Ayurvedic therapies with influence on the microbiome »

The microbiome is a term that describes the genome of all the microorganisms, symbiotic and pathogenic, living in and on all vertebrates. The gut microbiome is comprised of the collective genome of microbes inhabiting the gut including bacteria, archaea, viruses, and fungi. Information about these microbes living in our guts is growing at a tremendous rate. Till recently, heterogeneity among human populations was attributed to various allelic forms of genes. The human intestine harbors trillions of bacteria which constitute more genomes than all the human cells in the body. The distribution of microbes is spatial in the gut, with the colon containing the largest diversity and abundance of microorganisms. The colon also harbors more aerobes than the small intestine, owing to its proximity to the environment. Due to the anaerobic nature of the majority of commensals, especially in the upper gut, it has been difficult to culture them. Advances in omics-based approaches have helped further the understanding of the intestinal ecosystem and the multitude of factors that impact its microbial composition. This technology has opened many areas of research focused on the role of intestinal microbiota in immune system homeostasis that impacts health and disease.

Studies have revealed that the dominant phyla in humans include Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria, with the intestine being dominated by Firmicutes and Bacteroidetes. The colonization of the intestine begins at birth and has been shown to be influenced by vaginal or C-section birth. However, the microbiota changes with exposure to various environmental factors during maturation. Much like a genetic imprint of an individual, each individual has a unique microbiota, though approximately one-third of the species are common across most humans. Many factors influence intestinal microbiota including hygiene, diet, geographical locations, and host genotype. In addition, studies in humans and animals have suggested the role of sex hormones and age in determining intestinal microbial composition. Humans have coevolved with the commensals and maintain a symbiotic relationship. Intestinal microbes out-compete the pathogens and maintain the integrity of the epithelium which may be a key factor in preventing inflammation. Diverse microbial communities are essential for maintaining the intestinal ecosystem and play a vital role in harvesting energy from foods and producing micronutrients. In return the microbes receive food and a suitable environment for growth.

A very interesting discussion is found on pathogenic organisms in one of the chapters of the Caraka Samhita, an authoritative text book on general medicine in Ayurveda. The text classifies organisms into normal (sahaja) and the pathogenic or invaders (a–gantu). It is interesting to note that Ayurveda recognised the existence of non-pathogenic organisms that naturally inhabit the human body. However, the specific functions of these non-pathogenic organisms have not been elaborately discussed.

In his commentary on the Susruta Samhita, Dalhana mentions that the pathogens are innumerable and the twenty types mentioned in the texts are categories that can include the rest.

In his commentary on the Astanga Hridaya, Arunadatta clarifies that the pathogens of the blood are indeed totally invisible to the human eye and are therefore microscopic. He adds that their existence can be only inferred. This is a very clear statement of the existence of microscopic life and a piece of strong evidence to suppose that ancient Ayurvedic physicians were aware of microscopic life albeit they could not study it in sufficient detail.

The following points from Ayurvedic texts are significant in the context of the microbiome:

1. Ayurveda recognized the existence of microscopic organisms.
2. Ayurveda acknowledged the innumerability of such organisms.
3. Ayurveda pointed out that all such organisms are not pathogenic and there are organisms that naturally inhabit the human body without causing disease.

However, we do not have elaborate descriptions in Ayurvedic texts about the role of the microbiome and the effect of the various treatments on the microbiome. It would be preposterous to claim that Ayurveda already had detailed knowledge of the microbiome for many thousands of years. On the other hand, it is very likely that Ayurvedic treatments have a favorable effect on the microbiome and with the knowledge available today, it would be possible to study these effects.

For example, we know today that our hectic 21st-century Western lifestyle can affect our microbiome health. Stress lowers the number of beneficial Lactobacillus bacteria. Processed and low-fiber foods alter our gut microbiota, as does a lack of exercise. Ayurveda advises a healthy lifestyle and diet that is customized according to the constitution of each individual. There are also many formulations prescribed in Ayurveda for improving the gut health and immunity of the individual. These medications could have an impact on the microbiome.

Modern research is pointing to the possibility of Parkinson’s disease originating from the gut rather than the brain. Studies have also shown that the gut microbiome is altered in Parkinson’s patients. Ayurvedic management for Parkinson’s disease includes treatments that target the gut. It is likely that the positive effects seen with Ayurvedic treatments for Parkinson’s disease could be due to changes in the microbiome.

Researchers have reported that three main Prakriti types, Vata, Pitta, or Kapha, have a unique microbiome composition. The extreme Pitta individuals, for example, had more butyrate-producing microbes which might help protect them from inflammatory diseases. The extreme Kapha women had larger amounts of a type of bacteria called Prevotella copri, which has been associated with patients who have rheumatoid arthritis and insulin resistance. The study by Shalin et al showed that though the core microbiome was shared across all individuals, prakriti specific signatures such as preferential presence of Paraprevotella and Christensenellaceae in vata individuals were observed.

Apoorva Jnana et al points out that prakriti phenotyping can function as a potential stratifier of the gut microbiome in a given population and may provide evidence for the conceptual framework of personalized medicine in Ayurvedic system of medicine.

The gut microbiota can metabolize herbal medicines to produce new absorbable active small molecules which have active pharmacological effects. This means that microbiota is part of the Agni System of Ayurveda which aids in proper digestion. Also, herbal medicines can regulate the composition of gut microbiota and its secretions, then changed gut microbiota and its secretions play a therapeutic role.

Certain herbs can promote beneficial gut microbiota growth and inhibit the growth of harmful organisms.

Thus there is a lot of scope for studying Ayurvedic treatments and their effects on the microbiome by combining Ayurvedic knowledge with modern techniques of research.

We can say that the existence of microbiome was hinted in the early Ayurvedic texts and the Ayurvedic lifestyle, diet and treatment may have an effect on microbiome. With modern advancement of scientific knowledge of the microbiome, it becomes possible to study the effects of Ayurvedic treatments on the microbiome to prevent and treat diseases.