Ginkgo is the oldest surviving species of tree – traced back 300 million years. Research has shown ginkgo may be effective in enhancing memory and slowing Alzheimer's disease. Studies suggest that ginkgo also helps ease anxiety and PMS. Additionally, two small studies indicate that ginkgo can help vision in those with glaucoma and may slow macular degeneration. However, use caution as ginkgo can interfere with blood thinners and other medications.