Sports supplements: what works, what is a myth and what science really says
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The sports supplement industry moves billions per year. Scientific evidence says most of those products are irrelevant if your diet and training aren't in order.
Sports supplementation is probably the area where the gap between what marketing promises and what scientific evidence demonstrates is widest. Reviewing the available literature is revealing: of the hundreds of supplements sold to improve athletic performance or body composition, only a handful have solid evidence behind them.
What follows is an honest review, organised by level of evidence, of the supplements most commonly used by people training for strength and body composition.
Tier 1: solid, consistent evidence
Tier 2: moderate evidence with caveats
Tier 3: insufficient evidence or negligible effect
The conclusion that does not change
No supplement compensates for a poorly structured diet, a badly programmed training plan or insufficient sleep. The hierarchy of priorities is always: progressive training, then adequate protein intake, then appropriate calories, then sleep, and only last, supplementation. Inverting that hierarchy is the most common and most expensive mistake in performance optimisation.
Emerging supplements with promising (but still limited) evidence
Beyond the three tiers described, there is a category of supplements with promising early research worth following, though they still lack enough high-quality clinical trials to recommend broadly:
Omega-3 fatty acids (EPA/DHA): recent studies suggest that high-dose omega-3 (3-4 g/day of EPA plus DHA) may enhance muscle protein synthesis, especially combined with strength training in older adults. In trained young people the effect is far more modest. They also have anti-inflammatory effects that can reduce post-training soreness, although it is unclear whether that is beneficial or counterproductive in the long run.
Ashwagandha: several clinical trials show that ashwagandha (600-1200 mg/day of KSM-66 or Sensoril) lowers cortisol levels, improves post-training recovery and may increase strength in beginners and intermediates. The magnitude of the effects is moderate and study quality is variable. It is not a first-line supplement, but it could help people with chronically elevated stress.
Creatine loading versus continuous dosing: the traditional loading strategy (20 g/day for 5-7 days) followed by a maintenance dose (3-5 g/day) saturates phosphocreatine stores faster but produces more initial water retention. Continuous dosing without loading (3-5 g/day) reaches similar saturation in 4 weeks without the initial weight effect. Both strategies work; the choice depends on how urgently you want results and how you tolerate water weight.
Fraud in sports supplements: what to know before you buy
The sports supplement industry is notoriously under-regulated in most countries. A study by Geyer et al., published in the official journal of the International Olympic Committee, found that 15 per cent of the sports supplements analysed contained substances not declared on the label, including anabolic steroids and banned stimulants.
To protect yourself from adulterated or dubious products, follow these guidelines:
- Look for third-party certification: organisations such as NSF Certified for Sport, Informed Sport or USP Verified confirm that the product contains what the label says and no banned substances. These certifications matter especially if you compete in sports with anti-doping controls.
- Prefer simple ingredients: single-ingredient supplements (pure creatine monohydrate, anhydrous caffeine, whey protein with recognisable ingredients) are easier to verify than complexes or proprietary formulas that hide the dose of each ingredient.
- Watch for suspicious pricing: quality creatine monohydrate costs between 15 and 30 euros per kilo. A much higher price does not reflect documented additional quality. If the marketing promises effects 10 times better at 10 times the price, treat it as a warning sign.
The supplement pyramid: order of priority
The pyramid image helps clarify what actually matters: at the base are the fundamentals (sleep, nutrition, training). At the next level, Tier 1 supplements: creatine, protein powder, caffeine. On the third, Tier 2: beta-alanine, citrulline, omega-3. At the tip, the optional and context-specific: ashwagandha, vitamin D (if deficient), electrolytes for long sessions.
Ninety-five per cent of supplement benefits come from the first level of the pyramid. The upper levels offer marginal improvements that only make sense once everything below is perfectly established.
Taking apart the best-selling supplements
Weight-loss shakes: basically protein plus additional ingredients of dubious efficacy (Garcinia Cambogia, green tea extract, CLA). The component that works is the protein; the rest is marketing. Buy whey protein directly.
