What Do You Know About Caffeine?

Avatar for Hadyn Luke Hadyn Luke posted this on Tuesday 29th of October 2013 Hadyn Luke 29/10/2013


What Do You Know About Caffeine?

Most of us consume caffeine in some form or another, so this blog takes a look at some of the truths and myths behind the stimulant.


Caffeine is found in coffee beans, tea leaves, cocoa beans (also known as cacao beans, from the fruit of the Theobroma cacao tree) and kola nuts.


Coffee and tea – Both contain caffeine, but although tea leaves have slightly more caffeine per gramme than coffee, the amount of tea leaves used for a typical brew is less in weight. In general a cup of brewed tea contains around half the amount of caffeine of a cup of instant coffee, which in turn contains around half the amount of caffeine found in an espresso of the same volume. Decaffeinated coffee isn’t entirely caffeine free – EU requirements are for a maximum of 0.3% caffeine in instant coffee and no more than 0.1% in ground or roast coffee.

Sports and energy drinks – Because caffeine is a central nervous system stimulant, many personal trainers will work with clients who consume sports performance drinks containing caffeine. The Food Standards Agency website (www.food.gov.uk) states that: “Energy drinks can contain high levels of caffeine, usually about 80 milligrams (mg) of caffeine in a small 250ml can – the same as three cans of cola or a mug of instant coffee.”

Chocolate – Caffeine is naturally found in cacao beans, which are used to make chocolate.

Cola drinks – Originally made with caffeine from the kola nut, now usually made with caffeine from other sources.

Medicines – headache tablets, cold and flu medication and diet pills also often contain caffeine.


Fitness instructors will often find clients use caffeinated drinks to enhance sports performance, for example through quicker reaction times, improved alertness and higher concentration levels.


Those suddenly cutting out caffeine from their diet may suffer from headaches, fatigue and issues such as anxiety and irritability. However, these should only last a day or two, depending on how much caffeine the subject normally consumes in a day, and caffeine causes only mild physical dependence.


Although most healthy adults consuming moderate amounts of caffeine (two or three cups a day) should not be affected, and more studies are needed, there are certain health indications associated with caffeine.

Sleep – although caffeine can disturb sleep, it is mostly processed through the liver and has a short half life: so by 10pm the body will already have eliminated half of the caffeine in a cup of coffee drunk 5.00pm or 6.00pm. Drinking large quantities during the day or drinking coffee in the evening can affect sleep, which can in turn be detrimental to both physical and mental health.

When advising clients on avoiding caffeine in the evening, personal trainers should be aware that dietary products and fat burning pills often contain caffeine.

High blood pressure – People with specific conditions such as high blood pressure may find themselves more sensitive to the effects of caffeine, which can increase heart rate, and tablets or sports drinks containing caffeine often come with a warning. However, the links between caffeine and heart disease have not been proven in larger studies. Fitness trainers should be able to advise clients on how to read and understand labels on food and drink products.

Osteoporosis – Caffeine has not been shown to increase the risk of osteoporosis and any calcium loss can usually be mitigated by drinking milk with coffee or tea. As there are some links between caffeine and the risk of hip fracture in the older population, it may be worth limiting caffeine intake or asking a doctor for advice.

Miscarriage – The main reasons for women to limit or avoid caffeine intake during pregnancy are the links with an increased risk of miscarriage and low birth weight.

Dehydration – Coffee and tea are considered diuretics but because the caffeine is taken with water, it’s a myth that drinking coffee and tea causes dehydration. However, a personal trainer will usually recommend drinking water or a natural energy drink during a workout (see our blogs on The importance of Hydration and Sports Drinks: Hypo, Iso, Hyper-Tonic).

Concentration – One possible benefit of caffeine is increased concentration, which can help both in sports performance and alertness during work or study.

Anti-inflammatory properties – These are believed to help immune function, reduce allergic reactions and potentially relieve the symptoms of asthma.

Other diseases – More studies are needed but there has been some evidence to suggest that caffeine can reduce the risk of certain diseases and conditions, including Type 2 diabetes (see our blog on Personal Training – Diabetes), Parkinson’s, liver disease and colorectal cancer.


Caffeinated drinks are not recommended for children as they can cause temporary anxiety and, coupled with the high sugar content of many carbonated, caffeinated drinks, can cause a mood crash a few hours later.

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