The link between the gut microbiome and protection against viral infections

There are various protective measures that we can take to improve our immune defences such as eating healthily, getting enough sleep and taking supplements such as vitamins D and C. But did you know that supporting your gut is just as important for your immune system?

Immune defence begins in the gut

The digestive system is home to something called the Gut Associated Lymphoid Tissues or GALT and approximately 60% of the total immune system, and more than 80% of the immunoglobulin (Ig) producing cells, are located within the mucosa of the gastrointestinal tract. In fact, more immunoglobulins are made in the GI tract every day than in the rest of the body combined so it is worth looking after.

The primary purpose of the GALT is to provide a first line of defence against foreign invaders, such as food antigens, pathogenic bacteria, or toxins. When an invader is ingested, the GALT can prevent infection, neutralise viruses, and remove antigens before they cross the mucosal barrier and enter the systemic circulation, leaving them to be excreted directly through the faces. The secondary function of GALT is to begin the systemic (internal) immune response by alerting the rest of the body to the potential threat.

Damage to the gut = Damage to the immune system

This defence mechanism can be affected by a compromised mucosal lining. The mucosal lining can become damaged in the presence of an altered microbiome and altered intestinal permeability (leaky gut), which in turn can be caused by IBS, SIBO, food allergies, or localised gut infections such as parasites or candida, and this can reduce the effectiveness of this system and lead to an increase in infections reaching the internal immune system.

Nourishing the gut

A healthy, balanced gut bacterial environment can help to strengthen immune response, whereas alterations in bacterial balance may increase risk of infection. To achieve balanced gut health, functional medicine suggests a 5R approach of Remove, Replace, Re-innoculate, Repair and Retain.

  • Remove

This is an important first step in the 5R approach.

First, it’s important to remove any infectious organisms such as bacteria and parasites which may be residing in the gut and causing adverse symptoms. A course of broad spectrum herbal anti-microbials including garlic, oregano, grapefruit seed, berberine and caprylic acid is an effective way to do this.

In addition, remove from the diet, any foods which you may be allergic or intolerant to. Common dietary triggers include wheat, gluten and dairy.

  • Replace

For the second step, it’s important to replace key digestive factors that are often low.

The stomach produces hydrochloric acid (HCl), which helps to kill off any harmful bacteria still present in food and also starts the process of digestion by partially breaking down food in the stomach. Stomach production of HCl tends to decrease with age. A supplement containing betaine HCl helps to ensure this process is working effectively.

In addition, gentle plant-based digestive enzymes can be used as a supplement before meals to support the vital digestive process.

  • Re-inoculate

A healthy, diverse population of friendly gut bacteria is vital for health.

It’s important therefore to re-inoculate your gut with plenty of friendly bacteria. This can be done by adding extra fibre (fresh fruits & vegetables) and fermented foods (kefir, sauerkraut & kombucha) into your diet.

In addition, a high strength probiotic supplement that contains extensively researched probiotic strains such as Lactobacillus acidophilus NCFM®, Lactobacillus paracasei lpc-37, Bifidobacterium lactis Bi-07, Bifidobacterium lactis Bi-04 & Saccharomyces Boulardii is recommended.

  • Repair

Often, when digestive factors are low and infectious micro-organisms and/or allergenic foods are present in the diet, the gut wall can become damaged, so the fourth step focuses on essential repair of the gut wall. This is often referred to as a ‘leaky gut’ which can cause more systemic health problems such as food intolerances, inflammatory health problems such as arthritis and eczema and many more.

Important gut repair nutrients include the amino acid L-glutamine and the trace mineral zinc. In addition, antioxidant nutrients such as vitamins B2, C, E, manganese, alpha lipoic acid and green tea extract help to protect the gut lining from further damage.

  • Retain

The fifth step involves making an assessment of what you need to do now to retain your new level of gut health. Some people may continue to avoid wheat, whilst others may continue to take a daily dose of kefir. This is the time to assess where you’re at and build on what you’ve achieved.

