| Popis: |
Complementary and alternative medicines are a popular alternative to pharmaceutical medicines for weight loss and prevention of type 2 diabetes. The evidence to support their use is often unclear as few products have been investigated in high-quality randomised controlled trials (RCTs). This thesis assesses the effectiveness of complementary and alternative medicines for weight loss and prevention of type 2 diabetes and provides advice regarding research methods to improve their assessment. Two systematic reviews with meta-analyses of high-quality RCTs investigating herbal medicines and dietary supplements for weight loss were completed. An exemplar RCT was conducted to investigate the effects of two promising products, alpha-cyclodextrin and hydrolysed ginseng extract, on cholesterol lowering and glycaemic control, respectively, as well as weight loss, in adults with prediabetes and overweight or obesity. The RCT included 401 participants randomised to receive the active or placebo version of each product for 6 months. Some of the herbal medicines and dietary supplements meta-analysed were found to produce statistically significant weight loss compared to placebo, but the degree of weight loss was not considered clinically significant. Other products warrant further investigation after promising results in only a few RCTs. Neither alpha-cyclodextrin or hydrolysed ginseng extract were effective for cholesterol lowering or glycaemic control, respectively, or weight loss, in the exemplar RCT. Secondary analyses on the conduct of this RCT provide advice on improving that of future research related to eligibility criteria for diabetes prevention trials, cost-effective recruitment methods, and time-saving dietary assessment methods. The evidence from high-quality RCTs does not support the effectiveness of complementary and alternative medicines for weight loss or diabetes prevention. Future trial investigators can use the recommendations made in this thesis to inform their planning and reduce costs associated with conducting high-quality RCTs. |
