Zinc effective against respiratory infections?

I’ve previously written about the ability of vitamin C and vitamin D to protect against respiratory infections. Vitamin C has been found to shorten the duration of respiratory infections slightly, although it needs to be taken continuously throughout the year in order for there to be any benefit. Vitamin D has been found to shorten the frequency of respiratory infections, by a small amount in people who are not deficient, and by large amount in people who are deficient. I figure that it’s time to look at the third nutrient that is frequently touted as being protective against respiratory infections, zinc.

A systematic review was published in the Open Respiratory Medicine Journal back in 2011 that looked at the use of zinc lozenges in people with upper respiratory tract infections. 2011 may seem like a long time ago, but virtually of the studies on this subject were carried out in the 1980’s and 1990’s, so that isn’t a problem. Interest in zinc has waned, at least until covid-19 got people talking about it again.

The logic behind lozenges (i.e. tablets you suck on), rather than tablets you swallow, is that the zinc is released in the oral cavity, which should result in much higher local concentrations in the place where you want it most, the upper respiratory tract.

13 double-blind placebo-controlled trials were identified, with a total of 1,402 participants. The dose of zinc used varied enormously, from 30 mg per day to 207 mg per day, so the systematic review analyzed those giving a high dose (75 mg or higher) and those giving a low dose (less than 75 mg) separately, to see whether there was an effect of dose size on the results.

So, what were the results?

In the five trials using low doses, there was no difference between the treatment group and the control group on the duration of symptoms. In the eight trials using high doses, however, there was a big difference. All eight showed a reduction in symptom duration, and the overall average reduction was 32%. If an average cold lasts ten days, that would mean a shortening of symptom duration of around three days, which isn’t bad at all.

So, case closed, right? Zinc lozenges, when dosed at 75 mg or higher per day, shorten the duration of upper respiratory infections. Well… there is a big problem here, and that is that all but one of these trials was carried out before the birth of clinicaltrials.gov, and the one that was carried out later, was never registered there.

For those who are unaware, clinicaltrials.gov is a website that was set up in the year 2000, after it became clear that lots of trials were disappearing off the face of the earth after being completed, and that this was seriously skewing the evidence base. The problem is known as “publication bias”. Studies that show benefit are much more likely to get published, partly because they get more media attention, which means that scientific journals (which to a large extent depend on advertising for their income) are much more likely to want to publish them, and partly because most studies are financed by people with a vested interest in the result. If a company that makes zinc lozenges finances a trial that is supposed to show that the lozenges shorten the duration of respiratory infections, and the trial doesn’t show any benefit, then the company is probably going to do its best to bury that trial.

The main purpose of clinicaltrials.gov is to make it harder for people to “disappear” trials that show unwanted results, by asking them to register the trial there before they start recruiting participants. Since the systematic review we’re discussing here is based on studies that were conducted in the pre-clinicaltrials.gov era, it is perfectly possible that there were another 50 trials that were conducted on zinc lozenges, but that were hidden away and never published, because they failed to show benefit. It’s impossible to know.

Perhaps as a result of this, the author of the systematic review has carried out a new double-blind randomized controlled trial, that was published in BMJ Open in January 2020. This trial was pre-registered at clinicaltrials.gov.

It recruited workers over the age of 18 who reported having at least one cold per winter, on average. 252 people were recruited, and randomized to either placebo lozenges or zinc lozenges (containing 13 mg of zinc). The participants were instructed to start taking one lozenge every two hours in the event that they developed symptoms of a respiratory infection. This would result in a daily dose of 78 mg of zinc.

Of the 252 participants, 87 went on to develop an upper respiratory tract infection during the study period. of these, 42 participants were in the placebo group and 45 were in the zinc group. On average, treatment with the lozenges started within four hours of the beginning of symptoms of a respiratory infection. The participants consumed an average of five lozenges per day, not the planned six, so the actual average dose was 65 mg.

