How to Audit a Supplement Factory in China: What to Ask For Before the Order

A general China factory audit checklist will pass a supplement factory that should not pass. It looks at machinery, headcount, a quality manual, a sample room and an ISO 9001 certificate, and all five can be in good order in a plant with no functioning allergen control and no way to tell you which raw lot went into the batch you are about to buy.

The object of a food audit is not the equipment. It is the system that decides what enters a batch, what is done to it, and what is recorded about it afterwards. That system is mostly paper, and most of the paper can be checked before anyone books a flight.

Start on paper, in this order

Four documents, requested as scans and read in sequence, will resolve more than a day on site. Ask for all of them in the same email, because the order in which they arrive is itself informative.

For United States-bound product, add the factory’s FDA food facility registration number and confirm when it was last renewed — registration runs on a two-year cycle. Treat it as a filing, not an endorsement: FDA does not approve food facilities, and a supplier presenting registration as approval is describing something that does not exist. The guide to importing dietary supplements from China to the USA covers where the registration sits alongside prior notice and importer verification duties.

Scope is where most of these audits fail

The most common gap is not a missing certificate. It is a valid certificate that covers products the buyer is not buying. Chinese export food producer filings and food safety certificates both carry an explicit scope: a list of product types, and a site address, sometimes down to the floor. A filing naming tablet candy, gel candy, hard candy and solid beverage tells you nothing about capsules, softgels or liquids, and a certificate issued for the third and fourth floors of one building does not travel to a second site the factory acquired last year.

Three checks close the gap. Read the Chinese scope text rather than the English summary in the covering email, because summaries broaden. Match the site address on the certificate against the address where your batch will actually run. Then verify the certification body itself — whether it is accredited, whether that accreditation is recognised under the international mutual recognition arrangement, and whether the certificate number appears in the body’s own online register. A certificate that cannot be found in the issuer’s register is a document, not a certification. The differences between the schemes are set out in ISO 22000 versus HACCP versus GMP for supplement buyers, and the wider certificate landscape in ISO certifications for China manufacturers explained.

What to walk, and in what order

A food plant is best walked forwards, following material rather than following the guide. The route matters because it is hard to stage a whole flow.

• Goods-in and quarantine. Is incoming material held until released, and is there a supplier approval file for each active with its own certificate of analysis and incoming test result?
• Allergen control. Which allergens are handled on site, how are they segregated, and what is the changeover and verification routine between a run that contains one and a run that does not?
• The cleanroom claim against the evidence. A stated air class means differential pressure logs, gowning discipline, and cleaning and sanitation records. Ask for the log for last month, not the certificate on the wall.
• Water. Treatment, testing frequency, and who signs the results.
• Metal detection or X-ray at packing. Challenge test frequency, who performs it, and what happens to a rejected pack.
• Retention samples. Held for how long, stored under what conditions, and retrievable by lot within minutes.
• Coding and pack. How the lot code is generated and where it appears on the finished pack.

The general plant-walk discipline transfers from other categories — what to inspect in a single day and the factory visit checklist both apply. The food-specific items above are the additions, and they are the ones a general factory audit checklist will not prompt you to ask for.

The traceability walk-back, which is the hour that decides it

One exercise is worth more than the rest of the visit combined. Pick a finished lot number yourself — from a carton in the warehouse, not from a list they offer — and ask them to reconstruct it in front of you.

The chain should run: finished lot code, batch or production record, weighing record with signatures, raw material lot numbers, the supplier certificate of analysis for each of those lots, the incoming test result, then forward again to the finished-goods certificate of analysis and the retention sample for that lot. A plant that runs this every day will produce it in twenty minutes from a file or a system, with names and dates that match each other.

What a weak plant looks like is equally recognisable: records assembled while you wait, weighing sheets without signatures, a certificate of analysis naming a lot number that does not appear anywhere else in the chain, or a retention sample that cannot be found. None of that requires expertise to spot, which is why it is the exercise to insist on even if you are not a food technologist.

The per-batch document set, fixed in the contract

Audit findings decay. What survives is what the contract obliges the factory to send with every shipment. For supplements the minimum set is a certificate of analysis for the finished lot, an allergen statement, heavy metal and microbiological results, the agreed specification sheet, a reference to the master formula version used, and the retention sample policy. Name the documents individually rather than referring to “standard export documents”, and state which of them must arrive before the balance payment. The broader pre-order document list is in what documents to ask a China supplier for before the first order, and how ownership of the formula behind that specification is settled is covered in supplement OEM versus ODM versus private label.

