Supplements containing turmeric or its extract, curcumin, face economically-motivated adulteration in the supply chain, mainly through the use of synthetic curcuminoids. These synthetic alternatives could potentially pass as naturally-sourced in some common testing methodologies such as high-performance liquid chromatography (HPLC) and be mistakenly marketed as such in finished products.
 
In a recent case study published in the journal Food Chemistry researchers found that of 14 curcumin supplements analyzed only four met label claims for identity and potency. However, adulterated products subjected to only HPLC or carbon-14 testing alone would not have been detected for their respective quality issues.
 
The HPLC method of testing alone did not provide direct evidence of curcuminoids’ natural origin, while another method, carbon-14, was unable to test for the potency of the supplements as claimed on labels. So, the authors of the study, which included analytic experts from the Global Curcumin Association (GCA), Eurofins, and Beta Analytic, recommended utilizing both HPLC and carbon-14 as a reliable means of testing for both purity and potency.
 
This orthogonal turmeric quality control strategy, proposed by GCA as what should be a routine method of quality control and assurance, was shown to be comprehensive on both fronts of purity and potency.
 
Given that the authors of the study considered their relatively small sample of market-available curcumin products to be representative of the curcumin market on the whole, based on a diverse range of suppliers and per-milligram pricing, GCA reports there is an urgent need to make testing more comprehensive.
 
“Our recent GCA testing, confirmed by others, has determined that some products on the market are adulterated or lack adequate levels of active ingredients,” said Len Monheit, executive director of the Global Curcumin Association. “Turmeric is an ingredient with ample scientific evidence for health benefits, but if we lose consumer faith and trust, it will impact all companies in this market—bad actors as well as fully compliant organizations. For this reason, we are emphatic that better tools are needed for both brands and contract manufacturers, and while our initial findings changed sourcing practices and supply chain partners, more change in quality control is needed.”
 
GCA: C-14 Testing is Best Adjunct So Far
C-14 testing, in particular, is not included in the USP methods commonly used in turmeric supplements, Monheit said. “USP analytical methods are what’s typically used and they are appropriate for most nutraceuticals—in this case to test for curcuminoids to confirm label claim. But this method does not detect synthetics, so another method is needed, especially for turmeric. The USP methods in some cases do not address all suspected adulterants so in this case, the HPLC and Carbon-14 testing methods together help address those issues and are the optimal tests to use.”
 
The authors of the case study noted that curcumin is historically adulterated with a number of compounds, including other species of curcuma, starches, chalk powder, cassava, dyes, and synthetic curcuminoids, the latter of which can be concealed in visual observation and UV-VIS spectrophotometer tests. However, there are issues beyond a lack of active compounds. Previous studies have identified that the consumption of turmeric contaminated with lead chromate attributes to childhood lead-poisoning cases, and another turmeric adulterant, Metanil Yellow, has neurotoxicity concerns, the authors noted.
 
“There is no evidence or regulation to prohibit the consumption or trade of synthetic curcumin, and they are commercially available similarly as other common synthetic dietary ingredients such as resveratrol or vitamin C. However, laws protect consumers’ right to buy what is accurately claimed on the label,” the authors of the study noted.
 
On the low rate of unadulterated curcumin products from the sample of 14 tested, “we believe it reflects the current adulteration and quality situation in the turmeric extract marketplace,” the authors of the study noted. The data also implies that lower-cost turmeric products are more suspicious of containing fewer curcuminoids in their formulations.
 
“This work has been in process for many months and was written with input from the American Botanical Council (ABC) and the ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP), both of which GCA actively supports,” Monheit said. “Our goal is to steward growth and strengthen the category by communicating quality control strategies.”
 
“Right now, we face the challenge that C-14 testing is not common,” Monheit said. “There is currently some work being done to evaluate the alternatives that replicate and use more common analytical tools and equipment so that the methods can be done in-house or by more third-party labs. But currently, C-14 is the best to detect petrochemical-based carbon, and hence synthetic, as opposed to completely natural ingredients. GCA member companies regularly test their raw materials and we know of several contract manufacturers that are also quite rigorous in this. If you’re going to claim 100% natural on the brand label, not doing this testing can be a liability.”
 
Change Will Need to Come From Industry
According to Monheit, industry initiatives will be needed in order to mainstream an orthogonal testing strategy which takes botanical identity into account, as FDA’s priority is mainly tied to health risks over natural claims substantiation.
 
“FDA has been very clear that they prioritize risk and that is what really triggers enforcement action,” he said. “Not meeting label claim and the presence of synthetic materials has not yet been deemed a level of risk that would trigger FDA action.”
 
After GCA’s formation in 2018 by leading ingredient suppliers, a key component of the association’s work plan was to prioritize improving quality and testing methodologies across the category, Monheit said, which includes the random testing of products on the market in addition to showcasing existing and emerging science.
 
“It was late 2019 when we began talking with both Beta Analytic and Eurofins about a consolidated approach,” said Monheit. “When we confirmed in our second major testing that we had issues again with label claims as well as with the presence of synthetics, we had enough confirmation that the problem remained and that there was a solution we could publish and communicate to assist with better quality control in the category.”