Most supplements are expensive urine. A few earn their place. Here's which, and what the evidence actually says.
Awaiting clinical review. These ratings are written carefully from the research and our sources, but a qualified clinician hasn't signed them off yet. How we review.
Supplements aren't approved by the FDA for safety or effectiveness before they're sold. Choose products with third-party testing (such as NSF Certified for Sport or Informed Sport), and talk to your doctor or pharmacist before starting one, especially if you take medication, are pregnant, or have a health condition.
Consistent results across many good studies.
For strength, power and muscle gain alongside training
The most researched sports supplement. Taken daily while strength training, it tends to add a little more strength and muscle than training alone. Plain monohydrate is as good as any fancier form.
Dose studied: 3 to 5 g a day, with water.
Careful: Talk to your doctor first if you have kidney disease or are pregnant.
Sources: Kreider et al. (2017), ISSN position stand: creatine
For meeting a daily protein target
Not magic: a convenient way to reach the protein you'd otherwise get from food. Whey, casein, soy and pea all work; choose what suits your stomach and your ethics.
Dose studied: As needed to reach your daily target, often 20 to 40 g a serving.
Careful: Choose third-party tested products, especially if you compete.
Sources: Jäger et al. (2017), ISSN position stand: protein and exercise
For endurance, power and alertness
Consistently improves performance in many kinds of exercise. Most people get it from coffee; pre-workouts often contain a lot more than you'd guess.
Dose studied: around 3 to 6 mg per kg about an hour before training.
Careful: Mind your sleep. The FDA cites about 400 mg a day as an amount not generally associated with negative effects in healthy adults; less if you're sensitive, pregnant, or have heart or anxiety conditions.
Sources: Guest et al. (2021), ISSN position stand: caffeine and exercise performance · FDA: How much caffeine is too much?
Good support, for a specific kind of training or situation.
For hard efforts lasting roughly one to four minutes
Can help high-intensity efforts in that window. Less useful for heavy lifting or long endurance. The tingling is harmless and fades.
Dose studied: about 4 to 6 g a day, split into smaller doses, for several weeks.
Sources: Trexler et al. (2015), ISSN position stand: beta-alanine
For endurance performance
Beetroot juice and other nitrate sources can modestly help endurance performance, more so in recreational than elite athletes.
Careful: It may turn your urine pink. Don't be alarmed.
For long or hot sessions with heavy sweating
Useful when you sweat a lot for a long time. For a 45-minute class, water and your next meal are usually enough.
Careful: Check the sugar and caffeine content of electrolyte drinks.
Early or mixed research. Promising at best.
For recovery and training outcomes
Good for general health as part of a diet with oily fish. Evidence that it improves training results is still emerging.
Careful: Check with your doctor if you take blood thinners.
For joints and connective tissue
Some early research on tendons and joints, often alongside specific exercise. It's a poor protein source for muscle compared with whey or soy.
For stress and sleep
Some small studies on stress and sleep. Quality varies widely between products.
Careful: There are reports of liver injury. Avoid in pregnancy, and ask your doctor if you have a thyroid condition or take other medication.
For training performance
Most of the effect comes from the caffeine. Proprietary blends make doses hard to judge, and some products have contained banned stimulants.
Careful: Count the total caffeine. Choose third-party tested products.
Sources: Harty et al. (2018), Multi-ingredient pre-workout supplements: a brief review
Little benefit for most people who train.
For performance, if you're not deficient
Correcting a real deficiency matters for health. Beyond that, there's little evidence it improves training. Ask your doctor about a blood test rather than guessing.
Careful: Very high doses can be harmful. Get tested first.
For muscle building, if you already eat enough protein
If you hit your protein target, branched-chain amino acids add little. They're mostly a flavored drink.
Confident labels, not much else. Sometimes risky.
For raising testosterone
Over-the-counter "boosters" have little good evidence behind them, and some have been found to contain undeclared drugs. If you're worried about your testosterone, see a doctor and get a proper blood test.
Careful: Products sold as boosters have been found to contain hidden ingredients.
For fat loss
Mostly stimulants with confident labels. They don't replace a calorie deficit, and some carry real heart risks.
Careful: Avoid if you have heart, blood pressure or anxiety conditions.