Note: because not everyone reads to the end, I’d like to say right up here that the best advice I can give you is to go and talk to your doctor. Taking a supplement or not is a medical decision, and those are best made in consultation with experts who know more about your health than articles you find on the internet.
There’s something quite magical about the supplement aisle. You walk down a row of brightly-coloured bottles, each one trying to outdo the others on its wonderful benefit to your body. They can, apparently, boost your brain, make you stronger, and even make improve your immune system to levels heretofore unseen in the biological world.
And in a year of uncertainty and viral infection, the idea that we can boost or support our immune system with supplements is stronger than ever. Supplement sales have gone through the roof throughout the COVID-19 pandemic, because if there’s one thing that’s universally true it’s that fear sells and we have all spent much of this year being really quite scared.
Unfortunately for all of us out there popping pills, the reality is that supplements aren’t quite as magical as they pretend to be on the bottle, and in reality it’s unlikely that any of them can improve your immune system at all. Yes, people who are deficient in some vitamins might benefit from taking a supplement to bring them up to normal levels, but aside from that there’s often little evidence that these pills do much for our health.
Supplements probably don’t help for COVID-19 after all.
At the outset, I should be very clear — it is impossible to be certain that no supplement will benefit your immune system. The problem with supplements is that they are a poorly-regulated, often extremely diverse field, which means there are thousands of different products on the market that all claim to do similar things but can be quite different if you look closely at them.
To illustrate, here are some of the results I got when I typed “immune boost supplement” into Google. We’ve got a combined zinc/vitamin C tablet that claims to support healthy immune function, an immune boosting milkshake with dozens of odd ingredients, some immunity probiotics, immune boosting royal jelly, and an endless cavalcade of other products. In a single search, we had almost the entire flora and fauna of the biological world packed into bottles and sold for the explicit purpose of making your immune system better in a vague, indefinable way.
It’s clear that, even if I had endless hours to read every study on every ingredient in these pills, I still wouldn’t have time to go over them all. The range of products is so wildly diverse that it includes ground-up kangaroo, various parts of the olive tree, elderberries in every preparation imaginable, and even goat colostrum.
Looking at everything would be a full-time job, and sadly I already have one and a half of those.
But we can look at a few products to see what the evidence behind them is, as an illustration. Elderberries, for example, are in dozens of supposed immune-boosting supplements, but if you actually look for the evidence for their use as a supplement it is pretty slim pickings. A few positive studies, almost all funded by the industry, that show results that are statistically significant but largely clinically meaningless for colds and flu. For example, one study sponsored by the industry randomized air travelers to receive elderberry extract or a placebo and found that the extract did not improve physical health, the risk of getting a cold, mental health, or the use of cold medication. There was a very small difference in between the groups for the patients who did get a cold — the symptom severity was lower — but since the authors didn’t correct for multiple comparisons it’s likely that even this finding is questionable.
The story repeats itself when we look at another common ingredient in immunity products — echinacea. A rigorous Cochrane review on the product in 2014 found that it might have minor, clinically insignificant benefits — a modest reduction in the risk of experiencing a cold, but no benefit in terms of symptoms or duration — but no evidence that it was particularly useful.
Oddly enough, two of the things that have the best evidence for treatment of common colds are the easiest ones to find anywhere — zinc and vitamin D. There’s reasonably good evidence that vitamin D supplements can reduce your risk of having a respiratory infection by about 10%, but don’t impact the risk of hospitalization, severity of disease, length of disease etc. Zinc has been shown to modestly reduce the duration of colds, but doesn’t appear to reduce the risk of getting a cold nor how bad the disease is when you get it. Again, the benefits of taking a supplement, while sometimes real, tend to be very small.
And none of this is even about the immune system more broadly. There are, for example, hundreds of studies of vitamin D for the common cold, but none I could find for hepatitis. There’s a huge body of literature on echinacea for the sniffles, but look for evidence that it improves immune function in urinary tract infections and there’s nothing there.
This is not to say, of course, that the lack of evidence means very much. There are only so many studies done on each supplement, and it may be that no one has thought to conduct this particular piece of research. But it is quite telling that all of these supplements are marketed and sold with taglines like “immunity booster” despite no one ever checking whether it has any impact on your immune system beyond reducing the duration of colds by a few hours.
And I haven’t even touched on the astonishingly deep well of supplements for which there is basically nothing researched at all. The thing about supplements is that, subject to local laws, they tend to be largely unregulated. You can put almost anything in a bottle — kangaroo parts, astragalus, sheep placenta, oregano, cow collagen, cloves, bee venom, etc* — and make claims that are just vague enough to not breach advertising regulations without trouble in most places in the world. As long as the product meets basic safety standards, and doesn’t outright claim to cure disease, it’s rare that regulators take action.
Overall, there’s really not a lot of evidence that supplements do much for your immune system. Yes, some supplements may have a modest impact on things like cold symptoms or your risk of getting a respiratory infection over 12 months, but these benefits are rarely meaningful to the individual. If everyone in the United States was given a zinc/vitamin D supplement every day, you’d see a touch fewer colds at the population level, but most people taking them probably wouldn’t notice the difference.
It’s also worth noting that, like all medical interventions, supplements have side-effects. These are mostly very mild — zinc, for example, causes nausea — but if enough people take them the impact is similarly large. In fact, the negative impact is almost exactly equal to the positive one, with neither having a huge impact either way.
Many supplements also contain things that you can get in other ways anyway. Vitamin D is produced when you go out in the sunshine, zinc is in a host of foods, and garlic — another common immunity supplement — can be increased in your diet by cooking more Lebanese food. Unlike supplements, these things tend to have secondary benefits, like being outdoors more often or eating delicious garlic dip on a daily basis.
Ultimately, I can’t answer the question of whether you personally should take a supplement for COVID-19 or not. As ever, my best piece of advice is to go and see your doctor, because they’re the one that actually knows you and your medical history, and they can give you the best advice possible for your personal health.
What I can say is that most of the supplements you see sold around are, at best, largely without evidence. The few that have good evidence appear to have very modest benefits, and generally don’t have any evidence of a general “immune boosting” effect anyway. Knocking a day off your average cold doesn’t mean much for COVID-19, after all.
Supplements probably won’t hurt you that much, but they probably won’t help much either.
*Yes, these are all real examples