The list of sports supplements with strong evidence is short: creatine, protein, caffeine and beta-alanine. A few more have moderate support. The overwhelming majority of what is sold has no measurable effect on performance or body composition in people who are already eating adequately.
The four with strong evidence
- Creatine monohydrate — the most studied supplement in sports nutrition. Increases phosphocreatine availability, improving repeated high-intensity efforts. Effects on strength and lean mass are consistent across hundreds of trials. Cheap, and monohydrate is as good as any expensive variant. See what creatine actually does.
- Protein powder — works because it is protein, not because it is a supplement. Useful if you struggle to hit intake from food; it has no advantage over food if you already do. See what whey protein is made of.
- Caffeine — reliably improves endurance, alertness and perceived exertion. Tolerance builds within one to two weeks of daily use.
- Beta-alanine — buffers muscle acidity, benefiting efforts in the one-to-four minute range. Requires weeks of loading; the tingling is harmless.
Moderate evidence
- Citrulline malate — modest endurance and blood-flow effects at proper doses, which most pre-workouts do not contain
- Glutamine — useful in clinical settings; little evidence for performance in healthy trained people
- Vitamin D — matters if you are deficient, which many people in the UK are in winter. Not ergogenic if you are not
- Omega-3 — general health benefits; performance effects are small
The large category that does nothing
Testosterone boosters, most fat-loss blends, BCAAs alongside adequate protein, and the majority of proprietary formulas. The pattern is consistent — an ingredient with a real mechanism at a real dose in one study, included at a fraction of that dose in a blend.
BCAAs are the clearest example. They do something in a fasted or protein-deficient state. If you are eating adequate protein you are already getting them, and supplementing adds nothing.
The risk for tested athletes
This is the part that matters most and gets the least attention. Supplements are not assessed for content before sale, and contamination with banned substances is documented — through shared production lines, ingredient sourcing and cross-contact.
Under strict liability the positive test is yours regardless of intent. If you compete:
- Use only products with batch-level third-party certification and check the batch number, not the brand
- Re-check on every purchase — formulations change without the name changing
- Keep the tub and a sample
Our sports supplements category carries 203 lines. We do not hold certification data for them; if certification matters to you, treat that absence as your answer. The brands are covered in the supplement brands piece.
Where to spend
Creatine and protein cover most of what supplementation can realistically do. Adding caffeine before training and beta-alanine if your events sit in the right duration range covers nearly all the rest. That is a modest monthly cost, and the remainder of the market is largely competing for money that would do more as food.
Frequently asked questions
What supplements actually work?
Creatine, protein, caffeine and beta-alanine have strong evidence. Most of the rest do not have a measurable effect in people already eating adequately.
Do I need BCAAs?
Not if your protein intake is adequate — you are already consuming them. Their use case is fasted training or genuinely low protein intake.
Are supplements safe for drug-tested athletes?
Not automatically. Contamination is documented and strict liability means intent is no defence. Only batch-level certification meaningfully reduces the risk.