Translating traditional knowledge into clinical evidence: The journey of Ceylon cinnamon

Herbal medicines are increasingly used worldwide, particularly in low- and middle-income countries, yet many widely used remedies lack rigorous scientific validation. Sri Lanka, with its rich biodiversity and long-standing tradition of herbal medicine, provides a unique opportunity to address this gap. This work describes a structured translational research programme focused on Cinnamomum zeylanicum (Ceylon cinnamon), with the goal of generating robust clinical evidence from traditional knowledge. The aim was to systematically evaluate the safety, efficacy, and clinical applicability of Ceylon cinnamon in metabolic diseases through a stepwise research approach. 
Sequential phases of evidence synthesis were followed by pre-clinical experimentation, early-phase clinical trials, and randomised controlled trials. Initial systematic reviews identified promising biological effects but highlighted the absence of high-quality human data. Pre-clinical studies using diabetic rat models demonstrated significant improvements in glycaemic control and lipid profiles without toxicity. A Phase I clinical trial in healthy adults confirmed safety and suggested beneficial effects on blood pressure and lipids. Subsequently, a randomised, double-blind, placebo-controlled Phase II/III trial in patients with type 2 diabetes showed significant reductions in fasting plasma glucose, HbA1c, and LDL cholesterol, with good tolerability and no serious adverse events. These findings provide compelling evidence that Ceylon cinnamon is a safe and effective adjunct therapy for metabolic disorders. In conclusion, this work demonstrates that traditional herbal knowledge can be successfully translated into clinically relevant evidence through rigorous scientific methodology. It highlights a scalable framework for evaluating herbal medicines and underscores Sri Lanka’s potential to contribute to global evidence-based phytotherapy.