BCAAs: useful only if you train fasted or with insufficient protein intake. If you already eat enough complete protein, BCAAs are redundant because you already get leucine, isoleucine and valine from food. There is no need to pay for them separately.
Glutamine: the most abundant amino acid in muscle. However, the gut consumes almost all oral glutamine before it reaches the muscle. Supplementation produces no demonstrable muscle benefit in healthy people with adequate protein intake.
HMB (beta-hydroxy-beta-methylbutyrate): the only methodologically rigorous meta-analysis (Wilson et al.) shows benefits in absolute beginners and during periods of forced inactivity (injury, surgery). Marginal efficacy in trained people. High price for the benefit obtained.
Frequently asked questions about supplements
Are supplements safe? Those on the Tier 1 list have an excellent safety profile with decades of use. Branded pre-workouts and strong stimulants deserve more caution, especially for people with cardiovascular problems. Check with your doctor if you take medication or have existing health conditions.
At what age can they be taken? Creatine, protein and moderate caffeine are safe in healthy adults. For under-18s, most sports organisations recommend getting all nutrients from food before turning to supplements.
How to read a supplement label without being fooled
The industry uses several marketing tactics you should learn to spot. Proprietary blend: this lets the manufacturer list ingredients without revealing individual doses. It frequently means the effective ingredients are underdosed. Avoid proprietary blends for the ingredients you actually care about. Token doses of popular ingredients: a product listing ashwagandha extract 10 mg does so to appear on the label, not to produce an effect (the effective dose is 300-600 mg). Irrelevant certifications: non-GMO or gluten-free on a supplement that contains no gluten in the first place. These are signals that marketing outweighs substance. How to verify quality: look for third-party certification (NSF Certified for Sport, Informed Sport, USP Verified). These confirm the product contains what the label says and is free of contaminants and banned substances.
Building your stack, step by step
An effective supplement stack is built sequentially, adding one supplement at a time and assessing its impact for at least 4 weeks before adding the next. Month 1: creatine monohydrate, 3-5 g/day. Take it at the same time each day (the timing itself does not matter) to build the habit. Log your lifts at the start. Expect improvements in strength and muscle volume at 4-6 weeks. Month 2 (if the first month calls for it): protein powder, if you do not reach 1.6 g/kg/day through food. Use the shake to fill the gap, not to replace real meals. Month 3 (optional): pre-training caffeine at 3-6 mg/kg, taken 30-45 minutes before. Start with the low dose. Take a week off caffeine every 6-8 weeks. This sequential process has two advantages: you can attribute specific changes to a specific supplement (instead of taking eight things at once and never knowing what works), and you avoid spending money on supplements you may not need if the earlier ones already closed the gaps. Most people discover that creatine plus protein powder (when needed) is all they require, and the rest is noise.
Supplement budget: how to spend well
With 30-50 euros a month you can have a complete, effective stack: generic creatine monohydrate, 1 kg (around 15 euros), which lasts 6 months at 5 g/day. Whey protein concentrate, 1 kg (20-25 euros), 30-33 servings. Anhydrous caffeine, 200 mg per tablet, 100 tablets (8-10 euros). Monthly total: 15-25 euros for the three best-evidenced supplements available. Monthly supplement spending does not need to exceed 30-50 euros to be completely effective. The 100-200 euro monthly stacks sold by premium brands produce, at best, a 5-10 per cent difference compared with the basic stack described here. The price difference does not reflect a proportional difference in results.
Conclusion: simplify your stack, maximise your results
The supplement market is designed to create complexity and dependence. Science simplifies it: creatine, sufficient protein and pre-training caffeine are the only supplements with first-tier evidence for most fitness goals. Everything else is context-specific, optional or ineffective. Put the money saved on unnecessary supplements into better food, quality sleep and a good training programme: the return on investment will be incomparably greater.
Simplicity is a sign of deep knowledge. The most knowledgeable athletes use the simplest stacks. Those with less knowledge fall into the complexity trap set by marketing. Now you have the knowledge.
