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by Penny Crowther(more info)

listed in nutrition, originally published in issue 263 - June 2020

Caffeine is a naturally occurring chemical found in plant sources such as coffee, cocoa beans and tea leaves. It is also extracted and added to food, drink and some medicines.

If you struggle to reduce your daily fix of tea, coffee or diet coke, it’s worth remembering that caffeine is a drug. It belongs to a class of drugs known as psychoactive drugs which include illegal substances such as LSD?!

Caffeine may be natural but it is a central nervous system stimulator. It causes an increase in certain brain chemicals that can change your mood and behaviour. So it’s no wonder that so many people are hooked on it. It’s a topic that many of my nutritional therapy clients ask me about.



Skeletal formula of caffeine. Source: Courtesy of Wikipedia


Can Caffeine be Good for You?

First let’s start with the benefits.

  • The caffeine found in dark chocolate, coffee and tea is accompanied by antioxidant rich plant chemicals called polyphenols. These are anti-inflammatory. They are therefore highly beneficial because inflammation drives most chronic diseases today. Interesting fact -  a cup of coffee contains 2 and a half times more polyphenols than tea!;
  • Caffeine stimulates cognitive function and memory. It makes you more alert, relieves fatigue and improves your concentration. It does this by stimulating the release of two important brain chemicals dopamine and noradrenaline;
  • Caffeine may improve athletic performance;
  • Caffeine increases metabolism and fat burning.

And the Not So Good…

  • Caffeine impairs the absorption of nutrients such as iron and calcium;
  • Caffeine is dehydrating and a mild diuretic. That means it causes an increase in urination and therefore loss of certain water soluble nutrients such as B vitamins and vitamin C and electrolytes such as potassium;
  • Caffeine is linked with acid reflux and increased production of stomach acid and therefore ulcers. It speeds up the rate at which food mixed with acid leaves your stomach. This means it enters the first part of the small intestine more quickly and the acid can cause inflammation in the small intestine;
  • Caffeine can trigger migraine and raise blood pressure in people who are susceptible;
  • Caffeine negatively affects the time it takes to get to sleep and sleep quality;
  • Caffeine consumption has long been linked with anxiety. Caffeine-induced anxiety disorder is a recognised diagnosis. It is known to make anxiety disorders worse and to trigger panic attacks in people with a history of panic attacks;
  • Caffeine is thought to play a role in psychiatric disorders. A study from 2003 concluded that “Assessment of caffeine intake should form part of routine psychiatric assessment and should be carried out before prescribing”;
  • In pregnant women, It is known that caffeine crosses the placenta to reach the foetus. It seems from research that caffeine, at certain levels, affects the growth of the baby in the womb and may increase the risk of miscarriage or stillbirth or giving birth to a low weight baby;
  • Finally when it comes to coffee, we must not forget all those things that might be added like cream, sugar, chocolate etc.  This can hike the calories up to as much as 500 for one Frappuccino, for example!

How Much is Okay?

UK guidelines for caffeine consumption are 400mg maximum daily and no more than 200mg in one go. 400mg is about 4 medium to large cups of coffee.  See the table below for the caffeine content of your tea, coffee and chocolate.

These guidelines were made in response to a large review of 381 studies on caffeine over a 14 year period. It covered caffeine in foods, drink and medications. The conclusion was that negative health effects were only found where consumption of caffeine was over 400mg per day. However read on…

Your Individual Caffeine Limit

There is a big caveat when it comes to the general recommendations above. How much is good for you very much depends on your individual caffeine tolerance. 

For a start, your body weight is a big factor. If you weigh 8 stone you will tolerate about 200mg less caffeine daily than someone weighing around 16 stone. If you suffer from anxiety, panic attacks or nervous problems, you’ll be more sensitive to caffeine’s effects.

As caffeine depletes B complex and other nutrients, if your levels of these nutrients are not optimal in the first place, you could experience symptoms relating to deficiency. For example, lack of B vitamins contributes to tiredness and mental health problems.

