In recent times, the importance of immunity is being highlighted several times than probably in the last few decades. With the onset of the COVID 19 pandemic, the searches on google for immunity boosters and supplements to boost immunity rose by 90% in the month of March 2020 vs that in December 2019. It was this pandemic that brought the attention of people from ‘’ “Cure” to “prevent,” i.e. the ‘inner ability to fight a disease’-IMMUNITY.
Various opinions are expressed for improving immunity. Along with lifestyle improvements such as exercise, meditation, washing hands frequently, and good quality sleep for seven to eight hours per day, the focus is on supplements such as zinc, selenium, vitamin C, D as well as herbal concoctions consisting of numerous ingredients with and without scientific data.
Zinc: This micronutrient has been investigated for its impact on the duration of common cold, where it was concluded that supplementation of more than 75 mg of zinc per day reduced the duration of the cold by 33%.ii
Vitamin C: There are several studies conducted globally in last several decades on the benefit of Vitamin C. The most recent one demonstrated the reduction of the duration of the cold by 8% in adults and 14% in children with supplementation of 1,000–2,000 mg of vitamin C per day in a study that reviewed over 11,000 people.
Selenium: This essential micronutrient works by reducing the oxidative stress in the body, which helps enhance immunity.
Vitamin D: Vitamin D deficiency has been associated with increased risk for infections , so this supplement has caught attention in the last decade.
But one cannot forget that immunity lies within our body, and recent research has proven that this can only be enhanced with food-based strategies that can manipulate it to advantage.
Immunity and the Gut
Recent scientific studies state that 70% of the cells that make up our immune system are housed in the gut, and that the gut microbiome has a vital role in the improvement and maintenance of immunity. As the gastrointestinal microbiome is becoming more and more explored, the outlook towards immunity is undergoing a paradigm shift.
The microbiota is a multispecies microbial community living in synergy with the host and displays an enormous diversity. It is shaped by numerous factors, such as host genetics, gender, age, immune system, disease condition, geographic and socio-economic factors, medication usage, diet, etc. ,
One of the roles of the gastrointestinal microbiota is to develop the non-specific and specific immune system components throughout life. It acts as a barrier by inhibiting the adherence of pathogens, subsequent cellular colonization and by the production of bacteriocins and other toxic metabolites. Some gastrointestinal micro-organisms can also synthesize vitamins, such as B1, B2, B5, B6, B12, K, folic acid, and biotin, which also contribute to health.
Gut epithelial cells act as microbial sensors in response to bacterial entry and try to evade them by secreting factors such as IL-8, MCP-1, RANTES, TNF alpha and IL-6. This leads to the recruitment of neutrophils, monocytes, macrophages and T cells. ,
Risk and progression of infections
Imbalance in the gut microbiota may contribute to development of various diseases.
Pathogenic organisms use signals from the host gut flora to spread and accelerate the process of infection. Evidence from numerous studies has established the crucial role for the gut microbiome in immune responsiveness, , , as well as the pathogenesis of the diseases, with primary involvement outside of the gut, such as respiratory, hepatic and autoimmune conditions.
Gut microbiota could also have distal protective effects. There is evidence of the role of inflammasome activation in the immune defence against influenza virus infection; , it induces dendritic cell migration to the local lymph node to stimulate an influenza-specific T-cell response in the lung. , The commensal gut microbiota regulates the immunity of the respiratory mucosa against respiratory influenza virus through IgA secretion, and the proper activation of inflammasomes, Th1 cells, and CTLs, and through the upregulation of TLR7 signalling in the respiratory mucosa.xxii,
Can positive manipulation in the gut microbiome improve immunity?
Manipulation of the gut microbiota for healthy living dates back thousands of years ago to Ayurveda which advocated the daily consumption of buttermilk and yoghurt.
Probiotics have been shown to be an important means for microbiota regulation to prevent and control infectious diseases. Probiotic bacteria, particularly the Lactobacillus and Bifidobacterium species have been shown to reduce the severity of GI episodes as well as respiratory tract infections. However, therapeutic benefits of probiotics have been found to be highly strain-specific.
Hence, modification of the gut microbiota within the colon through supplementation of prebiotics can be a promising strategy to improve immunity.
The Prebiotic effect
Prebiotics like FOS and GOS are fermented by probiotics, mainly bifidobacteria and lactobacilli. This increases the intestinal levels of SCFAs, especially butyrate, which have been shown to confer immune-modulating effects helping in the prevention of age-related diseases such as C. difficile-associated diarrhoea, and common respiratory and gastrointestinal infections , . There is evidence to show the improvement of antibody response to influenza vaccine following FOS consumption, along with reduction in the side effects of the influenza vaccine. ,
A three week administration of FOS, 8g daily to frail elderly subjects in a nursing home, resulted in an increase in the numbers of faecal bifidobacteria and that was accompanied by considerable rises in counts of total lymphocytes, CD4+ and CD8+ cells, indicating a beneficial effect on immunity.
In summary, prebiotics are food for the good bacteria in the gut, that help increase the population of probiotic bacteria. And there is convincing preliminary data to suggest that the consumption of prebiotic fibres can modulate the immune parameters in GALT, secondary lymphoid tissues and peripheral circulation.
The future of immune modulation for health benefits may be quite different as more studies are conducted and evidence gathered. Using food to shape health is now becoming a reality. Are we now proving what ancient knowledge stated thousands of years ago?
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Strengthen Your Immune System With 4 Simple Strategies. Available at: https://health.clevelandclinic.org/strengthen-your-immune-system-with-simple-strategies/; as accessed on September 5, 2020.
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