USP is a third-party verification certification: https://www.usp.org/verification-services/verified-mark
It's private rather than governmental. On the consumer side, it is intended to achieve the following:
Seeing the USP Verified Mark on a dietary supplement label indicates
that the product:
- Contains the ingredients listed on the label, in the declared potency and amounts. Tests have shown that contents of some
supplements don't match the label and some contain significantly
less or more than the claimed amount of key ingredients. USP
Dietary Supplement Verification helps assure customers that they
are getting the value they expect from a product they are
purchasing.
- Does not contain harmful levels of specified contaminants. Some supplements have been shown to contain harmful levels of certain
heavy metals (e.g., lead and mercury), microbes, pesticides, or other
contaminants. At specific levels these contaminants can pose serious
risks to one's health.
- Will break down and release into the body within a specified amount of time. If a supplement does not break down properly to allow its
ingredients to be available for absorption in the body, the
consumer will not get the full benefit of its contents. USP Dietary
Supplement Verification tests products against performance standards.
- Has been made according to FDA current Good Manufacturing Practices using sanitary and well-controlled procedures. Assurance of safe,
sanitary, well-controlled, and well-documented manufacturing and
monitoring processes indicates that a supplement manufacturer is
quality-conscious, and that the supplement will be manufactured with
consistent quality from batch to batch.
In part, getting the certification on a per-product basis involves:
To obtain the USP Verification Mark, manufacturers must undergo:
- Manufacturing facility audit for compliance with USP General Chapter <2750>: Manufacturing Practices for Dietary Supplements and
FDA current Good Manufacturing Practices (21 CFR Part 111)
- Review of manufacturing and quality control product documentation;
- Laboratory testing of samples of dietary supplements for conformance to standards of quality found in the USP–NF, or to
appropriate pharmacopeial or manufacturer specifications and
- Off-the-shelf testing of USP Verified dietary supplements to confirm that the product continues to meet science-based quality
standards.