Insufficient diet management and monitoring of patients during phase 2 and 3 pharmaceutical clinical trials: A narrative review with a systematic approach

Clinical trials play a vital role in developing new medications for nutrition-related diseases, such as phenylketonuria (PKU), obesity, and diabetes. Dietary management is often a critical component of these trials, as consistency in diet can significantly influence outcomes and the evaluation of drug efficacy. While the Federal Drug Administration (FDA) provides guidance on managing and monitoring diets in clinical trials, the extent to which these practices are implemented remains unclear. This review examines diet management practices in phase 2 and 3 clinical trials for weight loss, type 2 diabetes, and PKU. A systematic review methodology was employed, with PubMed and Cochrane searches identifying 14 articles for weight loss and diabetes trials and 5 articles for PKU trials that met inclusion criteria. Key practices include the use of inclusion/exclusion criteria, study endpoints incorporating multiple biomarkers, and the implementation of specific dietary protocols. Weight loss and PKU trials were more likely to employ detailed dietary guidelines than diabetes trials. However, all the reviewed studies lacked critical elements outlined in published nutrition research guidelines. This review underscores the variability and deficiencies in diet management practices in clinical trials for nutrition-related disorders. These gaps highlight the need for more standardized and transparent approaches to dietary monitoring and reporting in order to improve the reliability and reproducibility of trial outcomes.