Ginkgo biloba leaves, the plant behind the most adulterated botanical in the published testing data.
Erdbaer
Illustrative. Ginkgo the plant, not a tested sample, a supplement capsule or a specific brand.
More Than Half of Ginkgo in Published Studies Was Not Really Ginkgo
If you buy ginkgo, there is a genuine chance the capsule in your hand is not entirely ginkgo, and the data behind that statement is stronger than most supplement headlines can claim. This is not a story about whether ginkgo works. It is a story about whether the bottle contains what the studies actually studied, and for six of the most popular herbal supplements, the honest answer is often no.
- A peer reviewed review of 78 studies and nearly 3,000 samples found ginkgo adulterated or mislabeled in 57 percent of published samples, black cohosh in 42 percent, echinacea in 29 percent, ginseng in 25 percent, turmeric in 22 percent, and elderberry in 17 percent.
- Essential oils tested worse. Roughly 65 percent of bergamot, 52 percent of lavender, and 42 percent of peppermint oil samples were adulterated, in cases linked to seizures and rancid oil sold as fresh.
- These are rates found in published testing, not a claim about what is sitting on a store shelf today.
- A Bangladesh program that measured lead contaminated turmeric and then enforced against it took contaminated market samples from 47 percent down to zero in four years, real proof this problem is solvable.
What "adulterated" actually means here
The American Botanical Council defines adulteration broadly: any accidental or intentional deviation in a botanical's declared identity, strength, composition, geographic origin or production method. The methods documented range from boring to dangerous. On the boring end, cheap dilution with maltodextrin simply makes a product weaker than its label promises. In the middle, marker spiking adds a chemical marker from a different, cheaper plant so a simple identity test passes even though the real ingredient is missing. On the dangerous end, testing has found sildenafil hidden in "sexual enhancement" supplements, a risk for anyone also taking nitrate medication, and a kava product spiked with undeclared kratom and akuamma that reportedly produced opioid dependence.
The rates come from a 2024 peer reviewed review in Natural Product Reports covering 78 published studies and nearly 3,000 samples, and they are worse for some herbs than others.
Share of published samples found adulterated or mislabeled, by herb.
The essential oil numbers are worse
Capsules and tinctures are only half the picture. Testing found roughly 65 percent of bergamot, 52 percent of lavender, and 42 percent of peppermint essential oil samples adulterated, some containing free fatty acids four to five times over permissible limits, meaning rancid oil sold as fresh. The most serious documented cases are injury causing rather than just disappointing. Researchers linked 126 reported seizures in India between 2018 and 2023 to eucalyptus oil contaminated with monoterpene ketones, byproducts of camphor synthesis.
The counterweight, and the reason this is not only a discouraging story, is a turmeric program in Bangladesh. Lead chromate was being added at polishing mills to brighten poor quality root. A 2017 to 2021 intervention combining media coverage, trader education and enforcement from the Bangladesh Food Safety Authority took market samples containing lead from 47 percent down to zero, mills adding lead chromate from 30 percent down to zero, and mill worker blood lead down a median of 30 percent. Adulteration is solvable when someone measures it and enforces against it.
Adulteration is solvable when someone measures it and enforces against it
One caution before you believe "on the rise"
Stefan Gafner, chief science officer of the American Botanical Council, presented this data at a conference in Reims at the end of August 2026 and argued that tariffs, military conflict, fertilizer and shipping costs, and climate driven supply shortfalls are pushing adulteration rates up, citing ginkgo climbing from roughly 39 percent in 2006 through 2010 to 57 percent now.
Honest caveat
The "on the rise" framing is the weakest part of this story and deserves real skepticism. The per herb percentages above come from a 2024 peer reviewed review. The claim that rates are currently increasing because of tariffs and conflict is a conference assertion from an industry group that has an interest in the concern, and it is not backed by a published, methodologically consistent time series as far as this reporting could establish. The ginkgo comparison from 39 percent to 57 percent spans different review periods and methods, and the review's own title flags the challenges and limitations of estimating adulteration rates at all. Published studies over sample material already suspected of a problem, so these numbers are not prevalence estimates for what sits on a retail shelf. Say "found in the published literature," never "on store shelves."
What this means for you
If you take ginkgo, black cohosh, echinacea, ginseng, turmeric or elderberry, or use essential oils like bergamot, lavender or peppermint, the single most protective habit is choosing a brand that carries third party testing, such as USP Verified or NSF Certified for Sport, or one that publishes a certificate of analysis for the specific batch you bought. A label claim alone is exactly what this data shows is not always reliable. None of this means these herbs do not work when they are genuine. It means genuine is the part worth checking.
Primary sources
- Orhan N, Gafner S, Blumenthal M. Estimating the extent of adulteration of the popular herbs black cohosh, echinacea, elder berry, ginkgo, and turmeric. Natural Product Reports, 2024, volume 41, issue 10, page 1604.
- Forsyth J, et al. Food safety policy enforcement and associated actions reduce lead chromate adulteration in turmeric across Bangladesh. Environmental Research, PMID 37286126.
- Botanical adulteration on the rise despite 15 years of industry action. NutraIngredients, September 17, 2026.
- BAPP review determines adulteration rates for 5 top botanicals. SupplySide Supplement Journal.
Common questions
Does this mean half the ginkgo on store shelves is fake?
Not exactly. These rates come from published testing studies, which tend to sample material already suspected of a problem, not from a random survey of retail shelves. The honest statement is that more than half of ginkgo samples tested in the published literature were adulterated or mislabeled, not that half of what you can buy today is fake.
What should I look for on a label to avoid this?
Look for third party testing marks like USP Verified or NSF Certified for Sport, or a brand that publishes its own certificate of analysis for the specific batch you are buying. These marks exist because label claims alone are not enough, which is exactly what this data shows.
Is botanical adulteration getting worse, or are labs just getting better at finding it?
Both are plausible and this data cannot fully separate them. The per herb percentages come from a 2024 peer reviewed review. The claim that rates are currently rising because of tariffs and supply pressure was presented at a conference by an industry group with an interest in the concern, and has not been confirmed in a published, methodologically consistent time series.
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