Creatine Supplementation: A Dietitian's Guide to Benefits, Dosage and Side Effects

You may have heard about creatine recently, but what actually is it and what is it used for? Creatine has been around for decades and is one of the most well-researched supplements available. It is used across a wide range of people, from athletes and gym-goers to older adults, and even those following a vegan or vegetarian diet. Unlike many supplements on the market, there is a strong body of evidence behind it.

What is Creatine?

Creatine is a naturally occurring compound made in the body from three amino acids: glycine, arginine and methionine. It is produced mainly in the liver, kidneys, and pancreas, and around 95% of it is stored in skeletal muscle. Smaller amounts are also found in the brain.

Creatine is also found in food, mainly in animal-based sources like red meat and seafood. A typical diet provides roughly 1–2 grams per day, which is generally not enough to fully top up muscle stores. This is where supplementation is useful.

People following a vegan or vegetarian diet tend to have lower creatine levels, as plant foods contain virtually none. Research shows that vegetarians have significantly lower muscle creatine stores compared to omnivores, which means this group is often likely to notice the biggest benefit from supplementing.

What Does Creatine Do?

Creatine plays a key role in how your body produces energy. Inside muscle cells, it is stored as phosphocreatine, which is used to quickly regenerate adenosine triphosphate (ATP), the main energy source your body runs on. During short bursts of high-intensity activity like sprinting, lifting, or jumping, your muscles rely heavily on this system to keep up with energy demands.

Supplementing with creatine increases the amount of phosphocreatine stored in your muscles beyond what you get from food alone. Most people’s stores are only around 60–80% full, so there is real room to top them up.

Sports Performance

This is where creatine has the strongest and most consistent evidence. Research shows that creatine supplementation can:

• Improve performance in high-intensity, short-duration exercise like sprinting, weightlifting, and team sports

• Increase strength and power output, with improvements of roughly 5–15% seen across studies in exercises like bench press, squat, and leg press

• Support greater gains in lean muscle mass over time when combined with consistent resistance training

• Help with recovery between repeated bouts of intense exercise

The International Society of Sports Nutrition (ISSN) recognises creatine monohydrate as the most effective ergogenic nutritional supplement currently available for increasing high-intensity exercise capacity and lean body mass during training. These benefits apply to both males and females.

Creatine works best for activities that rely on the phosphocreatine energy system, such as strength training, sprinting, team sports like football or basketball, and interval-based exercise. For longer endurance activities like distance running, the benefit is less pronounced.

Cognition

Beyond exercise performance, there is growing interest in what creatine does for the brain. The brain uses a lot of energy, and just like muscle cells, it relies on the phosphocreatine system to meet its energy needs. So it makes sense that increasing creatine availability might support brain function, and the early research is promising.

Emerging evidence suggests creatine supplementation may support:

•       Short-term memory and working memory, particularly in older adults

•       Cognitive performance during periods of stress, including sleep deprivation

•       Information processing speed

A 2024 systematic review and meta-analysis published in Frontiers in Nutrition looked at 16 randomised controlled trials and found that creatine supplementation had positive effects on overall cognitive function, memory and processing speed in adults. A separate 2024 study in Scientific Reports found that a single high dose of creatine could partially offset the cognitive decline and mental fatigue that comes with sleep deprivation, which has interesting implications for shift workers and people with disrupted sleep.

That said, the cognitive evidence is not as strong as the performance data yet. Some studies have found no significant benefit in healthy, well-rested young adults. Researchers consistently note that people with lower baseline creatine levels, such as vegetarians, older adults, and those under cognitive stress, tend to respond best. The European Food Safety Authority (EFSA) reviewed the evidence in 2024 and concluded that while results are promising, more research is needed before firm conclusions can be drawn across all populations.

The takeaway: creatine looks promising for brain health, particularly in certain groups, but it is not yet at the point where blanket recommendations are supported.

How to Take Creatine

Creatine monohydrate is the most well-researched and cost-effective form available. Other forms exist, such as creatine ethyl ester, buffered creatine, and creatine HCl, but the evidence does not show them to be better than monohydrate. Stick with the basics.

