Caffeine – fuel or foe?

This week, Sally reviews caffeine, to take a balanced look at the research behind its benefits and flaws when it comes to health. 

With #UKCoffeeWeek just kicking off, there is a lot of interest in how our caffeine levels are creeping up and up. Whether it’s a latte on the way to work or an espresso to get through the afternoon slump, coffee has become a routine pick-me-up for millions of Brits.

However, there are growing concerns about the number of us who are addicted to caffeine and consume cup after cup of the black stuff on a daily basis. In a recent study, one woman in ten claimed she couldn’t live without coffee. More than a third of those surveyed said they had to start the day with a cup.

Health guidelines recommend a maximum of 400mg of caffeine per day – but as there is caffeine in tea, chocolate and fizzy drinks as well as coffee, our daily allowance can quickly add up.  The increasingly large coffees offered in high street coffee chains and the surge in popularity of ‘energy drinks’ doesn’t help either. As a quick guide here’s the caffeine content in some popular drinks:

Type                                  Caffeine (average)

Espresso                            40-75mg/oz

Generic brewed coffee   19mg/oz

Generic instant coffee   12mg/oz

Red Bull                            9mg/oz

Coffee ice cream             7.5mg/oz

Black tea                          5mg/oz

Chocolate (milk)             4mg/oz

Diet Coke                        4mg/oz

Coke                                 3mg/oz

How much are you consuming each day?

Caffeine intake aside, as a nation we spent £730 million on coffee last year alone. It’s easy to brush off spending £3 a day on a latte – but that adds up to £60 a month, or £720 every year! Think what you could do with that cash!

But lets look at the health implications now in detail – is caffeine all bad….?!

Let me give you five reasons to quit caffeine… and then five reasons not to!

1. It can be bad for your heart
Some studies show it can reduce blood flow in your coronary arteries when you need it most – during exercise – as well as cause palpitations or irregular heartbeat and may possibly increase your blood pressure over time.(3)

2. It disturbs your sleep
People who drink more than three cups of coffee per day are scientifically proven to have less than restful sleep. One study showed a difference of 79 minutes sleep between drinkers of caffeinated vs decaffeinated drinks. If you struggle to get to sleep then caffeine should definitely be a no-go. It takes about 5 hours to clear from our system – so drinking coffee after lunch-time is worth avoiding. (4)

3. It is often linked with sugar
Even if we don’t add sugar to our coffee, we are often tempted to accompany it with a biscuit, cake or a breakfast muffin – particularly when encouraged to do so by high street chains. In addition there can be 11 teaspoons of sugar in some varieties of coffee – our total recommended daily intake. The calorie count of these specialist coffees can be huge too so not good if you are watching your weight.

4. It’s bad for your mood
Caffeine increases catecholamines such as adrenaline – known as the “fight or flight” hormone. No surprise then that caffeine can make you tense and jittery in high quantities. (5)

5. It can impact your fertility
Drinking more than five cups of coffee a day – the equivalent of about 500mg of caffeine – is linked with lower fertility. If you’re trying to get pregnant, it’s certainly worth cutting down, and once you are pregnant you’ll want to quit caffeine altogether or certainly cut back to less than 200mg per day as it may increase the risk of birth defects or reduce fetal growth.(6)

However, on the plus side…

1. It can improve sports performance
Drinking a caffeinated drink before sport is associated with improved endurance and other sporting measures. It seems that caffeine increases heart rate but reduces the pain felt during exertion, encouraging us to push it that bit further (7,8)

2. It can increase mental alertness
Studies performed on people in stressful conditions showed improved concentration, learning and reaction time after 200mg caffeine (9). In addition, there is some evidence that it can delay onset of Alzheimer’s disease.

3. It may reduce the risk of some diseases
Drinking coffee, though apparently of both caffeinated and decaffeinated types, is associated with a reduced risk of type 2 diabetes. It is also associated with a reduced risk of some types of cancer. Coffee adds high levels of antioxidants to our diet (up to to 64% in one study). Antioxidants protect us against various diseases, which may explain some of these benefits. (10)

4. It may protect the liver
Fatty liver disease is becoming an increasing problem due to the combination of alcohol and obesity. Excess fat in the liver can cause inflammation and lead to cirrhosis. Some studies show that caffeine intake may be associated with a lower risk of fatty liver. (11)

5. Caffeine cheers us up
Even just the smell of coffee can make us feel better and drinking it too is related to lower rates of depression.(12,13) Not to mention the social element of relaxing with friends over a cuppa.

So, what do we do?
It seems that going cold-turkey on caffeine is not necessary – and we may even be worse off. Instead, we just need to be aware of how much we drink and try to avoid those extra large coffees and energy drinks. Decaff tea and coffee is the obvious choice if you are avoiding caffeine (remember even decaff contains some caff!) but there are lots of other exciting options to tickle your taste buds. Peppermint and fruit teas are usually caffeine-free and make a welcome change from tea and coffee. It’s also a great time to increase your water intake. Just make sure you don’t choose sugary fizzy drinks or fruit juices instead.






3 Namdar M, Koepfli P, Grathwohl R, Siegrist PT, Klainguti M, Schepis T, Delaloye R, Wyss CA, Fleischmann SP, Gaemperli O, Kaufmann PA. Caffeine decreases exercise-induced myocardial flow reserve. J Am Coll Cardiol. 2006

4 Sleep Med. 2002 May;3(3):271-3.The effects of coffee consumption on sleep and melatonin secretion. Shilo L, Sabbah H, Hadari R, Kovatz S, Weinberg U, Dolev S, Dagan Y, Shenkman L.

5 Persad LA. Energy drinks and the neurophysiological impact of caffeine. Front  Neurosci. 2011

6 Sharma R, Biedenharn KR, Fedor JM, Agarwal A. Lifestyle factors and reproductive health: taking control of your fertility. Reprod Biol Endocrinol. 2013

7 Ivy JL, Kammer L, Ding Z, Wang B, Bernard JR, Liao YH, Hwang J. Improved cycling time-trial performance after ingestion of a caffeine energy drink. Int J  Sport Nutr Exerc Metab. 2009

8 Duncan MJ, Hankey J. The effect of a caffeinated energy drink on various psychological measures during submaximal cycling. Physiol Behav. 2013 May

9. Lieberman HR, Tharion WJ, Shukitt-Hale B, Speckman KL, Tulley R. Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Sea-Air-Land. Psychopharmacology (Berl). 2002

10 Discacciati A, Orsini N, Andersson SO, Andrén O, Johansson JE, Mantzoros CS, Wolk A. Coffee consumption and risk of localized, advanced and fatal prostate cancer: a population-based prospective study. Ann Oncol. 2013

11 Sinha RA, Farah BL, Singh BK, Siddique MM, Li Y, Wu Y, Ilkayeva OR, Gooding J, Ching J, Zhou J, Martinez L, Xie S, Bay BH, Summers SA, Newgard CB, Yen PM. Caffeine stimulates hepatic lipid metabolism by the autophagy-lysosomal pathway in mice. Hepatology. 2013

12 Seo HS, Hirano M, Shibato J, Rakwal R, Hwang IK, Masuo Y. Effects of coffee bean aroma on the rat brain stressed by sleep deprivation: a selected transcript- and 2D gel-based proteome analysis. J Agric Food Chem. 2008

13 Pham NM, Nanri A, Kurotani K, Kuwahara K, Kume A, Sato M, Hayabuchi H, Mizoue  T. Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population. Public Health Nutr. 2013