Abstract
Changing lifestyle and dietary habits, for example using herbal medicines, can influence the management and progression of some diseases, such as cardiovascular disease (CVD), diabetes and obesity. This thesis describes a series of in vitro experiments and human studies; the aims were to investigate the potential health benefits of Cinnamomum cassia (C. cassia) and Cinnamomum zeylanicum (C. zeylanicum) extracts in vitro, and C. cassia supplements on biomarkers of glucose, lipid profiles, weight, blood pressure, insulin and inflammatory markers. Both extracts were found to be rich in polyphenols and proanthocyanidins which can act as effective free radical scavenging compounds in vitro. Both cinnamon types dose-dependently reduced the rapidly available glucose (RAG) and increased the slowly available glucose (SAG) values of cornflakes, possibly due to their polyphenolic compounds which have the capacity to inhibit carbohydrate digesting enzymes, particularly α-glucosidase and α-amylase. The preliminary randomised cross-over control human study investigated the effect of ingesting capsules of 1 g C. cassia prior to consuming cornflakes (a high starch food) on the glycaemic response in healthy participants. The results showed there were no significant differences in glucose response, nor in the incremental area under the curve for the cinnamon supplement or the placebo. In an 8-week randomised controlled human study, 5 g of C. cassia supplementation in overweight individuals reduced body weight (P=0.01), plasma non-esterified fatty acid levels (P=0.017), systolic (P=0.01) and diastolic blood pressure (P=0.02), without significantly affecting LDL, CHO and HDL levels as well as fasting insulin and glucose levels. There were no significant effects of cinnamon supplementation on cytokine and adhesion molecule levels. However, IL-6, IL-8, TNF-α, IL-1-α, MCP-1, sPSEL levels were significantly altered due to time in both cinnamon and control groups. In conclusion, cinnamon supplementation (5 g/d for eight weeks) produced important health benefits in vitro and in vivo, therefore it may be useful as a natural herbal remedy for obesity and CVD.