Probiotics Linked to Fewer Respiratory Symptoms in Overweight, Older Adults


Individuals who took probiotics during the 6-month-long study had a 27% lower overall incidence of upper respiratory tract symptoms compared to the placebo group.

Daily use of probiotics is associated with fewer upper respiratory symptoms in overweight and older people, according to new research. These findings suggest a potential role for probiotics in preventing respiratory infections, according to the study authors.

Investigators re-analyzed detailed daily diaries of 220 patients who participated in an earlier double-blind, placebo-controlled study on probiotics and weight loss. They looked for common symptoms of upper respiratory infection, such as cough, sore throat, and wheezing. The researchers found that participants who took probiotics during the 6-month-long study had a 27% lower overall incidence of upper respiratory tract symptoms compared to the placebo group.

“This is not necessarily the most intuitive idea, that putting bacteria into your gut might reduce your risk of respiratory infection,” said Benjamin Mullish, MD, a lead researcher on the study and clinical lecturer in the Division of Digestive Diseases at Imperial College London, England, in the press release. “But it’s further evidence that the gut microbiome has a complex relationship with our various organ systems. It doesn’t just affect how our gut works or how our liver works, it affects aspects of how our whole body works.”

The effect of the probiotics was most significant among participants aged 45 years or older, as well as those with obesity, according to the study. The researchers noted that people with obesity are at higher risk for respiratory infections. Similarly, previous research has shown that probiotics reduce upper respiratory infections in healthy adults and children, but little data exist in older or overweight adults.

“These findings add to growing interest in the gut-lung axis—how the gut and the lungs communicate with each other,” Mullish said in the press release. “It’s not just the gut sending out signals that affect how the lungs work. It works in both directions. It adds to the story that changes in the gut microbiome can affect large aspects of our health.”

The investigators did not measure immune response, only respiratory symptoms. Future clinical trials should try to identify the mechanisms related to the reduction of respiratory symptoms and should explore the possible impact of probiotics on the immune system, Mullish said.


Probiotics Associated with Fewer Respiratory Symptoms in Overweight and Older People [news release]. Digestive Disease Week; May 14, 2021. Accessed May 19, 2021.

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