Can probiotics help us fight the coronavirus disease?

The coronavirus disease (Covid-19) has affected more than 2.4 million people across 185 countries. It infects the lungs and airways, causing acute respiratory infection. An inflammation in the lungs results in pneumonia, and at times leads to a fatal overreaction of the body’s immune system called cytokine storm syndrome. The good news is that among the asymptomatic cases which tested positive for Covid-19, many could successfully fight the infection. This speaks a lot for our immune system and its ability to protect us. And that’s where our hopes lie.

To fight the coronavirus disease, there are several classes of drugs under development, including antivirals, immunotherapies and vaccinations. Developing a vaccine is, however, a lengthy process as it requires rigorous assessment to ensure both safety and efficacy. Medications that have been tapped for Covid-19’s treatment include hydroxychloroquine, an anti-malarial drug, and azithromycin, a combination of anti-HIV drugs, remdesivir, which was earlier used to treat the 2014 ebola outbreak. However, they require more data and scientific validation for improving clinical outcomes. A commentary published in Lancet claims that steroids provide little benefit to Covid-19 patients, and, in some cases, may do more harm than good.

A landmark study published earlier this year in Nature Medicine by researchers at the Peter Doherty Institute for Infection and Immunity (Doherty Institute), Australia, showed that the immune system may play a vital role in deciding the course of the disease. This was observed when a 47-year-old woman from Wuhan travelling to Australia with a non-severe case of Covid-19 recovered rather quickly, without experiencing any complications such as respiratory failure or acute respiratory distress, highlighting the role of the immune system.

But even a strong immune system needs support to constantly fight infection and the onslaught of harmful viruses, bacteria and toxins. To keep its function optimal, it needs immune-boosting nutrients, physical activity, adequate hydration and good quality sleep. Another important way of building immunity against Covid-19 is to maintain intestinal health, because more than half the body’s immune system sits in the intestine.

One obvious way of improving the intestinal health is to ensure a constant supply of beneficial microbes, which helps maintain a balance among the trillions of bacteria integral to the intestine. Besides boosting the body’s immune response, they also strengthen the innate and acquired immunity, help maintain overall health, and aid the fight against infection.

It was observed that some of the Covid-19 patients in Wuhan had atypical gastrointestinal symptoms, and the virus was also detected in some of the faecal samples, suggesting a link between the intestine and Covid-19. This begs a question: Can probiotics help fight against the coronavirus disease?

A systemic review and meta-analysis of 20 clinical trials across the world found that probiotics lower inflammation, specifically the inflammatory marker C-reactive protein. A Cochrane review of 12 studies – based on a sample of 3,720 children, adults and elderly – suggested that probiotic consumption may be associated with fewer people suffering from upper respiratory tract infections and a lower incidence of the infection. Dr Irene Lenoir-Wijnkoop, senior scientist at Utrecht University in the Netherlands, has observed that probiotic use could save health care costs and productivity loss due to acute respiratory tract infections.

However, probiotic benefits are strain-specific, and it is important to identify the strain of bacteria that is scientifically proven for the benefit. Some strains of Lactobacillus gasseri, Bifidobacterium longum and Lactobacillus casei strain Shirota have been shown to boost immunity and reduce the incidence of upper respiratory tract infections or common cold and flu.

China’s National Health Commission and National Administration of Traditional Chinese Medicine have used probiotics along with conventional treatment in patients with Covid-19 infection for improving the balance of the intestinal flora and preventing secondary bacterial infections.

The way science works, we are still not sure of a clear benefit of probiotics in Covid-19 patients. But as most of our immunity resides in the intestine – which is determined by the kind of bacteria present there – it may be worthwhile to ensure a balanced intestinal flora. It could well be our best bet to fight Covid-19.

Dr Neerja Hajela is secretary, and NK Ganguly is president, Gut Microbiota and Probiotic Science Foundation

The views expressed are personal