What were the results?

Unfortunately, the participants in the zinc group recovered a little bit more slowly than the participants in the placebo group, although the difference was not statistically significant. However, the fact that there wasn’t even a hint of a benefit to zinc is disappointing.

This trial was most definitely designed to succeed. The lead author is a strong proponent of the beneficial health effects of vitamin and mineral supplements, and has written multiple opinion pieces arguing for the benefits of zinc in treating respiratory infections. So the fact that the trial failed to find any sign of benefit suggests strongly that there is no benefit, and that the beneficial effect seen in the systematic review was due to publication bias.

There are of course other possible explanations. One is that the dose given in the study was simply too low to have an effect. Maybe 65 mg per day simply isn’t enough to see any benefit. There is also the fact that the study was quite small, with only a little over 40 people in each treatment group, which means that there is some scope for random chance to mess up the results. However, a reduction in symptom duration of around 30%, as found in the systematic review, should be noticeable even with this relatively small number of participants.

A third hypothesis, suggested by the authors, is that maybe the zinc lozenges dissolved too quickly in the mouth. In this study, the lozenges took an average of eight minutes to dissolve. The studies in the systematic review that showed a beneficial effect were mostly using lozenges that took from 15 to 30 minutes to dissolve completely.

It is worth noting that the participants in the zinc group experienced far more side effects than the participants in the placebo group (63% vs 31%). The side effects took the form of odd oral sensations, such as a dry or aching mouth, and an affected sense of taste. So even if the zinc lozenges do in fact shorten the duration of upper respiratory tract infections by 30%, as the systematic review implies, it is not clear whether that benefit is big enough to outweigh the negative side effects.

So, what can we conclude from all this?

It’s still uncertain whether zinc lozenges have any role to play in the treatment of upper respiratory tract infections. The studies that do show a benefit with high doses were largely carried out before the existence of clinicaltrials.gov, and none were registered before commencing recruitment, so there is significant risk of publication bias. The one newer trial that was properly registered beforehand failed to find any benefit. And although it is unclear whether zinc lozenges are helpful, they do definitely cause mild but annoying side effects in a significant proportion of those taking them.

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45 thoughts on “Zinc effective against respiratory infections?”

  1. Hej,
    du skrev ingenting om att zink ska tas som förebyggande – är det falsk information?

  2. You realise that getting zinc into the cells ain’t easy, and requires a zinc ionophore in addition, to shuttle it in? Without this, I’d not expect much from such trials.

    Hydroxychloroquine is a pharma grade example of such an ionophore, hence those stressing it in combination with zinc for scv2 infections. But Quercetin, EGCG from green tea, are naturally occurring examples.

  3. Zinc needs a zinc ionophore to get into the cells to prevent viral replication. Therefor to only give zinc is too simple, as if it cannot reach the inside of the cells it can’t do the job.

  4. Yes, it is disappointing that the zinc has not shown the benefits that were hoped for. However, data from trials in recent times has been woefully unreliable. Vitamin C has to be taken in adequate doses for the circumstances present at the time. It is no good taking the RDA and expecting anything other than not getting scurvy. Vitamins were used before vaccines were available, and there was significant success if the dose was adequate. This has information about current uses of vitamin C, and though the claims could be argued about, there is no downside, except costing a relatively small amount of money, http://orthomolecular.org/resources/omns/v16n06.shtml

    It’s a pity that this had not come up earlier, as there is a series of vitamin articles on http://www.vitaminmasterclass.com, illustrating the benefits of good nutrition.

    If we go back a short while, The Lancet had to retract a publication on HCQ, for what amounts to deceiving manipulation. There is every reason to be sceptical of every trial, no matter who conducts it, given the current circumstances

    1. Absolutely. They were aware of this problem, so they took care in the study to use a form of zinc that would be easily released from its ionic bond once in the mouth. In this case they used zinc acetate.

