Fighting Live Viruses with Dead Bacteria

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Heat-killed Lactobacillus plantarum L-137 for respiratory health, immune function, and antiviral support

Lactobacillus plantarum is a type of lactic acid bacteria found in a variety of fermented foods. The heat-killed version of a specific strain of this bacteria, L. plantarum L-137 (HK L-137), has been shown to enhance immune activity, support respiratory health, and fight viral infections.[1],[2]

Health benefits of HK L-137

Upper respiratory tract infections (URTIs) – infections affecting the nose, sinuses, and throat – are common during cold and flu season. Illness is also more common during rough patches of physical and/or emotional stress, due to the immunosuppressive effects of these experiences.

In a recent study, however, taking 50 mg of HK L-137 daily for 12 weeks was shown to decrease the incidence, duration, and symptoms of URTIs in adults with psychological and emotional stress.[3]

50 mg of HK L-137 daily for 12 weeks was shown to decrease the incidence, duration, and symptoms of URTIs in adults with psychological and emotional stress.

HK L-137 likely staves off URTIs by increasing the immune signaling molecules (cytokines) interleukin 12 (IL-12) and interferon beta (IFN-β).[4],[5]

HK L-137 further works by modulating the response of white blood cells – the cells responsible for immune responses.[6] Specifically, HK L-137 supports a T cell class known as Th1, which distinctively attacks bacteria and viruses.[7],[8] In another study, 50 mg of HK L-137 taken daily for 12 weeks by adults age 40 and up enhanced T cell proliferation, Th1 levels, and health-related quality of life measures.[9] All of this translates into infection-fighting power.

HK L-137 supports a T cell class known as Th1, which distinctively attacks bacteria and viruses.

Oral HK L-137 has also been shown to protect against influenza A virus infection (flu) in mice.[10] Given that it enhances IFN-β in humans, HK L-137 is hypothesized to likewise protect us against the flu and other viral respiratory infections.[11]

No refrigerator required!

Although it’s prepared from lactic acid bacteria found in fermented food, HK L-137 isn’t a probiotic supplement, per se. HK L-137 hails from a sub-class of dead bacteria known as immunobiotics.

Fermented foods and probiotic supplements work by delivering “good” bacteria to the human digestive tract, where they propagate and yield health-boosting benefits.[12] Because they are heat killed, however, immunobiotics like HK L-137 do not (and cannot) grow in the human digestive tract. HK L-137 instead tonifies the infection-fighting branch of the immune system by activating gut immunity and triggering an immune system response as described above.

The process of heat-killing a probiotic also confers additional benefit: heat denatures the cell membrane, thus protecting the cell wall of HK L-137 from degradation by the digestive enzymes of the human gut.[13]

An additional benefit of immunobiotics like HK L-137 is that unlike their “classic” probiotic peers, they do not require refrigeration and are stable at room temperature. They therefore have a longer shelf life than regular probiotics. Furthermore, because there is no risk of it colonizing within the body, HK L-137 may offer a safer alternative to live probiotics for immune-compromised patients, such as those undergoing chemotherapy.

Conclusion

HK L-137 offers a truly unique approach to supporting the immune system, protecting the respiratory tract, and enhancing resilience to infectious illnesses. It turns out a “dead” bacterium has plenty to offer us during viral respiratory infection season.

More about immunobiotics can be found in this article.

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