Which supplements do athletes take and why?

At the 1992 Olympic Games in Barcelona, whispers began circulating around a new product that was being used by a number of Great Britain's elite athletes.

It was being described as a “secret weapon” because it appeared to increase muscle mass and improve athletic performance without breaking anti-doping rules.

The product was creatine.

More than three decades later, creatine has moved from the margins of elite sport to the mainstream.

It is now widely available in supermarkets and online stores and is among the most extensively researched sports supplements.

But its arrival in elite sport in the early 1990s was accompanied by suspicion, largely because athletes and the public were accustomed to associating performance-enhancing substances with doping.

For elite athletes, the search for improvement rarely stops.

From the moment they wake up until they go to bed, nutrition, training, recovery and preparation can all become part of an effort to gain even the smallest competitive advantage.

Supplements have consequently become an important part of modern sports nutrition.

Some are designed to support muscle growth and recovery, while others help athletes address nutritional deficiencies or provide energy during demanding competition.

Professor Graeme Close, a professor of human physiology at Liverpool John Moores University, says studies have suggested that as many as 90% of athletes use supplements.

In professional sporting environments where he has worked, he believes the figure may be even higher.

But experts stress that supplements should not replace a balanced diet.

Close describes them as the “final piece of the jigsaw”, rather than the foundation of an athlete’s preparation.

The priority, he argues, should be getting the fundamentals right: Eating well, training effectively, sleeping properly, recovering and staying hydrated.

Creatine provides a useful example.

The substance occurs naturally in the human body and is also found in foods such as meat and fish.

It is produced naturally in organs including the kidneys, liver and pancreas and provides muscles with a rapid source of energy.

That makes it particularly relevant to short-duration, high-intensity activities such as sprinting.

Its rise in sport accelerated during the 1990s.

Two scientists who had spent years researching creatine shared their findings with Steve Jennings, whose Maxim sports nutrition company supplied products to the British Olympic team.

During the Barcelona Games, journalist Doug Gillon reported on a secret trial involving British athletes and the use of Ergomax C150, an effervescent creatine tablet.

Research suggesting that creatine could improve explosive performance by between 1% and 3% helped trigger a major change in sports nutrition.

By the 1996 Olympics, an estimated 80% of athletes were using creatine.

Its influence has since extended beyond physical performance, with research also exploring possible cognitive benefits.

The breakthrough helped usher in what the Journal of the International Society of Sports Nutrition described as a new era in sports nutrition, encouraging wider research into other supplements.

Today, the sports supplement industry is part of a much larger global market.

The global dietary supplements market was valued at $209.5bn in 2025 and is projected to reach $431.7bn by 2033, according to Grand View Research.

Among elite athletes, protein powders are one of the most commonly used products.

Close places them at the top of the list, followed by creatine and vitamin D.

Protein powders can support muscle repair and contribute to muscle growth, while vitamin D is important for bone health and muscle function.

Carbohydrate supplements are another important part of modern endurance sport.

Gels and sports drinks can provide athletes with large quantities of rapidly available carbohydrate during prolonged competition.

They were particularly important in the fuelling strategy used by Kenyan distance runner Sabastian Sawe during his sub-two-hour marathon earlier this year.

The nutritional strategy involved consuming more than 100 grams of supplemental carbohydrate per hour, with reports indicating that Sawe reached approximately 110 grams per hour.

Yet the word “performance-enhancing” can create confusion.

A supplement that improves performance is not automatically prohibited under anti-doping regulations.

According to Close, the World Anti-Doping Agency considers three broad criteria when determining whether a substance should be placed on its prohibited list: Whether it is dangerous to health, whether it enhances performance and whether it violates the spirit of sport.

A substance does not necessarily have to meet all three criteria to be considered, but Close uses creatine as an example of a performance-related product that is not prohibited.

The fact that a supplement is legal, however, does not mean it is risk-free for athletes.

Elite competitors operate under the principle of strict liability, meaning athletes are ultimately responsible for substances found in their bodies.

UK Anti-Doping warns that no guarantee can be given that a particular supplement is completely free of prohibited substances.

An athlete who tests positive after unknowingly consuming a contaminated product can face the same consequences as someone who deliberately used a banned substance, including a potential four-year ban.

Contamination is therefore a serious concern.

Supplement-testing programmes such as Informed Sport attempt to reduce the risk by testing batches before products reach consumers.

Informed Sport says as many as one in 10 supplements may be contaminated with ingredients or compounds prohibited in sport.

Research cited by the organisation also found that product contamination was responsible for 8% of anti-doping violations between 2005 and 2022.

However, even certification programmes cannot completely eliminate the risk.

For athletes, careful record-keeping can become part of their daily routine.

British rower Heidi Long, for example, keeps a spreadsheet recording the batch number and expiry date of every supplement she uses.

She notes that once a product passes its expiry date, its Informed Sport certification can no longer be relied upon.

The risks are not limited to elite athletes. Consumers purchasing supplements online may have little information about where products were manufactured or how they were produced.

Close warns that some products could be made in poorly controlled environments, while research into some creatine products has found that they contained little or no creatine.

In the worst cases, poorly manufactured supplements could contain substances that pose health risks.

That has strengthened interest in a “food-first” approach. Instead of automatically reaching for a supplement, athletes can obtain many nutrients from ordinary foods.

Turmeric, pickle juice and nitrate-rich foods such as beetroot are among the examples cited as whole-food alternatives for particular nutritional purposes.

Teff, an ancient Ethiopian grain, has also attracted growing attention in sports nutrition.

Traditionally consumed in East Africa, it is rich in minerals including calcium and iron, contains vitamin C, is naturally gluten-free and provides all nine essential amino acids, making it a complete protein.

Its nutritional profile has attracted athletes including Olympic marathon champion Haile Gebrselassie and tennis star Venus Williams.

For British boxer Fran Hennessy, teff has become part of her daily diet.

She says it provides energy before training while also contributing to recovery, reflecting a wider shift towards viewing food as an important part of performance rather than treating supplements as a solution to every nutritional need.

Cost also influences the choices athletes make. Supplements can be expensive, meaning competitors have to decide when the potential benefit justifies the investment.

Long says supplements may make greater financial sense around major competitions, when performance is particularly important, while ordinary meals can often provide the necessary nutrients during everyday training.

Ultimately, supplements can offer athletes useful tools in the pursuit of marginal gains, but they are not a substitute for the basics.

Good nutrition, structured training, sufficient sleep, hydration and recovery remain the foundation of performance.

The story of creatine illustrates how quickly sports nutrition can change.

What was once viewed with suspicion as a “secret weapon” at the 1992 Olympics has become a mainstream product used by millions.

Yet the central lesson remains unchanged: athletes must understand not only what a supplement can do for performance, but also what risks it may carry.

In elite sport, where a tiny advantage can matter, the responsibility of knowing exactly what goes into the body is just as important as the search for the next marginal gain.