Sports Supplements That Actually Work (And the Ones That Don't)

The sports supplement industry is worth tens of billions of dollars and built on a simple psychological hack: training is hard, eating enough is hard, swallowing a pill is easy. That gap between effort and ease is where the marketing lives.

Here's the reality. Only a handful of supplements have consistently held up in well-designed studies. Even then, the effects are small, context-dependent, and only relevant on top of solid training, real food, and actual sleep. If you're not eating enough carbohydrates on long runs, not sleeping, or not lifting consistently, no powder or capsule is going to fix that.

A few ground rules before we get into it. Supplements are the last one or two percent, not the foundation. Always test anything new in training, never on race day. Buy products that are third-party tested, ideally NSF Certified for Sport or Informed Sport, because contamination is a documented problem in this industry. If you're managing a medical condition, under 18, or subject to anti-doping rules, talk to someone with actual credentials before trying anything.

We cover the evidence on supplements, fueling, and fitness industry claims at length on Your Diet Sucks. Here's what the research actually shows.

What Sports Supplements Are Backed by Research

Caffeine

Caffeine is the most consistently effective performance enhancer across sports. Its primary benefit is central nervous system: it reduces perceived exertion and increases alertness, letting athletes sustain harder efforts longer. That effect shows up across endurance, sprint, and team sports in the literature.

The catch: the benefit is real but modest, typically a 1 to 3% performance improvement. Individual response varies significantly based on genetics and how much caffeine you habitually consume. Some athletes just get jittery and nauseous with no performance upside. Chronic high use can tank your sleep, which has a much larger negative effect on recovery and adaptation than any short-term caffeine benefit.

Best for: endurance athletes racing half-marathon to marathon distance, team sport athletes, anyone competing in short intense events where mental sharpness matters. Less useful for ultrarunners unless carefully timed late in a race. For daily training, consider saving it for key sessions rather than using it constantly and building tolerance.

Creatine

Creatine monohydrate is the most research-supported supplement for strength and power. Decades of study confirm it increases phosphocreatine availability in muscle, improving high-intensity repeatability and supporting greater training volume in the weight room. Over time, that translates to measurable increases in strength and muscle mass.

The ergogenic effects are largely restricted to short-duration, high-intensity work, roughly 10 to 60 seconds. It does not meaningfully improve steady-state endurance performance. Some athletes dislike the body composition shifts from increased water retention, though that water retention is part of the mechanism.

Best for: strength and power athletes, team sports players, and hybrid athletes combining endurance with resistance training. Vegetarians and vegans tend to see the largest improvements due to lower baseline muscle creatine stores. Endurance athletes who don't lift consistently are unlikely to notice much.

Sodium Bicarbonate (Baking Soda)

Sodium bicarbonate buffers hydrogen ions in the blood, delaying fatigue during very high-intensity efforts lasting one to ten minutes. It's one of the oldest and most reliable buffering strategies in sport science, which is also why it's not exactly trendy.

The benefits are highly event-specific. Racing an 800m, rowing 2k, or doing repeated all-out intervals? There's a reasonable case here. Competing in anything beyond roughly 15 minutes? Acidity isn't the limiting factor at that point, so the advantage disappears. The bigger practical problem: GI side effects including cramps, nausea, and diarrhea are extremely common. Encapsulated products can reduce but not eliminate the risk.

Best for: middle-distance runners, rowers, track cyclists, athletes in sports involving repeated high-intensity bouts. For ultrarunners, marathoners, and triathletes, the downsides outweigh the nonexistent upside. More threshold training will do more for your performance than this.

Beta-Alanine

Like sodium bicarbonate, beta-alanine improves buffering capacity, but by raising intramuscular carnosine levels. It's consistently shown to improve performance in the 1 to 4 minute range of high-intensity effort, and unlike bicarb, the effect builds over weeks of daily supplementation rather than from acute dosing.

The limitations: benefits are specific to that effort duration, modest in size, and require sustained daily use. Most endurance athletes spend relatively little race time at those intensities. The main side effect is paresthesia, a harmless but sometimes uncomfortable skin tingling.

