BY ASHFAQ AHMAD SHAH
Man is not alone but accompanied by at least 100 trillion bacterial cells and other microorganisms including virus, protozoa, fungi, archaea and yeasts on and inside the body that without pathological conditions inhibit the anatomical sites of body normally. Such microbial population is thus termed normal human microbiota or human microbiome. These microorganisms colonize our gut, mouth, skin, genital parts etc. The gut contains the largest, densest, and most diverse microbial community in the human body. In fact, it is colonized by 1014 microbes, ten times more than the human cells. The number of genes in all the microbes in one person’s microbiome in 200 times the number of genes in the human genome. The human gut microbiota goes through a number of development stages until it is finally shaped. First, the fetus is colonized in uteri by the bacteria coming from maternal sources, including the intestines, oral cavity and vagina. Second, when going through the birth canal, the baby picks up other lot of its mother’s microbes. Breast milk is also not sterile and contains substantial amounts of bacteria, such as Streptococcus, Staphylococcus, Propionibacterium, and Bifidobacterium. Then diet regulate their composition throughout the life.
The role of the gut microbiota in pathology has been increasingly hypothesized, and the evidence to support those theories is growing considerably. The gut microbiota plays a cardinal role in protecting the intestine from pathogen dissemination through competition for nutrients and receptor engagements, a process called “Colonization resistance”. Another mechanism of colonization resistance is mediated by special antimicrobial proteins and peptides, the so-called bacteriocins, produced by the gut microbiota which have inhibiting effects on other pathogenic strains. In this way they act as first line of defense against invading pathogenic microbes. In the healthy state, the gut micro biota has myriad of positive functions such as supplying essential nutrients, producing vitamins, regulating our immune system, metabolizing xenobiotic substances, energy recovery from metabolism of non-digestible components of food like cellulose, promoting enteric nerve function etc. Some microbes of these populations have an effect on enhanced metabolism, cancer resistance, endocrine signaling, and brain function of the individual. They produce B vitamins including, thiamine, riboflavin, and vitamin k which is needed for metabolism. Now-a-days it is being proposed that autoimmune disease such as diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerotic and fibromyalgia are associated with dysfunction in the microbiome. Gut bacteria play an important immunoregulatory activities for pathogenesis of these diseases. When the gut microflora undergoes some imbalance, some diseases may occur, such as obesity, diabetes, carcinoma, abdominal infections, urinary tract infections, irritable bowel syndrome, inflammatory bowel diseases and behavior related disorders like autism, depression etc. Recent findings underline the crucial role of gut microbiota in the pathophysiology of depression. Depression is strongly associated with the gut microbiome in terms of its richness and biodiversity. The gut microbiome interacts with the brain via neuroimmune system, neuroendocrine system, autonomic nervous system, enteric nervous system which in total is described as Gut Brain Axis. Antibiotics which although have brought a dynamic change in medicine, may also increase the susceptibility towards depression by killing some beneficial microbes along with pathogens. Chronic stress induces dysfunction of gut brain axis resulting into decreased levels of hippocampus 5-HT content and disturbed gut microbiota in turn leading to depression. Traditionally antidepressant therapies target alleviation of brain abnormalities while gut brain axis dysfunction was ignored but the recent findings have induced a paradigm shift in the Major Depressive Disorder treatment approaches. In cases of severe MDD wherein the use of conventional antidepressants like Selective Serotonin Uptake Inhibitors, Tricyclic Antidepressants, Serotonin Norepinephrine Reuptake Inhibitors is utmost essential, combination of Probiotics along with these antidepressants may give better results.
Therefore, understanding how to manipulate the gut microbiota for a better health can be of immense use in treating infections, gut problems and other disorders. On our side there is an utmost need to take care of these benign microbes in such a way that their composition remains unchanged. The main reasons for this bacterial composition disturbance can be anything from illness, aging, bad dietary habits and lifestyle, to antibiotic usage. Heavy antibiotic use can cause dysbiosis (microbial imbalance) in the gut and hence, influence the overall health of that individual. It is possible to some extent to revert their natural composition by taking supplementary prebiotics and probiotics. Intake of prebiotics is known to stimulate growth and/or bacterial activity in the gut. The term “Probiotic” is the name given to live microorganisms which when administered in adequate amounts confer a health benefits on host. Some probiotic preparations are used to prevent diarrhea caused by antibiotics, or as part of the treatment for antibiotic-related dysbiosis. Several studies have confirmed probiotic effects on a variety of gastrointestinal disorders, including inflammatory bowel disease (IBD), Irritable bowel syndrome (IBS), and immune enhancement. Probiotics have also been thoroughly studied in relation with allergies like atopic eczema and other hypersensitivities. Probiotics have been in use for the benefit of humans since the time of consumption of fermented milk and milk products. Fermented milk products have been conventionally considered as the most excellent carriers for probiotics; however, the use of milk-based products may be also limited by lactose-intolerance, allergies, dyslipidemia and vegetarianism. Nowadays, a number of raw materials are available which can be explored as substrates to produce novel non-dairy functional foods. They may also be found in plant-based foods. As compare to traditional nutritional foods Probiotics can be considered as potential functional foods and exert more health benefits. Food and beverage manufacturers are looking to incorporate probiotic into all types of food groups. Diverse food innovations are possible through manipulations of synergies between probiotic strains and the component present in the food.
Ashfaq Ahmad Shah is Doctoral Researcher, Infection Immunity, Graphic Era University, Uk, India, can be reached at dr.ashfaq.ah.shah@gmail.com
