Contaminants in Dietary Supplements: Toxicity, Doping Risk, and Current Regulation

Athletes, both amateur and professional, often resort to the consumption of nutritional supplements without professional supervision and without being aware of the risks they may entail. We conducted an exhaustive literature search to determine the most common substances found as contaminants in dietary supplements. For each substance, we analyzed its mechanism of action, clinical indication, health risk, and putative use as doping agent. In addition, we evaluated the current regulation of these supplements. Contamination of nutritional supplements (accidental or intentional), especially with steroids and stimulants, is a hazardous situation. The prolonged consumption of these products without being aware of their composition can cause serious health risks and, in the case of professional athletes, a possible sanction for doping.

Dietary Supplements as Source of Unintentional Doping

Background

The substances used in sport could be divided into two major groups: those banned by the World Anti-Doping Agency and those which are not. The prohibited list is extremely detailed and includes a wide variety of both medicinal and nonmedicinal substances. Professional athletes are exposed to intense physical overload every day. They follow a relevant food regime and take specific dietary supplements, which is essential for the better recovery between trainings and competitions. However, the use of “nonprohibited” dietary supplements (DS) is not always completely safe. One of the risks associated with the use of dietary supplements is the risk of unintended doping—originating from contaminated products. The presence of undeclared compounds in the composition of DS is a serious concern. The aim of this study is to evaluate the risk of unintentional doping.

Materials and Methods

Literature search was done through PubMed, Science Direct, Google Scholar, and Web of Science. Studies investigating the presence of undeclared compounds, in dietary supplements, banned by WADA met the inclusion criteria. The last search was conducted in June 2021. The present review is based on a total of 50 studies, which investigated the presence of undeclared compounds in DS.

Results

The total number of analyzed DS is 3132, 875 of which were found to contain undeclared substances. Most frequently found undeclared substances are sibutramine and anabolic-androgenic steroids.

Conclusion

More than 28% of the analyzed dietary supplements pose a potential risk of unintentional doping. Athletes and their teams need to be aware of the issues associated with the use of DS. They should take great care before inclusion of DS in the supplementation regime.

Higenamine in Plants as a Source of Unintentional Doping

BACKGROUND

Higenamine is a β₂ agonist of plant origin. The compound has been included in WADA's prohibited list since 2017. Higenamine may be detected in different plants and many food supplements of natural origin.

METHODS

Our literature search was conducted through PubMed, Science Direct, Google Scholar, and Web of Science studies investigating the presence of higenamine in plants that are used in traditional folk medicine or included in food supplements. Our study aimed to assess the risk of adverse analytical findings caused by higenamine-containing plants.

RESULTS

Based on our literature search, Nelumbo nucifera, Tinospora crispa, Nandina domestica, Gnetum parvifolium, Asarum siebodii,Asarum heterotropoides, Aconitum carmichaelii, and Aristolochia brasiliensis are higenamine-containing plants. Based on data from Eastern folk medicine, these plants can provide numerous health benefits. Professional athletes likely ingest these plants without knowing that they contain higenamine; these herbs are used in treatments for different conditions and various foods/food supplements in addition to folk medicine.

CONCLUSION

Athletes and their teams must be aware of the issues associated with the use of plant-based products. They should avoid consuming higenamine-containing plants during and outside of competition periods.

Intended or Unintended Doping? A Review of the Presence of Doping Substances in Dietary Supplements Used in Sports

Introduction: The use of dietary supplements is increasing among athletes, year after year. Related to the high rates of use, unintentional doping occurs. Unintentional doping refers to positive anti-doping tests due to the use of any supplement containing unlisted substances banned by anti-doping regulations and organizations, such as the World Anti-Doping Agency (WADA). The objective of this review is to summarize the presence of unlabeled doping substances in dietary supplements that are used in sports. Methodology: A review of substances/metabolites/markers banned by WADA in ergonutritional supplements was completed using PubMed. The inclusion criteria were studies published up until September 2017, which analyzed the content of substances, metabolites and markers banned by WADA. Results: 446 studies were identified, 23 of which fulfilled all the inclusion criteria. In most of the studies, the purpose was to identify doping substances in dietary supplements. Discussion: Substances prohibited by WADA were found in most of the supplements analyzed in this review. Some of them were prohormones and/or stimulants. With rates of contamination between 12 and 58%, non-intentional doping is a point to take into account before establishing a supplementation program. Athletes and coaches must be aware of the problems related to the use of any contaminated supplement and should pay special attention before choosing a supplement, informing themselves fully and confirming the guarantees offered by the supplement.

Prohibited Contaminants in Dietary Supplements

CONTEXT

With the increasing use of unregulated dietary supplements, athletes are at continued risk from adverse medical events and inadvertent doping.

EVIDENCE ACQUISITION

A review of Clinical Key, MEDLINE, and PubMed databases from 2012 to 2017 was performed using search terms, including dietary supplement, contamination, doping in athletes, inadvertent doping, and prohibited substances. The references of pertinent articles were reviewed for other relevant sources.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 3.

RESULTS

Poor manufacturing processes and intentional contamination with many banned substances continue to occur in dietary supplements sold in the United States. Certain sectors, such as weight loss and muscle-building supplements, pose a greater threat because they are more likely to be contaminated.

CONCLUSION

Athletes will continue to be at risk for adverse events and failed doping tests due to contaminated dietary supplements until legislation changes how they are regulated. In the interim, there are several steps that can be taken to mitigate this risk, including improved education of medical staff and athletes and use of third party-certified products.

