Supplements that do not hold up
Evidence: weak
A consolidated, honest record of heavily marketed running supplements with weak or null evidence. None belongs in a distance runner’s kit on current evidence.
Not medical advice
This is a general knowledge base, not medical or dietary advice. If you are injured, unwell or weighing up a supplement or a change to your diet, speak to a doctor, physiotherapist or registered dietitian who knows your situation.
Keep it in proportion
The basics are where the real gains are: consistent volume, sleep and adequate fuelling. Weigh anything below honestly, and do not let a marginal or over-marketed aid pull attention from the things that actually move the needle.
The products below are marketed to runners but do not survive scrutiny for endurance performance, and none belongs in a distance runner’s kit on current evidence. They are judged against the IOC consensus and the Australian Institute of Sport classification, where Group C means no substantial evidence and Group D means banned or high-risk (Maughan et al. 2018).
- Glutamine. A well-powered review of 47 studies found no meaningful effect on immunity, aerobic performance or body composition (Ahmadi et al. 2019). Effectively Group C.
- HMB. A network meta-analysis found endurance improved with protein, not with HMB. Group C, weak.
- Arginine and citrulline “nitric oxide” products. Weak for endurance, with a 2024 trial showing no running benefit in the heat. These should not be confused with dietary nitrate, which works by a different pathway and does have evidence.
- MCT oil. Group C, no reliable endurance benefit, and a common cause of gastrointestinal upset.
- L-carnitine. Group B, but distance-running results are inconsistent and the fat-oxidation marketing is unsupported.
- Tart cherry. Group B for recovery: a moderate effect on strength and power recovery, weaker and inconsistent for soreness (tart cherry review 2026). As a polyphenol it may blunt adaptation if taken daily, so reserve it for acute recovery, not training blocks. See antioxidant supplements.
- Collagen. The exception on this list: Group B and genuinely promising for tendon and connective-tissue resilience, taken with vitamin C before loading, though it is not a running-performance enhancer and is no substitute for total protein. It has its own page: see collagen and vitamin C.
- ZMA, “greens” powders, deer antler. No credible endurance evidence; deer antler additionally carries doping and contamination risk, putting it in Group D territory.
The general rule from the protein and recovery evidence holds: a balanced diet plus the short list of proven aids does the job, and the supplement shelf mostly sells reassurance.