Best for: athletes in events like the 400m to 1500m, rowing, swimming, and VO2-max interval training blocks. Recreational athletes targeting long steady-state races are unlikely to notice much impact.

Nitrates (Beet Juice)

Nitrates improve exercise efficiency by reducing the oxygen cost of submaximal work. You maintain the same pace with slightly less effort, which has obvious appeal for endurance events. The evidence is strongest for time-trial efforts of 5 to 30 minutes, though some studies extend benefits into longer events.

The effect is relatively small, around 1 to 2% in most studies, and the benefit diminishes in well-trained and elite athletes. Beet juice concentrates can cause GI issues. Daily loading protocols are inconvenient. The supplements are expensive compared to just eating nitrate-rich vegetables.

Best for: recreational to sub-elite endurance athletes racing from 5k to marathon who don't consume many leafy greens or beets. Less useful for elite athletes, where marginal gains from nitrates may be negligible. Beets are also just good, so there's no reason not to eat them.

What About Protein Powder?

Protein is essential for muscle repair and adaptation, and powders offer a convenient way to hit daily targets. The evidence supports roughly 20 to 30 grams spaced throughout the day, with particular attention to post-exercise intake.

Protein powders are only "necessary" if you're not meeting your protein needs through food. Whole-food sources also provide additional nutrients, fiber, and satiety that a shake doesn't. Over-indexing on protein supplementation can crowd out carbohydrates, which most endurance athletes are already under-consuming.

Best for: athletes with high protein needs, people eating mostly or entirely plant-based, and anyone with a schedule that makes eating enough whole food genuinely difficult. If you're already hitting daily targets through diet, powder adds convenience but not much else.

The Bottom Line on Sports Supplements

Plenty of other supplements, including ketones, collagen, and antioxidant blends, have shown promise in individual studies. The reproducibility is poor. Single studies are not the standard of evidence worth acting on.

The ones with the most reliable evidence behind them: caffeine, creatine, sodium bicarbonate, beta-alanine, and nitrates. Used thoughtfully and in the right context, they can sharpen the edges of a well-built training plan. They will not substitute for one.

If the supplement is making promises that outpace the research, that's not a coincidence. The industry is built on selling you a gap between how you train and how you wish you trained. The most reliable performance intervention is still the boring one: fuel enough, sleep enough, train consistently.

Want more on what the evidence actually says about nutrition and performance? The Your Diet Sucks podcast goes deep on the science every episode. Or join the conversation on Patreon, where Kylee and I dig into listener questions and cover the research that didn't make it into the main feed.

References

Grgic, J., Trexler, E. T., Lazinica, B., & Pedisic, Z. (2018). Effects of caffeine intake on muscle strength and power: A systematic review and meta-analysis. Journal of the International Society of Sports Nutrition, 15(1), 11. https://doi.org/10.1186/s12970-018-0216-0

Lanhers, C., Pereira, B., Naughton, G., Trousselard, M., Lesage, F.-X., & Dutheil, F. (2017). Creatine supplementation and upper limb strength performance: A systematic review and meta-analysis. Sports Medicine, 47(1), 163–173. https://doi.org/10.1007/s40279-016-0571-4

Carr, A. J., Hopkins, W. G., & Gore, C. J. (2011). Effects of acute alkalosis and acidosis on performance: A meta-analysis. Sports Medicine, 41(10), 801–814. https://doi.org/10.2165/11591440-000000000-00000

Hobson, R. M., Saunders, B., Ball, G., Harris, R. C., & Sale, C. (2012). Effects of beta-alanine supplementation on exercise performance: A meta-analysis. Amino Acids, 43(1), 25–37. https://doi.org/10.1007/s00726-011-1200-z

Jones, A. M. (2014). Dietary nitrate supplementation and exercise performance. Sports Medicine, 44(S1), 35–45. https://doi.org/10.1007/s40279-014-0149-y