Confusion about caffeinated drinks is rife!

| Post published on June 3, 2015
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Veronika Powell shuns the sensationalism and charts a path through the caffeine labyrinth.

Caffeine is the most widely consumed pharmacologically active (drug-like) substance in the world. Found naturally in over 60 plant species, of which the best known are coffee, tea and cocoabeans, it is added to some soft drinks and a wide range of prescription and over-the-counter drugs.

Your body absorbs caffeine very quickly and peak concentration in the blood occurs 15 to 120 minutes after ingestion. The effect lasts for up to six hours but is less in smokers, doubles in women taking oral contraceptives and rises to 15 hours in the last trimester of pregnancy.

What Does it Do?

Caffeine fools your body into thinking that you face an emergency and so it releases an extra dose of hormones, including adrenaline (for fight or flight reaction), cortisol (for stress) and dopamine (for that short-term, motivational feel-good factor).

The effects of this hormone cocktail in your bloodstream are increased blood sugar levels, heart rate and blood flow to muscles and brain, while blood flow to the skin is reduced. In other words, blood is concentrated in the more important organs, making you feel alert and agitated and ready for a fight.

Vicious Circle

Drinking coffee or tea gives you a temporary boost but it’s also likely to make you tired and depressed later when the effect wears off. If you take more caffeine to counteract this downturn, you’re likely to spend the day in an agitated state and feel edgy at night. Increased cortisol levels can even lead to long-term health problems such as weight gain because it makes you crave fatty and sugary foods – and then encourages your body to store fat around your waistline.

Part of the reason many people drink coffee or tea is because it makes them alert. Even if you’re already alert and on your toes, it won’t stop the caffeine from working and this extra dose has the potential to produce uncomfortable and lasting anxiety.

Drinking caffeine-containing drinks whilst sitting at your desk working or when watching TV, ensures that adrenaline will remain in your blood for longer and may cause the jitters or insomnia.

On the other hand, you can always get rid of the caffeine through physical activity, when it has a much more positive effect – it prolongs the time to exhaustion and can speed up your metabolism, helping the body to break down fat more efficiently. Sorry chaps, it won’t happen without exercising.

Curb those Cravings

The fact that caffeine can increase your blood sugar levels means you feel less hungry for a while but when the sugar levels drop, the cravings for sweet and fatty food or more caffeine begin.

It’s impossible to give a realistic healthy minimum or maximum level for caffeine as every individual is different. And while it’s the caffeine itself that affects you rather than other ingredients in the drink, sugary caffeinated drinks give you a sugar rush on top of the adrenaline peak, leaving you even more tired hours later.

Those who have caffeine infrequently are likely to experience stronger reactions than regular users. Their sleep may be more disturbed and they may go to the loo more often because of its diuretic effect. That’s not to say that regular coffee or tea drinkers escape these effects entirely, they don’t and they might find themselves in a state of permanent stress caused by increased levels of stress hormones.

Mysterious Forces

However, there are things at work in these drinks other than caffeine. To digest coffee your stomach has to produce an extra dose of acid and this can cause unpleasant heartburn. The acid is then absorbed into the blood and needs to be neutralised, which can cause calcium to be leached from your bones.

Green tea, on the other hand, doesn’t produce any such reaction. It contains a substance called l-theanine, an amino acid that helps reduce anxiety, improves your mood and calms you down and therefore tends to counteract the caffeine content.

So what about normal black tea? It comes somewhere between green tea and coffee! It also contains l-theanine but has more caffeine than green tea so doesn’t balance out quite as well. It’s best to drink it with soya milk for the added benefit of unsaturated fatty acids rather than the saturated fats and hormones in dairy milk.

And Now the Good News

So now you’re probably in desperate need of some good news about your favourite drinks! And there is some! Coffee and tea are both high in antioxidants – substances well-known for defending your body from dangerous molecules of metabolic waste called free radicals – the body’s equivalent of damaging rust. Antioxidants can help prevent cancer, heart disease and neurodegenerative diseases.

Caffeinated soft drinks are usually devoid of antioxidants and benefit your health not one jot.

The table below looks at the antioxidant content of some selected foods.

Drink/food Antioxidant content  (mmol per regular sized mug or a serving)
Brewed coffee2.00 – 7.00
Instant coffee2.00 – 4.40
Tea1.60 – 2.40
Green tea2.40 – 5.20
Herbal tea0.20 – 2.00
Apples0.20 – 1.10












Is decaf the answer?

It does contain a small amount of caffeine (3 – 6 mg) and it still produces the same acid stomach reaction. Depending on the decaffeination method used, it may also come with an extra dose of a chemical that’s used – methylene chloride (which may cause skin irritation and even cancer).

The truth is, caffeine isn’t the only stimulant in coffee. There’s theophylline, which is known to
disturb normal sleep patterns and theobromine, which has a similar effect to caffeine. So, caffeine free doesn’t mean stimulant-free!

So what’s the final verdict on caffeine? Well, it’s a stimulant that can turn you into an addict! Withdrawal effects include headaches, tiredness and irritability but these tend to end after about three days when your energy levels will shoot back up again.

If you feel the need to change but don’t fancy switching to herbal tea or coffee alternatives, try replacing your usual coffee and tea gradually with green tea. You’ll still have some caffeine and lots of antioxidants but you’ll also get the extra benefit of being less stressed.

If you can’t or don’t want to give up your beloved cuppa, try to compensate for it with some physical activity (a good idea anyway) or don’t drink caffeinated drinks in the afternoon or evening.


Sources of CaffeineCaffeine Content
Plain, brewed 8 oz135 mg
Instant 8 oz95 mg
Espresso 1 oz30-77 mg
Plain, decaffeinated 8 oz3-6 mg
Green tea 8 oz25-40 mg
Black tea 8 oz40-70 mg
Soft Drinks 
Coca-Cola Classic 12 oz34.5 mg
Diet Coke 12 oz46.5 mg
Dr. Pepper 12 oz42 mg
Mountain Dew 12 oz55.5 mg
Pepsi-Cola 12 oz37.5 mg
Energy Drink 
Red Bull, 8.5 oz80 mg
Monster160 mg
Cocoa and chocolates 
Hot chocolate or cocoa4 -5 mg
Cocoa mix, powder 3 tsp5 mg


About the author
Veronika Prošek Charvátová
Veronika Prošek Charvátová MSc is a biologist and Viva! Health researcher. Veronika has spent years uncovering the links between nutrition and good health and is an expert on plant-based diets.

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