New Delhi: Feeding a baby born by caesarean-section milk containing a tiny bit of the mother’s faeces may provide beneficial microbes to their gut, a new clinical trial has found. The trial was conducted in Finland and reported in the journal Nature this week.
The trial, scientists from Finland have noted, suggests that the approach might one day help to prevent diseases during childhood and later in life in kids born through C-section, while also aiding the mounting evidence establishing a connection between gut health and immunity.
Over the last few years, a number of researchers from top universities have generated molecular proofs of the centuries-old concept of “you are what you eat”, demonstrating how diet ultimately affects immunity through the gut microbiome.
In 2021, for instance, a research paper by top scientists from the US, Australia and South Korea offered a unifying explanation for the complex interplay between diet, gut microbiota and immune function.
The experiments carried out as part of their research identified a microbial molecule, the synthesis and release of which are influenced by host diet. The molecule, in turn, stimulates the activation and signalling of a subset of cells known as natural killer-T cells—which are involved in immune regulation and implicated in a number of inflammatory conditions.
Since then, a number of studies have come out and thrown up crucial evidence demonstrating light the complex interplay between diet, gut microbiota and immune function.
As our understanding of the relationship between gut health and immunity has, quite dramatically, changed in recent years, experts say it has become theoretically feasible to understand its critical function in digestion and metabolism, even mood regulation, upon realisation of the trillions of microorganisms which constitute the gut microbiome.
“Diseases associated with modern lifestyles, like a number of allergies, autoimmune conditions, metabolic diseases and cancers, in fact, are—as expected—revealing the most striking relationships with gut bugs,” Dr Dipyaman Ganguly, physician-scientist, immunologist and cell-biologist told ThePrint.
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How gut bacteria work
Ganguly, who is associated with the Council of Scientific & Industrial Research-Indian Institute of Chemical Biology, pointed out that commensal bacteria—beneficial organisms that live on or inside the body and have a neutral relationship with the host—have not started inhabiting us after we knew about them but have been there all along.
In fact, they have been there within the first members of the homo sapiens, perhaps a lot of them got carried over from earlier related species as well and from the hunter-foragers, through the first agriculturists and came to the post-industrial revolution modern human beings.
Research studies have shown that gut-resident microbes produce molecules with enormous structural diversity. As part of some experiments, scientists used microbial and chemical tools to elucidate how these molecules are synthesised by gut bacteria and how they act in the host gut.
The human gut microbiota includes bacteria, yeast, viruses and parasites, yielding around 100 trillion microorganisms in total.
At birth, the human gut is almost sterile, and gets rapidly colonised by the mother microbiome, pointed out gastroenterologist and medical researcher Dr Rajeev Jayadevan.
The composition of the healthy gut microbiota is dominated for up to 90 percent by certain categories of bacteria, most well-known of which are lactobacillus, bacillus, enterococcus, ruminococcus and clostridium.
Gut microbiota is a dynamic ecosystem, which is influenced by several factors, including age, genetics, environment, lifestyle—but mainly diet.
As dietary habits are likely to differ according to geographical factors, this variability can also be seen reflected on the microbiota of different populations.
And while different compositions of diet can lead to changes of microbiota profiles, an unbalanced diet consumed over a period of time accompanied by an unhealthy lifestyle can leave traces of evidence on the microbiota as well.
Generally, people with obesity and those overweight, for instance, tend to show a lower diversity of gut microbiome.
Dr Deep Goel, principal director and head of surgical gastroenterology at BLK-MAX Super Speciality Hospital in Delhi, underlined that our understanding of gut health has shifted from primary driver of digestion to recognising the gut as central to immunity and overall well-being.
“Discovering the gut microbiome revealed its role in regulating immune responses through the gut-immune axis, where 70 percent of the immune system is controlled,” he said.
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Effect on inflammation
Inflammation is the body’s response to an illness, injury or something that doesn’t belong in the body, such as germs or toxic chemicals—it is a normal and important process that allows the body to heal.
However, chronic inflammation—which has now been established to have a link with our dietary choices apart from some autoimmune disorders—happens when the body continues sending inflammatory cells even when there’s no danger.
With chronic inflammation, processes that normally protect the body end up damaging it, and it can last for months or years.
