think we should have one? It’s easy enough to do.
In the meantime, all posts are being put up on @umrscblogs and @2020science
If this blog was going to be ongoing, I would absolutely say it should have a Twitter account. Because it is only going to last a few months, I would not recommend a Twitter account. Why not? Because people are only allowed to follow a certain maximum number of accounts on Twitter, and it would place the burden on them to remember to unfollow the account at the end of the term. Rather than that, perhaps integrate the feed into either of the existing Twitter accounts of @UMRSC or @2020science?
Excellent article! You ended with your personal conclusion, which is exactly what we should all do.
I have tried Zicam and can anecdotally report that after 2 days of the doseage recommended on the package, I had a burning sensation in my stomach. I will await more research.
Thanks for your comments!
Great post! It was helpful that you included explanations regarding what zinc is, how the method of delivery may affect its (potential) effectiveness, the limitations of the study, etc. Stories on remedies are so often filled with fluff. It was great to read a piece that actually delves into some of the details. I am now wondering what other studies are out there on zinc and what they say about its potential as a remedy!
(By the way, I love the mention about chicken noodle soup having zinc!)
I am always skeptical about remedies and the information that is out there about them, hence what prompted my post! I’m not sure I’m ready to throw in the towel on zinc just yet, but I will definitely be looking for more information as it is studied in the future. Thanks for reading!
Hi Ashley! I would have read this one since I do take zinc lozenges on occasion.First, from a writer’s perspective, I really like the way you began and ended this piece. I’ve seen piece where someone starts out with a discussion of something like your ‘chicken soup start’ and they never return to tell you what the decision was or what happened (oops, I might be guilty of that). It takes discipline to make sure you don’t wander off on tangents.
The one thing that seemed a little off to me was the reference to the Cochrane. Is it important? Is it the gold standard for research? Who is your audience? Will they know about the Cochrane Review or does that matter? I’m glad to get the information about zinc. Thank you. Cheers, Maryse
Thanks for the comments! I wasn’t previously familiar with Cochrane reviews so I included the specific mention in case there is special significance. You bring up a good point though that a broad audience may not be as interested in who performed the review, as they are in the findings. I hope you’ll keep reading!
The Cochrane Collaboration is indeed the gold standard for systematic reviews, with reviews that tend to be much more rigorously reviewed than many published elsewhere in the peer reviewed literature. The idea of the systematic review is to rigorously and systematically review a body of literature on a clear research question, with a goal of determining if the literature is moving towards or has achieved consensus on the question. These reviews are then updated every five years, which is especially important if the finding is (as is typical in a initial review) insufficient. The systematic review on zinc is not an early one but has multiple iterations. One of those was withdrawn, and this is, I believe, the replacement for that version (which evidently had some errors). I have been involved in the withdrawal of a Cochrane review, so even though these are the gold standard, that still doesn’t mean they are 100% guaranteed perfect. Nothing is. Remember the phrase “Who watches the watchers?” This applies to all research. My primary mentor in systematic review methodology, Amid Ismail, often emphasized, “Best AVAILABLE evidence. Integrated with clinical expertise.” It isn’t just the evidence. It is also the personal history of the patient, the judgment of the clinicians, the shared decisionmaking, a consensus decision or solution that is achieved through the combination of evidence, experience, lifestyle and preference.
Thanks for the additional information. I had done a little research on the Cochrane group when I first found the review, but I wasn’t quite sure how they ranked compared to other reviewing groups. This review was looking to determine whether or not zinc could shorten a cold and/or reduce cold symptom severity, and I think the data from the studies reviewed does support there is a positive result. However, as you noted, not all research and reviews are totally perfect. Even when “evidence” is found to support the research question in mind, other factors are sometimes glossed over, particularly when the findings are communicated in the media. I hoped my post would get people thinking beyond just the general conclusions of research and to really think critically about getting a larger picture before making final decisions. Thanks again for the extra information about Cochrane reviews and for reading!
I have been pondering and researching for days, wanting to write a BIG reply about the conclusions here. I am such a fan of zinc gluconate that I stockpile it, and keep it in four locations so that I will never be far from it. This is a combination of both the science and personal experience. But I think perhaps I should write this up on my own blog.