  5. Do we know if any of the trials measured zinc levels in the participants before giving them supplements? Some foods, such as shellfish are particularly high in zinc. Different people with different diets might therefore have different levels of zinc to start with, and isn’t it the overall levels that matter, rather than whether they are reached through food or supplements?

    Interestingly the article notes long term zinc supplementation can result in copper deficiency. How can we get the balance right between the two nutrients?

  6. Maybe zinc works better in conjunction with vitamin C,D3, I don’t know anyone who takes just takes zinc.
    In the present time I see people taking more note of there health, which is good thing. I don’t believe in taking anything from big Pharma, it’s just a vicious circle.
    Forcing people to take a vaccine for a virus with a survival rate of 99%, other than supporting the healthy options as well, but even worst than that banning them, shows me one thing.

  7. I’ve read that zinc requires an ionophore to deliver it to the cells – either quercetin or hydroxychloroquine. Western medical thinking does get rather fixated on single substance efficacy rather than thinking in terms of combination therapies and their synergistic actions/benefits.

  8. The theoretical reason why zinc should work:
    Zinc is highly regulated essential micronutrient for optimal immunological function. Zinc deficiency, even in developed countries, is common. In vitro experiments show direct anti-viral activity by zinc. The anti-viral activity is somewhat virus specific. For rhinovirus (the most common cause of the common cold), zinc directly inhibits viral polyprotein cleavage and processing. For coronavirus, it directly inhibits RNA polymerase.

    A significant barrier: The problem is how to achieve sufficient intra-cellular concentration to get the viricidal effect without killing the human host cell as zinc is a highly controlled metal (with most systems designed to remove zinc).

    Two variables must be controlled: time to onset of symptoms and local concentration achieved. Similar to all anti-virals, the anti-viral must be taken before the virus gains a significant foothold and initiates marked viral replication. High enough local concentrations to be effective. Note: There is a third variable. The supplementation industry is poorly controlled. It is vital that a high quality supplement that actually contains the desired supplement in sufficient concentration be used. Consumerlabs evaluates supplements and I highly recommend that before any supplement is bought that it is clear the supplement contains the desired compound and concentration.

    Sufficient tissue concentration: The issue has been achieving a high enough zinc concentration that kills the virus and does not kill the human cell. Required viricidal activity is about 1000X higher than that found in the plasma and 100X higher than normal intra-cellular levels. Intracellular zinc is highly regulated so that it is difficult to achieve high enough concentrations. The anti-viral level cannot be achieved by oral zinc supplementation. Lozenges, if slowly dissolved may help but are also probably insufficient to achieve the required concentrations.

    Note: The use of quercetin and other bioflavonoids may help as they have in vitro anti-viral activity and quercetin increases zinc uptake into cells. For coronavirus they directly inhibit the protease necessary to activate the fusion action of the S protein.

    To overcome the local effect, the original formulation of Zicam supplied zinc nasal swabs. If taken as soon as one felt a cold coming on, the cold never came. My family (including extended family of aunts, uncles, cousins) and my employees went multiple years without a cold. Unfortunately a few people (about 800 out of the millions if not tens of millions of people who used the swabs) developed anosmia . The FDA used this excuse to ban the use of the zinc formulation. Zicam changed the formula to exclude zinc.

    Copper is promoted as an anti-viral. Copperzap is designed to deliver high concentrations of copper ions locally and works. It must be used early in the disease process (promptly with the onset of the first symptoms) and care must be taken not to overexpose tissue to high copper concentrations.

    It is my impression that when reviewing clinical studies one must remember two things: he who pays the piper calls the tune and a study can be desired to prove inefficacy as a headline while in fact, proving nothing at all.

  9. Of course, all of the trials you are citing were using zinc lozenges so we are still not any the wiser about the zinc status of the individuals before the trials and whether other forms of zinc supplement may have had a better, or no, effect than lozenges.

