Supplements and caffeine

Be informed about the potential benefits and harms of taking supplements.


There are many supplements that people can take to help enhance performance or optimise health. What is worth taking and what is best left on the pharmacy shelf?

Most supplements marketed to improve health or exercise performance are based on theory but haven’t necessarily been rigorously tested in practice.

Supplements that hit the mark in terms of their benefit are those which have been studied in humans and show either an increase in muscle hypertrophy (growth) or a performance enhancement (strength, power, speed or endurance). Those that show strong evidence of efficacy and safety across a range of populations and are categorised as Class A, as detailed by the International Society of Sports Nutrition.

Supplements which show mixed evidence to support their benefit (either there isn’t enough research or we find benefits in certain groups but not others) are categorised as Class B, and those with little to no evidence to support either a performance enhancement or a good safety profile are categorised as Class C.


Category Muscle building supplements Performance Enhancement
A. Strong evidence to support efficacy and apparently safe HMB
Creatine monohydrate Essential amino acids (EAA) Protein
β-alanine Caffeine Carbohydrate Creatine Monohydrate Sodium Bicarbonate Sodium Phosphate Water and Sports Drinks
B Limited or mixed evidence to support efficacy Adenosine-5′-Triphosphate (ATP)
Branched-chain amino acids (BCAA)
Phosphatidic acid
L-Alanyl-L-Glutamate Arachidonic acid Branched-chain amino acids (BCAA) Citrulline Essential amino acids (EAA) Glycerol HMB Nitrates Post-exercise carbohydrate and protein Quercetin Taurine
C Little to no evidence to support efficacy and/or safety Agmatine sulfate
Conjugated linoleic acids (CLA)
D-Aspartic acid
Fenugreek extract
Gamma oryzanol (Ferulic acid) Glutamine
Growth-hormone releasing peptides and Secretogogues Isoflavones
Ornithine-alpha-ketoglutarate Prohomones
Tribulus terrestris
Vanadyl sulfate
Zinc-magnesium aspartate
Arginine Carnitine Glutamine Inosine Medium-chain triglycerides (MCT) Ribose

Creatine monohydrate

Creatine increases energy production and our muscles fuel availability. Working as an antioxidant it can reduce muscle damage and improve alertness if sleep deprived.

Dosage. 3 grams per kg bodyweight (25g/d 7 days then 2.5g/d thereafter) and 5 grams per day ongoing, timing not important.


Over the course of a day, you get sleepy as adenosine binds to receptors in your brain. Caffeine blocks adenosine from binding, thus making you feel alert and also helping you feel better. Caffeine may have many benefits:

  • Increased fatty acid oxidation
  • Improves muscular and aerobic endurance
  • Improves muscular and anaerobic strength
  • Reduces rate of perceived exertion (RPE)
  • Increases ability to increase training volume.

Results may vary due to many contributing factors including type of caffeine consumed (liquid, capsule or gum) and timing of consumption. Habitual consumers may have a different response compared to people who don’t usually consume caffeine. 

Dosage. 3-6mg/kg bodyweight most effective.

Beta alanine

Beta alanine is a building block of carnosine, a molecule that helps buffer acid in muscles. Exercise causes hydrogen to accumulate in muscles (acidic environment), carnosine buffers hydrogen ions, helping muscles maintain a stable environment, and delays fatigue. Beta alainine also appears to be an antioxidant and anti-aging compound. 

Application. Ideal for use for intermittent or continuous exercise lasting 30s – 10 min duration. For example 100-200m swimming, 4km cycling (track), 2000m rowing, 800m running

Dosage: 3.2-6.4g. Large doses may result in a tingling feeling called paresthesia ('pins and needles'). Avoid using a time-release formulation or by taking smaller doses (0.8–1 g) several times a day.

Third party certification

Third-party certification organisations provide independent testing to evaluate supplements and their ingredients. Although this does not ensure the effectiveness of a product, certification programmes do verify that a product consists of the ingredients listed on the label and does not include any undeclared ingredients.

Informed Sport and Informed Choice are two good places to start your research. They will give you more information and confidence in choosing the right supplements for you.

Free of banned substances

Although there is no such thing as a ‘100% guarantee’ that tested supplements are free of all banned substances, both programmes aim to provide an effective risk management service, allowing you to make informed choices about the products you choose to use.

Certified product brands

The Informed Sport and Informed Choice certification are voluntary programmes for reputable supplement companies who wish to register some, or all, of their products and carry the appropriate logo on those products. Consumers who see either the Informed Sport or Informed Choice logos on a product can be assured it has undergone rigorous checks and testing to ensure that it is not contaminated with banned substances and is safer to use.

Regularly tested

Not all companies that appear on the Certified Product List have their entire product range certified. And as the certification is batch specific, there is no guarantee that future batches of the same product will be the same.