Creatine

Creatine is the most researched, most reliably effective sports supplement on the market — and, underneath the tub, it’s a small amino-acid-derived molecule your body already makes and stores in muscle. Its job is to recharge your cells’ fastest energy system, which is why it helps you squeeze out an extra rep or a faster sprint, and why researchers are increasingly interested in what it does for the brain.

What is creatine?

Creatine is a non-proteinogenic amino acid derivative — built from amino acids, but not itself used to make proteins. About 95% of your body’s supply sits in skeletal muscle as phosphocreatine, a kind of rechargeable battery for energy. You make some yourself and eat more in meat and fish. The supplement version, creatine monohydrate, is the same molecule in cheap, well-tested powder form.

What does creatine do in the body?

Creatine’s headline job is speed. Your cells run on ATP, but they only keep a couple of seconds’ worth on hand. Phosphocreatine acts like a pit-crew, instantly recharging spent ATP so a muscle can keep firing through a heavy lift or a short sprint. More creatine in the tank means more of these fast recharges before fatigue sets in. The brain uses the same energy system, which is why creatine’s role there is a live and interesting research question.

Where do you get creatine?

The natural food sources are all animal: red meat (especially beef) and fish like herring, salmon and tuna, with smaller amounts in poultry. You’d have to eat a lot of steak to match a supplement, though — one reason creatine monohydrate is so popular, and why vegetarians and vegans, who eat almost none, often see the biggest gains from taking it.

What does the research show?

For strength and power, the evidence is about as strong as it gets. Dozens of randomized controlled trials show creatine plus resistance training reliably builds strength, power and lean mass beyond training alone. For the brain, controlled studies suggest it may sharpen cognition under stress, sleep loss, or low baseline stores — a real and growing signal, if smaller in people who are already well-rested and well-fed. And in older adults, creatine helps training preserve muscle and strength. Few supplements pair this much high-quality human evidence with this low a price.

Is creatine safe?

Creatine has one of the best safety profiles of any supplement, studied for decades at 3–5 grams a day. The main effect newcomers notice is a couple of pounds of water weight as muscle cells draw in fluid — harmless. The recurring kidney-damage worry hasn’t held up in healthy people; if you already have kidney disease, clear it with a doctor first.