As the novel coronavirus spreads around the globe, one way you might be preparing is by shoring up your immune system. One popular strategy? Stocking up on dietary supplements that promise to fend off infection.
Some common ones you might have heard about include Echinacea, elderberry, colloidal silver, chaga mushroom and probiotics — plus old-school standbys like vitamin C and zinc.
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But popping a pill isn't all it's cracked up to be. By and large, claims that supplements support immune function have either been debunked by research or have zero scientific grounding to prove their effectiveness. What's more, they may actually damage your health. Here's what you need to know.
Why Supplements Won’t Improve Your Immunity
Put simply: They're pointless. "For the average healthy adult, there is no evidence that supplements work," Pieter Cohen, MD, associate professor of medicine at Cambridge Health Alliance, tells LIVESTRONG.com. "We get plenty of vitamins and minerals in our regular diet."
And by the way, that's true whether we're cooking at home or picking up McDonald's takeout. "Supplements are often marketed as if we are missing vitamins when we eat fast food, but even processed foods are fortified," says Dr. Cohen, who has published several research papers on the supplement industry. (That said, homemade meals are of course the healthier option.)
"If you think a vitamin can replace a good night's sleep, a healthful diet or exercise, then you are doing yourself a disservice."
In extreme situations — say, if someone has a severe deficiency of a particular vitamin — a person might be more susceptible to infection, and a supplement could help.
"While that's not uncommon in developing countries, it doesn't occur here in the U.S. unless an individual has an illness or a severe absorption problem," Dr. Cohen says. "In that case, your physician might suggest you take a vitamin or mineral."
7 'Immune-Boosting' Supplements — Debunked
Let's take a closer look at some of the studies — or lack thereof — around common supplements that vow to strengthen immunity:
A February 2015 Cochrane review found that Echinacea does not provide benefits for treating the common cold, while a January 2015 Pharmacognosy review pointed out that side effects of the supplement include nausea, abdominal pain and rash.
2. Colloidal Silver
Colloidal silver has zero research backing up its health claims, according to the National Institutes of Health (NIH), and can cause serious side effects like skin discoloration and poor absorption of medicine such as antibiotics.
People who took elderberry syrup experienced some relief from upper respiratory cold and flu symptoms, as noted in a February 2019 analysis in Complementary Therapies in Medicine, but large-scale, independent studies have not been done, so there's no way to know the effects for sure.
4. Chaga Mushroom
While some laboratory and animal-based studies have shown a possible link between chaga mushroom and immunity, there have not yet been any human studies in this area, according to Memorial Sloan Kettering Cancer Center.
"Probiotics are promoted to…sustain immunologic health [yet] there are no large, long-term clinical trials proving that they offer benefits for people who are already healthy," wrote Dr. Cohen in an October 2018 article in JAMA. "Probiotic supplements may also present risks, such as opportunistic infections and allergic reactions."
6. Vitamin C
Vitamin C won't reduce the risk of developing a cold for the general population (exceptions include smokers, the elderly and people exposed to very cold environments or extreme physical activity, like marathon runners), according to the NIH. It may modestly shorten the duration of a cold.
Zinc supplements only improve immune function in people who are severely deficient, according to the NIH, although zinc lozenges can significantly reduce cold symptoms like coughing, runny nose and achy muscles.
The Risks of Relying on Supplements
1. They're Not Guaranteed to Be Safe
You might assume the products you see in the supermarket and pharmacy have been vetted for safety and effectiveness, but that's not the case.
"Although the FDA does regulate supplements, the requirements to bring a product to market are extremely lax," Dr. Cohen says. "They don't look at the evidence that a supplement works in humans or that it's safe before it's on the store shelves."
2. They're Not Guaranteed to Be Effective
In order to manufacture a supplement, companies must have some form of evidence on file for at least one ingredient — no matter how shaky the science is. For example, let's say that four decades ago scientists sprinkled an ingredient on a rat cell culture and found that it affected immunity. A firm could use this as proof that a supplement containing this ingredient will boost consumers' immune systems.
"Jumping from rat cells in a petri dish to claiming that this will work in human beings is absurd from a scientific perspective, but that's exactly what's permitted under the current regulation," Dr. Cohen says.
He points out that even if newer research proves that a certain ingredient is not effective in improving immunity, you can still market it that way using outdated evidence.
"Supplement law permits companies to advertise the vitamin, mineral or botanical as if it will improve or maintain a healthy immune system, even if there is absolutely no evidence in humans that this is the case."
3. They're Generally Not Monitored Unless Something Goes Very Wrong
Manufacturers must register their facility with the FDA. After that, they're good to go.
From then on, the FDA only gets involved if a facility is chosen for an infrequent spot inspection to ensure the environment is sterile. In addition, they might investigate if people are getting sickened by a certain supplement and calling them to complain. "The FDA is very short-staffed, so they might not do anything even if they do receive calls," Dr. Cohen says.
In addition, firms are forbidden from making false health claims — like promising that their product will prevent COVID-19. (The FDA recently sent out several warning letters to companies promoting fraudulent cures.)
"Still, supplement law permits companies to advertise the vitamin, mineral or botanical as if it will improve or maintain a healthy immune system, even if there is absolutely no evidence in humans that this is the case," Dr. Cohen says.
4. They May Not Contain the Ingredients They Claim
Although manufacturers are directed to avoid experimental new ingredients, the FDA doesn't test products to confirm what's in them. Thanks to this lack of oversight, supplements frequently do not contain what's on the label.
