Thinking about: Caffeine

October 2020

Wrapping my hands around a steaming mug of coffee on a cold morning, or sharing a cup of tea with a friend are a couple of my favourite simple pleasures. But I am often asked if the caffeine within these warming drinks has any health effects we should know about?

As always, there is no absolute ‘right’ or ‘wrong’ in nutrition and so arming ourselves with some knowledge of the underlying nutritional science enables us to make informed decisions about the food and drinks we enjoy. You’ll find lots more of this in the nutrition articles section of this website.

Photo by Jen Rich

Let’s start with what Caffeine actually is.

Caffeine is a naturally occurring plant compound, which is thought to function for the plant as an insect repellant and herbicide (Wikoff et al., 2017).  In humans, it is the most commonly consumed stimulant worldwide and is well known for its effects on our wakefulness, focus and concentration.

Once consumed, caffeine is rapidly absorbed into our bloodstream and starts to have an effect just 15 – 20 minutes later. How long those stimulatory effects last varies significantly from person to person, but can be anywhere between 2-8+ hours.

How much caffeine do you drink?

Drink Approximate caffeine per serving
Mug of filter coffee 90 – 140mg
Mug of instant coffee 60 – 100mg
Single espresso (60ml) 80mg
Mug of black tea 50 – 75mg
340ml coca-cola / diet coke 35 – 45mg
50g dark chocolate 20 – 35mg
Mug of cocoa 15mg
Green tea 15mg

What are the health benefits of caffeine?

The good news first. Beyond the obvious benefits that caffeine can have in terms of pleasure (there is often an enjoyable ritual in making and drinking a cup of tea or coffee), helping us to get going in the morning, maintaining focus and concentration at work, or keeping us awake on late-night drives, caffeine may also come with some other health benefits.

Caffeine-containing drinks, including coffee, black tea, green tea and even cocoa, for example, also may contain relatively high amounts of health-boosting polyphenols.

Polyphenols are a group of beneficial dietary antioxidants and are found in particularly high concentrations in brightly coloured fruits and vegetables, tea, coffee, spices, dark chocolate and red wine. Take a look at this article on why eating the rainbow is not a cliched phrase for more background on this topic.

Polyphenols have been reported to play a possible role in the prevention of some cardiovascular disease, neurological diseases and perhaps even diabetes (Scalbert et al., 2005). More specifically, caffeine consumption has been linked to a possible decreased risk of Parkinson’s disease in some people (Costa et al., 2010), while green tea may potentially be beneficial for reducing heart disease and stroke risk (Pang et al., 2016). More research is required to confirm such associations, but they do offer some hopeful possibilities for future studies to build upon.

A review published in the British Medical Journal examining lots of different studies into coffee and various health outcomes found that the greatest benefit of coffee consumption for all-cause mortality and cardiovascular disease was seen at around 3 cups a day (although this is a population level study, so this intake might not apply to you as an individual). Interestingly, decaffeinated coffee was also found to have beneficial effects on the same outcomes, with estimates suggesting 2-4 cups a day having the largest effects (Poole et al., 2017). However, more rigorously designed studies are again needed to confirm these findings.

Caffeine may also be beneficial to support sports performance, by reducing perceived fatigue (Doherty and Smith, 2005) and potentially increasing muscle power output. This is often used to athletic advantage, as fortified sports gels frequently contain the same amount of caffeine as a large mug of coffee.

Are there any downsides of caffeine?

Alongside the potential benefits mentioned above, there are also a few circumstances where excessive caffeine may be detrimental to our health.

Although this is not a completely comprehensive list, below are a few examples of times when being conscious of your caffeine consumption may be beneficial:

  • If you are planning pregnancy or are currently pregnant, national guidelines recommend that you avoid consuming more than 200mg caffeine per day, as high caffeine consumption has been potentially linked to an increased risk of miscarriage, having a baby with a low birth weight and preterm birth (Poole et al., 2017).For more information on this; https://www.nhs.uk/chq/Pages/limit-caffeine-during-pregnancy.aspx
  • If you suffer from anxiety or panic, the physical symptoms of caffeine consumption (such as nervousness, palpitations, irritability or stomach upsets) can sometimes make your worry feel worse. It may be better to cut right down on caffeine in these instances. It’s one of the first things that may be recommended to clients who are particularly struggling with worry and poor sleep.
  • Excessive caffeine consumption can, in some cases, lead to palpitations and ‘ectopic’ heartbeats (the feeling of your heart beating in your chest). Of course, it is absolutely essential to discuss any symptoms like these promptly with a doctor, but you may find that you are encouraged to moderate your caffeine as part of your management plan.For more information on this; https://www.nhs.uk/conditions/heart-palpitations/
  • If you suffer from insomnia or sleeping difficulties, you are probably already being mindful of minimising your evening caffeine intake. But any caffeine consumption, even first thing in the morning, could still be having an impact. It will somewhat depend on your genetics, however – that’s why some lucky people can neck a couple of espressos before bed and still sleep like a baby.If, however, you are struggling with your sleep, you may like to try cutting down (or even cutting out) caffeine completely for a couple of weeks to see if this makes a difference. Start by reducing caffeine consumed after 3pm. Some people find that they need to stop caffeine as early as 10am to positively impact their sleep. It is a case of individual trial-and-error to see what works best for you, understanding that this may well change over time.
  • Habitual caffeine consumption may lead to a certain amount of tolerance; you may end up needing a bigger ‘hit’ to get the same energising effects. This can be a particularly vicious circle for those suffering from fatigue; the more tired you feel, the more you reach for a caffeine boost – which eventually increases your tolerance and means you need even more caffeine to feel ‘normal’.If you suffer from fatigue that is impacting your daily life, it is always worth discussing this with a qualified healthcare professional to see if there is any underlying cause that needs addressing in the first instance.
  • Caffeine intake may also increase blood pressure slightly (although potentially less so when consumed as coffee than from other sources) (Noordzji et al., 2005). If you suffer from high blood pressure, it may therefore be worthwhile sticking to moderate amounts of caffeine (approximately 200-300mg/day). More research is required to give definitive answers on this topic.
  • If you suffer from osteoporosis, or are considered to be at risk of developing weak bones, it may be sensible to limit the amount of caffeine you consume, as it can potentially interfere with calcium absorption and excretion, particularly with higher intakes (Wikoff et al., 2017). This effect may be more significant in women (Poole et al., 2017). Again, the pragmatic solution might be to just stick to a sensible and moderate amount (no more than 400mg/day) and to make sure you are consuming plentiful of sources of calcium in your diet too.

Things to consider when cutting down caffeine consumption…

Dramatically cutting down caffeine can trigger headaches and significant fatigue in many people and even more so in those prone to migraines or frequent headaches. It is therefore recommended than anyone considering reducing their caffeine intake should cut down consumption slowly (by around 1 cup/day every 4-5 days), rather than trying to go ‘cold turkey’.

The bottom line?

  1. Moderation is probably key when it comes to caffeine; 1-3 cups of coffee or 2-4 cups of tea (perhaps including some green tea) a day is a sensible caffeine intake for most people. Some people can tolerate more than this, some people less. As always, there’s no single ‘rule’ for everyone. Have a play around to work out what suits you.
  2. For some, cutting out caffeine completely may be appropriate – perhaps for a short while anyway. It is recommended that this is done slowly over time.
  3. If you love the taste of tea and coffee but would still like to cut down on your caffeine consumption, look out for organic decaffeinated versions. Clipper does the best decaf tea I have personally tasted, or there is an amazing array of herbal teas available.

Written by my colleague Rosamund Yoxall BMBS BSc.

SHOP THE EDIT

CRU Kafe organic coffee capsules

These are my go to coffee capsules that work in the nespresso machine. They are organic, biodegradable and taste delicious.

SHOP

Clipper decaf tea

I love clipper everyday tea but this decaf option is the best I have tasted if you want a decaf option.

SHOP

Green tea

This one is my favourite and I add a little squeeze or slice of lemon to it.

SHOP

Herbal tea

There are so many to choose from but this fennel one is the one I buy time and time again.

SHOP

Tea set

If I could, I would buy tea sets forever and am often hunting in second hand shops for lovely cups. No one does tea better than Fortnum & Mason and I have been saving up for this gorgeous green set for a while now.

SHOP

Coffee machine

I use this machine and find it really easy to use and a much faster solution than brewing coffee in the traditional way.

SHOP

For more information:

This fact sheet on Caffeine is produced by the European Food Standards Agency and is a treasure trove of information.

For professionals:

Coffee consumption and health: Umbrella review of meta-analyses of multiple health outcomes.

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References & Bibliography

Costa J., Lunet N., Santos C., Santos J., Vaz-Carneiro A. (2010) Caffeine Exposure and the Risk of Parkinson’s Disease: A Systematic Review and Meta-Analysis of Observational Studies, Journal of Alzheimer’s Disease, 20(1); S221-S238

Doherty M. and Smith P. (2005) Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis, Scandinavian Journal of Medicine & Science in Sports, 15 (2); 69-78

Noordzij M., Uiterwaal S, Arends LR, Kok FJ, Grobbee DE, Geleijnse JM. (2005) Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. Journal of Hypertension, 23(5); 921-928

Pang, J., Zhang, Z., Zheng, T., Bassig, B.A., Mao, C. and Liu, X. (2016) ‘Green tea consumption and risk of cardiovascular and ischemic related diseases: A meta-analysis’, International Journal of Cardiology, 202, pp. 967–974.

Poole, R., Kennedy, O., Roderick, P., Fallowfield, J., Hayes, P. and Parkes, J. (2017). Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ, p.j5024.

Scalbert A., Manach C., Morand C., Remesy C., Jimenez L., (2005) Dietary polyphenols and the prevention of diseases. Critical Reviews in Food Science and Nutrition 45 (4): 287-306

Wikoff D., et al. (2017) Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children, Food and Chemical Toxicology, 109(1); 585-648.