    Also, without reading the trials, it’s difficult to ascertain what the amount of elemental zinc was being used, because it’s not always easy to find out from supplements what that might be. On the label you often just get “contains xxx zinc” but the elemental amount may be a lot less and isn’t always specified.

    This example shows that it contains 34mg zinc acetate but “delivers 10mg active ionic zinc”


    Zinc lozenges typically contain zinc in the form of gluconate and from what I’ve just found on the internet, zinc gluconate only contains about 14.3% of elemental zinc- so it would be important to know whether that amount was used in the studies or whether the amount in the lozenges was just the amount of zinc gluconate? Because that would make an enormous difference when working out the actual amount of zinc available to the participants – one would hope that the studies were referring to “elemental zinc”.

    “Different salt forms provide different amounts of elemental zinc. Zinc sulfate contains 23% elemental zinc; 220 mg zinc sulfate contains 50 mg zinc. Zinc gluconate contains 14.3% elemental zinc; 10 mg zinc gluconate contains 1.43 mg zinc.”


    As Roland Ayers mentioned, it is often recommended that copper is taken with zinc if the latter is supplemented for any length of time, and often the two minerals are found in the same supplement, usually in the ratio of 1mg copper to 15mg elemental zinc.

    Of course, all minerals and vitamins work in concert and so it’s not so easy to work out how much to take of one or another without having an adverse effect in some way, but for acute conditions, it probably wouldn’t hurt to take zinc and a very high dose of vitamin C to assist the body in its defence!

    1. Yes, the 13 mg per lozenge was elemental zinc. Luckily, the authors had been studying zinc lozenges for years, so they knew what they were doing. They wanted this to be a positive study, and believed that it would be, so they were probably pretty surprised that it wasn’t.

      As you note, most commercially sold zinc lozenges don’t come anywhere near the doses that the authors of the systematic review and randomized controlled trial consider to be necessary.

  10. Looking at Zinc alone without an ionophore like Quercetin reminds me of the tests of HCQ which all seemed to scrupulously avoid the triple therapy used by Zelenko, Didier, et. al., with such apparent success.

    1. That study told us a lot more about the researchers and their funders than the undoubted benefits of properly absorbed zinc.

  11. Thanks so much for looking into Zinc supplements in great detail and providing the data and analysis. I’d like to suggest three things that I find make a difference that I have trialled on myself. Firstly, I select foods for my diet that ensure I get adequate zinc, Vit C and natural anti-inflammatories. This has worked for me since I committed to using food as my first go to for ‘medicinal’ purposes. Secondly, I about half a clove of raw minced garlic (that has oxidised for 15-20 mins to deactivate the alliinase to form allicin, the active component. Garlic serves several health purposes. Ginger in the diet also serves as a mild anti-inflammatory. I get adequate levels of zinc from the foods I love to eat daily. Living in sunny Queensland has really improved my health (since I left Victoria in 1998), where I certainly don’t need any extra Vit D supplements. Finally, I use Echinacea purpura as my ‘go to’ anti-inflammatory, the moment I get the beginnings of a possible sore throat. I buy the highest concentration in liquid form. I add some drops to a small amount of water and gargle with it, prior to swallowing it (to allow it to pass into my blood stream more easily at my throat surfaces). I only need to do this once in the morning and evening for 1 day (sometimes 2 days) and it always works for me. I haven’t had a cold or flu for 23 years ….. except for that one time I had the worst ever flu, followed by bad bronchitis (sick for 8 weeks), which developed straight after my one and only flu vaccine (imposed by my then work place) in 2014. Won’t be doing that again!

  12. Sebastian,
    Let me give you a different slant on this issue of prophylactics.
    I have a boat built of wood, in order to preserve my boat, I apply varnish to the wood to protect it from water damage. Each year I apply a new layer of varnish until one year I fail to do this and the weathered varnish cracks and flakes off. The wood is now exposed to the water and suffers damage. If I now apply a new layer of varnish to cover up the cracks will this repair the damaged wood?
    Prophylactic use of zinc is like this, it provides a defence but once breached the “paint” will not produce a repair of the damaged tissue.

