One winter surprise we don’t need is a bout of influenza. The influenza vaccine is the best protection against the seasonal flu, although the protection varies seasonally. How well the vaccine protects against influenza depends on how closely the vaccine matches the strains that are circulating. Some years the coverage is better than others. Even if the vaccine doesn’t have to cover the most common seasonal strains, the vaccine may still provide some protection by boosting your immune system non-specifically.
Knowing the coverage isn’t perfect, you might wonder what else you can do to protect yourself against influenza? Handwashing and avoiding people who are ill is a good start, but are there supplements that protect against the flu virus? There isn’t a supplement that guarantees you won’t catch the flu, but there are some that are promising. Here’s what research shows about supplements and influenza.
Zinc is a mineral your body needs for wound healing, fertility, and immune health. Studies show that sucking on zinc lozenges when you have an upper respiratory infection, like a cold, may shorten the length of a pesky cold by a few days, but you must start taking them as soon as you develop the symptoms. Zinc may work by reducing the replication of respiratory viruses and by keeping inflammation in check. It’s not clear whether this is also true for the influenza virus. There are downsides to using zinc lozenges. They can cause nausea and a metallic taste in the mouth, but this should go away when you stop using them. Never use zinc nasal spray as there are cases where people lost their sense of smell after using them.
Many people are low or borderline low in vitamin D, a vitamin that impacts immune function. According to a large meta-analysis of 25 studies, supplementing with vitamin D may lower the risk of respiratory infections. However, the benefits are greatest for people who are low in vitamin D. For those who were vitamin D deficient, supplementing with vitamin D daily or weekly cut the risk of developing a respiratory infection in half. Those who had a higher level of vitamin D only enjoyed a 10% reduction in respiratory infections. Still, that’s not insignificant! It’s another reason to check your vitamin D level before flu season begins and supplement if it’s low.
Studies don’t clearly show that vitamin C can prevent colds in the general population. However, it may shorten the course of the common cold once it appears by a day or two. A study among endurance athletes, a group at high risk due to the heavy training they do, showed those who took a vitamin C supplement slashed their risk of catching the common cold by 50%. These findings apply to the common cold and it’s not clear whether supplemental vitamin C lowers the risk of developing the flu. However, being deficient in vitamin C would likely increase the risk since vitamin C is important for healthy immune function and it may have anti-viral activity too.
Should you invest in a bottle of vitamin C supplements? Not so fast! There are drawbacks to taking a high-dose vitamin C supplement, including digestive upset and a higher risk of kidney stones in those who are prone to them. Your best bet is to add more vitamin C-rich foods to your diet during flu season. Raw fruits and vegetables are the best sources since vitamin C is destroyed by heat.
These days, we hear a lot about probiotics, the gut microbiome, and the role they play in health. Can supplementing your microbiome with probiotics lower your risk of influenza? There is some evidence that consuming probiotics and prebiotics, the fiber probiotic bacteria feed on, can boost the vaccine’s effectiveness. However, it’s not clear how strong the protective effect is.
Other research shows that probiotic bacteria in the gut enhance the activity of natural killer and phagocytic cells that fight viruses. Based on these findings, it wouldn’t hurt to eat a serving of fermented foods daily a week before and after getting the influenza vaccine. It’s a good practice to do that anyway! You could also take a probiotic supplement, but the quality varies widely. Some may not contain enough active probiotic bacteria to have a benefit.
Elderberry Syrup or Extract
In studies, people with the flu who took an elderberry supplement shortened the duration of their flu symptoms by 4 days. Elderberries also contain proteins called hemagglutinin proteins that thwart the ability of viruses to stick to cells. It may also boost the immune response to viruses. If you add elderberries to your anti-flu regimen, use a supplement from a reputable manufacturer. Elderberries contain cyanide, but cooking inactivates the cyanide. If you eat them raw, you may develop nausea, and if you eat enough, cyanide toxicity.
Other Ways to Lower the Risk of Influenza
Beyond supplements, make sure you’re eating a nutrient-dense diet and getting enough sleep. Rest and adequate sleep are essential for healthy immune function, your internal defense against the flu virus. Studies also show that exercising in moderation, meaning don’t over-train, can reduce the risk of respiratory infections. Exercising modestly boosts the activity of white blood cells that fight viruses.
Keep moving! A 2008 study found that people who exercise moderately have a lower rate of influenza-related mortality. As mentioned, wash your hands every few hours throughout the day. Skip the hand sanitizer. A recent study showed that washing with plain soap and water is more effective than commercial hand sanitizers for killing influenza viruses. If you don’t have access to a sink, a hand sanitizer is an acceptable alternative.
Most importantly, get the seasonal flu vaccine! None of these preventative strategies is as effective as getting the seasonal influenza vaccine. It only takes a few minutes to get a flu vaccine and it could save your life.
- Mayo Clinic. “Zinc for Colds: The Final Word”
- com. “Vitamin D protects against colds and flu, finds major global study”
- PLoS One. 2008; 3(5): e2108.Published online 2008 May 7. doi: 10.1371/journal.pone.0002108.
- com. “Can you boost your flu shot with prebiotics and probiotics?”
- Pharmacy Times. “Elderberries: A Potent Cold and Flu Remedy?”