When our daughter Katyayani was but a 7 day-old infant, she had a bout of non-stop diarrhoea and became dehydrated. Her paediatrician, Dr Chikarmane, not only put her on intravenous feed but also had her stools examined and found her stomach infected ( in utero ) with the pathogen E. hist . After getting rid of it using antibiotics, he re-colonized her stomach with lactobacillus, the microbe that helps in digesting milk.
Presence of mind
Thanks to his expertise and presence of mind, Katya was saved and in a few weeks became (and continues to be) a healthy and cheerful girl.
This episode brought home the point that the gut of a newborn baby is sterile at birth, and becomes colonized with microbes, some good and needed and some harmful and pathogenic. What Dr. Chikarmane did was to get rid of the pathogen and colonize the baby's gut with the helpful one. In doing so, he was repeating what the Russian Scientist Ilya Mechnikov did in 1905.
Mechnikov showed that eating curd is very healthy, since it introduces helpful bacteria like lactobacillus , and bifidia . He called fermented milk as a pro-biotic, a food that contains organisms which help the host body digest food, gain immunity and lengthen life. For this path- breaking discovery, Mechnikov shared the Nobel Prize in 1908.
We have since come to realize that the human gut (gastro-intestinal or GI tract) is teeming with microbes. Current estimates put the number as 10{+1}{+4} or 100 trillion. This number is at least 10 times more than the total number of cells that our own body has! In other words, 90 per cent of the total cells contained in each of us are actually bacterial cells — 500 different varieties of them living in a stable, nutrient- rich medium.
While the GI tract of the new born is pretty much sterile, it gradually acquires these microbial populations postnatally, through contact with the environment, type of feeding, hygiene levels and so on. The human gut is thus an ecosystem, containing the genomes of all these gut microbes or microbiome .
Why are they there? Are they helpful, harmful or freeloaders? We are getting answers to these questions only during the last decade or so. These extra genes from the microbiome endow us with functional features that we have not had to evolve ourselves.
In other words, we humans have been co-evolving with them. Consider this in another way, in the language of computers. Recall the situation twenty years ago what our computer scientists did when the US refused to sell India supercomputers. We put together a network of several computers, each doing what it was designed to do job, interacting and collaborating with others in the network, and processing in parallel such that the entire system became a supercomputer called PARAM.
Hardwired in genome
Many functions that we are not hardwired in our genome to perform we get sharing from a member of the neighbouring microbiome, each doing its job in parallel and contributing to the whole ecosystem.
Or is it the other way around? Each species which has colonized our gut downloads programs from our genome? Either way, the relationship is mutual; each party benefits from the other. Molecules that we produce through digestion of our food turn out to be useful for the growth and sustenance of the gut bacteria, and molecules that they produce through their metabolism are helpful for us.
Curd is one such example. Molecules in it, produced by microbial digestion of milk, such as lactic and other related ones help us in our growth, even as these microbes feed on the products that we make. Dietary fibres are another outstanding example.
When we eat cereals and lentils (rice, wheat, barley, various grams and lentils), we do not digest all their contents. Some indigestible starch remains. It is these that our gut microbes feast and forage on. And what they produce upon metabolizing this resistant starch is useful for us.
Probiotics, prebiotics
We call these organisms, and/or their molecules, as probiotics and prebiotics. The microbes are called probiotics, and the indigestible (to us) material that they feed on is the prebiotic. Prebiotics are nonliving material such as starch or husk, while probiotics are live organisms. (And biotic means relating to, produced by, or caused by living organisms).
Without them, we cannot make some essential nutrients such as vitamin K, or metabolize bile acids, cholesterol and some short chain fatty acids. They also help us in fighting pathogenic bacteria and viruses — a case of internal colonizers acting as defending soldiers against alien invaders.
Readable article
What diet you eat thus becomes important. Indian food, from the Indus Valley days, always had millets, grams and lentils. A readable article on prebiotics in ancient Indian diets, ( >Prebiotics in ancient Indian diets ) written by Drs. A.K Sarmanta, A.P. Kolte, S. Senani, M. Sridhar and N. Jayapal, appears in the 10 July issue of Current Science .
As they write, prebiotics have been with us for long and their beneficial effects are not only limited to the gastrointestinal ecology, but also in physiological processes like immune modulation, blood cholesterol regulation and bone mineralization.
And this is exactly what Dr Chikarmane did to Katya. Hence too the wisdom in the exhortation “eat more fibre”. You not only help your gut microbiome but yourself.
dbala@lvpei.org