Now, scientists have been able to successfully test different configurations of the microbe-made immunomodulatory molecules—which act on the pathways that regulate the immune system’s activity—to determine how each one interacts with the immune cells that regulate inflammation.
In the study cited earlier, synthetic, lab-made branched-chain lipid molecules induced T-cells to release the immune-signalling chemical IL-2, whereas the lab-made straight-chained versions of these molecules did not.
Thus activated, the T cells, in turn, induced the expression of genes that regulate immunity but not of genes that drive inflammation. This demonstrated the significance of certain food molecules on key immunity cells.
“This realisation should make us appreciate how, in human physiology, different organs and systems work and have actually evolved together with the bugs in our guts,” Ganguly said, adding that bugs formed molecules that affected human tissues, and some, if not most of them, became dependent on such interactions.
Cells of the immune system are no exceptions, he said.
“Recent studies are revealing such interactions in great detail and we are getting a rather unappreciated holistic picture of our bodily functions,” he underlined.
Relationship with diseases
Several approaches have been used to demonstrate that signals derived from gut microbiota are critical for the development of the immune system.
Among them, germ-free (GF) models, where animals are reared in a sterile environment and have never been exposed to any microorganisms, are a powerful approach that reveals the importance of the microbiota in shaping both innate and adaptive immunity.
Similarly, the manipulation of microbiota, either with antibiotic treatment or microbiota reconstitution, also provides key evidence of the role of the microbiota in immune homeostasis.
As life expectancy is increasing, a number of age-related diseases are also being more prevalent, and they also show intricate dysregulations in gut bug consortia associated with them.
Immune cells that have normative interactions with gut bugs in a healthy individual also start functioning poorly as and when such interactions break down, affecting how they respond to infections, either resulting in undesired inaction or inadvertent hyperactivity, Ganguly underlined.
According to Dr Imran Shaikh, consultant gastroenterological surgeon at Wockhardt Hospitals in Mumbai, dysbiosis, or the imbalance of gut bacteria, may lead to inflammation and immunological dysregulation.
A number of chronic diseases that have been linked to dysbiosis include obesity, diabetes, inflammatory bowel diseases and even cancers, and as gut bacteria may actually create neurotransmitters that govern mood and other cognitive functions, the gut-brain axis even emphasises the link between gut health and mental well-being, he stressed.
Shaikh added that the need for prebiotics, a type of fibre which is good for the growth of helpful gut bacteria, and probiotics is now felt as we understand how they are crucial to nurture a healthy gut microbiome.
Services promoting gut health
A number of companies, including quite a few in India, now offer advanced services to promote gut health, using personalised microbiome analysis and targeted nutritional interventions.
At the core of the approach of Leucine Rich Bio, which calls itself South Asia’s first microbiome company, is BugSpeaks, a proprietary test that assesses the unique microbial composition of an individual’s gut.
This analysis, said Dr Debojyoti Dhar, co-founder and director of the company, helps identify imbalances and specific needs, enabling the recommendation of tailored dietary adjustments along with personalised prebiotic and probiotic regimens for optimal gut health.
“The outcomes from our services address a variety of health concerns, from improved digestion and enhanced immunity to reduced symptoms of conditions like irritable bowel syndrome and metabolic disorders,” Dhar told ThePrint.
He also claimed that many clients report higher energy levels, mental clarity and an overall sense of well-being, and additionally the solutions offered support gut-brain health, positively impacting mood and cognitive function.
“With a focus on sustainable health benefits, our science-driven interventions empower clients to achieve lasting improvements in their gut health and quality of life,” he asserted.
Independent experts, too, said such services could be useful. “Services to promote the microbiome such as supplements and testing of the microbiome could be useful, but their efficacy is different. Many studies promote the use of probiotics to restore balance in the microbiome, especially after antibiotics, whereas prebiotics feeds the good bacteria,” said Shaikh.
New personalised services testing for specific microbiomes are starting to be offered, which allow tailored recommendations to each individual’s gut profile, optimising gut health. Not all probiotics are equal, and it is really important to have high-quality ones, he added.
Shaikh also emphasised that a healthy gut can lead to enhanced immunity, good digestion, improved mood and effective weight management.
“Overall, integrating microbiome improvement services into a holistic approach towards overall health and wellness can lead to the best results,” he said.
(Edited by Nida Fatima Siddiqui)
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