Thomas is founder of the consulting firm PlantaPhile, which is based in the US, Germany, and the UK. It focuses on all aspects of herbal product development, registration and licensing. For almost three decades, Thomas has developed and managed projects for industry on the use of plants in medicine, food and cosmetics.
In addition to his consulting work with PlantaPhile, Thomas is Principle Scientist R&D at Traditional Medicinals. He is also a co-founder of the Association of African Medicinal Plants Standards (AAMPS) and has served as its director since 2005. Further, he is affiliated with the Department of Botany and Plant Biotechnology at the University of Johannesburg, South Africa.
Thomas has co-authored numerous books, book chapters, and scientific articles, and is on the editorial boards of Phytotherapy Research and the Journal of Ethnopharmacology. Thomas is part of the Advisory Board of the American Botanical Council and was the 2019 recipient of the ABC Champion Award.
He is also a member of multiple organizations and committees, including the US Pharmacopeial Convention Expert Committee Botanical Dietary Supplements and Herbal Medicines, the Society for Medicinal Plant and Natural Product Research (GA), European Scientific Cooperative on Phytotherapy (ESCOP), International Society of Ethnopharmacology, and American Herbal Pharmacopoeia.