Dietary supplements are often blamed for Adverse Analytical Findings in doping controls. Indeed, several studies have shown that contamination may occur even in products where one would not reasonably expect it (Geyer et al., 2004; De Hon & Coumans, 2006). As a result, many sport organisations, such as the International Olympic Committee and the World Anti-Doping Agency, have advised athletes to exercise extreme caution when using supplements. This has left many well-intentioned athletes feeling insecure about supplement use, even when dieticians believe that supplements will benefit the health and/or performance of these athletes. At the same time, malpractice in some areas mean that many well-intentioned producers of dietary supplements are tarred with the same brush as their less ethically-minded colleagues.
In the Netherlands, the possible contamination of supplements was proven by a study performed in 2001 (Schilt et al., 2002). This led a joint effort by several partners to give Dutch athletes the option of using dietary supplements when these are deemed appropriate, and to provide the athletes with the maximum safeguards to ensure they can use supplements that do not contain prohibited substances. This project is the “Dutch Safeguards System for Dietary Supplements in Elite Sport”, or “NZVT” (the acronym in Dutch).
The NZVT was established to provide athletes with as much assurance as possible that the supplements they wish to take do not contain prohibited substances that are not on the label.
The NZVT is a joint effort involving the Netherlands Olympic Committee * Netherlands Sports Confederation (NOC*NSF), the trade organisation for supplement producers and providers in the Netherlands (NPN), and the Anti-Doping Authority Netherlands, in close cooperation with the NOC*NSF Athletes’ Committee, the Institute of Food Safety of Wageningen University and Research Centre (RIKILT), and the Ministry for Health, Welfare and Sports (VWS).
The NZVT was established because many athletes supplement their diets. Sports nutritionists and other dietary experts agree that the use of dietary supplements is only worthwhile if the regular diet is already optimal given the needs of the individual person. For athletes, this means that both their basic dietary requirements and the sport-specific requirements are already being met as well as possible.
All athletes are, and remain, strictly liable for all substances in their bodies. The NZVT approach and its accompanying database are information services for athletes that help them find dietary supplements and minimise the risk of using supplements contaminated with prohibited substances. The NZVT partners are not responsible for the products listed in the NZVT database.
The manufacturers of dietary supplements who follow specific guidelines to rule out contamination with doping substances and who are willing to submit their products to specific laboratory testing play the key role in the NZVT system. The heart of the NZVT system is self-regulation with the aim of minimising the risk of inadvertent doping with dietary supplements.
Anti-doping efforts in the area of dietary supplements are only relevant to the specific batch that is subjected for testing. Approval by the NZVT can only be given for the specific batches that are submitted for testing. It has been seen frequently that new batches of the same product can produce different results in laboratory tests. The NZVT database of tested and approved products therefore mentions specific product-batch combinations only.
Please click here to see an overview of the product-batch combinations that have been tested. Since the system has been established for Dutch athletes, the database and its disclaimer are available in Dutch only. If more English information is desired, you can contact one of the NZVT partners (see internet sites below) or send an e-mail to firstname.lastname@example.org.
The database lists the contact details of manufacturers who may be able to help athletes to find where NZVT products are sold. Alternatively, you may wish to contact the company Sportvitamines 4U (telephone +31 70 30 10 658; e-mail email@example.com), which has many product-batch combinations in stock.
There are numerous approaches in the world to informing athletes about the doping risks of dietary supplements. The NZVT partners are in contact with most of these approaches and/or testing systems.
Schilt et al. “Onderzoek naar het voorkomen van dopinggeduide stoffen in voedingsmiddelen in de aanloop naar de Olympische Winterspelen in Salt Lake City”. [research into the prevention of doping in the nutrition of athletes preparing for the Winter Olympics in Salt Lake City] TNO Nutrition and Food Research (TNO-voeding) and the National Institute of Public Health and the Environment (RIVM), the Netherlands, 2002.
Geyer et al. Analysis of non-hormonal dietary supplements for anabolic-androgenic steroids - results of an international study. Int J Sports Med 25(2): 124-9, 2004.
De Hon & Coumans. The continuing story of nutritional supplements and doping infractions. Br J Sports Med 41(11): 800-5, 2007.