Loading Phase (Optional)

Some people start with a loading phase, taking around 20 grams per day, split into four doses of 5 grams each, for 5–7 days. This fills up muscle stores quickly.

A loading phase is not essential though. Skipping it and going straight to a lower daily dose will get you to the same place, it just takes longer, around 3–4 weeks to fully saturate stores.

Maintenance Dose

Once stores are topped up, 3–5 grams per day is enough to keep muscle creatine levels elevated. This is the right dose for most people and is suitable for long-term use.

When to Take It

Timing is not as important as it is with some other supplements. Taking creatine around your workout, either before or after, is a practical approach. Some research suggests taking it after training alongside a carbohydrate source may help with uptake, as insulin plays a role in how creatine gets transported into muscle cells.

Consistency matters more than timing though. Taking it every day, including rest days, is what keeps stores maintained.

Who Is It For?

Creatine is generally considered safe and beneficial for:

•       Adults doing resistance training or high-intensity sport

•       Vegetarians and vegans, who tend to have lower baseline creatine levels

•       Older adults looking to support muscle mass and potentially cognitive health

If you have a pre-existing kidney condition, speak to your GP or dietitian before starting creatine. It is safe for healthy individuals, but research in those with existing kidney issues is more limited and caution is recommended.

Side Effects:

Fluid Retention

One of the most common concerns about creatine is whether it causes water retention or bloating. Here is what is actually going on.

Creatine is osmotically active, meaning it draws water into cells alongside it. When creatine levels in your muscle cells increase, water follows. This happens inside the muscle cells themselves, not under the skin, so it is different from the puffiness you might associate with eating too much salt or hormonal changes.

In practice, what you might notice:

• A small increase on the scales, typically 1–2 kg, especially in the first week of a loading phase

• Muscles that look slightly fuller

• Some mild digestive discomfort initially in some people

This is a normal response and is actually a sign that the creatine is being absorbed and stored effectively. Research also suggests this intracellular fluid plays a useful role in muscle function and may support muscle protein synthesis. A 2021 review in the Journal of the International Society of Sports Nutrition found that creatine does not always lead to water retention, and the effect varies quite a bit between individuals. Longer-term studies also show that creatine does not significantly change total body water relative to muscle mass.

Tips if fluid retention is a concern:

• Stay well hydrated. Drinking enough water, at least 2–2.5 litres per day, helps your body regulate fluid balance.

• Skip the loading phase. Starting at 3–5 grams per day avoids the bigger initial water shift. You will still reach the same end result, just over a few weeks rather than days.

• Spread your dose. Taking smaller amounts across the day may help reduce any digestive discomfort.

To be clear: some fluid retention can happen early on, particularly with a loading phase. It is happening inside the muscle cells, it is normal, and it is not fat gain. It also fully reverses if you stop taking creatine.

The Bottom Line

Creatine monohydrate is one of the safest and most well-researched supplements available. Taken consistently at the right dose, it can make a real difference to sports performance, muscle strength, and potentially cognitive health, particularly as we get older or in those with lower baseline levels.

Like any supplement, it works best alongside good nutrition, adequate protein, quality sleep, and consistent training. If you would like personalised guidance on whether creatine suits your needs and how to fit it into your overall nutrition plan, feel free to book a consultation.

Author: This blog post was written by Melissa D’Elia (APD)

Disclaimer: The content of this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Please consult with your Dietitian or GP for individualised advice.

References

1.     Kreider RB, et al. International Society of Sports Nutrition position stand: Safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18.

2.     Xu C, et al. The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis. Front Nutr. 2024;11:1424972.

3.     Gordji-Nejad A, et al. Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation. Sci Rep. 2024;14:4937.

4.     EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Creatine and improvement in cognitive function. EFSA Journal. 2024;22(2):e8613.

5.     Candow DG, et al. Heads up for creatine supplementation and its potential applications for brain health and function. Sports Med. 2023;53(Suppl 1):49–65.

6.     Lanhers C, et al. Creatine supplementation and lower limb strength performance: A systematic review and meta-analyses. J Int Soc Sports Nutr. 2021.

7.     Burke DG, et al. Effect of creatine and weight training on muscle creatine and performance in vegetarians. Med Sci Sports Exerc. 2003;35(11):1946–1955.