Interactions between natural products and cancer treatments: underlying mechanisms and clinical importance

Natural products, also referred to as dietary supplements, complementary and alternative medicines, and health or food supplements are widely used by people living with cancer. These products are predominantly self-selected and taken concurrently with cancer treatments with the intention of improving quality of life, immune function and reducing cancer symptoms and treatment side effects. Concerns have been raised that concurrent use may lead to interactions resulting in adverse effects and unintended treatment outcomes. This review provides an overview of the mechanisms by which these interactions can occur and the current evidence about specific clinically important natural product-drug interactions. Clinical studies investigating pharmacokinetic interactions provide evidence that negative treatment outcomes may occur when Hypericum perforatum, Grapefruit, Schisandra sphenanthera, Curcuma longa or Hydrastis canadensis are taken concurrently with common cancer treatments. Conversely, pharmacodynamic interactions between Hangeshashinto (TJ-14) and some cancer treatments have been shown to reduce the side effects of diarrhoea and oral mucositis. In summary, research in this area is limited and requires further investigation.

Automated summary

Natural products, such as dietary supplements and health supplements, are commonly used by cancer patients to improve quality of life and reduce treatment side effects. However, there is concern that the concurrent use of these products with cancer treatments can lead to adverse effects and unintended treatment outcomes. Limited research suggests that some natural products may interact with common cancer treatments, while others may actually reduce side effects. Further investigation is needed in this area.