Hi Ashley, Very nice article. I do support the tips about formatting above. Take advantage of the internet and the blogging platform. The next thing I say seems a bit in opposition to some of the comments above so take it with a grain of salt. You make a lot of references to the Cochrane study. This is great in the beginning as it points out that the info you are giving is backed up by science. But the continuing insistence on ‘Cochrane says this’ and ‘Cochrane says that’ is a bit annoying for me. It sounds a bit like you are reminding me that you are a scientist and you got this from a science study over and over. I feel like saying ‘yes yes yes I know that, can you tell me more about the zinc’. Its a difficult balance to emphasise the authority of science but not overstate it, but I think after the first time you could just have said ‘research’ or ‘the studies’ rather than ‘the studies in the Cochrane review’. You can always emphasise the research in the footnotes for those who need reassurance about legitimacy and provide a cleaner read in the main text. Loved the ending. Left people with a perfect ice breaker/ talking point about the subject, and a smile. IT will be a fact that jumps back and reminds me of the points in the blog whenever anyone mentions zinc or chicken soup and colds in future.
Thanks for the feedback, Michelle! As for the repeated mentioning of “Cochrane review” in my post, it was purely for clarity as I was, prior to writing this post, unfamiliar with what a Cochrane review is exactly. I wasn’t sure if there was significance in saying that the review of the studies was by Cochrane or not, so I included it to be safe! I understand exactly what you are saying about its repetition as opposed to being a bit more conversational.
2 questions:
1. How would you characterize the *effect size* in the studies that show “zinc works…”? How *much* does it increase the likelihood that a cold will be reduced by *how many* days? Too much science reporting — maybe just too much science — proceed as if the question in a medical trial were binary: “works”/”doesn’t work.” In fact, treatments that work change likelihoods of outcomes; & if they change it by only a tiny amount, then the cost of the intervention, particularly relative to other things, might not be worth it. Zinc lozenges have been around for over a decade; the nasal spray was really popular until it was discovered to pose a high risk of destroying users’ sense of smell. My guess is that the net benefit in terms of “days of reduced cold duration” is a lot smaller than the profit margins that companies that manufacture the pills have made during that time–particularly given how many users *very foreseeably* start use of the lozenges way too late to make any difference. Companies shouldn’t be allowed to peddle snake oil remedies just b/c there is some scientific proof of an effect in lab that can’t be expected to translate into an effect in the world
2. How should information of the sort I’m describing be communicated by “science communicator intermediaries” — experts like you, who translate the science into terms that can be disseminated by journalists and others to the public?
In response to your first question, I agree with you that simply concluding that an intervention “works” or “doesn’t work” doesn’t really give us enough information, particularly in terms of cost effectiveness. Because of the nature of this source being a review, the hard data on “how much” reduction and “how many” days shortened across all of the studies wasn’t explicitly quantified to give one set of data. The review found that they studies provided effective results, but there were a lot of differences among the study designs. I don’t think the review gives inaccurate information, zinc can have a positive effect on a cold. I completely agree that the results determined in labs and by a review panel have tremendous potential to vary among the general population because of the complex circumstances needed to yield them. I hoped my post would provide some food for thought about those things and that we shouldn’t take research conclusions for certain without considering the implications.
As for your second question, I think that when scientific research is communicated to a wider audience of consumers, it’s necessary to disclose and explain how the research was conducted, how the results were truly obtained, how far those results can be applied to others, and if there are any potential confounding factors. The vast majority of people will never read an actual research paper, and they rely on science communicators to provide them with accurate and complete information. Currently, the details of science research are lost and only generalized findings make their way to the larger public. I feel it is irresponsible of the media, or anyone else who disseminates scientific information (perhaps including researchers themselves), to leave out the circumstances surrounding research results.
I hope this answers your questions! Thanks for reading and commenting!
Love it Ashley! Would like to read more of your’s about the merits of other cold remedies. Also, how do you best identify the start of a cold? This seems to be key for so many cold remedies.
For me personally, I’ve learned over the years that a flurry of sneezes usually is the earliest sign of an on-coming cold and if closely followed by a sore throat, I know for sure! I think symptoms vary from person to person though, so I suppose it’s a matter of learning the signs your body gives you. Thanks for reading!
I have found colloidal zinc to be very effective in the nanoparticulate non-oxidising form, rather than ionic. You can make your own colloidal zinc using my colloidal generator.
There has been research that suggests that the modern western diet is seriously deficient in zinc. the generally quoted figure in the food industry is 70% of the population has less than 70% of the minimum zinc requirement. The original data was for Australia and the suggestion is that it applies elsewhere where diet is highly processed. In view of this the indicated effect of zinc is hardly surprising. On medical advice I started taking zinc suppliments myself. The most obvious effect was the dramatic increase in the frequency of fingernail cutting required.
Thanks for the information about the likeliness of dietary zinc deficiency. The review did mention that consistent, adequate levels of zinc may have protective factors against even developing a cold in the first place, so your taking of zinc supplements may help your susceptibility. Thanks for reading!