REF-1591 · Al-Saad et al., 2026 · Frontiers in Sports and Active Living · Paper · PubMed · Free full text

A 2026 systematic review of analytical studies (2010 to March 2025) found prohibited or unapproved drugs hidden in sport supplements across many classes

Stimulants in the most articles, then anabolic steroids, SARMs and others — most often in performance and pre-workout, steroid-type, weight-loss and muscle-building products; its headline that about 9-15% of tested supplements were contaminated appears only in the abstract, is not derived in the results, and studies that found no contamination were excluded, so it is not a usable contamination rate

Main caveat: Studies without detected contamination were excluded, so no share of contaminated products can be read from the included set.
limited, mixed evidenceMeasured on a mixed groupRead in full

Al-Saad and colleagues reviewed laboratory studies that tested commercial supplements for substances on the WADA list, substances caught by its catch-all clauses for similar structure or effect, and other potent unlisted drugs. From 12,031 records they included 44 studies (46 in the methods).

They counted how many articles reported each drug class, each product category and each detection method. Stimulants were reported in the most articles, followed by anabolic steroids; SARMs, hormone and metabolic modulators, higenamine, diuretics, peptide hormones and related substances (GHRP-2, ibutamoren), beta-blockers and dexamethasone also appeared.

Performance and pre-workout products, steroid-type products and weight-loss products were the categories reported most often. Liquid chromatography-mass spectrometry was the most used method. The abstract adds that about 9-15% of supplements tested in the studies were contaminated, but the results section gives no such figure or calculation.

Participants

No people: the units are analytical studies of commercial supplements (44 in the abstract, 46 in the methods), the largest numbers from the USA (7), then Korea (6), Italy and Germany (5 each).

Protocol

Inclusion: original empirical studies with analytical screening of supplements for prohibited or unapproved substances, 2010 to March 2025, English. Excluded: reviews, book chapters, conference papers, behaviour or health studies without analysis, and studies lacking evidence of contamination or anti-doping violations.
Extraction: two reviewers, a standard form, kappa 0.753.
Appraisal of included studies: none described.
Funding: Qatar Anti-Doping Agency (QADA-RP-2025-01.02); no conflict declared.

Key Results

Drug class foundArticlesExamples named
Stimulants21DMAA, octodrine, BMPEA, ephedrine, sibutramine, hordenine
Anabolic-androgenic steroids11nandrolone, testosterone esters, methandienone, DHEA
Beta-2 agonist (higenamine)6higenamine
Diuretics and masking agents6hydrochlorothiazide, bumetanide, acetazolamide
SARMs5ostarine, LGD-4033, RAD-140
Hormone and metabolic modulators5tiratricol, arimistane
Peptide hormones and related2GHRP-2, ibutamoren
Beta-blockers1propranolol, atenolol
Glucocorticoid1dexamethasone
Product categoryArticles
Sports and general performance (pre-workout, energy boosters)14
Steroid-based or hormonal11
Weight loss and fat burning10
Protein and muscle-building4
Diuretic or masking products4
Herbal and traditional3
Detection: LC-MS in 28 articles, GC-MS in 6, other chromatography in 5; not all studies used WADA's identification criteria (TD IDCR).
The discussion states that 35% of sports supplements tested in the Australian online market contained prohibited substances, mostly naturally occurring stimulants; that sentence carries no citation, though the reference list holds a 2025 survey of the Australian online market, cited in the paragraph before it.

Practical Application

**How often are supplements contaminated?This review shows hidden stimulants, steroids and SARMs keep turning up in sport supplements, most often in pre-workout and performance, steroid-type, weight-loss and muscle-building products, but its 9-15% figure is not worked out in the paper and studies that found nothing were excluded, so the base still has no reliable contamination rate.** The practical line stands: tested athletes buy third-party-certified products (base practice, SYNTH-67).
Highest-risk categories by article count: performance and pre-workout (14), steroid-type (11), weight loss (10). These are counts of articles, not of products (our reading), so they rank how often a category was reported contaminated, not how likely a given product is.
Substances the review groups as peptide hormones and related (GHRP-2, ibutamoren) were found in supplements in 2 articles. Inference, not tested here: a product need not be sold as a peptide to contain one.
The authors argue that "natural" or herbal products were reported contaminated less often but, when spiked, carried potent stimulants under plant names, and that a safe image may make them riskier; that is their interpretation.

Limitations

Studies without detected contamination were excluded, so no share of contaminated products can be read from the included set; the abstract's 9-15% has no derivation in the paper.
No risk-of-bias or quality appraisal of the included studies; identification criteria varied between laboratories.
The abstract and the methods disagree on the number of included studies (44 vs 46).
English only; the Middle East, North Africa and South Asia are barely represented (authors).
How this entry was checked and changed
Why this level

a systematic search of cross-sectional product analyses, but with no quality appraisal of the included studies and no pooling; held at B- because studies lacking evidence of contamination were excluded by design, the 9-15% figure is not derived anywhere in the paper, and the number of included studies is 44 in the abstract and 46 in the methods