What is the evidence on the safety of supplements such as fiber, garlic, ginger, green tea, and red yeast rice?
The evidence on the safety of dietary supplements such as fiber, garlic, ginger, green tea, and red yeast rice is inconclusive. A systematic review by Onakpoya et al. (2014) reviewed 20 RCTs and assessed the effectiveness of green tea supplements on blood pressure and lipid parameters. The evidence demonstrated no increased adverse events. A systematic review by Fogacci et al. (2019) reviewed 53 RCTs and assessed the safety of red yeast rice supplements. These supplements were compared to either a statin or placebo and the follow-up ranged from 1 month 4.5 years. The authors concluded red rice yeast supplements were safe for use but caution is recommended when used with other medications, especially other cholesterol-lowering agents, due to possible interactions. The Work Group's confidence in the quality of the evidence for these dietary supplements was very low.