Fight the Flu with ‘Good’ Bacteria

It's that time of year again when everyone seems to be getting sick with the flu. But what if there was a way to help your body fight off these infections naturally? Believe it or not, your microbiome—the trillions of bacteria that live in and on your body—can play a major role in preventing illness. These beneficial microbes play a crucial role in keeping us healthy by helping to fight off infections and building a strong immune system. Let’s find out how to strengthen your microbiome, and which probiotics are the best if you want greater protection from cold and flu this winter.

Do probiotics help your immune system?

Between flu season, the common cold, and the seemingly ever-present threat of Covid, taking measures to arm your body's natural defenses is well worth it. And some probiotic strains appear to provide several advantages in the fight against both bacterial and viral microbes, while some may even predict COVID-19 severity (1).

Probiotics are live bacteria that help to maintain the balance of microbes in our gut. Probiotics help to keep our gut healthy by suppressing the growth of harmful bacteria and promoting a healthy immune response.

Beneficial bacteria in the microbiome has been shown to help:

  • Digestive problems, including chronic issues like Crohn's and, IBD, and ulcerative colitis
  • Bacterial and fungal infections
  • Allergies, eczema, and dermatitis
  • Cold, flu, and respiratory infection
  • Ear infections
  • Helicobacter pylori infection, which causes stomach ulcers
  • Lyme disease
  • Urinary tract and vaginal infections

Try these: Top 5 Fermented Foods for Gut Health

The flu-fighting pathway of good bacteria

Healthy gut flora are essential for good digestion, but probiotic bacteria that reside in and outside of your gut can help you weather this cold and flu season in other ways, too.

A research team led by an immunologist found that mice treated with antibiotics were more susceptible to influenza viruses than mice who were not treated with antibiotics. According to this study, antibiotic-sensitive bacteria normally present signaled the production of T cells and antibodies that fight influenza infection in the lungs (2).

The bacteria kick-started this flu-fighting pathway by activating 'inflammasome' proteins within the immune system. These inflammasomes are basically sensory and signaling complexes that then push key immune proteins—like the cytokine interleukin 1-β—into a ready-to-respond state (3). Interleukin 1-β triggered immune cells then migrate to lymph nodes in the lungs, where they initiate a pointed attack on influenza viruses. When antibiotics eliminated these bacteria, inflammasomes failed to launch this process and the virus multiplied.

Related: 12 Natural Antimicrobials to Help You Stay Well This Winter

Helpful bacteria don't stop at the gut

The lungs, respiratory system, nose, and digestive system all contain beneficial bacteria that make up your microbiome. And it’s a good thing, too, because virus invasion and replication can take place in any of these locations. Here’s how probiotic bacteria help fight off harmful microbes outside of the digestive system.

Blocking virus replication

The microbiome can block virus replication in various locations within the body. While researchers are still working to fully understand how this happens, they believe a few of the possible mechanisms include (4):

  • Direct probiotic cell interaction with the targeted viruses
  • Production of antiviral metabolites
  • Modulation of the immune system

Some antiviral probiotics might even be a preferable alternative to more conventional antiviral agents due to the growing trend of viruses that are resistant to commonly used antivirals. Probiotics are effective options in some cases for the treatment of various intestinal, respiratory, and urogenital diseases caused by viruses. 

Read: Strengthen Your Immune System After COVID with Holistic Medicine

Want to learn more?

Preventing respiratory infections

There is evidence that probiotics may help to prevent or treat a number of infections, including upper respiratory tract infections. In one study, people who took a probiotic supplement for 6 weeks had a significantly lower risk of developing a respiratory tract infection than those who did not take a probiotic (5).

Upper respiratory tract infections (URTI) are among the most common illnesses for which patients seek medical care, and result in excess costs and absence from work or school. 

Related: The Best Immune Supplements to Stock Up on Before Cold & Flu Season

Microbes that predict COVID-19 severity

A strong correlation has been reported between the severity of COVID-19 and the composition of the gut microbiota. Some patients with COVID-19 showed intestinal microbial dysbiosis, with a decrease in cell numbers of Lactobacillus and Bifidobacterium (6). 

