Most athletes need fewer supplements than the industry suggests, but a handful have strong evidence behind them. The ones worth your money fall into two categories: performance supplements that directly improve how you train or compete, and micronutrients that fill gaps your training creates. Everything else is either unproven or only useful in narrow situations.
Creatine for Strength and Power
Creatine monohydrate is the most studied performance supplement in sports nutrition, and the evidence is overwhelming. It works by helping your muscles regenerate their primary short-burst energy source faster, which means more reps, more power, and over time, more muscle. It benefits any sport involving repeated high-intensity efforts: sprinting, lifting, team sports with bursts of speed, even repeated interval work.
The traditional approach is a loading phase of 20 to 30 grams per day, split into four to six smaller doses, for about five to seven days. After that, 3 to 5 grams daily maintains elevated levels. If you skip loading and just take the maintenance dose from the start, you’ll reach the same saturation point in about three to four weeks. Creatine doesn’t need fancy timing or cycling. Take it consistently with a meal, and it works.
Protein for Recovery
Protein supplements aren’t magic, but they solve a logistics problem. Getting enough total protein across the day matters more than any single shake, but a supplement makes it easier to hit your targets, especially around training. For most athletes, 1.6 to 2.2 grams of protein per kilogram of body weight daily supports muscle repair and growth.
Per-meal dosing matters too. Each protein-rich meal should contain enough of the amino acid leucine to flip the switch on muscle rebuilding. Research points to roughly 3 grams of leucine as the threshold for maximizing that response, which translates to about 30 to 40 grams of a high-quality protein like whey. Younger athletes can get away with slightly less per meal (around 20 grams), while older athletes generally need more to trigger the same effect. Whey protein is popular because it’s leucine-rich and digests quickly, but any complete protein source works if the total amount is sufficient.
Caffeine for Endurance and Focus
Caffeine improves performance across nearly every type of exercise: endurance, strength, power, and repeated sprints. It works primarily by reducing your perception of effort, meaning you can push harder before your brain tells you to stop. At higher doses, it may also have direct effects on muscle function.
The effective range is 2 to 6 milligrams per kilogram of body weight, taken about 30 to 60 minutes before training or competition. For a 70-kilogram athlete, that’s roughly 140 to 420 milligrams, or about one to three cups of strong coffee. Higher doses (up to 9 mg/kg) have been studied but don’t reliably improve performance further and increase the likelihood of jitteriness, a racing heart, and disrupted sleep. Start at the lower end and find what works for you. If you’re a regular coffee drinker, you may need slightly more to feel the same effect, but habitual use doesn’t eliminate the performance benefit entirely.
Beetroot Juice for Endurance
Beetroot juice works because it’s rich in dietary nitrate, which your body converts into a molecule that widens blood vessels and helps muscles use oxygen more efficiently. The benefit is most pronounced in sustained efforts lasting a few minutes to several hours: running, cycling, rowing, swimming.
The Australian Institute of Sport recommends 350 to 500 milligrams of nitrate (about 6 to 8 millimoles), consumed two to three hours before exercise. A single shot of concentrated beetroot juice typically delivers this amount, but check the label. The product needs to contain at least 5 to 6 millimoles of nitrate to be effective. Taking more than 10 to 12 millimoles doesn’t add further benefit. The gains are modest, typically a 1 to 3 percent improvement in time-trial performance, but at a competitive level, that margin matters.
Beta-Alanine for High-Intensity Buffering
Beta-alanine is useful for efforts lasting roughly one to four minutes, the range where acid buildup in your muscles becomes the limiting factor. Think 400- to 1500-meter running, hard cycling intervals, or a wrestling match. It works by increasing your muscles’ stores of a buffering compound that neutralizes the acid produced during intense exercise.