Where to start
With creatine, enough protein and pre-workout caffeine, you have 95 per cent of what supplements can offer for 10 per cent of the cost of a premium stack. The rest is marketing noise you now know how to identify and avoid. Invest the difference in quality food and hours of sleep.
The two documents worth reading before you buy anything
The tier classification in this article is not an opinion: it lines up with the official position stands of the International Society of Sports Nutrition (ISSN), which are reviews signed by panels of researchers and updated periodically. Two of them cover precisely the two supplements in the top tier.
The creatine stand (Kreider et al., 2017) concludes that supplementation is safe and well tolerated even at doses far above the usual ones, up to 30 g daily for five years in healthy people. The caffeine stand (Guest et al., 2021) puts the effective range at 3 to 6 mg per kilo of body weight and adds a detail that rarely reaches the gym floor: alternative formats — gum, gels, mouth rinses — also improve performance, particularly in aerobic efforts.
| Supplement | Supported dose | When to take it | What usually gets missed |
|---|---|---|---|
| Creatine monohydrate | 3-5 g/day (or 20 g/day for 5-7 days if loading) | Any time; daily consistency is what counts | It works by saturation: rest days included |
| Caffeine | 3-6 mg/kg of body weight | Around 45-60 min before the effort | Tolerance builds fast; cycling preserves the effect |
The reason to cite position stands rather than single studies is simple. One isolated trial can land in any direction; a position stand summarises the body of evidence and commits to a recommendation. When a product has been on the market for years and no scientific society has backed it in a document like that, the absence is already an answer.
- Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. 2017;14(1):18.
- Guest NS, VanDusseldorp TA, Nelson MT, et al. International Society of Sports Nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition. 2021;18(1):1.
More frequently asked questions
Is creatine monohydrate safe for long-term use?
Yes. Creatine monohydrate is one of the most studied sports supplements, with decades of research confirming its safety at standard doses (3–5g/day). Long-term use in healthy individuals shows no kidney or liver harm. The myths about creatine causing kidney damage stem from confusion between creatine and creatinine (a waste metabolite). As always, consult a physician if you have existing kidney issues.
Do I need a loading phase when starting creatine?
No. A loading phase (20g/day for 5–7 days) saturates muscle creatine stores faster but is not required. A standard 3–5g daily dose achieves the same saturation in 3–4 weeks. Skipping the loading phase avoids gastrointestinal discomfort (bloating, cramping) some people experience during loading. Either approach works — the loading phase just reaches full saturation sooner.
Why do BCAAs have poor evidence when protein synthesis requires them?
BCAAs (leucine, isoleucine, valine) are essential for muscle protein synthesis. However, muscle protein synthesis requires ALL essential amino acids simultaneously — not just BCAAs. When you consume BCAAs in isolation, your body still needs the remaining essential amino acids from existing muscle protein breakdown to complete synthesis. If total protein intake is sufficient, adding isolated BCAAs on top provides no additional stimulus. The amino acids in complete protein sources (whey, food) are more effective because they provide the full spectrum.
How does caffeine enhance strength training performance?
Caffeine works through several mechanisms: it competitively blocks adenosine receptors (reducing perceived fatigue), increases calcium release from the sarcoplasmic reticulum (enhancing muscle contractility), and stimulates the central nervous system (improving focus and reaction time). For strength training, the primary benefit is reduced perceived effort — the same weight feels lighter at the same true exertion level. Effective dose: 3–6 mg/kg body weight, 45–60 minutes before training.
Are expensive pre-workout supplements worth it?
Rarely. Most commercial pre-workouts are primarily caffeine (which you can get cheaply) plus beta-alanine (with moderate evidence) plus a long list of ingredients at sub-therapeutic doses included for marketing appeal (the "kitchen sink" approach). The active ingredients with real evidence — creatine, caffeine, beta-alanine, citrulline malate — can be purchased individually at a fraction of the cost of branded pre-workout blends. Read labels and compare doses against therapeutic thresholds rather than brand claims.