That's why you need to be particularly cautious when it comes to anything labeled as an immune-booster. "Supplements that are heavily marketed to have a health effect like this can create a perverse incentive for manufacturers to put actual drugs or experimental compounds into it in order to make people feel as if they are working," Dr. Cohen says.
Although he hasn't researched this issue relating to immune-boosting supplements per se, he has seen it happen with those promoted for weight loss, exercise and sexual function.
5. You Could Overdose
Another concern is taking too much of a supplement. "Just as being extremely deficient in a vitamin can cause harm, getting too much of it can cause harm as well," Dr. Cohen says. "If you do take a supplement, stick to multivitamins, which have a small amount of a lot of different vitamins, rather than a big dose of an individual vitamin — unless your doctor recommends otherwise."
For example, megadoses of vitamin C can cause diarrhea, vomiting, headache and insomnia, according to the Mayo Clinic.
Ingesting a surplus of zinc has similar side effects — along with suppressed immunity and low levels of HDL ("good") cholesterol, per the NIH.
6. You Could Embrace Other Unhealthy Habits
A supplement habit can also lead to poor lifestyle choices if you take the wrong approach.
"I see this among some of my patients who think as long as they take their vitamins every day, they don't have to take care of themselves," Dr. Cohen says. "If you think a vitamin can replace a good night's sleep, a healthful diet or exercise, then you are doing yourself a disservice."
Better Ways to Bolster Your Immunity
These moves are actually proven to help you stay healthy:
1. Wash Your Hands
Scrub with soap and water for 20 seconds, especially after you have been in public or after blowing your nose, coughing, or sneezing, per the Centers for Disease Control and Prevention.
Can't get to the sink? "If you are in a public space, carry hand sanitizer with you and use a little whenever you touch anything," Dr. Cohen says. "As soon as the hand sanitizer dries on your skin, you know it has worked."
Also, wipe down frequently touched items like your phone, doorknobs, light switches, keyboards and faucets with an alcohol-based disinfectant.
2. Stay at Home
If you do venture out, keep at least six feet of physical distance between yourself and other people. FaceTime, Google Hangout, Marco Polo and What's App are great ways to connect with your tribe from afar.
3. Manage Your Stress
Many people are experiencing coronavirus-induced anxiety — and stress inhibits immune function. To alleviate your worries, Harvard Health Publishing suggests staying in touch with friends and loved ones virtually, not overdosing on the news and only tuning into credible sources.
Other proven stress relievers include yoga, meditation, a gratitude practice and controlled breathing.
4. Get a Good Night's Sleep
Adequate shut-eye helps you fight infection, according to a February 2019 study in the Journal of Experimental Medicine.
Tips to get a truly restorative rest:
- Wake up and go to bed at the same time each day
- Turn off electronics 90 minutes before you turn in (seriously!)
- Don't look at the news before bed
- Get regular exercise (more on that next)
5. Break a Sweat
An April 2018 article in Frontiers of Immunology confirmed that exercise can help protect you from viruses. So hop on your Peleton or try these tips for an at-home workout that will get your heart thumping.
6. Eat Healthy
A good diet is linked to strong immunity, as evidenced in an August 2018 article in the journal Nutrients.
The good news: Since many of us are forced to cook at home these days, hopefully we're consuming fewer processed and fast foods. Check these ideas for creating yummy, nutritious meals by raiding your pantry.
Concerned About COVID-19?
Read more stories to help you navigate the novel coronavirus pandemic:
- Council for Responsible Nutrition: "Dietary Supplement Use Reaches All Time High"
- IRi Worldwide: "Supplements for Coronavirus Probably Won’t Help, and May Harm"
- Cochrane Database Systems Review: "Echinacea for preventing and treating the common cold"
- Pharmacognosy Review: "Echinacea purpurea: Pharmacology, phytochemistry and analysis methods"
- Complementary Therapies in Medicine: "Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: A meta-analysis of randomized, controlled clinical trials."
- JAMA: "Probiotic Safety—No Guarantees"
- FDA: "Coronavirus Update: FDA and FTC Warn Seven Companies Selling Fraudulent Products that Claim to Treat or Prevent COVID-19"
- Center for Healthy Minds: "Stress and the Immune System"
- Journal of Experimental Medicine: "Gαs-coupled receptor signaling and sleep regulate integrin activation of human antigen-specific T cells"
- Frontiers of Immunology: "Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan"
- Nutrients: "Diet and Immune Function"
- Mayo Clinic: "Supplements: Nutrition in a Pill?"
- National Institutes of Health: National Center for Complementary and Integrative Health: "Colloidal Silver"
- Memorial Sloan Kettering Cancer Center: "About Herbs, Botanicals & Other Products"
- National Institutes of Health: "Vitamin C"
- National Institutes of Health: "Zinc: Fact Sheet for Health Professionals""
- Mayo Clinic: "Too Much Vitamin C: Is It Harmful?"
- National Institutes of Health: Zinc: Fact Sheet for Consumers"
- Centers for Disease Control and Prevention: "When and How to Wash Your Hands"
- Harvard Health Publishing: "Stress"
- Memorial Sloane Kettering Cancer Center: "Chaga Mushroom"
- Mayo Clinic: "Supplements: Nutrition in a pill?"
- NIH: "Colloidal Silver"
- NIH: "Vitamin C Factsheet for Health Professionals"
- NIH: "Zinc"
- Mayo Clinic: "Is it possible to take too much vitamin C?"
- NIH: "Zinc Factsheet for Consumers"
- Harvard Health: "Coping with coronavirus anxiety"
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.