How to read a laboratory report for omega-3

Start with the sample, not the word “pass”. A laboratory report describes what was examined in a particular sample. To use the results, you need to know which product and batch they concern, what was measured and what the result is being compared with.

A fixed reading order helps separate a test result from a product specification and information that is still missing.

What is a certificate of analysis or CoA?

CoA stands for Certificate of Analysis. It generally lists examined properties, results and specifications. For omega-3, entries may concern DHA, EPA, oxidation and particular contaminants.^[1]

Check who issued the document and who performed the measurements. A manufacturer’s summary and the original laboratory report can be different documents. The word “certificate” does not itself establish that an independent laboratory selected or tested the sample.

A specification states a requirement, such as “maximum 26”. A result states what was reported for the sample. Do not confuse those columns.

1. Check the product, batch and tested material

First, find the product description, sample or report number and batch code. Compare them with the pack you are looking up. A brand name alone is not enough to establish the connection.

Then check what material was examined. A report may concern ingredient oil, oil extracted from capsules or the complete finished product. That distinction determines what the result applies to.

A report on ingredient oil remains evidence about that ingredient. It is not automatically a measurement of capsules later made with the oil. If the link between ingredient batch and finished-product batch is missing, do not invent it.

2. Check dates and sample origin

Distinguish the sampling date, receipt date, analysis date and report issue date. A report issued later does not necessarily mean the measurement was performed later. The best-before date is another fact again.

Also check who selected and supplied the sample. A brand can send a sample to a laboratory for testing. That does not establish that the laboratory independently selected random retail packs.

If this information is missing, sample selection remains unknown. Do not turn that gap into a claim about the rest of the batch.

3. Read each row as: determination, result, unit

A result per gram of oil is not yet a result per capsule. If a capsule in this example contains 0.8 grams of this oil, the two fatty-acid entries give:

(300 + 200) mg/g × 0.8 g = 400 mg DHA+EPA per capsule.

That is a calculation using the stated oil mass. The report may not have measured the mass per capsule itself. Also check that the basis on which DHA and EPA are expressed matches the comparison you are making.^[1]

For the oxidation entries, see What is the TOTOX value of fish oil?.

What do mg/kg, ppm and ppb mean?

The unit belongs to the number. For a mass ratio, the following are equivalent:^[3]

Check that ppm or ppb is being used as a mass ratio. Milligrams per litre and milligrams per kilogram cannot simply be equated without density information.

Check the reporting basis too: per kilogram of oil, per kilogram of the whole product or another basis. A figure without that denominator cannot be compared properly. For sums of substances, the report must also make clear which substances are included.

Does “not detected” mean nothing is present?

No. “Not detected” is a statement within the capabilities and conventions of the method used. It does not establish absolute absence.^[2]

Two terms help:

• Limit of detection (LOD): an estimated low concentration at which the method can detect a substance with a stated level of confidence.
• Limit of quantification (LOQ): the low level from which the method can determine the amount with performance suitable for the application.^[2]

The fictional extract reports Substance X as “<0.010 mg/kg”, with 0.010 mg/kg as the LOQ. That is not an exact result of zero or 0.010 mg/kg. The entry alone also does not establish whether a signal below the LOQ was observed.

Read the legend for abbreviations such as ND and for less-than signs. If the reporting threshold is unclear, ask for an explanation.

A reporting threshold is not a permitted maximum either. “<0.010 mg/kg” alone does not establish compliance with a hypothetical limit of 0.005 mg/kg.

What does “within the limit” mean?

Find the name, version and application of the limit being used. A laboratory may compare a result with a legal requirement, an industry specification or a customer’s requirement. Those are different references.

Check that the result and limit concern the same substance, material and unit. Also check which entries “pass” refers to: one determination or a whole series.

A statement of conformity uses a decision rule: how is measurement uncertainty taken into account when comparing the result with the requirement?^[5] Measurement uncertainty describes uncertainty associated with the result. It can matter when a result is close to a limit.^[4]

If a number is accompanied by “±”, do not turn it into a universal acceptance or rejection rule yourself. Read the laboratory’s explanation. A status without an identifiable requirement and decision rule provides less information than a result with its supporting context.

Who performed the tests, and what does accreditation mean?

Check the name of the laboratory that performed the work. If accreditation is stated, check its scope: the activities covered by that accreditation. The Dutch Accreditation Council (RvA) publishes scopes in its register.^[6]

A general accreditation statement does not itself establish that every determination in the report falls within that scope. Nor does it identify who selected the sample. Keep the laboratory, sampling and parameters examined separate.

What can you establish after reading?

You can identify which results the document reports for the specified sample, using which method and comparison. Questions that were not examined remain unanswered.

A result for one batch is not a permanent result for a product or brand. A report you cannot find publicly does not establish that no testing took place.

Keep the original source, including relevant pages and explanatory notes. If reports have been revised, check which version replaces which earlier version and why.

Reading report information on SUPPFAX

SUPPFAX brings together label information and available Netherlands shop prices. Read published test information with its source, date, batch and tested material.

Price per gram of DHA+EPA, declared composition and a laboratory result each answer a different question. Matching the information to the right product makes it useful.

Sources

Consulted on 31 October 2026.

1. GOED — CoA information and reporting basis for omega-3. For examples of product, batch, laboratory and measurement information and DHA and EPA reporting basis; not a product seal or a general legal reporting requirement. ↩ ↩
2. Eurachem — The Fitness for Purpose of Analytical Methods, third edition, 2025 (PDF). For LOD, LOQ and method context, particularly section 5.3. ↩ ↩
3. US EPA — Data Reporting Questions, archived technical information. For mg/kg–ppm and µg/kg–ppb mass ratios; not evidence of Netherlands supplement limits. ↩
4. Eurachem/CITAC — Use of uncertainty information in compliance assessment, second edition, 2021. For measurement uncertainty when comparing results with requirements. ↩
5. ILAC G8:09/2019 — Decision Rules and Statements of Conformity (PDF). For decision rules and the scope of conformity statements. ↩
6. Dutch Accreditation Council — register and scopes. For looking up the scope of accreditation; source in Dutch. ↩