Up to 40% of some herbal supplements are mislabelled or contain adulterants

Rhodiola (Golden Root) supplements can be a beneficial – but do you know what you’re taking? Shutterstock

The use of food supplements and herbal medicinal products by the public, including athletes, is common practice – but it is not well regulated. There are guidelines on which supplements may be prohibited in competitive sports but there is little reliable information on which herbal medicines and supplements are of good quality.

At first glance, many supplements appear well labelled and their associated websites can provide plenty of information regarding ingredients. But problems can arise when someone – particularly an athlete – takes a product in good faith, which turns out to be something different to that which is presented on the label. At best, this results in the consumer not receiving the product they paid for. At worst, it could result in a competitive athlete being disqualified from competition for taking a banned substance, albeit unknowingly.

In research, conducted at UCL School of Pharmacy, on Ginkgo, Milk Thistle and Rhodiola rosea products, we discovered that 20-40% of the sampled products were mislabelled or contained adulterants. Any of these products may be used by athletes, but the case of Rhodiola rosea is particularly worrying. It is used purposely and widely to increase physical and mental endurance.

Rhodiola rosea, is also known as golden root, Russian root and Arctic root, names linked to its economic value and preferred habitat – cold locations, often at high altitude. It was used in the Russian space programme by cosmonauts to combat space fatigue, and is also utilised as a memory enhancer and aphrodisiac. Rhodiola rosea was traditionally used to prevent altitude sickness by helping to ensure good tissue oxygenation, which is also a prerequisite in sporting endurance and a reason why it is still widely – and legally – used by athletes today.

The safety and quality of herbal medicines available to consumers is a key issue for medicines regulators. In the EU, the Traditional Herbal Medicinal Products Directive (THMPD) and traditional herbal registration (THR) provides a way for consumers to access a wide variety of popular herbal medicines of assured quality and with a well-researched safety profile.

However, there are still a large number of medicines left unregulated and widely available. Increasingly, they are sourced from the internet. Economically lucrative products, including Rhodiola rosea products, are likely candidates for adulteration, especially when the raw plant material is in short supply.

Best opt for certified products. Shutterstock

In the UCL study of Rhodiola rosea products, the characteristic marker compound, rosavin, was not detected in 23% of unregistered products that claimed to contain it. Rosavin is the main compound in Rhodiola rosea that has been investigated and shown to have medicinal properties and so its presence is considered of vital importance.

Two of these products were adulterated with material not from the genus Rhodiola and one of these was positively identified as 5-hydroxytryptophan, a (plant-derived) amino acid commonly, and legally, used as an anti-depressant or an aid for weight loss.

It is unclear whether this is a deliberate or accidental adulteration since attempts to clarify this with the many companies involved have been unsuccessful. However, whether deliberate or not, these findings show that there is a monumental failing in the quality control systems employed.

Additionally, it was found that about 80% of unregistered products contained lower amounts of rosavin than the certified THR products tested. This may indicate that there are common but different species of Rhodiola substituted or used within mixtures in Rhodiola rosea labelled products. The most common adulterating species we found was Rhodiola crenulata, which is chemically similar but lacks rosavin.

While adulteration by other Rhodiola species, including Rhodiola crenulata presents one particular problem, adulteration with 5-hydoxytryptophan or other similar substances is even more worrying. Future investigations will focus on the isolation and identification of these compounds.

Buying unregistered herbal medicines and food supplements presents a clear risk in that these products have not been subjected to the same rigorous controls as products manufactured under a strictly regulated and closely monitored process. While herbal medicines registered as THR products offer real assurances, unregistered ones make it problematic for the general public, including athletes, to differentiate genuine products from poor quality and adulterated ones.