What’s the best probiotic for your immune system?

A probiotic is a great addition to your supplement routine, but which ones help support the immune system? Here are some of the most well-researched probiotic strains for supporting immunity, as well as a healthy digestive system. And if you’d like to add even more beneficial probiotics to your diet, we’ll give you examples of some of the best ways to incorporate these into your day.

Shop gut-healing supplements here.

LGG, L. CASEI and BB-12 may play an important role in immune function 

There are hundreds of probiotics, but clinical studies show that the probiotics LGG®, L.CASEI and BB12 are effective at supporting your immune system.


BB-12 improves bowel function, has a protective effect against diarrhea, and reduces side effects of antibiotic treatment, such as diarrhea. BB-12 also increases the body’s resistance to common respiratory infections as well as reduces acute respiratory tract infections (7). 


Lactobacillus rhamnosus GG (LGG) is one of the most widely used probiotic strains. Studies suggest that LGG may help promote the immune system and may help reduce the incidence of flu-like symptoms.

In one study involving students on a college campus, researchers gave participants probiotic supplements containing LGG for 12 weeks. And while they found that students caught colds at roughly the same rate, the students who took the probiotic supplementation experienced (8): 

  • A duration of colds that was two days shorter (4 days vs. 6 days)
  • Symptoms that were 34% less severe
  • A higher quality of life that resulted in fewer missed school days (15 vs. 34 missed by students taking the placebo).


Lactobacillus casei may help reduce the duration of the common cold and upper respiratory tract infections by about 2 days, according to one study (9).

A 2007 trial showed that a probiotic drink containing L. casei, L. bulgaricus, and S. thermophilus may reduce the incidence of antibiotic-associated diarrhea and C. difficile-associated diarrhea (10). 

Quick tips to strengthen your gut for cold & flu season

Here are some quick tips to help you strengthen your gut and keep your immune system strong this cold and flu season:

  • Cut out processed foods, sugar, and alcohol, and eat more whole, nutrient-rich foods.
  • Include fermented foods in your diet, such as yogurt, kimchi, sauerkraut, and kefir
  • Take a probiotic supplement daily, containing different strains of Lactobacillus and Bifidobacteria
  • Exercise regularly and get enough sleep to reduce stress levels and support gut health.

By following these tips, you can help ensure that your gut is in tip-top shape to fight off harmful microbes this flu season. For more, follow these steps to boost immune function.

Other helpful measures to take against the Common Cold

If your cold is severe, it is important to take multiple steps to protect yourself and your family from developing a more serious illness.

Additional nutritional supplements may also help strengthen your immune system as well:

Grab these! The Best Immune Supplements to Stock Up

What to remember during cold and flu season

As we head into the colder months, it’s important to remember that good gut health is key to keeping our immune system functioning at its best. Probiotics play a major role in strengthening immunity against seasonal pathogens, including viruses that cause cold and flu. Certain probiotic strains are directly active against harmful microbes and help your body’s immune system mount a strong response to infection. Probiotics can help reduce the duration of the common cold, and upper respiratory tract infections, which are responsible for many missed school days and doctor’s visits for adults and school-aged children alike. So if you’re looking for an easy way to boost your immune defenses this winter, take care of your gut health by boosting your intake of probiotics!


  1. https://www.translationalres.com/article/S1931-5244(20)30199-7/fulltext
  2. https://www.nature.com/articles/news.2011.159
  3. https://www.nature.com/articles/s41421-020-0167-x
  4. https://www.frontiersin.org/articles/10.3389/fmicb.2020.01877/full
  5. https://pubmed.ncbi.nlm.nih.gov/26322544/ 
  6. https://pubmed.ncbi.nlm.nih.gov/32391658/
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5029483/
  8. https://www.sciencedaily.com/releases/2012/10/121022162335.htm
  9. https://academic.oup.com/ajcn/article/101/6/1188/4564548 
  10. https://www.bmj.com/content/335/7610/80 


gut health, Immune Health

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