  13. I have been a huge fan of zinc and have used it successfully for me and my family to treat colds for over 20 years. In my observations the key is immediate and large doses of zinc taken orally with food (or it can upset your stomach). Immediately after feeling symptoms I take 50mg every hour or two to get at least 200 to 250mg in my system before heading to bed. This has proven to be highly effective in actually stopping the cold completely, meaning no symptoms at all the following day! Once sick I have found it hard to determine if it reduces or has other benefits since my sample size is rather small. 😉 I am not a doctor and this is only me sharing my personal experience with the use of zinc.

    1. If taken at the first symptom of a cold, the very first minor sign, perhaps a sore throat beginning, zinc absolutely stops the cold from going further. My family is living proof of i,.over and over again. It’s the only study I need. These studies are a waste of time. My doctor told me Glucosamine would not work for my knee and joint pain based on studies. Well, I didn’t listen and I am joint and knee pain free after just one month’s usage daily. When I tell him he tells me its all in my head. On the other hand Tumeric supplements did nothing for my joint pain but helps my wife. So lots of time the only study that matters is personal.

  14. Varnishing a boat is not really anything like a human immune system. You can make a comparison that looks plausible, but is about as valid as saying masks must provide some protection against a virus.

  15. We could learn a lot from Vets, especially the “Large Animal” variety, those that usually deal with cows, sheep and pigs. A farmer loves his animals but they must pay their way so a vet needs to keep them healthy in the most economic way or the animals are slaughtered. In an agricultural supplies shop you can see calcium, sulphur, magnesium etc as single supplements, animal mineral licks to be left out as self-medication (animals are very wise!). This means that generally the beasts are in tip top condition. Humans, on the other hand, bumble along, less than fit on inadequate diets/lifestyles, until they are sick enough to see a doctor or start dosing themselves in the vain hope of correcting a lifetime of bad habits. It is unfair to dismiss the zinc, vitamin C, Vitamin D etc as ineffective because they seem to have no effect on colds/flu/covid19. Those that have taken care of their health will probably sail through these, those that just follow the media headlines will probably be disillusioned by all natural health solutions . I have followed a healthy lifestyle all my life (72) never had a flu vaccination, never had flu, not had a cold for years, not seen a Dr in a long time, had a dose of Covid19 back in March 2020 which had me in bed for 3 days but up and ready in 4. So minerals, vitamins whether in supplements or good food choices, a Government that will listen to up to date dietary advice to help us make the right choices and an emphasis on getting a healthy immune system would seem more important now.

    1. Sue,
      I totally agree. It is pointless to claim that something which you take to protect yourself but in someone else fails to restore them after the damage is already done, proves that the protection did not work for you.
      That seems to me to be the basic fallacy here.

  16. This is to congratulate on Dr. Rushworth for his common sense comments on health issues. I also very much appreciate thoughts from people that follow Sebastian which are well thought out and friendly. This is one of my favorite websites. Thank you all.

