Liu Wei Di Huang Wan - Rehmannia Six Formula Supplements and nourishes the liver and kidney.* Source Key to Diagnosis and Treatment of Children’s Diseases (小兒藥證直訣, Xiao er Yao Zheng Zhi Jue). Quality Assurance Treasure of the East® herbal formulas are full-spectrum, pharmaceutical-grade, and extracted only with purified water to replicate a traditional decoction. They are produced by Tianjiang Pharmaceutical, the world's largest producer of herbal granules, in a facility that is fully automated and computer-controlled to ensure quality and reliability. Products are tested extensively in Tianjiang's CNAS National Laboratory, yielding high-precision data regarding each herb's identity, origin, concentration of effective components, heavy metal and pesticide residues, and proper dosage in concentrated form. Tianjiang's production protocols for concentrated herbal extracts have been internationally recognized and adopted into the pharmaceutical and food standards of the China Food and Drug Administration.