How to fight the flu with fermented food

Fermented foods support your health in so many ways…

They tame tummy issues, reduce your risk of diabetes, keep your mental health in check and help you maintain a healthy weight, among other things.

But have you ever thought about using fermented foods to fight the flu?

I’ll admit, the thought hadn’t crossed my mind until recently, although it makes perfect sense. After all, 70 to 80 percent of your immune system is in your gut. And fermented foods inject your gut with a hefty dose of healthy bacteria that keeps those immune cells thriving.

In fact, the latest research shows there’s one particular healthy bacteria in fermented foods that may protect you from the flu’s worst effects — lactic acid.

The flu is no match for lactic acid

A recent study from researchers at Georgia State University found that lactic acid reduces the severity of the flu in mice.

GSU researchers already knew lactic acid had the ability to fight bacteria and viruses from previous studies, which showed it offered protection from Streptococcus pneumoniae (a bacterial infection which can cause pneumonia), colds and flus. But they wanted to add to the evidence supporting lactic acid’s pathogen-fighting effect…

In their study, they treated mice with a type of lactic acid called Lactobacillus casei DK128. Then they infected them with a strain of the influenza A virus. The mice who received this lactic acid bacteria also received impressive protection against this flu…

They had more immune cells clearing nasty stuff out of their lungs and nasal passages. They had more virus-fighting antibodies on the scene to battle the replicating virus, and these antibodies showed up quicker. They also developed immunity to other strains of the influenza virus and had less of the inflammation-producing proteins known as cytokines.

Basically, their immune systems put up an impressive fight. So impressive that the mice who received lactic acid had 18 times less of the influenza virus in their lungs than mice who didn’t receive this beneficial bacteria. Mice who received lactic acid were also less likely to lose weight or die due to the flu virus.

Where to get your flu-fighting lactic acid…

It seems like lactic acid could be an effective way to help your body fend off the flu. So why not give it a try?

Since lactic acid is found in healthy, tasty and totally safe fermented foods, you have nothing to lose. In fact, you should be eating these foods to promote good health whether it’s flu season or not. You’ll find lactic acid in foods, like:

  • Yogurt
  • Kefir
  • Sauerkraut
  • Tempeh
  • Pickled vegetables
  • Sourdough bread
  • Miso
  • Red wine
  • Kombucha

Besides fermented foods, another source of lactic acid is exercise. So make sure to stay active during flu season too.

Now, a quick warning…

You can get too much lactic acid, which puts you at risk for a dangerous (and sometimes deadly) condition called lactic acidosis. It’s happened to people who have over-exercised before. But the chances of developing this problem from eating fermented foods is slim… unless you start eating insane amounts of fermented foods daily.

Rather than gorging yourself on fermented foods at every meal, just make sure you eat or drink something fermented every day. That may be a bowl of yogurt for breakfast, a serving of sauerkraut with lunch or a kombucha as a mid-afternoon snack. That should be enough to keep you healthy and flu-free.


  1. Vighi, et al. “Allergy and the gastrointestinal system.” — Clinical & Experimental Immunology. 2008 Sep; 153(Suppl 1): 3–6.
  2. Lactic acid bacteria can protect against Influenza A virus, study finds — MedicalXpress
  3. J. Jung, et al. “Heat-killed Lactobacillus casei confers broad protection against influenza A virus primary infection and develops heterosubtypic immunity against future secondary infection.” — Scientific Reports, 2017.
  4. B. Rubins. “Alveolar Macrophages: Wielding the Double-Edged Sword of Inflammation.” — American Journal of Respiratory and Critical Care Medicineol. Jan. 2003; 167(2).
  5. Foods Containing Lactobacillus & Bifidobacterium —
  6. Jong Rhee, et al. “Importance of lactic acid bacteria in Asian fermented foods — Microbial Cell Factories. 2011; 10(Suppl 1): S5.
  7. Causes of acidosis — Healthline
Jenny Smiechowski

By Jenny Smiechowski

Jenny Smiechowski is a Chicago-based freelance writer who specializes in health, nutrition and the environment. Her work has appeared in online and print publications like Chicagoland Gardening magazine, Organic Lifestyle Magazine, BetterLife Magazine,, and