Creatine is the most studied supplement in all of sports nutrition, with hundreds of trials behind it — and, unusually for this field, the headline claims have held up. Your body already makes creatine and stores most of it in muscle as phosphocreatine, a rapidly available energy reserve. During short, hard efforts — a heavy set, a sprint — phosphocreatine helps regenerate ATP, the cell’s energy currency. Supplementing simply tops up those stores, and the benefits follow from there [1].
Strength, power and muscle
The clearest, most consistent effect is on the ability to train hard and build muscle. Pooling randomized trials in adults under 50, a recent meta-analysis found that creatine combined with resistance training produced greater strength gains than training with a placebo — roughly 4 kg more on upper-body lifts and 11 kg more on lower-body lifts [2]. The effect on muscle size is real but smaller: studies using direct imaging (MRI, CT and ultrasound) show a modest additional increase in muscle thickness on top of what training alone delivers [3]. In practice, creatine won’t build muscle for you — it lets you get a little more out of the training you already do.
Especially valuable with age
Muscle and strength decline with age (sarcopenia), and this is where creatine may earn its keep most. In older women, adding creatine to resistance training improved strength beyond training alone, with the benefit clearest when programs ran for at least 24 weeks [4]. Because maintaining strength underpins independence, balance and fall prevention later in life, this is arguably as important as any gain a young athlete sees.
The brain runs on the same system
Your brain is metabolically hungry and relies on the same creatine–phosphocreatine energy shuttle as muscle, which is why researchers have turned to it as a possible cognitive aid. The evidence is now substantial but nuanced. A meta-analysis of randomized trials found creatine improved memory, with the strongest effect in older adults aged 66–76 [5]. A larger 2024 review reached a similar verdict: benefits for memory, attention and information-processing speed, but no measurable effect on overall cognition or executive function — and bigger gains in people who were older, under strain, or had a relevant health condition than in healthy young adults [6].
The practical reading: creatine is not a general “smart pill” for the already-sharp and well-rested, but it appears to help when the brain’s energy system is stressed — by ageing, sleep loss or illness.
How to take it, and is it safe?
The dosing is refreshingly simple. Around 3–5 g of creatine monohydrate per day — the cheapest and best-studied form — is enough; a high-dose “loading phase” fills muscle stores faster but isn’t required, and steady daily intake reaches the same level within a few weeks [1][7].
On safety, creatine is one of the most reassuring supplements available. Long-term use has been studied at up to 30 g/day for five years in healthy people without harm [1]. The persistent worries are largely myths: in people with healthy kidneys it does not cause kidney damage, it is not an anabolic steroid, and it does not cause hair loss or dehydration — an expert review worked through these one by one and found the scary claims unsupported [7]. (As always, anyone with existing kidney disease or who is pregnant should check with their doctor first.)