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Is good gut flora an “off switch” for damaging cytokines?

By Dr. Sarika Arora, MD

When a viral invasion is detected in the body, your cells send an SOS alert signal to the immune system to summon special anti-inflammatory peptides called cytokines. In theory, it’s a perfect relay system — as long as everything is working as it should. However, a variety of factors can cause the immune system to overreact and send too many cytokines, creating a “cytokine storm” in which the body attacks its own cells and tissues instead of killing off the viral invader cells.

A women who needs to improve her gut flora

Cytokine storms have been linked to increased risk of severe complications in Covid-19 patients. Cytokine storms also make it more difficult for the body to clear out infected cells as efficiently as it should during an acute infection. Because of this, researchers recently turned their attention to locating a biological “off switch” for these brewing storms.

It didn’t take long to find one. According to a new study out of Moscow, published last month in the journal Anaerobe, researchers discovered that a particular strain of probiotic Bifidobacterium longum (B. Longum) may help capture excess cytokines before they can flare up and go on the attack.

What does a bacteria that lives in your gut have to do with your immune response? As we’ve noted before, over 70% of your immune cells reside in the lining of the gut, side by side with your gut microbiome. The bacterial flora in your gut is in constant contact with your immune cells.

This new study is important because it helps to uncover just how deep this communication goes: Bifidobacterium longum contains special protein receptors that appear to recognize and bind to the specific class of cytokines that create cytokine storms. When these cytokines arrive to kick up inflammation and wreak havoc, Bifidobacterium longum has the ability to neutralize them.

It’s fascinating to see the pivotal role gut bacteria plays in regulating the body’s immune response and it may also help to explain why children show increased resilience and better Covid outcomes when compared to adults. Children naturally have higher levels of Bifidobacterium longum, which could be the reason their immune response is so effective and why they’re much less likely to experience cytokine storms.

What about your own levels of Bifidobacterium? Unfortunately, they are probably much lower than they once were, as most adults have an imbalance of gut flora. Levels of Bifidobacterium longum decline in adulthood for many reasons, including use of antibiotics, chronic stress, and dietary choices that harm gut flora.

This is why, for adults in particular, supplementation with a high-quality probiotic is essential for rebuilding and maintaining Bifidobacterium longum and other healthy intestinal flora. Good gut health does more than boost the immune system — it also improves brain function, balances hormones, clears skin issues, and more.

Tip: Before buying a probiotic supplement, check the label for “B. Longum” as one of multiple strains.

The good bugs really are the good guys, especially when it comes to immune health in the time of Covid-19. So this season, as you stock up on Vitamin D and other immune boosters, my message to you is — don’t forget about your gut!

Learn more: Best vitamins & nutrients to boost the immune system. 


Dyakov IN, Mavletova DA, Chernyshova IN, et al. FN3 protein fragment containing two type III fibronectin domains from B. longum GT15 binds to human tumor necrosis factor alpha in vitro. Anaerobe. 2020;65:102247. doi:10.1016/j.anaerobe.2020.102247.

Last updated on 10/04/2020

Last Updated: November 18, 2022
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