While we all have our favorite brands of dietary supplements, the brands may not be as distinct as we think from a manufacturing perspective. Dietary supplement manufacturing spans a wide spectrum. One of the most common manufacturing methods is for a finished product company to contract the manufacturing to another entity.
For all other information about potential contaminants in a supplement, the manufacturer is currently allowed to rely on a certificate of analysis from the raw material vendor. The supplement manufacturer does bear the responsibility for verifying the authenticity of the certificate of analysis, but vendors may be “qualified” using a vendor qualification process, after which the manufacturer may perform skip lot testing to periodically confirm this “qualification.”