By Ellen Wan
Recent research shows that taking probiotics may reduce the risk of COVID-19 infection and the onset of symptoms in unvaccinated people.
The study, conducted by Duke University and published in Clinical Nutrition in December 2023, included 182 participants. All of them had been in contact with family members who had contracted COVID-19, but the participants had not exhibited symptoms themselves, and none had received the COVID-19 vaccine. The researchers randomly divided participants into two groups, one taking probiotics and the other taking a placebo (control group) for 28 days.
The results revealed that among the 91 individuals in the probiotics group, 24 exhibited symptoms, while in the placebo group of 91 individuals, 39 showed symptoms. This indicated a significantly lower likelihood of developing symptoms in the probiotics group compared to the placebo group. Moreover, the incidence of COVID-19 diagnosis in the probiotics group was 8.8 percent, compared to 15.4 percent in the placebo group. Notably, individuals in the probiotics group experienced a prolonged time to confirmed diagnosis.
The researchers also collected 260 stool samples from 106 participants and analyzed them to assess the gut microbiome. They found that, compared to the control group, individuals in the probiotics group had significantly higher levels of L. rhamnosus (beneficial bacteria for the gut) in their stool samples.
Dr. Paul Wischmeyer, the associate vice chair for clinical research in Duke’s Department of Anesthesiology and the co-lead author of the study, stated in a press release that there was already compelling evidence predating the COVID-19 pandemic demonstrating that probiotics contribute to the prevention of respiratory infections.
He cited a large-scale study on infants in India, published in Nature in 2017, indicating that probiotics can enhance immune function through various mechanisms. These mechanisms include increasing the number of regulatory T cells, reducing pro-inflammatory cytokines, strengthening the protective barrier against lung infections, and modulating antiviral gene expression.
Dr. Wischmeyer added that, although the sample size is limited, this study substantiates the notion that the microbes within the human body can fight the COVID-19 virus and ward against future pandemics.
Probiotics Reduce the Risk of COVID-19 Infection
An earlier study found that probiotics can alter the host’s gut microbiota, produce antiviral metabolites, and interact with the gut-related immune system, enhancing immunity. The immune effects of the gut microbiota, facilitated by the movement of immune cells, can transfer to the lungs, protecting the respiratory system.
This study, which included over 370,000 participants across three countries, revealed that individuals taking probiotics had a 14 percent lower risk of contracting the COVID-19 virus than those not.
The Role of Diet in Cultivating Beneficial Gut Bacteria
In addition to taking probiotic supplements, healthy dietary habits can provide an optimal environment for probiotics. Dr. Hsu-hua Lin, a family physician in Taiwan, stated that cultivating a healthy gut microbiota starts with fundamental practices, including maintaining a balanced diet and regularly consuming foods rich in Lactobacilli, such as yogurt, kimchi, natto, miso, and more. Establishing good sleep patterns, engaging in moderate exercise, and prioritizing stress management are also crucial. Dr. Lin suggests incorporating foods rich in dietary fiber, such as vegetables, fruits, and whole grains, to naturally promote probiotics’ growth and survival.
Ying-Chieh Tsai, a professor at National Yang Ming Chiao Tung University in Taiwan and an expert in probiotics, shared on the “Health 1+1” program that consuming yogurt is the most efficient way to supplement probiotics. A single serving can provide billions of beneficial bacteria. Additionally, moderate kimchi consumption can help increase dietary fiber and oligosaccharide intake. These components, known as prebiotics, serve as food for probiotics, contributing to the optimal growth of beneficial bacteria in the gut.
Moreover, there is a variety of functional probiotic supplements on the market. Mr. Tsai advises consumers to pay attention to the strain of the probiotics and later search online to see if relevant research papers confirm its efficacy.