Supplements: what is worth it
A plain-English traffic light. What has good evidence, what depends, and what to skip.
- Food and training come first. Supplements add a small extra.
- Only a few have good evidence: creatine, caffeine, protein powder (for convenience), and vitamin D in a UK winter.
- If you compete in tested sport, check every product for banned substances.
The International Olympic Committee puts it bluntly: nutrition usually makes a small but valuable contribution to performance, and supplements make a minor contribution to that. Only a few performance supplements, including caffeine and creatine, have good evidence of benefit. Here is how that looks in practice.
Green: good evidence
| Supplement | What the evidence says | How to use it |
|---|---|---|
| Creatine monohydrate | The most studied performance supplement. Improves high-intensity performance and training adaptations. Short and long-term use is safe and well tolerated in healthy people (ISSN). | 3 to 5 g a day, any time, every day. Cheap plain monohydrate is enough. |
| Caffeine | Improves performance in many studies, most consistently in endurance exercise. Benefits seen at 3 to 6 mg per kg body weight (ISSN, 2021). Very high doses cause more side effects without extra benefit. | About 60 minutes before training. For a 75 kg person, 3 mg per kg is about 225 mg, roughly two strong coffees. Start lower and see how you feel. Keep your total under 400 mg a day from all sources (UK Food Standards Agency). Pregnant: no more than 200 mg a day (NHS). Avoid it in the last 6 hours before bed. |
| Protein powder | No magic. It is a convenient way to reach your daily protein target (ISSN). | One scoop when food is not practical. See our protein guide. |
| Vitamin D | In the UK, from October to March most people cannot make enough from sunlight. The NHS suggests considering a daily 10 microgram (400 IU) supplement in autumn and winter. People with little sun exposure or darker skin may need it all year. | 10 micrograms a day. Never more than 100 micrograms (4,000 IU) a day (NHS). |
Amber: depends on you
- Iron, vitamin B12, omega-3: useful when your diet or a blood test shows a gap, for example heavy periods, a vegan diet or no oily fish. Test first, do not guess. The NHS advises two portions of fish a week, including one oily, as the food-first route to omega-3.
- Vegans: the NHS advises a vitamin B12 supplement or fortified foods.
- Multivitamins: rarely harmful and rarely needed if you eat varied, mostly unprocessed food.
Red: usually not worth your money
- BCAAs if you already eat enough protein.
- Fat burners, detox teas, "testosterone boosters": big claims, weak evidence, and some carry real risks.
- Anything promising fast results with a "secret blend".
Written by Maor Lilov, strength and conditioning coach working in men's professional football. BSc (Hons) Strength & Conditioning Science in progress. UKSCA member.
Not medical advice. This guide is general information for healthy adults. Speak to a doctor or registered healthcare professional before changing your exercise or diet, especially if you have a medical condition, an injury, are pregnant or breastfeeding. Sources: International Society of Sports Nutrition position stands: creatine (Kreider et al., 2017) and caffeine (Guest et al., 2021). IOC consensus statement: dietary supplements and the high-performance athlete (Maughan et al., 2018). NHS: vitamin D; vitamins and minerals; fish and shellfish. UK Food Standards Agency and EFSA: caffeine (400 mg a day). © ML Performance Coaching.