  17. I can also attest to the great effect of healthy plant based diet, exercise, lifestyle and consistent intake of optimal doses of zinc, D, C, selenium and other supplements to protect me from infections, without vaccinations and keep me in tip top shape. I have never missed a day of work in 40 years and am now a happy healthy pensioner, plus as a nutritionist naturopath, I have seen the great power of the synergism of healthy diet and lifestyle together with supplements and herbs with thousands of patients. The pharmaceutical model of studying supplements in isolation like one does drugs is faulty at the start, plus these recommendations are not individualized to the needs of the person and do not take into account the synergistic actions of supplements and nutrients. Our physiology responds to millions of different imputs from our foods, thoughts, lifestyles and uses them in the best way possible to keep us in homeostasis. Multimodal therapies and synergistic principles rule, as do patient outcome studies , lab data before and after and lifestyle quesionairs before and after multimodal interventions–and now we have AI and systems biology to crunch numbers and evaluate combinations of end points. Even single D vitamin supplementation studies are often very flawed and do not take into consideration genetics such as VDR SNPs, skin color, food and sun exposure, prior levels and needs. In addition the studies use often suboptimal levels of supplementation because they are still stuck in the 1960s thinking that all you need is RDI and minimal levels to protect you from osteoporosis. Vitamin D is a hormone with receptors on all cells and an immune modulator amoung other things. The use of vitamin D with synergists such as vitamin A, K and magnesium also greatly enhances the effects of D. Everone should aim for a protect level of 55-80 ng/ml which usually takes a dose in winter time of 5,000-10,000 ius a day and most studies only use 400 to 4,000 iu daily doses. Read the research of Michael Holick who has studied this for 50 years and invented the vitamin D tests.
    Thanks for all your great work and courage to stand up to the very flawed narrative and treatment of this virus. Too bad that the scientific room is not a safe and large room for serious discussions, concerns, varying views but with respect for all.

  18. One of the problems with many of the studies regarding nutritional supplementation is whether the participant actually needed, in this case, zinc, It would be interesting to see if those with zinc deficiency improved quicker than those with optimum zinc levels. Clinically let’s take vitamin D. Those with a true deficiency once supplemented to a level of 50-80 ng/ml see less episodes of immune dysfunction (common cold). If a patient already has optimal levels taking more will not assist the pathway regarding Vitamin D.

  19. I mean no disrespect Sir, quite the opposite, but many decades of examining RCT reports against real life observations with passion to understand the complexity has taught me to question the “gold standard” claim.
    Hopefully one day when you have studied more RCTs that fail to show effects observed in real life, that the value of observational trials will figure more in your acquisition of knowledge. I admire what you do, how you think and your motivation, Doctor, but you still need to unlearn some things from your pharma training.

  20. No benefit is the conclusion. What about Dr. Zelenkos’s suggestion that zinc needs an ionophore to get inside cell in a way to inhibit viral replication? He touts HCQ and quercetin as efficient ionophores to get the zinc to act.

  21. Here is the problem: if you believe RCTs show “the truth”, by definition there can be no publication bias with RCTs. So if you believe the more recent RCT showed that zinc doesn’t work, you’re at pains explaining how earlier RCTs had found zinc to be effective. The only way out of this situation is to accept that RCTs aren’t as reliable as you may have thought. There are many factors that can influence them, both on purpose and not on purpose (as an example, “the cold” can be caused by many different viruses). Running meta-analyses on poor RCTs only makes matters worse. Essentially, this is cargo cult ‘science’. We have seen it many times during the COVID pandemic.

    1. As mentioned in the article, trials carried out before the year 2000 or after that year but that have not been pre-registered at clinicaltrials.gov are inherently suspect because the risk of publication bias (and of switching end points) is much bigger. RCT’s most definitely are not free from the risk of publication bias, since that is a bias that has nothing to do with the construction of the study, but has to do with the fact that studies showing benefit are much more likely to be published.

      RCT’s are by no means perfect but they are inherently less susceptible to biases caused by study construction than observational studies. There are countless examples of interventions that have been given based on observational studies or hypothetical reasoning, that have later had to be withdrawn after randomized trials showed them to be ineffective or even harmful. There are also examples of interventions that have come in to use that have later had to be taken out of use (for example one egregious example relating to a certain SSRI) after it became clear that multiple RCT’s that showed zero benefit had been buried.

      1. I guess you didn’t get the point: either RCTs are reliable, then there can’t be publication bias. Or they are not reliable, then you can’t rely on them. Whether they were published before or after 2000 and clinicaltrials.gov makes no difference. I guess what you underestimate is how easily RCTs can get skewed, by commercial interests, poor design, unaccounted factors, bad luck, whatever. So an RCT, especially a small RCT, does not automatically supersede an observational study, especially a large observational study, or another RCT. Medicine is more complex than that.

