How to Check a Berberine Supplement: Lab Reports, Heavy Metals and Authenticity

Why berberine quality is a real question

Berberine is an alkaloid (a nitrogen-containing plant compound) that gives roots and bark a yellow colour. It is extracted from several plants, including barberry (Berberis vulgaris), tree turmeric (Berberis aristata) and goldenseal (Hydrastis canadensis) [1]. Trade press reports rapid growth in UK sales [3]. Four distinct things can go wrong in a bottle: the capsule contains less berberine than the label says, the extract comes from a different plant than stated, synthetic berberine has been substituted for plant-derived material without saying so, or the raw material carries contaminants such as metals.

The regulatory backdrop adds context. ANSES, the French food-safety agency, concluded in 2019 that the safety of berberine food supplements cannot currently be guaranteed [5]. EFSA, the European food-safety authority, then produced a draft opinion on plant preparations containing berberine, which a trade-press report summarises as concluding that no safe intake level could be established. The consultation ran until 4 May 2026, and the final opinion is not expected until early 2027, after which the European Commission will decide on any action [3]. EFSA’s own stakeholder slides describe berberine content data as heterogeneous, which is a polite way of saying the amounts in products vary widely [6]. These are European assessments; they do not by themselves change what is sold in Great Britain, and readers should watch for UK Food Standards Agency announcements.

How to read a berberine certificate of analysis

A certificate of analysis is a laboratory report on one specific batch. Think of it as a receipt for what was actually measured, as opposed to a label, which is a promise. A reputable seller can supply one on request. Read it in four parts.

1. Identity: which plant, which part

The CoA should name the plant by its Latin binomial (for example, Berberis aristata) and the part used, such as root or bark. This matters because berberine occurs in many plants, and a plain berberine assay will return a positive result for any of them. In a metabolomic study of 35 goldenseal supplements, three products (9%) were not goldenseal or were mixtures, and the adulterants identified were Berberis vulgaris, Mahonia aquifolium (now classified as Berberis aquifolium) and Coptis chinensis [7]. All three of those plants are recognised berberine sources [1] [2] [3]. A berberine-only test would not distinguish them from goldenseal, so for goldenseal-labelled products, identity testing is a separate question from potency.

2. Assay: how much berberine was actually measured

The assay is the measured berberine content, normally by chromatography, which separates a mixture into its components so each can be counted. The potency survey used ultra-high-performance liquid chromatography with tandem mass spectrometry [1]. Look for the result expressed both as milligrams per capsule and as a percentage of the label claim. In that survey, potency was judged against the 90 to 110% of label claim range commonly required for pharmaceutical preparations by the United States Pharmacopeia; nine of 15 products failed it, with an average of 75% of the claim [1]. No UK legal requirement to meet that range was identified for food supplements, but it is a useful yardstick.

Also check how the label is written. A capsule described as “500 mg berberine” and one described as “500 mg extract standardised to 50% berberine” are different products. By simple arithmetic, the second supplies about 250 mg berberine. If the label gives only the weight of the extract or root powder, the CoA is the only way to learn the berberine dose.

3. Contaminants: metals and microbiology

The report should list lead, cadmium, mercury and arsenic as numerical results, not simply “pass”. Retained legislation published on legislation.gov.uk sets maximum levels for food supplements as sold of 3.0 mg/kg for lead, 1.0 mg/kg for cadmium (a higher figure applies to seaweed-based supplements) and 0.1 mg/kg for mercury [4]. That amendment does not set a supplement limit for arsenic, so it is reasonable to ask the laboratory to report it anyway and to ask which limit the supplier applied. The contaminants rules have been amended over the years, so confirm the current consolidated text before relying on these figures.

A worked example helps. A limit of 3.0 mg/kg equals 3 micrograms per gram. A 500 mg capsule weighs half a gram, so at the legal ceiling it could contain up to about 1.5 micrograms of lead, and three such capsules a day about 4.5 micrograms. That is a legal maximum, not a judgement about health risk. Results far below it are better. No published survey of heavy metals specifically in berberine supplements was identified for this article, so how often berberine products approach these limits cannot be stated. Testing remains a sensible precaution for any plant material.

4. Batch, date and laboratory

The batch or lot number on the CoA should match the one printed on your bottle. A generic document with no batch number, or a report on the raw ingredient rather than the finished capsule, tells you much less. Look for the testing laboratory’s name and contact details, the date of analysis and the methods used. Ask whether the laboratory is independent of the manufacturer and accredited to a recognised testing standard such as ISO/IEC 17025.

Is it real, synthetic or filler?

Synthetic berberine is the same molecule as the plant-derived one. The concern raised in the 2026 isotope study is economic: synthetic material made from petrochemical starting materials is typically 25 to 30% cheaper than natural extract, which creates an incentive to substitute it in products labelled natural. The researchers measured stable isotope ratios (the proportions of heavier and lighter forms of carbon, nitrogen, hydrogen and oxygen), which differ between plant-made and factory-made berberine. A market survey of low-cost supplements labelled natural found that most samples matched values typical of synthetic berberine, which the authors interpret as widespread undeclared substitution [2]. The sample size was not available to this review, and the study did not examine UK products specifically, so it signals a risk rather than a measured UK prevalence.

For consumers, the practical lesson is that origin claims are verifiable only in a specialist laboratory. If a seller says “natural”, ask what test supports it. A low price, on its own, does not prove a problem, but it is the context in which the 2026 study found one.

