Sports Supplements: Evidence Review
What the research actually supports (and what's marketing hype)
The Supplement Industry Reality
The sports supplement industry is worth billions, but most products have weak evidence, exaggerated claims, or negligible real-world effects. This review focuses on supplements with robust, peer-reviewed evidence for performance enhancement or recovery in athletes.
Key principle: Supplements are called "supplements" for a reason—they supplement a solid nutrition foundation. Fix your diet first. No pill replaces sleep, proper training, or adequate calories.
Evidence-Based Tiers
Tier 1: Strong Evidence (Worth Considering)
Caffeine
Effect: 2-4% performance improvement in endurance, strength, power, and cognitive tasks
Mechanism: Adenosine receptor antagonist → reduced perceived exertion, enhanced CNS drive
- • Dose: 3-6 mg/kg bodyweight (200-400mg for 70kg athlete)
- • Timing: 45-60 min before exercise
- • Forms: Coffee, caffeine pills, gels with caffeine
- • Caution: Tolerance builds with daily use, GI issues in some individuals
✓ Verdict: One of the most effective legal performance enhancers.
Creatine Monohydrate
Effect: 5-15% strength/power gains, enhanced muscle mass, improved high-intensity repeat efforts
Mechanism: Increases muscle phosphocreatine stores → faster ATP regeneration during short, intense efforts
- • Dose: 3-5g daily (no loading phase needed)
- • Timing: Doesn't matter (cumulative effect)
- • Best for: Strength athletes, sprinters, team sports. Less useful for pure endurance.
- • Side effect: 1-2kg water weight gain (stored with creatine in muscle)
✓ Verdict: Most researched supplement, highly effective for strength/power.
Beta-Alanine
Effect: 2-3% performance boost in efforts lasting 1-4 minutes (400m-1500m, VO2max intervals)
Mechanism: Increases muscle carnosine → buffers hydrogen ions (reduces acidosis during high-intensity work)
- • Dose: 3-6g daily for 4+ weeks (cumulative loading)
- • Best for: Middle-distance runners, rowers, 1500m swimmers
- • Not useful for: Marathons, ultras, low-intensity steady-state
- • Side effect: Harmless tingling sensation (paresthesia)
✓ Verdict: Effective for specific event types (1-4 min high-intensity).
Sodium Bicarbonate (Baking Soda)
Effect: 2-3% performance boost in 1-10 minute high-intensity efforts
Mechanism: Buffers acidosis (similar to beta-alanine but acute, not cumulative)
- • Dose: 0.3 g/kg bodyweight 60-90 min before exercise
- • Example (70kg): ~21g sodium bicarbonate
- • Caution: High GI distress risk—practice in training
- • Alternative: Sodium citrate (better GI tolerance)
⚠ Verdict: Effective but GI side effects limit practicality.
Beetroot Juice / Nitrate Supplementation
Effect: 1-3% endurance improvement, reduced oxygen cost of exercise
Mechanism: Nitrate → nitric oxide → improved blood flow and mitochondrial efficiency
- • Dose: 300-600mg nitrate (500ml beetroot juice) 2-3 hours before exercise
- • Or: 70ml concentrated beetroot shot
- • Best for: Time trials, 5-40 min efforts, altitude
- • Note: Avoid mouthwash (kills nitrate-reducing bacteria)
✓ Verdict: Small but consistent effect, worth trying for TTs and races.
Tier 2: Moderate Evidence (Situational Use)
Omega-3 Fatty Acids (Fish Oil)
Effect: Reduced inflammation, possible recovery enhancement
- • Dose: 2-4g combined EPA+DHA daily
- • Note: Takes weeks to build up in tissues
Vitamin D
Effect: Corrects deficiency (if present), supports bone health and immune function
- • Dose: 1000-2000 IU daily (or based on blood test)
- • Check serum levels: Target >30 ng/mL
Protein Powder (Whey, Casein, Pea)
Effect: Convenient protein source, no advantage over whole food protein
- • Useful for meeting daily protein targets (1.6-2.2 g/kg)
- • Whey: fast-digesting (post-workout)
- • Casein: slow-digesting (before bed)
Tier 3: Weak Evidence (Save Your Money)
BCAAs (Branched-Chain Amino Acids)
Verdict: No advantage if you're already consuming adequate protein. Redundant and expensive.
Glutamine
Verdict: Weak evidence for immune support, no performance benefit. Save your money.
Antioxidant Megadoses (Vitamin C, E)
Verdict: May actually blunt training adaptations by reducing oxidative stress signals. Get antioxidants from food.
Collagen Supplements
Verdict: Weak evidence for tendon/joint health. Inferior protein source (incomplete amino acid profile). Not harmful, but not impressive.
Testosterone Boosters (Tribulus, etc.)
Verdict: No evidence for increasing testosterone in healthy individuals. Marketing hype.
Tier 4: Avoid (Harmful or Banned)
Anabolic Steroids / SARMs
Verdict: Illegal in sport, serious health risks (liver damage, cardiovascular issues, hormonal disruption). Don't.
Ephedra / DMAA
Verdict: Banned substances with cardiovascular risks. Not worth it.
Chronic NSAID Use (Ibuprofen, etc.)
Verdict: Impairs muscle protein synthesis, increases GI/cardiovascular risks. Occasional use OK, chronic use harmful.
Recommended Supplement Stack for Athletes
Minimalist Evidence-Based Approach
Baseline (Everyone)
- • Vitamin D: 1000-2000 IU daily (if insufficient sun exposure or low serum levels)
- • Omega-3: 2-4g EPA+DHA daily (if not eating fatty fish 2-3x/week)
- • Protein powder: Only if struggling to hit 1.6-2.2 g/kg from food
Strength/Power Athletes (Add)
- • Creatine: 3-5g daily
- • Caffeine: 3-6 mg/kg pre-training (strategically, not daily)
Middle-Distance Athletes (Add)
- • Beta-alanine: 3-6g daily (if racing 800m-1500m, 400m track, etc.)
- • Caffeine: Pre-race
- • Beetroot juice: 2-3 hours pre-race
Endurance Athletes (Add)
- • Caffeine: Pre-race or mid-race gel
- • Beetroot juice: Pre-time trial
- • Iron: Only if deficient (blood test required)
Budget-Conscious Hierarchy
If money is limited, prioritize in this order:
- 1. Quality food (whole diet trumps supplements)
- 2. Vitamin D (if deficient—cheap and impactful)
- 3. Caffeine (coffee = essentially free, proven performance boost)
- 4. Creatine (if strength/power athlete—very cheap)
- 5. Protein powder (only if can't hit protein targets from food)
- 6. Everything else (marginal at best)
Key Takeaways
- Most supplements have weak evidence—fix diet and sleep first
- Caffeine (3-6 mg/kg) is the most effective legal performance enhancer
- Creatine (3-5g/day) highly effective for strength/power, not endurance
- Beta-alanine useful only for 1-4 minute high-intensity events
- BCAAs, glutamine, "test boosters" = waste of money
Key Research References
- • Maughan, R. J., et al. (2018). IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine, 52(7).
- • Burke, L. M. (2017). Practical Sports Nutrition. Human Kinetics.
- • Peeling, P., et al. (2018). Evidence-based supplements for the enhancement of athletic performance. International Journal of Sport Nutrition and Exercise Metabolism, 28(2).
