Sports supplements and accidental doping – how big is the risk?

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The vast majority of professional cyclists take nutritional supplements of some kind and they certainly aren’t alone – many amateur riders do as well. But according to several riders that have been accused of doping in recent years, nutrition supplements can often be to blame for a positive test.

So is that the case, or are these simply excuses in the wake of being caught out? How likely is it that taking nutritional supplements could lead to a positive test? And what can amateur cyclists (and indeed the pros) do to avoid an inadvertent positive test? Sports dietitian Alan McCubbin investigates.

In 2014 Orica-GreenEdge rider Daryl Impey tested positive for the banned substance Probenecid at the South African Road National Championships. Impey claimed that the substance had entered his system due to cross-contamination of gelatine capsules he purchased to fill with sodium bicarbonate (a legal supplement used to enhance high-intensity exercise performance).

The capsules, he argued, were bought from a local pharmacy in South Africa, where the pharmacist had recently handled Probenecid for a non-athletic customer (Probenecid is a medication used to treat gout). After providing sales records from the pharmacy to demonstrate the sequence of events, it was deemed likely that the pharmacist had traces of the substance on his hands, and Impey was not sanctioned.

Of course this is one of many stories that have arisen in the wake of a doping positive, and the “contaminated supplements” defence has been used by many athletes over the years, with varying degrees of success. When Tom Danielson revealed he’d tested positive for synthetic testosterone on the eve of this year’s Tour of Utah he suggested that supplements might be to blame.

Given that the majority (over 90% in some studies) of elite athletes use some form of dietary supplements, it’s not a surprise that this is often the reason cited when someone tests positive. And when you look at the supplement regimes employed by some WorldTour teams, it’s not just one or two products they’re taking.

Check out the catalogue of products used by Orica-GreenEdge, as seen during CyclingTips’ visit to the team’s service course in 2013.

And it’s not just the pros that need to consider supplements and the potential doping risk they pose. With national anti-doping agencies testing at non-UCI-classified events – such as St. Kilda Cycling Club’s Supercrit in Melbourne or at Gran Fondo New York, say – amateur racers and those not competing at elite professional level still need to be aware of the risks.

So how big are those risks? That is, given how prevalent the use of nutritional supplements is, how likely is it that such supplements could be to blame for a positive test?

Doping positives and supplement use

It’s impossible to say exactly how often positive doping tests (known by WADA as Adverse Analytical Findings, or AAFs) are caused by dietary supplements, either inadvertently or deliberately. But a look at AAF records and the substances in question can give us some insight.

The WADA website provides comprehensive stats on doping positives, the relevant sport and the nature of the substance(s) used. In the Australian lab in 2014 there were 62 AAFs, none of which came from cyclists. Not all AAFs result in an Anti-Doping Rule Violation (ADRV), as some of these may have come from athletes with a therapuetic use exemption (TUE) for the substance detected.

Looking more closely, 22 (36%) of the Australian AAFs were for stimulants and 22 AAFs were for anabolic agents. The next highest category of substances was diuretics and masking agents, accounting for just six AAFs for the whole year.

This pattern of equal AAFs for stimulants and anabolic agents in Australia is in stark contrast to other countries – anabolic agents accounted for 49% of all AAFs worldwide in 2014, with just 15% coming from stimulants. Which raises the question – why is the Australian pattern skewed towards stimulants?

At a Sports Dietitians Australia Supplements Symposium in 2014, Dr Susan White (who sits on several anti-doping tribunals as well as having anti-doping roles with the International Swimming Federation FINA, and WADA), gave her thoughts on this unusual pattern. She believes it’s at least in part because ASADA (Australia’s anti-doping agency) is thought to test down to less elite levels of sport compared to many countries.

The AAFs for stimulants often occur in younger, less-educated athletes who inadvertently ingest them in dietary supplements in the days before competition. At the same time it appears Australian athletes are less likely to use (or at least less likely to be caught using) anabolic agents.

A ASADA list shows that Methylhexanamine, a stimulant added to some pre-workout supplements, was a cause of the AAF in four of the 47 currently sanctioned Australian athletes. Five sanctions were for Oxilofrine, an ingredient found in some “fat burner” capsules, and one sanction resulted from sibutramine, an appetite suppressant which has turned up in some weight loss supplements.

So how likely is it that a supplement contains banned substances?

There are a few consumer surveys and published studies that investigate this issue. The most recent survey, conducted by LGC and published in 2013, involved the random selection and purchase of supplements available in the European market.

The products were then tested for the presence of banned substances. Of the 114 products tested, 13 contained at least one banned substance. This and other surveys have resulted in a commonly thrown-around figure that 10% of supplements are contaminated, implying that sports foods and supplements are inherently risky for athletes.

