USP Seal Consumers concerned about the quality and purity of vitamins and other dietary supplements can now look for the United States Pharmacopoeia's (USP) new Dietary Supplement Verification Program (DSVP) certification mark on product packaging. The DSVP mark signifies that the supplement has undergone rigorous independent testing and verification from the same public health organization that has been setting medicine and dietary supplement standards since 1820. Nature Made is the first participant in the DSVP supplement quality program.