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Duke University Medical Center Assesses Probiotics for COVID-19

Duke University Medical Center Assesses Probiotics for COVID-19

The material provided below is for informational purposes only. It is not intended to replace the diagnosis or treatment by a qualified healthcare professional. You should always seek medical advice before consuming any new medicines or supplements.


Back in 2020, Duke University researchers began a randomized, double blind, placebo-controlled clinical trial of a probiotic in COVID-19 exposed households. The trial specifically studied and utilized Lactobacillus rhamnosus GG (LGG®) in household contacts at high risk for COVID-19. 

The clinical trial sought to learn if taking LGG® probiotic daily for 4 weeks following COVID-19 exposure would be effective in preventing development of symptoms, as compared to a placebo.

So, what were the results? This randomized clinical trial of 182 participants showed that only 26.4% developed symptoms while taking LGG® versus 42.9% who took the placebo -- a significant difference! This means that LGG® probiotic strain may protect against the development of symptoms if taken daily within 7 days after COVID-19 exposure.*

More About The Clinical Trial

Led by Drs. Paul Wischmeyer and Anthony Sung, the study aimed to learn about epidemiology of COVID-19 in household contacts and the role of the microbiome in COVID-19 risk and illness. The researchers anticipated that probiotics may reduce the risk of SARS-CoV-2 infection and severity of COVID-19 disease in household contacts and caregivers of known COVID-19 patients.

The clinical trial, which started in the summer of 2020, was based on multiple clinical trials and meta-analyses that have shown that prophylaxis with probiotics, working through the gastrointestinal microbiota, may reduce upper and lower respiratory tract infections, sepsis, and ventilator-associated pneumonia by 30-50%. These benefits appear to be mediated by the impact of probiotics on the immune system.

These immune system effects are especially relevant to individuals who are at risk of developing severe COVID-19 disease, and for those at high risk for SARS-CoV-2 exposure such as health care providers, teachers, retail workers and those whose close contacts cannot be vaccinated. COVID-19 has been characterized by severe lower respiratory tract illness, with the potential for increased complications and mortality. “We hypothesize that Lactobacillus rhamnosus GG will directly influence the microbiota which may in turn reduce COVID-19 infection risk and severity of disease and symptoms,” said Wischmeyer. This study provides for greater understanding of how to care for the most at-risk populations.

Lactobacillus rhamnosus GG was selected for inclusion in the study based on evidence from over 200 clinical trials proving the bacterial strain’s health benefits, including immune support and decreasing the risk of respiratory tract infections.

More About The Results

This study suggests that LGG® is associated with prolonged time to development of COVID-19 infection, and reduced incidence and severity of symptoms, when used within 7 days after exposure to SARS CoV-2.

The results showed that those exposed to SARS CoV-2 who took LGG® were not only less likely to be diagnosed with COVID-19 but they:

  • were significantly less likely to develop symptoms versus those taking placebo (26.4% vs. 42.9%,)
  • had a substantially prolonged time to symptom onset.
  • had a greater abundance of Lactobacillus rhamnosus in their gut in conjunction with a significant change in the gut microbiota
  • found the probiotic to be well-tolerated with no increased side effects versus placebo.

This means Lactobacillus rhamnosus GG may provide certain protection against the development of symptoms when used as post-exposure prophylaxis within 7 days after COVID-19 exposure.

LGG® is a trademark of Chr. Hansen A/S

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