How efficient your liver is at metabolising caffeine is another important consideration.  Just as some people have a higher alcohol tolerance, the amount of caffeine we can manage without ill effects varies.


Penny Crowther 263 Caffeine


How Long does it Take to get Caffeine out of Your Body?

Caffeine is thought to have a half-life of about 6 hours.  A half-life is how long it takes for half of the drug to be metabolised.  So if you consumed 150mg caffeine at 11am you would still have 75mg left in your body at 5pm. But this does vary from one individual to another.

My Best Tips for Tea & Coffee Drinking

  • For every caffeinated drink, drink a large glass of water to help flush the caffeine out;
  • Keep caffeinated drinks at least one hour away from meals to reduce the likelihood of iron and calcium absorption being blocked;
  • Take a B complex with vitamin C if you drink a lot of tea and coffee to replace lost vitamins;
  • If there is osteoporosis in your family history, think about your calcium and magnesium  intake from food and supplements;
  • Don’t forget unexpected sources of caffeine. Check the label of over-the-counter painkillers as some contain up to 130mg caffeine per tablet;
  • Coffee brewed through a paper filter contains less cafestol, a substance in coffee that raises LDL cholesterol. Other types of brewed coffee contain more cafestol;
  • If you are making your own tea and coffee, brewing it for less time will reduce the caffeine content;
  • Fresh coffee is preferable to instant. Whilst instant contains less caffeine it contains higher levels of acrylamide. Acrylamide is formed during the roasting process and has been linked to cancer. It does occur In other foods as well such as well-done toast, cereals, chips and crisps. Incidentally cereal based coffee substitutes contain much higher levels than real coffee!
  • Avoid caffeine from mid-afternoon onwards;
  • If you have high blood pressure, anxiety or depression or are pregnant consider drastically reducing your caffeine;
  • If you are pregnant, restrict your caffeine intake (NHS guidelines are 200mg in pregnancy). Avoid caffeine altogether if you are susceptible to miscarriages.

Want to Know how much Caffeine is in your Tea, Coffee & Chocolate?

The caffeine content below is for an 8floz tea or coffee (except for espresso). 8floz is the small size in most coffee chains. There can be a lot of variation in the caffeine content of different brands of tea and coffee. For example there was a study on several brands of green tea which involved brewing each of the teas for exactly the same time. The caffeine content of each cup of tea varied from 47mg down to 12mg! Of the coffee chains, Starbucks seems to be the only company who are  transparent and helpfully list the caffeine content of all their coffee.


Well done on finding time to read to the end! I hope you found it informative.


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About Penny Crowther

Penny Crowther BANT CNHC qualified as a nutritional therapist in 1997 and has been in clinical practice ever since. She has seen several thousand clients over the years, at her practice in London and online. Penny now specializes in nutrition for women in their 40s and beyond, particularly around peri and post menopause. Mid Life for women can be a time when fluctuating hormones play havoc with your wellbeing. In the midst of all the publicity around HRT, it's easy to forget just how powerful diet and lifestyle changes can be when it comes to navigating the menopausal years.

Penny will guide and support you through specific changes to your diet, targeted to you specifically, in midlife. She provides practical, easy to follow menu plans with easy and delicious recipes. The food you eat affects every cell and system in your body. It optimizes how you look and feel, both mentally and physically.

To book an appointment view consultation options here >>

As well as being a regular columnist for Positive Health, Penny has written for Holland and Barrett, and contributed to articles for the Daily TelegraphThe Times Literary supplement, Pregnancy & Birth and Marie Claire. She has been featured in the Daily Express, Daily Mirror and on local radio.

Penny is a registered nutritional therapist with standards of training endorsed by BANT (British Association for Applied Nutrition and Nutritional Therapy) and CNHC. This includes completing 30 hours of continuing professional development, annually.

Penny’s approach to health is holistic, and takes into account emotional, mental and environmental factors as well as nutrition. She has trained in coaching and studied many complementary therapies before qualifying as a nutritionist, which provides a broad foundation of knowledge in her nutrition practice. Penny may be contacted on Tel: 07761 768 754;

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