The recommended dose is 5 to 6 grams per day, split into smaller doses with meals (about 2 grams each) to reduce the most common side effect: a harmless but sometimes intense tingling sensation on the skin, known as paresthesia. It takes several weeks of daily supplementation to build up sufficient muscle stores, so this isn’t something you take the morning of a race and expect results. If your sport rarely pushes you into that sustained high-intensity zone, beta-alanine probably won’t make a noticeable difference.
Electrolytes for Long Training Sessions
For sessions under an hour in moderate conditions, water is usually enough. Once you’re training hard for longer than that, especially in heat, replacing sodium becomes important. Sodium is the primary electrolyte lost in sweat, and losing too much without replacing it can impair performance and, in extreme cases, become dangerous.
General guidelines suggest adding 0.5 to 0.7 grams of sodium per liter of fluid you drink during exercise. That’s roughly 500 to 700 milligrams per liter. Individual sweat rates and sodium concentrations vary enormously, so some athletes need significantly more. If you notice white streaks on your clothing after training, you’re likely a heavy salt sweater and should pay closer attention to replacement. Most commercial sports drinks contain some sodium, but athletes doing long endurance events in the heat often need additional electrolyte tabs or capsules.
Vitamin D and Iron: The Two Gaps That Matter Most
Vitamin D insufficiency is common in athletes, particularly those who train indoors or live at higher latitudes. The standard threshold for sufficiency is a blood level of 30 nanograms per milliliter, but research suggests elite athletes should aim for around 40 ng/mL. Below 20 ng/mL is considered deficient and can impair muscle function, bone health, and immune resilience. A simple blood test tells you where you stand. If you’re low, supplementing with vitamin D3, typically 1,000 to 4,000 IU daily depending on your starting level, is the standard approach.
Iron deficiency is especially prevalent among female endurance athletes, though male athletes aren’t immune. Ferritin, the blood marker for iron stores, should be at least 30 micrograms per liter in athletes over 15. Values below 15 indicate depleted stores. Even mildly low iron can reduce oxygen delivery to working muscles, causing unexplained fatigue and declining performance that no amount of training will fix. Don’t supplement iron without a blood test, because excess iron causes its own problems. If your ferritin is low, work with a professional to determine the right dose.
Collagen and Vitamin C for Tendons
If you’re dealing with tendon issues or want to support connective tissue health, the combination of gelatin (or hydrolyzed collagen) and vitamin C has emerging support. One well-known study found that 15 grams of gelatin combined with about 50 milligrams of vitamin C, taken one hour before exercise, increased collagen-building activity in ligament tissue. The protocol is simple: mix the gelatin or collagen into a drink, take it about an hour before a short session of tendon-loading exercises (such as calf raises or isometric holds), and let the increased amino acid availability do its work. This isn’t a general performance supplement. It’s specifically targeted at connective tissue repair and resilience.
Avoiding Contaminated Products
Supplement contamination is a real risk for competitive athletes. Products can contain banned substances that don’t appear on the label, either from poor manufacturing practices or intentional spiking. NSF’s Certified for Sport program tests for over 290 banned substances including stimulants, narcotics, steroids, diuretics, and masking agents, along with potentially harmful contaminants. Informed Sport offers a similar certification. If you’re subject to drug testing, only use products carrying one of these third-party seals. Even recreational athletes benefit from choosing certified products, because the same contaminants that trigger a positive test can also pose health risks.
What You Probably Don’t Need
The list of supplements with strong evidence is short. BCAAs are unnecessary if your total protein intake is adequate, since whole protein sources already contain them. Glutamine has not been shown to improve performance or recovery in well-nourished athletes. Testosterone boosters sold over the counter don’t meaningfully raise testosterone levels. Most “pre-workout” blends are just caffeine with underdosed amounts of other ingredients at prices far exceeding what you’d pay for the effective components separately.
The foundation always comes first: enough calories, enough protein spread across the day, adequate sleep, and a training plan that makes sense. Supplements fill in the margins once that foundation is solid. If your diet and recovery are a mess, no pill or powder will compensate.