Curcumin and Adulteration in the Natural Products Industry

Although turmeric and curcumin have been in the spotlight for some time, the adulteration challenges they face provide a valuable example for manufacturers of natural products and supplements. Economically motivated adulteration is a significant problem in the industry, and with the global curcumin market expected to reach USD 110.5 million by 2024 as consumers become more interested in natural products, the financial incentive for adulteration of curcumin products will continue to increase.

The main health benefits of turmeric are associated with the active curcuminoids it contains, notably curcumin, being associated with anti-inflammatory, antioxidant properties along with potentially preventative action against cancer and cardiovascular disease. Turmeric has long been used as a spice. Owing to its associated health benefits, extracted curcumin has been increasingly popular as a dietary supplement.

As techniques and methods to detect adulteration become more sophisticated, so do the methods of adulteration. The introduction of adulterants breaks supply chain integrity, regardless of whether the adulterant is a health risk, and leaves manufacturers unable to fully account for what their product contains, which can be further complicated if making any ‘all-natural’ claims. The consequences of adulteration include not only the potential health issues but also potential legal and financial repercussions. Rigorous quality control with several approaches to catch adulteration benefits all stakeholders.

Common Adulterants and How to Detect Them

The powdered form of turmeric and curcumin lends itself to easy adulteration by dilution with other powdered substances. Examples of these adulterants include chalk and extracts from other curcuma plants in contrast to the curcuma longa that turmeric originates from.

The distinctive yellow color of turmeric used to be regarded as an indicator of its purity and curcumin content. However, as synthetic dyes have entered into the mix of adulterants, color is no longer an accurate indication of authenticity. One example of a dye adulterant is metanil yellow, a synthetic food dye that is not permitted for use in the European Union or the United States due to indications of potential toxicity issues. Lead chromate is another dye that has been found in ground turmeric, with exposure to increased lead levels being the major associated concern. Fourier-Transform Raman and Fourier-Transform Infrared spectroscopy have been able to detect the presence of metanil yellow. The target of lawsuits in recent years, synthetic petrochemical-derived curcumin has also been used to adulterate natural curcumin from curcuma longa.

Synthetic curcumin is significantly cheaper to produce and a clear example of economically motivated adulteration. In 2017, the price of natural curcuminoids was about USD 150 per kilogram whereas synthetic curcumin was about USD 50 per kilogram. Synthetic curcumin can be difficult to detect using methods commonly used for other adulterants since it is chemically identical to its natural counterpart. Carbon-14 testing is a reliable and accurate method to detect the presence of synthetic curcumin. A weakly radioactive isotope of carbon-12, carbon-14 (also referred to as radiocarbon) is produced in the atmosphere and present in all living organisms as part of the carbon cycle. Once no longer living and exchanging carbon, the carbon-14 level decreases in accordance with radioactive decay at a known rate. Petroleum and its derived chemicals are sufficiently old that they will not contain any carbon-14; measuring the carbon-14 content of a material is therefore a reliable method to differentiate whether a material is plant and animal-derived or petrochemical-derived.

Supply Chain Integrity and Food Safety

The presence of adulterants poses a number of problems for manufacturers. There are the direct health concerns, namely toxic adulterants like lead chromate and chalk. On the other hand, there are adulterants which may not pose an obvious health threat but should not be taken lightly.

An understandably significant concern are the adulterants that may harm consumers, and these are the cases that will most often garner significant media attention and pose severe legal and financial consequences for the company involved. An example was the discovery of nuts in cumin seed products in 2015, potentially fatal for consumers with allergies. With several toxic adulterants of curcumin present in the market, this is a worry for manufacturers.

The presence of non-toxic adulterants should, however, not be underestimated. Although consumers may not fall ill, the presence of any adulterant throws the integrity of the supply chain into muddy water. Even if the adulterant in question is not dangerous in itself, the lack of accountability and traceability means there may be traces of other potentially toxic substances present, like any solvents used in the synthesis of a synthetic adulterant.

The presence of any adulterant is a serious matter, as when the supply chain is compromised, the final product can no longer be guaranteed to a certain standard by the manufacturer. Good relationships with suppliers is valuable but must be complemented with rigorous quality control measures throughout the supply chain.

Food safety is not the only concern when it comes to natural products like turmeric and curcumin. Claims made to consumers are the next step that requires careful navigation.

The ‘Natural’ Label

The popularity of the ‘natural’ label makes it attractive to manufacturers. However, the lack of regulation on the claim paired with growing consumer interest in natural products, results in an uncertainty for manufacturers and a lack of clarity for consumers.

Misuse, deliberate or otherwise, of the ‘natural’ label can have legal and financial repercussions for manufacturers. While companies have been the target of lawsuits by consumers over this problem, manufacturers have also taken on suppliers found to be providing them with adulterated goods, an example of which was natural curcumin that was found to contain synthetic curcumin using carbon-14 testing.


The adulteration challenges faced by turmeric and curcumin manufacturers highlight the importance of a comprehensive quality control program. Economically motivated adulteration can hurt manufacturers on several standpoints – from breaching food safety standards to the potential financial and legal repercussions from the presence of adulterants while using the ‘natural’ label.

The difficulty for manufacturers is that reliably detecting adulterants necessitates a variety of techniques. While testing methods like carbon-14 can reveal a specific type of adulteration, a single method cannot guarantee authenticity. The popularity of natural products means increasing numbers of manufacturers are being faced with an associated host of challenges, ranging from formulation to marketing. Staying on top of quality control and the detection of adulterants is one important piece of the puzzle for natural product manufacturers.

Anna Lykkeberge,
Research Assistant.

This article is available in the SSW Special Issue 2018 of Nutraceuticals Now

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