Marathon Supplement Science: Separating Evidence from Marketing

The sports supplement industry markets countless products claiming to enhance running performance, recovery, or health. Understanding which supplements have actual scientific support versus which are expensive placebos helps you make informed decisions about what deserves your money.
Caffeine is among the few supplements with robust evidence supporting performance benefits. Moderate doses (3-6 mg per kilogram of body weight) taken 30-60 minutes before exercise improves endurance performance through multiple mechanisms including reduced perceived effort and enhanced fat utilization. Most runners can consume this through coffee or caffeine gels without needing pills. However, benefits vary individually, and some people experience negative effects like stomach distress or jitteriness.
Beta-alanine buffers lactate accumulation during high-intensity efforts, potentially improving performance in efforts lasting 1-10 minutes. Evidence suggests modest benefits for track distances but limited relevance for longer road races where lactate buffering isn’t the primary limiting factor. Side effects include harmless but annoying tingling sensations. Given limited benefits for distance running and the need for weeks of loading doses, beta-alanine isn’t particularly compelling for most runners.
Beetroot juice and nitrate supplements increase nitric oxide production, potentially improving oxygen efficiency and endurance performance. Evidence shows small but consistent benefits for endurance performance, making beetroot juice among the more legitimate supplements. However, benefits are modest, and consuming actual beetroot juice is as effective as expensive supplements. Downsides include bright purple urine and potential digestive issues.
Protein supplements aren’t necessary if you’re eating adequate protein through whole foods, but they provide convenient way to increase protein intake if you’re consistently falling short. Whey protein, casein, and plant-based proteins all effectively support muscle recovery when consumed after workouts. However, whole food protein sources provide additional nutrients and satiety that isolated protein powder lacks. Use supplements to fill gaps rather than as primary protein source.
Glucosamine and chondroitin are frequently taken for joint health, but evidence of benefits is weak and inconsistent. Some studies show modest improvements in joint pain while others show no effect beyond placebo. They’re generally safe but expensive given questionable efficacy. Similarly, collagen supplements marketed for joint health lack compelling evidence despite popularity. Your money is better spent on high-quality whole foods that provide comprehensive nutrition.
Multivitamins seem beneficial in theory but show limited benefits in research for people eating reasonably varied diets. Specific deficiencies deserve specific supplementation—vitamin D if you’re deficient, iron if tests show low levels, B12 for strict vegetarians. But taking multivitamins “just in case” usually creates expensive urine without actual health benefits. Food-first approach with targeted supplementation for tested deficiencies is more effective than untargeted multivitamin use.
Most supplements marketed to runners have either no scientific support or such modest effects that they don’t justify cost. Companies exploit regulatory gaps allowing health claims without proving effectiveness. Before purchasing supplements, research actual scientific evidence (not company marketing) supporting claimed benefits. Consider whether whole foods could provide similar benefits more cheaply. Recognize that supplements can’t compensate for poor training, inadequate sleep, or deficient nutrition from whole foods. They’re called supplements because they’re meant to supplement already solid training and nutrition foundations, not substitute for them. The unsexy truth is that consistent training, adequate sleep, stress management, and nutritious whole food diet produce far more performance improvement than any supplement regimen. Most runners would see better results investing supplement money in higher quality food, better running shoes, or coaching than in pills promising marginal performance gains.