Third-party audits, and where they stop

SGS, Bureau Veritas, Intertek and TÜV will all run a food safety audit to a defined protocol, and commissioning one is sensible when a first order is large or the buyer cannot travel. Two boundaries are worth knowing before paying for one. Social compliance audits — BSCI, Sedex SMETA and similar — assess labour and ethical conditions, not food safety; the two are separate exercises with separate reports, as set out in the social compliance audit guide. And a pre-shipment inspection is not an audit at all: it checks a specific consignment against a specific specification, which is valuable but says nothing about the system that produced it. The distinction is drawn in product inspection before shipment. If neither travel nor a full audit is proportionate, when to hire a factory visit agent covers the middle option.

Red flags worth ending a conversation over

1. “GMP certified” with no scheme named and no certificate produced. GMP is a family of standards, not a badge; ask which one and by whom.
2. “FDA approved” or “FDA certified”. FDA registers food facilities and does not approve them or the dietary supplements they make.
3. The name on the certificates is not the entity on the contract or the invoice. Related-company structures are normal in China; an unexplained mismatch is not.
4. An English summary of a certificate scope that is broader than the Chinese original.
5. Reluctance to let you choose the lot for the traceability walk-back.

Verifying the entity behind the certificates is a separate step and worth doing first — the supplier verification guide and factory versus trading company cover how, and the supplier scorecard gives a way to record what you find. The buyer-side view of what an auditor is actually looking at is in what buyers actually check in a China factory audit.

What a filing-complete factory looks like on paper

As a worked example of the document set above, Guangci Nutraceuticals, listed on ChinaMakersHub, was founded in 2014 in Fenggang, Dongguan and works as a pure OEM, ODM and private-label contract manufacturer with no stock SKU catalogue. Its ISO 9001:2015 and ISO 22000:2018 certificates were issued by Zhongjian Certification and run to 7 October 2026; the food safety scope names solid beverage, hard candy, tablet candy and gel candy, and the certified production workshop is identified by floor. Its China export food producer filing, number 4400/11384, names the same four forms, and it holds a US FDA food facility registration, number 17267166330, renewed biennially, plus a registered foreign-trade operator filing, number 04900619. Every one of those is a number a buyer can ask to see on the certificate and check against an issuer — which is the only thing that makes a certification claim worth anything. The factory profile lists them in full.

Common questions

How is a supplement factory audit different from a general China factory audit?

A general audit assesses production capability, quality management and commercial stability, while a supplement audit assesses a food safety management system — raw material release, allergen segregation, hygiene zoning, foreign body control, batch records and end-to-end traceability — which is a different object of inspection built on different evidence. A factory can pass the first comfortably and fail the second, which is why the general checklist should be treated as a starting point rather than the scope.

Can a Chinese supplement factory be “FDA approved”?

No — FDA does not approve dietary supplements, their manufacturers or the facilities that make them, so no Chinese factory can hold such an approval; what a factory producing food for the United States market must hold is an FDA food facility registration, a filing renewed on a two-year cycle that carries a registration number. A supplier describing that registration as approval or certification is misrepresenting what it is, whether deliberately or through translation.

How do I check that an ISO 22000 certificate is genuine?

Read the certificate number, the issuing body, the scope text and the validity dates, then look the number up in the issuing body’s own online register rather than relying on the scan you were sent. Check that the body is accredited and that its accreditation is recognised internationally. Finally, confirm the site address on the certificate is the site where your product will be made.

What is the single most useful thing to do on site?

Pick a finished lot number yourself, from a carton in the warehouse rather than a list the factory offers, and ask them to trace it backwards to the raw material lots and their supplier certificates and forwards to the retention sample and the finished-goods certificate of analysis. A plant with a working system produces that chain in about twenty minutes, with internally consistent dates, lot numbers and signatures. This one exercise tests record keeping, raw material control and staff competence at the same time, and it needs no technical background to judge.

Do I still need an audit if I am only buying private label?

Yes — private label changes who designed the product, not who answers for it once a brand name is on the label, because the marketing-side obligations for label accuracy and claim substantiation sit with the company selling the product in the destination market rather than with the factory that made it. The manufacturing system behind a private-label line therefore deserves the same scrutiny as a bespoke formulation, and usually gets less.

Audit the system, not the showroom, and put the per-batch documents in the contract while you still have leverage. If you want a food-safety brief run against a verified Greater Bay Area manufacturer with the filings already on record, send the requirement through ChinaMakersHub.