Not surprisingly, back-to-school season also brings an uptick in advice on how to boost kids’ immune systems with a trip down the supplement aisle. Wellness bloggers share the supplement regimens that they swear keep their kids healthy through the winter. At my daughter’s back-to-school open house, the PTA handed out free samples of gummies (a form my kids find irresistible) infused with black elderberry extract, claiming to be “delicious immune support for the whole family.” My toddler’s daycare provider even asked if she could give him a mega-dose of vitamin C to protect him from the inevitable fall outbreak of colds.
As a parent, fresh in my mind is the recent recall of Hyland’s teething tablets, which turned out to have inconsistent and sometimes toxic levels of belladonna (also known as “deadly nightshade”). The FDA has received reports of hundreds of seizures and even deaths in infants after they were given the tablets, and all of this was from a product that many parents swore by and a company they trusted. (Hyland’s teething tablets were classified as homeopathic remedies, which are regulated a bit differently from supplements, but they suffer from a similar lack of oversight.)
Lots of supplements have a study or two or even more that show some beneficial effects, but it’s important to look at all available research with a close eye for study design and the dose and preparation tested. For example, you’ll find plenty of studies of the effects of Echinacea and elderberry on isolated cells in test tubes or petri dishes, but we want to know whether these preparations are safe and beneficial in the human body. And before I give a supplement to my kids, I want to know that it’s actually been tested in children, because their small, not-fully-developed bodies might process it differently than adults.
Vitamin and mineral supplements may seem more straightforward, but don’t assume that just because they’re made of nutrients that they’re safe. Supplements often use doses much higher than you’d find in food, and this can have unintended consequences. Case in point: a study published last month in the Journal of Clinical Oncology found that men who took high-dose vitamin B6 and B12 supplements – often marketed as boosting energy – were nearly twice as likely to end up with lung cancer.
Suffice it to say that I have a high bar for evidence that a supplement is beneficial and relatively safe before I’d consider giving it to my kids or taking it myself. But on the other hand, it would be pretty awesome to have less snot in my life this fall, so I took a look at several supplements with claims that they protect against the common cold.
Elderberry (and Other Parts of the European Elder Tree)
Let’s start with those elderberry gummies, because my kids are still waiting to hear if they get to eat them. A couple of small human studies have looked at the effect of elderberry supplementation on flu and the common cold with some encouraging results that it might shorten the duration of illness. However, these were done in adults, and I couldn’t find any data specific to kids. (A 1995 study treated 15 flu patients, age 5 to 50 with elderberry syrup, but that’s a tiny sample size to start with, and the paper doesn’t give details on how many were kids.) On the safety side, the National Institutes of Health’s National Center for Complementary and Integrative Health (NCCIH) says this: “The leaves, stems, raw and unripe berries, and other plant parts of the elder tree contain a toxic substance and, if not properly prepared, may cause nausea, vomiting, and severe diarrhea.” That sounds worse than a cold, so I’ll pass and get my kids some gummy bears to make it up to them.
In a randomized controlled trial published in JAMA in 2003, 524 kids received either Echinacea extract or a placebo when they felt a cold coming on. There was no difference between groups in the duration or severity of their cold symptoms, but the kids taking Echinacea were more likely to get a rash. A rash sometimes comes with a viral infection, but because it was more common in the Echinacea group (7.1 percent of kids taking Echinacea versus 2.4 percent of those taking the placebo), the authors think it could have been a reaction to the herb. A 2014 Cochrane review combined results from previous trials – all in adults except the 2003 study just mentioned – and also concluded that there was no evidence of benefit of Echinacea for colds.
The good people at Cochrane also looked at garlic, but they only found one study that met their criteria for quality. Published in 2001 in Advances in Natural Therapy, this was a randomized controlled trial in which one group took a daily garlic supplement (equivalent to eating 10 cloves of garlic) and the other took a placebo for 12 weeks. The garlic group had far fewer colds, and when they did get sick, they suffered for fewer days. The results seem promising, but here’s the thing: the study was authored by one guy who also happened to be the director of something called the Garlic Centre in East Sussex, U.K. In their coverage of the study, the BBC called him a “garlic enthusiast,” and he’s now selling garlic supplementson the internet. And while the paper says that it was a double-blind study, meaning that neither the participants nor the researcher should have known who was taking garlic or the placebo, smelly burps were noted as a common side effect by those taking garlic.
There are too many red flags here, and there haven’t been any studies since to try to replicate the findings. The Cochrane review says there’s not enough evidence to support using garlic for colds, and I agree.
Vitamin C has been a popular cold remedy for decades, and as a kid, my mom encouraged me to swallow large, acidic-tasting pills whenever I felt a cold coming on. These days, big doses of vitamin C are marketed in tastier forms like Emergen-C and Airborne, but none of these have been shown to do much good. A 2013 Cochrane review combined the results of 29 studies, together with more than 11,000 participants, and concluded that taking vitamin C won’t reduce your chances of getting sick. The exception was for hardcore people doing strenuous exercise; in marathon runners, skiers, and soldiers training in subarctic conditions, taking vitamin C cut their chances of catching a cold by about half.
Vitamin C does seem to have a consistent but small benefit of reducing the length of cold symptoms. It amounts to shortening colds by 8 percent for adults and 14 percent for kids – maybe one day less of suffering. However, to see this benefit, you have to take vitamin C every day, and often in pretty high doses. Some of the doses studied in kids were higher than theUpper Limit established by the Institute of Medicine, above which vitamin C can cause nausea, diarrhea, and abdominal cramping.
Of all the supplements we’ve discussed, zinc lozenges may have the most promise for treating cold symptoms. They’ve been well-studied in randomized controlled trials of adults, and several meta-analysesconsistently find that they reduce the duration of colds, particularly if you take at least 75 milligrams per day, starting when symptoms begin. At that dose, cold duration was reduced by 42 percent in adults. Most studies on zinc have been in adults, but a 2013 randomized controlled trial conducted in Thailand found that kids age 8 to 13 taking a daily dose of zinc for three months had much shorter colds than those taking a placebo.
But once again, the doses of zinc used in these studies are far more than we usually get from food and are close to or above the upper limitrecommended for daily consumption, so there may be some risk there. The Thai study in kids involved taking a high dose for months as a prophylaxis, not just an occasional treatment, which makes me even more wary. Nasal zinc has also been shown to cause a loss of your sense of smell, so definitely steer clear of that.
In the end, every supplement is a little bit of a gamble. Some promise benefit, but your results may vary, and most carry some risk of side effects. We need more well-designed research to clarify that tradeoff, but in the meantime, my family will stick to washing our hands, coughing in our elbows, getting enough sleep, and enjoying non-drug-infused gummy bears.