Supplement doping cases cluster in pre-workouts and boosters
In short
A review of literature published between January 2000 and December 2025 found contamination risk varies sharply by product category and is highest for multi-ingredient products, pre-workout supplements, weight-loss products, muscle-building products, testosterone boosters and SARMs. Only creatine and caffeine carry consistent evidence for performance outcomes. Because anti-doping operates on strict liability, ignorance is not a defence, so third-party certification and lot-level documentation are the practical protections.
When someone tests positive because of a supplement, it gets treated as bad luck. But the risk is not randomly scattered. The map this review draws is surprisingly narrow — it concentrates in multi-ingredient products, pre-workout supplements, weight-loss products, muscle-building products, so-called testosterone boosters, and substances such as SARMs sold as supplements despite a pharmacological profile.
How many supplements actually have solid evidence?
The review found the most consistent performance evidence for exactly two: creatine and caffeine. Beta-alanine, dietary nitrate and sodium bicarbonate were classed as context-specific — they work in particular situations, not universally.
Iron and vitamin D are a different case. Their clinical indications are clear when a deficiency is present, but evidence for routine use in athletes who are already replete is limited. Most of the remaining recovery- and health-oriented products rest on smaller, heterogeneous studies or indirect outcomes.
Why are pre-workouts the problem?
More ingredients means more risk. A multi-ingredient product has a longer raw-material supply chain and more cross-contamination pathways from shared manufacturing equipment. Pre-workouts, weight-loss products and muscle-building products are structurally ingredient-heavy.
On top of that, testosterone boosters and SARMs are cases where a substance with a genuine pharmacological profile is distributed in supplement packaging. Sometimes that is not contamination at all — it is the intended formulation.
What should you actually do?
- Confirm a real deficiency through individual nutritional assessment first. With no gap to fill, most supplements have no reason to exist in your routine.
- Choose single-ingredient products with clear evidence behind them.
- Check for third-party certification, and verify down to the lot number.
- Document what you took, which lot, and over what period. That record is the only evidence you will have after the fact.
Anti-doping runs on strict liability. Not knowing, or the substance not appearing on the label, is not a defence in principle. If you plan to compete, product selection is risk management rather than preference.
How this connects to your Muscle Index
When the Big 3 stall, the supplement aisle is the wrong first stop, and this review confirms it again. Two things have consistent evidence; everything else is uncertainty you pay for in risk. Supplements come after creatine selection and total daily protein are already sorted.
The review's conclusion is a change of posture. Supplements should be treated not as routine practice but as a controlled, individualised and documented intervention — the authors call it a shift from performance-driven to risk-aware supplementation.
Frequently asked questions
Which supplements carry the highest contamination risk?
Multi-ingredient products, pre-workout supplements, weight-loss products, muscle-building products, testosterone boosters, and pharmacological substances such as SARMs distributed as supplements. More ingredients means a longer supply chain and more cross-contamination pathways.
Which supplements have the strongest performance evidence?
Creatine and caffeine. Beta-alanine, dietary nitrate and sodium bicarbonate are classed as context-specific, showing benefits only in particular situations.
Should I just take iron and vitamin D anyway?
Their clinical indications are clear when a deficiency is present, but evidence supporting routine use in already-replete athletes is limited. Confirm the deficiency through individual nutritional assessment before supplementing.
If a substance was not on the label, am I off the hook?
In principle, no. Anti-doping operates on strict liability, so ignorance is not a defence. Choosing third-party certified products and keeping records down to the lot number are the practical protections.
Does this mean I should avoid supplements entirely?
No. The recommendation is to treat supplements as a controlled, individualised and documented intervention rather than a routine habit. Individual nutritional assessment, evidence-based selection, third-party certification, product verification and systematic documentation together reduce the risk substantially.
Source: Translational Sports Medicine