Impact of Dietary Supplementation with Haritaki - Terminalia chebula Retz. (Combretaceae) and Amalaki - Phyllanthus emblica L. (Phyllanthaceae) on Human Gut Microbiota: A Comparative Study

The gastrointestinal (GI) system plays a crucial role in systemic health, with gut microbiota influencing immunity, digestion, and metabolic functions. Ayurveda emphasises digestive health through botanicals like Haritaki - Terminalia chebula Retz. (Combretaceae) and Amalaki - Phyllanthus emblica L. (Phyllanthaceae), traditionally used to promote gut balance. This study aimed to evaluate the impact of Haritaki and Amalaki supplementation on gut microbiota composition in healthy elderly volunteers over an 8-week period. A randomised, open-labelled, controlled experimental study was conducted at Dr. D.Y. Patil College of Ayurved and Research Centre, Pune, involving 30 participants aged ≥ 60 years. Participants were assigned to two groups: Haritaki (Group A, n=15) and Amalaki (Group B, n=15), receiving 2 grams of the respective herbal powder twice daily with lukewarm water. Stool samples were analysed pre- and post-intervention using 16S metagenomic sequencing to assess microbial diversity and composition. Results demonstrated distinct microbial shifts. Haritaki reduced Firmicutes and Bacteroidetes while increasing Actinobacteria, enhancing microbial stability and immune modulation. Conversely, Amalaki increased Bacteroidetes and fibre-fermenting genera while reducing Firmicutes, promoting microbial diversity and metabolic balance. Both interventions optimised short-chain fatty acid (SCFA) production without inducing dysbiosis. These findings support the Ayurveda's use of Haritaki and Amalaki in gut health, revealing their potential as microbiome modulators. Future studies should explore their long-term clinical applications and molecular mechanisms using functional metagenomics and metabolomics.