Ginkgo biloba is a popular herbal medicine that is reputed to improve cognitive functioning. Even though randomized controlled trials do not show that it prevents dementia or Alzheimer’s disease, millions of older people take it in the hopes of warding off mental decline.
A new study from the National Toxicology Program suggests that there may be hidden hazards associated with ginkgo. The investigators assessed safety of this herbal extract in several species of laboratory animals. They found a significant link to liver cancer in mice and thyroid cancer in rats. The animals also experienced nasal tumors. The liver tumors were especially worrisome because they included some aggressive cancers rarely seen in mice.
The herbal industry has complained that the doses which were used were excessive and don’t reflect the real world use of ginkgo. Because the FDA rarely reviews safety data for dietary supplements before they are marketed, consumers should consider this new evidence before embracing ginkgo biloba supplements for long-term use.