Caffeine... Good, Bad or Indifferent?

Type the words 'caffeine' and 'health' into google and you get a sneak peak at the sort of conflicting information that is online, especially for health and nutrition. You will find that Googles top returned articles are ...'Top 23 Caffeine Health Benefits' as one of the first few searches, directly above the title '20 Harmful Effects of Caffeine'...Come on, any chance?

For those who don’t wish to or simply who do not have time to delve into the research, these sort of publications online and in the popular media make it very difficult to get a clear view of the research on any topic related to nutrition and to get a clear cut answer. Luckily for you we are going to delve into the research and break it down for you once again.

The Low Down on Caffeine

Caffeine is one of the most popular and commonly used forms of stimulant in the world due to its ease of availability and because of the popularity of caffeine containing drinks such as tea, coffee and sodas. It is most commonly found naturally in the form of tea leaves and coffee beans as well as food sources such as cocoa beans, but in a much lower dose.

The other common form of caffeine is a synthetic form called caffeine anhydrous, which is a concentrated form of caffeine usually found in a powder form (often converted into pill form) and is made by boiling the leaves, stems, beans of caffeine containing plants before allowing the water to evaporate off, leaving the white caffeine powder behind.

This synthetic form of caffeine can either be purchased separately as a powder or commonly found in energy and sports drinks and pills.

Caffeine Powder/Pill: 100mg serving will provide 100mg Caffeine

Large Americano Coffee (500ml): 150-200mg

Caffeinated Energy Drink (500ml): 160mg

Espresso Shot: 80-100mg

Large Cup Tea (500ml): 30-80mg

80% Dark Chocolate (100g): 40-50mg

Caffeinated Soft Drink (500ml): 50mg

How Does Caffeine Work?

Caffeine works primarily on the central nervous system (CNS) via its ability to block the action of adenosine on its receptor. Adenosine promotes drowsiness and sleepiness and therefore caffeine is effective as a stimulant as it blocks adenosine working to its maximum capacity.

How effective caffeine is will depend on a few different factors both externally controlled (dose and tolerance) but also internally regulated (metabolism rates). A greater intake of caffeine will compete and block more adenosine than a smaller dose and lead to a greater stimulating effect.

It is note worthy to say at this point that caffeine at high intakes can be toxic (although very rare, >5g) and can have negative side effects such as headaches, restfulness, stomach upsets, irritability and raised heart rate if excessive caffeine is taken or if an individual is not used to having caffeine.

A tolerance to caffeine can occur if caffeine is habitually consumed, in this instance the stimulatory effects of caffeine will be weakened and a complete break from caffeine for up to a month may be necessary to regain it's sensitivity.

Variations in caffeine metabolism (caused by a defect of the CYP1A2 gene) will also influence how effective and what dosage is necessary to elicit a response to caffeine.

Fast metabolisers of caffeine will utilise and use caffeine far quicker than those who are slower metabolisers of caffeine. This variation can affect how well the body handles caffeine, especially at larger doses. The same 200mg hit of caffeine in a strong coffee may barely have an affect on one person whilst may lead to severe anxiety and discomfort in others. If you know you don't handle caffeine well, then limiting your intake to small, manageable doses is certainly a good idea.

Caffeine : The Good

For those who can handle caffeine, it can be a great asset for training performance, cognitive improvements and better mood whilst potentially also providing a benefit when trying to manage hunger.

Numerous studies have shown that supplementing with caffeine prior to exercise can improve sports performance via increased power output, anaerobic and aerobic capacity.

Due to caffeine blocking the adenosine receptor, it has also been shown that caffeine can help with mental clarity and has also been shown to improve mood via the release of dopamine and adrenaline.

Caffeine when consumed in the form of tea and coffee has been associated with lower risk of cardiovascular disease, obesity and even seems to have some neuroprotective properties which may help reduce the risk and severity of alzheimers and dementia.

The potential beneficial effects of caffeine containing drinks on long term health, specifically cardiovascular disease, Alzheimer's and diabetes therefore may be more specific to the known compounds in tea and coffee which have been associated with health improvements rather than the caffeine itself. This is further supported by the fact that decaffeinated coffee has also been associated with a lower risk of developing diabetes.

Caffeine: The Bad

Caffeine intake, especially at high concentrations may not be ideal for anybody with high blood pressure due to caffeine inducing a contracting and stiffening of blood vessels (vasoconstriction). Contracting blood vessels will raise blood pressure in the short term, whilst this nothing to worry about for individuals with healthy blood pressure, those with already high blood pressure may want to limit caffeine for that reason.

The stimulating effects of caffeine may also have an influence on sleep and circadian rhythm if not regulated properly in the diet. Caffeine's half life is roughly 5-6 hours and so consuming caffeine late in the evening can cause issues with sleep onset (remember caffeine is used to promote wakefulness) especially those who are sensitive to its effects.

Limiting caffeine to early in the day and avoiding caffeine in the 5-6 hours prior to bed will be a good idea for most people to avoid any interference with sleep onset.

Finally, it is advised that pregnant women consider lowering caffeine intake to no more than 200mg per day (1 cup coffee/ 2 cups tea).

Summary & Recommendations

Caffeine, especially when consumed in tea, coffee and cocoa may provide some benefits for lowering the risk of developing a number of cardiovascular and metabolic health conditions as well as potentially having some neuroprotective properties . Selecting a comfortable dose (eg. 3-4 cups coffee per day for most people) for your tolerance level and ability to handle caffeine is important.

Caffeine can also improve mood and alertness, unless you are particularly sensitive to caffeine, in which case reducing caffeinated drinks and replacing with decaffeinated tea and coffee may present similar cardiovascular and metabolic benefits.

Due to its half-life lasting around 5-6 hours, consuming caffeine earlier in the day is usually a good idea for most people, especially if you are somebody who has trouble sleeping.

Pregnant women will need to reduce caffeine intake to around 200mg per day.