On-site Audits

To understand a manufacturer's quality process, you may need to see it firsthand

By Lise Alschuler, ND, FABNO

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One of the most revealing aspects of evaluating a dietary supplement manufacturer is an onsite audit. There is nothing quite like seeing the production processes with your own eyes to determine the quality of the manufacturer. To some extent, anyone can visit a manufacturer and, without any specific knowledge of manufacturing, obtain a general impression of the quality processes in place. These types of audits, conducted by customers without specific training in quality, are sometimes referred to pejoratively as “tourist audits.” While having someone with experience in quality manufacturing typically results in the best audits, there are ways to transform a “tourist audit” into a meaningful and rigorous assessment of quality practices. Below I’ll highlight some of the most important components of an audit.

While surprise audits might be revealing for the FDA, they will be less likely to serve your needs.


Before visiting a manufacturer, it is important to do your homework on the company.

  • Visit their website to learn about how long they have been in business, their company size and structure, and their product portfolio. Looking at a manufacturer’s website will also reveal their knowledge of, and adherence to, FDA and FTC guidelines in terms of information and marketing claims about their products.
  • Ask for a copy of the standard operating procedures (SOP) index. This will give you a good idea of the breadth of the company’s manufacturing and will also provide an overview of the extent of their quality processes.
  • While surprise audits might be revealing for the FDA, they will be less likely to serve your needs. As a customer, you will want to be guided through the facility during the audit by a member of the quality department, which will require advance scheduling. Additionally, it is not uncommon for companies to require you to sign a non-disclosure agreement (NDA) before your audit. This protects their proprietary processes.
  • Create an audit checklist before you go to make sure you cover all of the areas of interest.

Focus Areas

The following areas of manufacturing and site evaluation deserve your attention, as deficits in these areas can affect product quality significantly.

  • Material receipt and storage. Look for a designated receiving area that is clean and well demarcated. Watch the process for receiving materials to see that materials are kept in closed containers, are well labeled, tracked, and appropriately quarantined until released by quality control. Look for a separate and contained area for all allergens.
  • Raw material sampling. Observe the sampling procedures used and inquire about the method of sampling. All manufacturers must, at a minimum, confirm the identity of every incoming ingredient; some conduct additional purity tests. Keep on the alert for good hygiene practices around any exposed products.
  • Manufacturing area. Observe the area’s sanitation and maintenance (you can ask to see maintenance records). Find out how and when equipment is cleaned. Assess how well product contamination is prevented. Find out how the air and water is filtered.
  • Manufacturing process. Watch the manufacturing process and inquire if the personnel are following a master manufacturing record (or equivalent) and documenting their adherence to and deviations from this process. Look to see that each quality checkpoint has a quality review that is recorded. Inquire about the training and qualifications for the employees involved in manufacturing and in the quality control activities. Inquire about the condition of the equipment used in the manufacturing.
  • Laboratory analysis. Find out which tests are conducted on manufactured products and how often. Observe the products sampling for testing. If there is an on-site laboratory, look for clean, well-functioning equipment that undergoes daily calibration and maintenance. Ask for the testing method validations if non-compendia methods are being used. Find out about the training of the laboratory personnel.
  • Final product. Observe the final packaging of products. Look for in-line metal detection, closed systems, and quality control of the final material and labeling. Assess the storage conditions of the final products and learn how long the products remain in the warehouse. Observe the “retains room” (where retained samples of each product lot are kept).

Critical Findings

Record what you learn throughout the audit.

  • It is helpful to take notes during your audit. For each area noted above, make note of good and questionable practices.
  • Make sure that you ask the quality personnel about your areas of concern during the audit. You may find that you missed something or didn’t fully understand the process. If your concerns are not addressed, then you need to determine how impactful this shortcoming will be to the quality of the product.


After the audit, you need to decide what to do with the information you’ve uncovered.

  • It is entirely appropriate for you to communicate your overall impression back to the manufacturer—verbally and/or in writing. This can provide companies with valuable feedback.
  • Remember that you are not a certification body, nor are you an FDA agent. If you signed an NDA, you must honor that. Your observations are for your purposes only to give you confidence in utilizing the company’s products. Any information that you want to communicate to others about your audit should be pre-approved by the manufacturer, unless you are not under an NDA. Keep in mind that you will be responsible for proving the veracity of any public statements that you may make about the manufacturer.
  • If your audit reveals serious quality issues that could present potential harm to consumers, you can certainly contact the FDA and suggest that they conduct an audit of the manufacturer. You can make this request without revealing information protected by an NDA.

Onsite audits are always educational and are an important aspect of supporting quality practices in the industry. Every customer audit reinforces the importance of quality manufacturing and supports manufacturers that invest in quality.

About the Author

Lise Alschuler, ND, FABNO, is a professor of clinical medicine at the University of Arizona where she is the associate director of the Fellowship in Integrative Medicine at the Andrew Weil Center for Integrative Medicine. Alschuler obtained her naturopathic medical degree from Bastyr University where she completed her residency in general naturopathic medicine. She received her bachelor of science degree from Brown University. She is board-certified in naturopathic oncology. Alschuler is past-president of the American Association of Naturopathic Physicians and a founding board member, immediate past-president and current board member of the Oncology Association of Naturopathic Physicians. She is coauthor of Definitive Guide to Cancer, now in its 3rd edition, and Definitive Guide to Thriving After Cancer.