The effects of herbal teas and supplements on the human microbiota and metabolism

Okeyoyin, Oluwadamilola Racheal; Adukwu, Emmanuel; Gould, Oliver

Abstract

Background: For centuries, herbal teas have been consumed by people of all ages and has been used for therapy in different civilisations and medical systems such as the Chinese, Indian, indigenous, and African. The aphorism- ‘Nature is the best chemist’ has a long historical pedigree and it is believed that bioactive compounds- phytochemicals contained in herbal teas have a wide range of biological effects. Research show that herbal teas can contribute to health via the microbial flora which is found majorly in the gut and oral cavity. However, the mechanisms by which they contribute to health and wellness is not well established. This research will look at what happens to the human microbial flora from the point of inhalation of aromatic compounds produced by herbal teas, to digestion.
Aim and Objectives: The aim of this research is to determine the effects of selected herbal teas on oral and gut bacterial species and their mechanisms of action. Some of the objectives include determining the volatile phytochemical composition of the selected herbal teas and determine the susceptibility of the bacterial species against the selected herbal teas.
Methodology: The herbal blends investigated include the mint, fennel, ginger, and lemongrass tea blends. The bacterial species investigated include Streptococcus mutans, Streptococcus pyogenes, Methicillin-resistant Staphylococcus aureus, Methicillin-susceptible Staphylococcus aureus (MSSA) and Escherichia coli strain (ATCC 25922). Head Space Gas Chromatography Mass Spectrometry (HS-GC-MS) was used to determine the phytochemical composition of the steam of the herbal brews and the antimicrobial effects of the herbal teas on the bacterial species were determined using agar dilution and disk diffusion assays.
Results: This research show that the herbal tea vapours have extensive volatile phytochemical profiles with some key Volatile Organic Compounds (VOC’s) identified. For example, menthol was identified in the 3-mint tea as the most abundant VOC in its steam, eucalyptol the most abundant VOC in the ginger tea and anethole the most abundant VOC in the steam of the fennel tea. Furthermore, the herbal teas showed some antimicrobial activity on the bacterial species with the most effective being the ginger tea with the most susceptible bacterial specie being S. pyogenes and least susceptible being E. coli. The effects of oxygen presence and absence was evaluated, and results show that oxygen provision or deprivation influenced the antimicrobial ability of the herbal teas against the bacterial species.
Conclusion: The results show that herbal teas do have inhibitory effects on the growth of certain bacterial species however, further research is required to determine the mechanism by which they exert these functions and how to determine their antimicrobial activity over time.

• Presentation Conference Type: Presentation / Talk
• Conference Name: Microbiology Society Early Career Microbiologists’ Forum Summer Conference
• Start Date: Jul 25, 2023
• Deposit Date: Mar 8, 2024
• Public URL: https://uwe-repository.worktribe.com/output/11768997
• Additional Information: Poster and Oral Presentation