For thousands of years leaves from the Ginkgo biloba tree have been a common remedy in Chinese medicine. Nutricost's Ginkgo Biloba Extract is always from the finest quality available worldwide. Ginkgo supplements are generally considered safe. In some individuals they can cause nausea headache dizziness and diarrhea. If you take any other supplements or medicines regularly including blood-thinners or aspirin talk to your health care professional before you start ginkgo supplementation.