Additional product testing revealed that under a third of the products (seven soft gels, 10 hard shells, and five tablets/caplets) failed to disintegrate, reported Dr. Banaz Jalil and Professor Michael Heinrich from the University College London (UCL) School of Pharmacy in the European Journal of Pharmaceutical Sciences.
“This is the first study looking into the dosage form performance (pharmaceutical quality) of HMPs [herbal medicinal products] and DSs [dietary supplements] available on the global market,” they wrote. “It will improve the understanding of the effects and importance of these HMPs or DSs formulations and research on the efficacy and bioavailability of HMPs or DSs in animal or human trials.
“The study highlights the need for quality assurance beyond defining the chemical composition (e.g., in a pharmacopoeia) and the urgent need for better quality assurance with HMPs and DSs.”
Implications for formulators and ingredient sourcing professionals
“Approximately 30% of the products failed disintegration testing, meaning the capsules/tablets did not disintegrate reliably in simulated gastric fluid within the prescribed time,” Dr. Jalil told NutraIngredients. “The observed variability in dosage-form performance underscores a production risk: Even if the botanical extract is well characterized, the delivery format may compromise bioavailability and functional equivalence.”
She added that the implication for formulators and ingredient sourcing professionals is that investing in robust disintegration testing and considering shell material and excipient matrix are critical for medicinal plant-derived product applications, which is essential for both compliance and consumer benefit.
Study details
The study used high-performance thin-layer chromatography (HPTLC) to determine the authenticity of 71 lavender (Lavandula angustifolia, Lamiaceae) and two spike lavender (L. latifolia, Lamiaceae) products. Twenty-seven products were labeled as only containing Lavandula essential oil or flower extract (plus excipients), and the other 46 were multi-component products also containing other herbal extracts, vitamins and minerals. Thirty products were soft gel capsules, 26 were hard shell capsules, 13 were tablets and caplets, and the remaining four were liquid products labeled to contain lavender.
Just under 65% of the products contained less or none of linalool, linalyl acetate and cineole, the main marker compounds for Lavandula.
Additional product disintegration tests, performed using the specifications of the European Pharmacopoeia, revealed that 30% failed to disintegrate, with pass rates for gelatine-based capsules higher than for non-gelatine (cellulose-based) capsules.
“Overall, our findings highlighted problems with the pharmaceutical performance and phytochemical quality of the investigated products,” Dr. Jalil and Professor Heinrich wrote.
‘Adulteration of lavender essential oil is very common’
Commenting independently on the study’s findings, Dr. Stefan Gafner, chief science officer for the American Botanical Council, told NutraIngredients that the publication presents “a fairly dismal picture of dietary supplement products containing lavender.
“Contrarily, all three products registered as herbal medicine in Europe were considered of good quality, confirming what we have seen for other botanical ingredients,” he added.
Dr. Gafner noted that adulteration of lavender essential oil is very common, and this was previously outlined in a bulletin by the ABC-AHP-NCNPR Botanical Adulterants Prevention Program. However, further inspection of the products that were analyzed revealed that 34 of them did not specify that they contained lavender essential oil, especially products sold as hard-shell capsules or tablets/caplets, he said.
Some were labeled as lavender flower dry extract, lavender flower (without any further specifications), or even—in two cases—fermented lavender aerial part and fermented lavender flower.
“Since the test method, especially for hard shell capsules and tablets, was developed to measure the essential oil components, it may not have been suitable to measure the quality of aqueous extracts or fermented lavender flower,” Dr. Gafner said. “Therefore, it is difficult to say how many of the dietary supplement products were actually adulterated or mislabeled.
“On the other hand, the information in the paper begs the question on what basis any health claims were made for lavender products that lack the essential oil, since most of the human clinical studies have investigated the essential oil, either as an oral application, by inhalation, or as a topical treatment.”
Dr. Gafner said that there are data suggesting that water extracts of lavender have been used traditionally, with several human clinical studies using lavender tea or lavender flower extracts reported to show decreases in anxiety and depression.
“Still, the available clinical data in support of lavender flower tea or any type of lavender extracts are certainly much less compelling than data for the essential oil,” he said.
Source: European Journal of Pharmaceutical Sciences, 2025, Vol. 208, 107042. doi: 10.1016/j.ejps.2025.107042. “Pharmaceutical quality of herbal medicinal products and dietary supplements – a case study with oral solid formulations containing Lavandula species”. Authors: B. Jalil and Michael Heinrich.
