Nutritional supplements’ doping risks

July 24, 2026

Nutritional supplements’ doping and other contamination risks

Nutritional supplements may contain undisclosed impurities, including substances banned in sport. In an Australian study [1], Barker et al. (2025) found that over a third (35%) of 200 supplements ordered online contained prohibited doping substances (classified by the World Anti-Doping Agency WADA). Most of them were stimulants, with products marketed as ‘pre-workouts’, ‘fat burners’, or ‘muscle builders’ posing the highest risk. Beyond banned doping substances, some products have also been found to contain heavy metals, harmful chemicals, or medicinal substances not listed on the label, often due to poor manufacturing standards or inadequate quality control.

Red flags for high-risk products

Watch for the following red flags in nutritional supplements [2,3]:

1. exaggerated or misleading marketing
2. unrealistic or drug-like claims of effect,
3. an incomplete ingredient list,
4. references to doping substances, hormones, or performance and image enhancing drugs (PIEDs),
5. marketing that features people known to use doping (‘enhanced athletes’), and
6. injectable or other non-oral supplement formats

Public high-risk lists, such as USADA’s Supplement Connect (High Risk List) and the FDA’s Health Fraud Product Database, can help flag known problematic products, though neither list is exhaustive.

Minimizing risks

Step 1: Do you actually need supplements?
Before reaching for a supplement, athletes and physically active people should first ensure their training, sleep, and overall diet are well optimized. Supplements are meant to complement a normal diet, and they cannot substitute for adequate sleep, regular training, or a healthy, balanced diet. Only once training, sleep, and nutrition have been optimized, ideally with a professional’s help, does it make sense to look into a specific supplement for a specific goal. After this, it is worth doing thorough research into whether the supplement actually works. Exaggerated marketing claims and personal recommendations from peers can sometimes turn this priority order upside down.

Step 2: Assessing supplement reliability

Check the supplements’ label or product information for:

1. a complete ingredient list
2. exact dosage and recommended daily intake
3. side effects and warnings
4. best-before/expiry date with a batch number
5. manufacturer/importer details.
6. third-party testing* [4]

* Especially for products ordered from online markets, also check whether the product has been third-party tested (which batch, and the results), and whether it carries a valid third-party certificate. Certification programs (such as Informed Sport, Informed Choice, NSF Certified for Sport, BSCG Certified Drug Free, HASTA Certified, NZVT, and the Cologne List) aim to screen supplements for banned doping substances to reduce the risk of unintentional doping violations but simultaneously help reduce broader contamination-related health risks. Remember that certification programs can’t fully guarantee that the supplement product is safe to use.

Step 3: Where to find reliable information

Look for evidence-based information from expert and research organizations (e.g., In Finland, the Finnish Institute for Health and Welfare, the Finnish Food Authority) and peer-reviewed scientific publications. Consult a qualified healthcare professional, while also checking their credentials (in Finland, via Valvira’s JulkiTerhikki register) and whether the professional has acquired any specialized training in sports nutrition. For evidence on specific supplements, check the IOC consensus statement [5] and the Australian Institute of Sport’s ABCD classification system [6]. The AIS framework grades supplements from A (strong evidence) to D (high risk of contamination or banned substances)

For any anti-doping-related information in competitive sports, please refer to the Finnish Center for Integrity in Sport FINCIS’ resources: https://suek.fi/en/ [7], and/or equivalent international anti-doping organizations’ sources.

Mikko Lemettilä, MSc (Pharm.Sci.), A-Clinic Foundation

The IRIS project (2024-2026) focused on improving athletes’ risk appraisal and informed decision-making towards nutritional supplement use in recreational and competitive sports. Read more about the project on A-Clinic Foundation’s website (in Finnish) or the IRIS project website.