But that’s the overall figure. It turns out that some types of products are much higher risk than others. After speaking to those behind the survey, it turns out that 10 of the 13 contaminated products were either capsules (four) or tablets (six). The remaining three were powder-based products, while none of the liquid products (primarily sports drinks and ready-to-drink protein drinks) were contaminated.

I spoke to LGC earlier this week and they confirmed the results of a similar survey in the Australian marketplace will be available in early 2016.

Why do supplements contain banned substances?

There are four ways that dietary supplements could lead to a positive test. Firstly and most obviously, the athlete may have taken a supplement knowing that it contains a banned substance, thinking they wouldn’t be tested or the substance would no longer be in their system by the time of the test.

Secondly, there are countless stories (sadly many of them juniors) of athletes taking a supplement and testing positive, with no idea that the supplement contained a banned substance despite it being listed on the label. They make the assumption that if it can be bought at the health food store then it must be OK. But dietary supplements are made for a wide range of consumers, most of whom never compete in sports that comply with the WADA code.

These are particularly sad stories – often teenagers taking a supplement that well-meaning parents or friends provided for them, none of them having any idea that they contained banned substances. The kid is banned from sport, their reputation permanently tarnished. However there are ways for athletes to check the ingredients list of their supplements online (see below), so this situation is for the most part preventable.

Thirdly, an athlete may take a supplement that contains a banned substance that was not listed on the label. This can happen particularly for multi-ingredient supplements, many of which contain “proprietary blends” – code for “we’re not telling you exactly what’s in it and in what quantities”. But other supplements have been found in testing to contain ingredients that were not included on the label at all. In these cases the athlete may have inadvertently ingested a banned substance due to cross contamination somewhere in the manufacturing and distribution process.

This is the reason that capsules and tablets are the highest risk supplements. Liquids and many powdered products are often produced in food manufacturing facilities. In contrast, capsules and tablets are frequently made in the same facilities that produce prescription medications, increasing the likelihood of cross-contamination with traces of pharmaceuticals left on machinery.

What should I do about it?

While there are a few strategies you can employ, the only 100% guaranteed way to avoid a positive test is to not take dietary supplements at all. This is the line taken by ASADA in their athlete education sessions with athletes. This approach can be over-the-top though – I’ve heard stories of traumatised young athletes coming out of “the talk” from ASADA, too scared to buy a Gatorade from the local service station for fear of going positive.

For those who don’t get face-to-face ASADA education, there are some excellent free online learning modules on the ASADA website (minus the heavy-handed attitude of some of the educators) that cover all aspects of the WADA code, the drug testing process, and a section about supplements.

Because the high risk supplements are often the multi-ingredient products, go for supplements in pure form. This might mean buying multiple products instead of one, but it does allow more certainty about what you’re getting.

If you’ve got a supplement with an ingredients list that requires a biochemistry degree to interpret, ASADA also has a “Check Your Substances” website that allows you to check the individual ingredients listed on the label. Just plug in the ingredient name and it will tell you whether or not it’s a banned substance. But of course this only tells you about substances that appear on the label.

To minimise the risk of cross-contamination, third-party testing businesses have gained momentum in recent years. These companies test samples of every batch of a supplement for banned substances, certifying the batch that’s tested. The supplement companies pay for the testing and certification, with the cost either absorbed or passed onto the consumer.

The most well-known batch testing company in Australia, the UK and the US is Informed-Sport/Informed-Choice. Products that have been tested will display a certification label on the packaging, and this certification is now used as a key marketing strategy for several brands.

Some of the brands more familiar to readers might include BodyScience, Etixx, Lucozade, Swisse, Science in Sport (SiS) and Beet It. Bear in mind that not all of a brand’s products (or all batches of a product) are tested, so only certain products will contain the certification logo.


Finally, the small number of athletes funded through Cycling Australia’s High Performance Unit (HPU) are required to comply with CA’s sports supplement policy. Almost every National Sporting Organisation (NSO) developed similar policies in the wake of the “supplement scandal” at the Essendon AFL club in 2012 (which ironically had nothing to do with dietary supplements, but that’s another story).

The CA policy requires all HPU athletes to consult their program’s sports dietitian prior to commencing any supplements, to ensure the product is both appropriate and necessary. They are also required to provide a list of all sports foods and supplements they use or intend to use (yes, even the brand of gels and sports drinks) and have them approved by the CA Supplements Standards and Policy Committee every six months. This list of supplements is then recorded in a central register. This is designed to ensure appropriate professionals are checking off the supplements an athlete uses to minimise the risk of supplement misuse and anti-doping violations.

So yes, there is a serious risk of inadvertent doping when using dietary supplements. And yes, there’s a chance that you could be tested, even if you’re not taking part in a professional race. Some types of supplements are higher risk than others. But by reading labels, checking ingredients against the ASADA website, being cautious about capsules and tablets (and potentially buying those certified by a third-party tester), cyclists at all levels of the sport can minimise their risk of a nasty surprise following a doping control.

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