When sourcing health diet drinks, the primary focus must be on ingredient transparency and safety certifications. Ensure the manufacturer complies with FDA (U.S.), EFSA (EU), or CFDA (China) regulations depending on your target market. You should prioritize suppliers with HACCP, ISO 22000, or GMP (Good Manufacturing Practice) certifications to guarantee a sterile production environment. Always request a Certificate of Analysis (COA) for every batch to verify that the nutritional content matches the label and that the product is free from heavy metals or microbial contamination.