An introduction to caffeine

Caffeine is a naturally occurring stimulant belonging to the alkaloid family. It has been termed the most widely consumed psychoactive substance in the world. The two most popular sources of caffeine are coffee and tea leaves. Other sources include cocoa beans, energy drinks and some over the counter medications. The caffeine content of foods varies quite considerably depending on the type, serving size of the food/drink and how it is prepared.


Pros and cons of caffeine

Whether you’re drinking coffee, tea, caffeinated soft drinks or even hot chocolate, low doses of caffeine can typically make you feel more alert and energetic. At higher doses though, some people find they feel anxious, irritable and unable to switch off or sleep. Over time, too much caffeine weakens the adrenal glands, depletes vital nutrients and interferes with hormonal balance. A cycle develops where greater amounts are needed to achieve the familiar high and symptoms such as headaches and indigestion can occur if we don’t get our fix. In short, caffeine is addictive.

The scientific evidence seems to suggest that for healthy adults a moderate amount of tea and coffee is okay and won't damage your health. Other studies suggests that three to four cups of coffee are safe and even possibly beneficial for those with heart disease and diabetes. Other studies infer that one or two cups of coffee a day can help boost memory function in both young and older adults.

How much caffeine is too much?

Before you order that extra-large triple-shot latte, keep in mind that experts do agree that if you’re drinking more than four to five cups of tea, coffee or caffeinated drinks a day, it is best to cut down. Use your common sense; some people are more sensitive than others to caffeine and should limit it or choose decaf. Too much caffeine can contribute to insomnia, nervousness, anxiety, gastrointestinal issues and may cause heart palpitations. There is specific advice for pregnant women, so check with your doctor if you are unsure. Also, what you add to your cuppa such as syrups and sugar should be kept to a minimum, because these are ‘free’ sugars, the type we are advised to cut back on. These additions can have a significant impact on your waist line and disrupt blood sugar control.

Daily caffeine guidelines

The truth is that due to our individual metabolisms, which are genetically determined, not everyone responds to caffeine in the same way. That is why some people have one cup in the morning and can’t sleep for days and others can have a double espresso after dinner and hit the pillow and drop off immediately. The following guidelines suggest the maximum amounts of caffeine that can be safely consumed each day and how much caffeine you can expect to find in different beverages.

Daily guidelines

  • Moderate daily caffeine intake at a dose level up to 400mg/day (in a 65kg person)
  • Women who are pregnant should consume no more than 200mg/day (for a 65kg person)
  • Children should consume no more than 45mg-100mg/day (depending on their age)

How much caffeine is in my drink/snack?*

  • 1 mug of filter coffee – 140mg caffeine
  • 1 mug of instant coffee – 100mg caffeine
  • 1 can of energy drink – 80mg caffeine
  • 1 mug of tea – 75mg caffeine
  • Small bar of chocolate – 25-50mg caffeine
  • Can of cola – 40mg caffeine

*all figures are approximate

Signs of dehydration

While tea and coffee can count towards your recommended daily intake of fluid, caffeine is a diuretic – a substance that increases water loss from the body through urination. Consumption of diuretics such as caffeine (and alcohol) therefore result in the need to drink more water and can cause dehydration. Symptoms of mild dehydration include muscle pain, lower back pain, headaches and constipation, as well as lack of concentration and alertness. Thirst is an obvious sign of dehydration, as is a strong odour and yellow colour to your urine. If you know you consume too much caffeine, try to keep hydrated.

Mineral depletion

Although tea and coffee are known to contain some antioxidants, it’s not an excuse for glugging back gallons of flat whites. A diet rich in fruit and vegetables is a far more effective means of achieving plenty of protective nutrients in your diet.

Caffeine has been identified as a potential risk factor for bone fracture, as it causes calcium to be excreted in the urine and faeces, depleting the amount retained by the bones and possibly contributing to osteoporosis. For those with sensitive constitutions, excess caffeine can cause diarrhoea, reflux and heartburn.

How to cut down on caffeine

Looking to cut down? Consider the following to help you reduce your intake:

  • Cut back gradually over a two-to-three week period. Rapid withdrawal can leave you with headaches. Try diluting smaller amounts of regular coffee to lower your intake.
  • If you’re in a cafe, order a small rather than a large beverage.
  • Try decaffeinated tea and coffee – look out for products decaffeinated using the chemical-free Swiss Water method.
  • Make one cup at a time instead of a whole pot/cafetière.
  • Buy a smaller mug!
  • Consider herbal varieties such as chicory.
  • Choose caffeine-free soft drinks.
  • Drink more water and herbal teas, as well as fruit and vegetable juices. Dilute juices with sparkling water.
  • Experiment with herbal teas such as dandelion, lemongrass, peppermint, ginger root, red clover, rosehip, nettle and chamomile.


If caffeine is your crux, why not try one of our wonderful alternatives:

Citrus iced tea
Elderflower, lemon & vanilla cordial
Cranberry & raspberry smoothie
Tropical breakfast smoothie

Occasional consumption of substances such as alcohol, sugar, or caffeine causes no harm, but regular, habitual use and addiction may cause significant risk. But more importantly, it can have a negative effect on the quality of life for many who drink it – they sleep poorly and are more tired and irritable and anxious. For something that is supposed to give you more energy, it usually offers only a brief lift with increasingly diminishing returns. The surprising thing many former coffee drinkers discover is that they have more energy, not less, when they finally kick the habit.

This article was last reviewed on 12th July 2017 by nutritional therapist Kerry Torrens.

A registered Nutritional Therapist, Kerry Torrens is a contributing author to a number of nutritional and cookery publications including BBC Good Food magazine. Kerry is a member of the The Royal Society of Medicine, Complementary and Natural Healthcare Council (CNHC), British Association for Applied Nutrition and Nutritional Therapy (BANT).

Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Follow her on Twitter @nutri_jo.


All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

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