Creatine: What Is It, When To Take it, Benefits & Side Effects

  • By Dr Paul Rimmer BSc (Hons), MSc, PhD
  • 4 minute read
Creatine: What Is It, When To Take it, Benefits & Side Effects

Everything you need to know about Creatine. What it is, how it works and what it can do for you.

Creatine is one of the most well researched and effective supplements on the market.

A must for muscle builders everywhere. 

But despite its popularity, there are still a number of myths surrounding creatine, Including exactly what it is... how it works... and who it is useful for.

In this article we will address all those questions. Looking at the mechanics of creatine; its structure, function and application.

Highlighting some of the lesser-known but research-backed benefits of this fairly cheap, widely available super fuel.

What is creatine?

Creatine is a naturally occurring amino acid with food sources including animal proteins - especially red meat and seafood. It can also be synthesized from the amino acids methionine, arginine and glycine. 

A diet containing animal protein can provide the body with ~1g of creatine per day and another 1g is synthesized in the liver and kidneys.

Our muscles are responsible for around 95% of our body’s stores, with the other 5% being in our brain and testes.

Around two-thirds of creatine in our muscles is in the form of phosphocreatine (PCr). This is an important energy store in the body and a major reason as to why we want to maximize creatine stores

As our dietary sources of creatine are mostly from consumption of animals and amino acids found in protein, it is often suggested that vegans and vegetarians should supplement with creatine.

A no-brainer for muscle builders

It is likely that our individual response to creatine supplementation is partially determined by the amount we consume via diet and synthesize naturally. So some people may find they are more responsive to creatine than others.

That said, creatine supplementation is likely to be useful for fully saturating muscle stores. Even for meat eaters. This is due to the saturation potential being much higher than we can typically get from food and natural rates of synthesis.

So, based on cost and availability, creatine supplementation is a no-brainer for muscle builders looking to gain its benefits.

Use among athletes is very common. Showing performance benefits in short duration and repeated bouts of high intensity exercise. With perhaps even ‘signal’ adaptations to support recovery.

Because creatine has a role in both muscle and brain metabolism, it has been investigated for injury prevention, slowing the progression of several brain diseases and recovery from brain trauma.  

How does creatine work?

When stored in our muscles as PCr, creatine is an important part of our body's energy system. Providing power when demand is rapid and high.

Our body’s energy substrate is called Adenosine Tri-Phosphate (ATP) and when it loses a phosphate, this facilitates a release in energy. In muscles, that energy causes movement.

What we have left is called Adenosine Di-Phosphate (ADP).

To keep producing energy, ATP needs to be recycled from ADP. And although this can happen using other fuels - such as carbohydrates and fats - to support the process. PCr can almost immediately donate phosphate to recycle ATP without additional time-consuming metabolic processes.

This means the more PCr we have... the more ATP we can provide... and the more high-intensity work we sustain, for longer. 

Which allows for increased workout volumes at higher loads/power outputs. Which translates into better quality training and faster adaptations.

There is also some evidence that creatine might also have a direct signalling effect on muscle growth by ‘switching on’ anabolic pathways.

In the elderly in particular, it appears creatine may also positively effect specialist parts of our cells that produce muscle proteins. Which may help protect against age-related declines in muscle quality.

What is the best form of creatine?

Creatine comes in many different forms, the most widely researched and demonstrated to be effective form is ‘creatine monohydrate’.

Creatine monohydrate can cause some people digestive issues, especially if not consumed with sufficient water. Other forms like micronized creatine are absorbed a little easier, so might be preferable. 

All forms of creatine will typically cause weight gain. This is because it increases water content in muscles to maintain the correct concentration levels. This could be a issue for weight class athletes, or endurance athletes who are concerned with maximizing power to weight ratio.

In these situations, creatine can be cycled to maximize performance and adaptations during certain high intensity or strength training blocks. Then reduced around competition/weigh-ins if needed.

How do you take creatine?

There are many different forms of creatine available on the market, but creatine monohydrate is the cheapest and most effective. Another option is micronized creatine monohydrate, which dissolves in water more easily.

Typical advice for creatine is to go through a ‘loading phase’ of around 20g per day for 5-7 days (usually in 4 doses of 5g). Then onto a 'maintenance phase' of 5g per day.

You could also choose to dose creatine on a grams per kg of bodyweight basis. Using the same pattern as above but at a dose of 0.3g/kg.

So for example, a 100kg athlete would need (100kg x 0.3g =) 30g of creatine per day in the loading phase.  

Who shouldn’t take creatine?

One of the most persistent myths is that creatine is damaging to kidneys. As we mentioned earlier, creatine is ‘metabolized’ in the body via the kidneys - and one of the by products is called creatinine.

Creatinine is naturally elevated when consuming a high protein diet - sometimes with creatine supplementation - after intense exercise when we 'damage' the body.

This link with damage - especially to the kidneys - was naturally a cause for concern when using creatine.

No link between creatine (or creatinine) and kidney damage

However, it has been clinically shown (repeatedly) that rises in creatinine through creatine use are NOT related to any issues with kidney function.  

These studies include men, women, athletes, the elderly - and even one case of a person with just one kidney!

The only issues involving creatine have been associated with drug use in body builders. Which is known to cause stress and damage to the kidneys.

Therefore, creatine has been shown to be very safe, even for long periods of sustained usage.


Creatine is naturally occurring in meat and is also synthesized in the body.

Creatine supplementation is likely to maximize creatine stores in most people.

Creatine allows the storage of more phosphate, which can be used to recycle ATP (our energy currency) rapidly.

Creatine can improve performance in strength and high intensity exercise and may boost muscle growth by improving training ‘quality’ and perhaps signal muscle building process.

Creatine is safe to use at effective doses.

Further Reading:

  1. Safety and efficacy of creatine supplementation in exercise, sport, and medicine.

    Effects of Creatine Supplementation on Renal Function: A Systematic Review and Meta-Analysis

    Creatine supplementation in the aging population: effects on skeletal muscle, bone and brain

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