What the yellow stain test can and cannot show

Berberine is yellow, so a common home test is to dissolve a little powder in water and look for a strong yellow colour or staining. That test shows that something yellow is present. It cannot measure how much berberine there is, and because other berberine-bearing plants and synthetic berberine look the same, it cannot show which plant or process produced it. Isotope analysis was needed to separate natural from synthetic origin in the 2026 study [2]. A colour test is therefore not a substitute for a laboratory assay.

Which plant source gives the best quality?

No study found for this article ranks berberine products by plant source on purity. What differs between plants is the company berberine keeps. Each preparation contains other compounds, and an ingredient-supplier representative quoted in trade press makes the point that safety profiles differ by plant and should not be pooled [3]. Three published or reported facts are useful.

• Goldenseal has a documented adulteration problem: 3 of 35 products tested were not goldenseal or were mixtures [7].
• EFSA’s draft cites a two-year rodent study linking berberine from goldenseal to carcinogenic activity in the liver, according to the trade-press summary [3]. That is animal evidence and does not establish a human outcome.
• For Berberis aristata, the same report quotes an ingredient-supplier representative saying there is essentially no dedicated repeated-dose toxicity literature, which he describes as a data gap rather than a demonstrated hazard [3]. Read that as an interested party’s statement.

EFSA’s mandate covered 13 berberine-containing plant parts [6], so the question is being actively assessed. For now, the quality of a bottle depends more on batch testing than on the name of the plant on the label.

What third-party seals tell you

A third-party seal means an outside organisation checked something about the product. Which thing it checked varies. The United States Pharmacopeia runs a voluntary Dietary Supplement Verification Program that awards a USP Verified Mark to products meeting its requirements [8]. It is a US programme, and you would need to confirm that the specific product appears on its listing. Sport-oriented schemes concentrate on banned-substance screening, which is a different question from whether the capsule contains the stated amount of berberine. Before relying on any seal, check what it covers, whether it applies to this product and batch, and whether the certifier publishes a searchable list.

A seal and a batch CoA complement each other. The seal indicates a recurring programme of checks. The CoA shows what was measured on the batch in your hand.

Frequently asked questions

Editorial summary

Published surveys show that berberine supplements can differ from their labels, in amount, in origin and in the identity of the plant [1] [2] [7]. The evidence comes from small studies, mostly outside the UK, and cannot be turned into a statement about any particular brand. What is certain is the method for checking: a batch-specific CoA with an assay, an identity test and contaminant results set against statutory limits [4]. What testing cannot do is resolve the safety questions that ANSES and EFSA have raised [5] [3]. Readers considering berberine should weigh those alongside quality, and speak to a GP or pharmacist first if they take medicines or have a health condition.

References

1. Funk RS, Singh RK, Winefield RD, et al. Variability in potency among commercial preparations of berberine. PubMed Central PMC5807210. https://pmc.ncbi.nlm.nih.gov/articles/PMC5807210
2. Perini M, Pianezze S, Apelganets E, et al. Berberine from Berberis aristata: how stable isotope analysis enables the discrimination between natural and synthetic origins. Journal of Food Composition and Analysis. 2026;151:108989. https://doi.org/10.1016/j.jfca.2026.108989
3. Nicolle L. Safety in question: What is the future of berberine? NutraIngredients, 31 July 2026 (trade-press report on EFSA’s draft opinion and consultation). https://www.nutraingredients.com/Article/2026/07/31/safety-in-question-what-is-the-future-of-berberine/
4. Commission Regulation (EC) No 629/2008 of 2 July 2008 amending Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs. legislation.gov.uk. https://www.legislation.gov.uk/eur/2008/629/data.xht
5. ANSES (French Agency for Food, Environmental and Occupational Health & Safety). Use of berberine-containing plants in food supplements. 25 November 2019. https://www.anses.fr/en/news/use-berberine-containing-plants-food-supplements
6. EFSA Nutrition and Food Innovation Unit. EFSA’s draft opinion on the safety of plant preparations containing berberine (stakeholder webinar slides, 22 April 2026). https://www.efsa.europa.eu/sites/default/files/2026-05/2026_04_22_FBOs%20meeting_BBR_final.pdf
7. Wallace ED, Oberlies NH, Cech NB, Kellogg JJ. Detection of adulteration in Hydrastis canadensis (goldenseal) dietary supplements via untargeted mass spectrometry-based metabolomics. Food and Chemical Toxicology. 2018. https://doi.org/10.1016/j.fct.2018.07.033
8. United States Pharmacopeia (USP). Dietary Supplement Verification Program. https://usp.org/node/10776
9. Guo Y, Chen Y, Tan Z-R, Klaassen CD, Zhou H-H. Repeated administration of berberine inhibits cytochromes P450 in humans. European Journal of Clinical Pharmacology. PMID 21870106. https://pmc.ncbi.nlm.nih.gov/articles/PMC4898966
10. MHRA. Herbal and homeopathic medicines: reminder to be vigilant for suspected adverse reactions and to report them to the Yellow Card scheme. Drug Safety Update, 7 July 2021. https://www.gov.uk/drug-safety-update/herbal-and-homeopathic-medicines-reminder-to-be-vigilant-for-suspected-adverse-reactions-and-to-report-them-to-the-yellow-card-scheme