Quantification of Three Chiral Flavonoids with Reported Bioactivity in Selected Licensed Canadian Natural Health Products and US Marketed Dietary Supplements

Purpose. Research indicating potentially beneficial bioactivity of flavonoids has produced a market and demand for natural health products and dietary supplements containing flavonoids. Implementation of the Canadian natural health product (NHP) regulations in January of 2004 increased regulation and oversight of NHP manufacture and marketing leading many consumers and clinicians to assume a similar pathway of development and approval to over-the-counter or prescription drugs. Methods. Three stereospecific liquid chromatograph/mass spectrometry (LC/MS) methods were used to assess the flavonoids, liquiritigenin, pinocembrin, and pinostrobin, in selected Canadian licensed NHP’s and US marketed dietary supplements. Results. The present study quantifies bioactive flavonoids in these products and notes variability in flavonoid content. Conclusions. Efficacy and safety of NHP’s and dietary supplements should not be assumed due to differences in criteria for NHP licensure by Health Canada as well as variation of flavonoid content between manufacturers and products with similar indications for use. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.