A comprehensive powdered supplement that contains a maintenance level of L-glutamine and zinc alongside easy to absorb vitamins, minerals and probiotics is a great maintenance supplement to retain your newly improved gut health.

Can probiotics help?

Working on your gut can be complex and take a while but if you want to get started straight away then consuming fibre from plant foods, taking fermented foods (such as kefir or kombucha) or using a probiotic may be helpful. Research has shown that certain probiotics can have a positive effect on our immune system.

  • Rhinovirus

A 2017 randomised, placebo-controlled study published in Beneficial Microbes was carried out to determine the effects of supplementation with Bifidobacterium lactis Bi-04 on innate and adaptive host responses to experimental rhinovirus challenge. The results suggest that ingestion of Bifidobacterium lactis Bi-04 can modify the inflammatory response to rhinovirus infection. There also appears to be an effect on rhinovirus replication manifest by decreased shedding of virus in the nasal secretions.

  • Respiratory infections

A 2014 randomised, double-blind, placebo-controlled study was carried out on 465 healthy participants who exercise regularly. This particular group was selected because regular significant exercise is known to stress the immune system. Australian researchers compared the effects of supplementation with either a probiotic containing B. lactis Bi-04 alone (Group 1), a blend of L. acidophilus NCFM® & B. lactis Bi-07 (Group 2) or placebo (Group 3) over 5 months. Over the 5 month-study period, researchers found that Group 1 had a 27% lower incidence of upper respiratory infections and Group 2 had a decreased incidence of infections (although the beneficial effects were not as pronounced as Group 1). The researchers noted however that Group 2 in particular undertook considerably more physical activity than the placebo group which may have influenced the results. Overall, the results showed that probiotic supplementation, especially with B. lactis Bi-04, improved immunity compared to placebo.

  • Colds and flu

To test the efficacy of probiotics for preventing colds and flu, and to identify possible synergy amongst probiotic strains, a total of 326 children aged between 3–5 years were randomly divided into 3 groups. Group 1 received placebo, group 2 were given L. acidophilus NCFM® and group 3 received a blend of L. acidophilus NCFM® & B. lactis Bi-07. Over a period of six months, results showed that probiotic supplementation significantly reduced incidence of fever, rhinorrhoea, cough incidence, duration & antibiotic prescription incidence and the number of missed school days attributable to illness. L. acidophilus NCFM® alone was effective, however, a broader protective effect was observed with the combination of L. acidophilus NCFM® and B. lactis Bi-07.

  • Vaccine efficacy

In a 2008 randomised, placebo-controlled study published in FEMS Immunology & Medical Microbiology, researchers evaluated the immunomodulatory properties of a blend of probiotic strains on 83 healthy volunteers aged 18 – 62 years given an oral cholera vaccine. Included in the seven strains were B. lactis Bi-04, B. lactis Bi-07, Lactobacillus acidophilus NCFM® and Lactobacillus paracasei Lpc-37. Results showed that specific strains of probiotics may act as adjuvants to the humoral response following oral vaccination.



Stellapharm is one of leading generics pharmaceutical companies and strong producer of anti-viral drugs in Vietnam. The company established in Vietnam in 2000; and focuses on both prescription drugs and non-prescription especially in cardiovascular diseases, antiviral drugs, anti-diabetics drugs, etc. and our products are now used by millions of patients in more than 50 countries worldwide.

The company is globally recognized for its quality through our facilities have been audited and approved by stringent authority like EMA, PMDA, Taiwan GMP, local WHO and others.

Additional information for this article: Stellapharm J.V. Co., Ltd. – Branch 1
A: 40 Tu Do Avenue, Vietnam – Singapore Industrial Park, An Phu Ward, Thuan An City, Binh Duong Province, Vietnam
T: +84 274 376 7470 | F: +84 274 376 7469 | E: | W:

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