N,N-dimethyl-2-phenylpropan-1-amine quantification in urine: application to excretion study following single oral dietary supplement dose

N,N-dimethyl-2-phenylpropan-1-amine (NN-DMPPA) is a new designer stimulant prohibited in sport in-competition according to the List of Prohibited Substances and Methods published by the World Anti-Doping Agency (WADA). The first published data on the excretion study of NN-DMPPA to support the knowledge of NN-DMPPA in routine anti-doping control have been presented. The reliable gas chromatography-mass spectrometry quantitative method (GC-MS) has been validated and applied to the excretion study of NN-DMPPA. The validation parameters of the GC-MS method for determination of NN-DMPPA in human urine were the linear calibration range of 100 to 7500 ng/mL, the LOD of 13.9 ng/mL and the LOQ of 42.2 ng/mL. According to the obtained repeatability, intermediate precision, and trueness, the applied GC-MS method was precise and accurate. Urine samples from three volunteers in the excretion study were collected for 5 days after single oral administration of the supplement NOXPUMP containing NN-DMPPA. The obtained results showed the maximum concentration of NN-DMPPA (189-303 ng/mL) in urine samples at a time of 2-3 h post-administration. The NN-DMPPA concentration in urine samples was higher than 50 ng/mL until 22-23 h after the dietary supplement ingestion. This means that according to the WADA rules the use of a supplement containing NN-DMPPA may be related to a positive case when athletes took this supplement in-competition. Moreover, excretion results demonstrate also that NN-DMPPA may be detected in urine samples by the applied GC-MS method till 46 h after supplement administration. Additionally, the excretion study of β-methylphenethylamine as the second prohibited substance present in the supplement NOXPUMP has been investigated. Graphical Abstract Excretion study of new designer stimulant, N,N-dimethyl-2-phenylpropan-1-amine, and β-methylphenethylamine following single oral NOXPUMP supplement dose.

Advances in the detection of designer steroids in anti-doping

The abuse of unknown designer androgenic anabolic steroids (AAS) is considered to be an issue of significant importance, as AAS are the choice of doping preference according to World Anti-doping Agency statistics. In addition, unknown designer AAS are preferred since the World Anti-doping Agency mass spectrometric identification criteria cannot be applied to unknown molecules. Consequently, cheating athletes have a strong motive to use designer AAS in order to both achieve performance enhancement and to escape from testing positive in anti-doping tests. To face the problem, a synergy is required between the anti-doping analytical science and sports anti-doping regulations. This Review examines various aspects of the designer AAS. First, the structural modifications of the already known AAS to create new designer molecules are explained. A list of the designer synthetic and endogenous AAS is then presented. Second, we discuss progress in the detection of designer AAS using: mass spectrometry and bioassays; analytical data processing of the unknown designer AAS; metabolite synthesis; and, long-term storage of urine and blood samples. Finally, the introduction of regulations from sports authorities as preventive measures for long-term storage and reprocessing of samples, initially reported as negatives, is discussed.

N,N-dimethyl-2-phenylpropan-1-amine - new designer agent found in athlete urine and nutritional supplement

Reports of new designer agents banned in sport being detected in supplements widely available for athletes are constantly emerging. The task of anti-doping laboratories is to control athletes for the presence of substances listed by the World Anti-Doping Agency (WADA) and those that are structurally/biologically similar to them. Recently, a new designer stimulant, N,N-dimethyl-2-phenylpropan-1-amine (NN-DMPPA), was detected by the WADA accredited anti-doping laboratory in Warsaw during routine anti-doping control. The urine samples from four athletes were analyzed in the screening method for stimulants and narcotics and the presence of NN-DMPPA was detected. The identity of NN-DMPPA was confirmed by gas chromatography-mass spectrometry using a synthesized reference standard. The measured concentrations of NN-DMPPA were between 0.51 and 6.51 µg/mL. The presence of the NN-DMPPA compound has been detected in the 'nutritional supplement' NOXPUMP that had been purchased in a store in Poland. NN-DMPPA at 121.7 µg/g was indicated in the investigated supplement together with another banned stimulant β-methylphenethylamine. The presence of this new stimulant was not indicated on the labelling of the supplement, a situation which is not unusual within this market. Thus, it is important to make athletes aware of the risk related to the use of supplements. Moreover, specific legistation dealing with the commercialization of drugs banned for sport should be undertaken.

Detection of β-methylphenethylamine, a novel doping substance, by means of UPLC/MS/MS

Novel substances of expected doping activity are constantly introduced to the market. β-Methylphenethylamine (BMPEA) is classified as a doping agent by the World Anti-Doping Agency as it is a positional isomer of amphetamine. In this work, the development and application of a simple and rapid analytical procedure that enables discrimination between both isomers is described. The analytes of interest were extracted from urine by a two-step liquid–liquid extraction and then analyzed by UPLC/MS/MS under isocratic conditions. The entire analytical procedure was validated by evaluating its selectivity, discrimination capabilities, carry-over, sensitivity, and influence of matrix effects on its performance. Application of the method resulted in detection of BMPEA in eight anti-doping samples, including the first report of adverse analytical finding regarding its use. Further analysis showed that BMPEA may be eliminated unchanged along with its phase II conjugates, the hydrolysis of which may considerably improve detection capabilities of the method. Omission of the hydrolysis step may therefore, produce false-negative results. Testing laboratories should also carefully examine their LC/MS/MS-based amphetamine and BMPEA findings as both isomers fragment yielding comparable collision-induced dissociation spectra and their insufficient chromatographic separation may result in misidentification. This is of great importance in case of forensic analyses as BMPEA is not controlled by the public law, and its manufacturing, distribution, and use are legal.