The 10 Most-Studied Supplements on Earth

If something is going to fall apart under replication, it usually does it before it gets to 500 trials. These 10 supplements have survived more scrutiny than most prescription drugs — and they're the ones we genuinely know the most about, for better or worse.

1. Creatine monohydrate — 500+ trials and counting. Strength, recovery, and (per new meta-analyses) cognition.
2. Omega-3 (EPA/DHA) — Meta-analyses pool 40,000+ subjects. REDUCE-IT: 25% drop in cardiac events at high-dose EPA.
3. Vitamin D3 — Hundreds of trials. The most-tested fat-soluble vitamin in modern medicine.
4. Caffeine (standardised) — The most-studied ergogenic aid in sports science, period.
5. Psyllium husk — 420 indexed trials and an FDA-authorized coronary heart disease claim.
6. Oat beta-glucan — Cochrane meta-analysis of 58 RCTs (N=3,974). LDL drops 5–10%.
7. Zinc — 2024 Cochrane review pooled 34 trials and 8,500+ people for cold and immune outcomes.
8. Melatonin — Hundreds of trials across sleep, jet lag, ICU delirium, even chemo-supportive care.
9. Oral rehydration salts — Decades of WHO data. Possibly the most-studied formulation in any pharmacy.
10. Whey protein — The most-trialled protein source in sports nutrition, with strong sarcopenia evidence too.

Bottom line

The most-studied supplements aren't always the most marketed. Creatine and psyllium have more clinical evidence than most patented drugs — and most consumers haven't heard half of what they actually do.

See the full breakdown with study counts and citations on Discover →