      2. My humble view is that both RCTs and observational studies may have learnings or may fail to provide useful answers. It all depends on the study aims, available data, objectivity, and rigour of the study. RCTs have been abused to discredit observational studies, as if the RCT is necessarily superior. A good observational study does not deny half the participants the benefit of the trial or the accompanying treatments they may choose. Understanding real life and complexity of a diverse population isn’t easy but science should pursue this with vigor and rigour. Isn’t that the main way science has developed in non-medical fields?

  22. Dr Rushworth

    Was the baseline zinc level meassured and reported in the studies? Was there a difference in response for people with low baseline level compared to high?

  23. Good comment from John Castleman. It is a benefit that the Covid affair has exposed so much incompetence and deliberate malfeasance. Among the things we have learned is that respectable imprimatur doesn’t mean a thing; think of the Lancet study with elite faculty authors that was a complete fraud. There is a strong, even overpowering desire in people to place faith in purported expertise; it is one manifestation of a salvationist hope that we can have a collective rational management of human affairs so as to ward off tragedy and contingency from our lives. The Covid experience will likely induce more realistic thinking among a marginal few, though most will remain oblivious rather than sacrifice their aspirational mental comfort.

  24. I would not expect zinc to be effective as an antiviral without an ionophore. I also would expect to measure serum and cellular zinc levels if I were testing prophylaxis or the impact of zinc deficiency on the immune system, which is where supplementation might help.

  25. I was disappointed that Dr. Rushworth didn’t remark on which cohorts tend to have zinc deficiencies and the impact of zinc deficiency on the immune system.

  26. Having read for some months various so called learned tomes by various and opposing experts the only conclusion I’ve come to is that the best example of an Oxymoron, at least in the English language, is :-

    “I’m a Doctor, Trust Me”

    Sorry to be so blunt.

  27. I find the experimental results astonishing. As a treatment for colds and sinusitis, I suck 15mg zinc citrate tablets (not lozenges) broken in half, whenever eating and drinking is finished for a while so that the zinc lingers in my throat. I begin the treatment immediately on experiencing symptoms and I repeat it several times a day, so total daily dose probably is around 60mg or a bit more, although it seems to me that dose may not be the important thing, it’s the repeated administration of a small dose whenever eating and drinking is finished, so that the back of the throat stays coated.

    For me zinc has been amazing. Since I started that regimen exactly 4 years ago, cold symptoms have been very mild, they have largely gone away after 48 hours and the 5-week bouts of sinusitis that I used to get every winter have gone.

    1. Yes, I have the same results. I’m basically a skeptic on things and don’t believe in miracle cures but Zinc does squash the cold and stops it from progressing. My entire family has had the same results at lower doses as well in the form of a popular lozenge brand. It absolutely does work if you get in very early on the first symptoms. I am amazed how so many studies contradict the benefits I find in natural supplements. Glucosamine for me as been a miracle drug but the studies say otherwise. Magnesium too is amazing for headaches and sleep and memory but my doctor keeps tell me its the placebo effect and tries to prescribe me Ambien. I take other natural supplements that work.I think it’s time for a new doctor with better nutritional /natural training and more of an open mind . Part of the problem is Big Pharma. They fund most medical schools and they have no interest in promoting any product they can’t brand and make money from. I strongly suggest you subscribe to Consumer lab. An independent testing laboratory that gives you the whole story and not just what some questionable one sided studies might say.

    2. I used to have a very poor sense of smell, but after I started taking zinc my sense of small improved remarkably. It seems that zinc is the critical mineral that the body needs for this sensor needs to work properly.

  28. Dr Rushworth I would be very interested in seeing a review by yourself on AREDS supplements for intermediate and late age related macular degeneration.

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