Turmeric supplements under the microscope

Study highlights progress in turmeric supplement quality, but concerns around synthetic curcumin adulteration

By Stephen Daniells

- Last updated on GMT

The US market for turmeric-curcumin dietary supplements is over $70 million.   Image © Getty Images / Torjrtrx
The US market for turmeric-curcumin dietary supplements is over $70 million. Image © Getty Images / Torjrtrx
A new analysis of 87 different turmeric dietary supplements has highlighted the diversity of available products and the challenges this gives consumers. Concerns were also raised around potential adulteration with synthetic curcumin.

Scientists from the University of Arizona and Vanderbilt University report that over 80% of the products tested (which mostly contained turmeric‐derived curcuminoid extracts) were within 20% of the labeled amounts.

The data, published in Molecular Nutrition & Food Research​, also indicated solvent residues were within USP limits and that only one product contained lead in levels exceeding USP limits.

But it was the potential presence of synthetic curcumin in some of the samples that is a cause for concern, said Stefan Gafner, PhD, Chief Science Officer at the American Botanical Council.

“The products tested were chosen based on cost, commercial availability, turmeric type, and inclusion of other bioactives. Overall, the results suggest deviations from what consumers expect the products to be, but I don’t see these as major issues,” ​Dr Gafner told us.

“If there is one concern about the products, it is the fact that 16% of the analyzed products contained relatively high amounts of curcumin compared to dimethoxy- and bisdemethoxycurcumin. It points to the possibility of admixture of synthetic curcumin, an ingredient that is available at fairly low cost, and may put reputable companies at a competitive disadvantage.”


The researchers also found a negative association between the cost of the supplements and the higher amounts of curcumin (relative to dimethoxy- and bisdemethoxycurcumin) suggesting that less expensive products may contain synthetic rather than turmeric–derived curcuminoids.

The results highlight the challenges faced by consumers in making informed decisions at the point of sale, said the researchers, led by Janet Funk, MD, from the University of Arizona.

US Dollar sales for turmeric dietary supplements 
Natural channel data (excluding Whole Food Market) provided by SPINS. Mainstream Multi-outlet channel (excluding Walmart) provided by SPINS/IRI

And there are plenty of consumers buying them, and in ever growing numbers: According to data from market research firm SPINS, sales of supplements based on turmeric and curcumin more than doubled between 2013 and 2016, growing from $20,082,843 to $47,654,008. Turmeric has been the top-selling dietary supplement in US natural food stores since 2013.

The success has also been seen in mainstream retail outlets, growing from $9,752,445 (and number 22) in 2012 to $22,057,946 in 2016 (and number 10 in the top-selling list).

The Botanical Adulterants Prevention Program (BAPP)​, spearheaded by the American Botanical Council in cooperation with the American Herbal Pharmacopoeia and the National Center for Natural Products Research, recently published a Botanical Adulterants Bulletin on turmeric. For more information about this, please click HERE​.

Study details

Dr Funk and her co-workers purchased 87 unique turmeric dietary supplements available for sale in Tuscon, AZ. They recorded point of sale information and related this to measures of quality relevant to safety.

The data indicated that 94% of the products contained turmeric‐derived curcuminoid extracts (the rest were turmeric root only), and these were combined with other bioactives in 47% of products. The main additive was piperine, which can enhance bioavailability.

The majority of products contained curcuminoid at levels that were within 80% of the label claims, but the composition of curcumin relative to dimethoxy- and bisdemethoxycurcumin (the three curcuminoids that exist naturally together) was not did not match USP criteria in almost 60% of the products. Importantly, 16% of products contained curcumin at over 90% of total curcuminoids.

Curcumin supplements © Getty Images frank600
© Getty Images / frank600

This, said the researchers, was suggestive of: “1) possible substitution of chemically synthesized curcumin for plant-derived curcuminoids, a practice forbidden by US federal regulation, or 2) the unlabeled use of curcumin-only extracts further purified from turmeric-derived curcuminoid.

“Because turmeric-derived curcumin-only extracts are not readily available commercially, while surreptitious substitution of synthetic curcumin for turmeric-derived curcuminoids is a practice of unknown scope that has been reported by the nutraceutical industry, it seems likely that products with high percent [curcumin] may contain synthetic curcumin.”

Other potential issues like solvent levels and lead content were predominantly within USP levels, added the researchers.

Dr Gafner told us that he was particularly happy” ​to see the lead levels at acceptable concentrations. “There have been a few FDA enforcement actions on turmeric shipments coming into the USA in recent years because of high lead levels, so the new study suggests that the picture may have improved.

“At one time, lead chromate, a yellow pigment, was used to make turmeric roots visually more appealing, but the results suggest that this practice may have stopped, at least for products exported to the USA.”

GCA: We are taking steps to define the scope of the synthetic curcumin issue

Asked to comment on the study’s findings, Len Monheit, executive director of the recently formed Global Curcumin Association​, told NutraIngredients-USA: “This review, while presenting a detailed overview of marketed turmeric and related products, as well as underscoring the complexity of trying to compare products, formulations and underlying processes, does suggest product quality issues and concerns that may be misleading or avoidable through smart sourcing and buying practices.

“Some concern is legitimate—we (the Global Curcumin Association) can confirm the presence of curcumin products adulterated with synthetic curcumin, and we are taking steps to define the scope of this issue. We will work with our member companies and broader industry to provide more transparency, so that sourcing quality ingredients is easier, and that this transparency in quality and process is reflected to retail, consumers and practitioners,”​ added Monheit.

Turmeric searches via Google Trends, 2014-present
Consumer interest in turmeric and curcumin are growing, as can be seen in searches for turmeric and curcumin via Google. Source: Google Trends, 2014-present

“This paper, in its scope, covers turmeric products, including root material, extracts, and curcumin standardized extracts which is reflective of the diversity of products in the supplement market. Further complexity is inherent in the dialogue surrounding bioavailability, and the use of technology and ingredients specifically intended to enhance it. It should be noted that almost all products referenced in the study appear to conform to cGMP standards.

“The issue of technologies or other ingredients to enhance the bioavailability and efficacy of curcumin extracts is complex, often involving significant research and investment. It is also challenging from a measurement and sampling standpoint (curcumin and other metabolites) and diligence is required in reporting on this compound.

“Extrapolation and comparison can be difficult, potentially even further complicated by brand product formulation. GCA would support further efforts to work with the analytical and research communities to ensure best practices and more uniform detection methods in different matrices.”

Monheit continued: “Safety data and lack of adverse events reported since the combination of curcumin and piperine were introduced in the mid-1990s support the safety of the combination. That lack of data on adverse events is reinforced by research performed by Tufts University, studying specifically the safety of composition of Curcumin C3 Complex and BioPerine. The results showed that use of BioPerine and Curcumin C3 Complex is safe and unlikely to cause any significant interaction with drugs such as Midazolam (CYP3A substrate), flurbiprofen (CYP2C9) or paracetamol / acetaminophen (UGT and SULT substrate). (Source: LP Volak et al. Br. J Clin Pharmacol. 2012​: 75(2): 450-462)

“The Global Curcumin Association recognizes and welcomes that this high growth category is likely to undergo scrutiny as it continues to mature,”​ he concluded.

Source: Molecular Nutrition & Food Research
Published online ahead of print, doi: 10.1002/mnfr.201800143
“Curcuminoid Content and Safety‐Related Markers of Quality of Turmeric Dietary Supplements Sold in an Urban Retail Marketplace in the United States”
Authors: M.B. Skiba et al.

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