Compliance and composition of herbal weight loss supplements and in vitro analysis of their safety using 1H NMR spectroscopy

Emily C Davies

Herbal weight loss supplements (WLS) have become increasingly popular in recent years, however there is limited evidence to support their use. Regulation of herbal supplements by the Therapeutic Goods Administration (TGA) is typically via a trust-based system, raising concerns for product composition, safety and overall quality. A growing number of these products have been implicated in cases of contamination, adulteration and toxicity, all of which can have serious consequences for consumers. Given the rise in WLS use, it is important to ensure these products are safe and consistent. This project analysed the compliance of 49 WLS with TGA labelling guidelines and compared these results with those of the TGA’s own compliance reviews. Three WLS then underwent composition analysis using 1H nuclear magnetic resonance (NMR) spectroscopy, to develop a high throughput method for monitoring active ingredients and batch consistency in WLS. Next, 10 WLS were selected for in vitro safety screening in human liver and intestinal cells. Initial screening was performed using the MTT cytotoxicity assay, and WLS that reduced cell viability by 25-50% subsequently underwent metabolomic analysis using 1H NMR spectroscopy. Finally, 12 active compounds commonly included in WLS underwent safety screening following the same method to identify any ingredients that should be of concern. Of the 49 WLS examined for compliance, 37% were not appropriately listed on the Australian Register of Therapeutic Goods, and 73.5% were found to be in breach of TGA labelling guidelines. The poor compliance observed here demonstrates the need for greater premarket screening and ongoing monitoring of these products. 1H NMR spectroscopy successfully identified all targeted active ingredients in the three WLS analysed, and significant variation was observed between different batches of these products. This indicates closer compositional monitoring of WLS is necessary, and 1H NMR spectroscopy is an efficient tool suited to this purpose. Six of the 10 WLS that underwent safety screening in liver cells and seven in intestinal cells met the criteria for 1H NMR analysis. All combinations showed metabolite changes that were consistent with oxidative stress. This demonstrates that WLS could potentially cause harm in consumers and therefore require more stringent premarket safety evaluation. Analysis of active compounds only identified epigallocatechin-3,0-gallate (EGCG), a green tea catechin, as causing significant toxicity. This suggests that aside from EGCG it is unlikely a single active compound is responsible for WLS-induced toxicity, and interactions between these compounds and other components of herbal ingredients should be studied. Overall, this project has demonstrated the need for greater premarket screening and postmarket surveillance of WLS. It has also identified 1H NMR spectroscopy as a cost-effective, high-throughput method for monitoring the compositional and safety aspects of supplement quality.

Compliance and composition of herbal weight loss supplements and in vitro analysis of their safety using 1H NMR spectroscopy

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