Do you rely on a cup of tea or coffee to kick-start your day? Or do you reach for a can of cola every time you need an afternoon pick-me-up? Perhaps an energy drink after a late night out?923

Caffeine is one of the most popular substances on earth – consumed in some form or other by almost every culture across the globe. Read this guide to find out more about this drug and how it affects you and your health.

Where’s the caffeine?

Caffeine occurs naturally in more than 60 different types of plants. It is also produced artificially and added to certain foods.

For Australians, coffee is the biggest source of caffeine, and it’s easy to see why. The delicious aroma, rich taste, and unmistakable buzz of a cup of coffee is hard to beat. It’s one of life’s simple pleasures that people everywhere find hard to resist. Coffee is also an important social centerpiece in Australian life. Can you imagine a catching up with a friend or sitting through a meeting without a hot cuppa?

While most people still get their caffeine in the traditional form of a mug of coffee or a cup of tea (or in what’s become another traditional form – a bottle of Coke), energy drinks can also be a source of caffeine. Guarana is an active ingredient in many of these energy drinks, 4 grams of which contains about 160 mg of caffeine. That’s twice the amount of caffeine in an ordinary cup of instant coffee.

Caffeine is also found in chocolate, painkillers and over-the-counter tablets such as No-Doz.

The espresso effect – caffeine in your system

Caffeine affects different people in different ways. The amount of caffeine you have, your age, any medications you are taking, any alcohol you drink, the time of day you get your caffeine, your mood, your level of tiredness, and how sensitive your body is in general, all make a difference to how caffeine affects you.

  • Wake-up call, energy-boost, and pick-me-up are among the most quoted physical benefits of caffeine. Some studies have even shown that caffeine can increase memory, powers of reasoning, athletic performance, motor skills and reaction times. (However, improved performance with caffeine can also be considered an effect of addiction!).
  • Sleep disturbance is one of the more negative effects of caffeine consumption. Some people find that as little as one cup of coffee can interfere with their sleeping patterns. However, if you stop caffeine consumption at least five hours before sleeping, the effects should be minimal.
  • Other negative effects of caffeine include the loss of calcium and potassium, which causes sore muscles and delayed recovery after exercise.
  • Among the lesser  effects of caffeine are that it raises body temperature and makes your digestive system produce more acid. Polyphenols in coffee and tea can interfere with iron absorption, so it you’re at risk for anemia it’s best to drink caffeinated beverages an hour before a meal, rather than afterward.
  • Caffeine is a also diuretic, so it dehydrates your body and sends you to the little room more often.

Is it addictive?

Caffeine is a drug. Most people who drink caffeine on a regular basis develop a tolerance to its effects. This means that, over time, you need to drink more and more cups of coffee, tea, cola or energy drinks to get a caffeine buzz. However, caffeine is generally safe to use at levels of up to 250 mg per day (about two cups of drip coffee or three shots of espresso). Regular large amounts (over 350 mg/day) may cause dependency (caffeinism) and adversely affect health.

The fact that many people experience caffeine-withdrawal symptoms when any heavy coffee drinking is suddenly reduced also indicates that caffeine is an addictive substance. As little as 1-2 cups of coffee (100-200 mg caffeine) daily can produce withdrawal effects which are immediately relieved by getting some caffeine. However, unlike many addictive substances, caffeine can be given up fairly easily by most people.

Caffeine and weight control

If you drink black coffee or tea without milk, the only thing caffeine might do is stimulate your appetite for a biscuit to go with your drink! There are almost no calories in black coffee and tea. There are also no calories in diet soft drinks.

However, if a double-cream frappucino is more your scene, your waistline will pay a high price for your caffeinated beverage. Of course, it’s not the caffeine that’s the problem, it’s the sugar, cream, milk, flavoured syrup and other goodies that might get added to your brew.

If you’re trying to lose weight or improve your weight control, don’t forget to find out how many calories you are drinking when you have a coffee, tea or soft drink. For some people, giving up their daily full cream milk latte and replacing it with a lower-calorie drink is enough to help them lose weight.

Here are the calories, fat and carbs in some of the most popular caffeinated beverages.

Coffee with 2Tbsp reduced fat milk and 1 packet sugar505g3.5g
Caffe Latte with whole milk 300ml (Gloria Jean’s)17110g12g
Grande Latte with non-fat milk (Starbucks)160020g
Grande Cappuccino with whole mik (Starbucks)1508g13g
Skim milk cappuccino 300ml (coffee shops)78015g
Grande Latte with soy milk (Starbucks)2106g28g
Chai Latte with low fat milk (Hudsons)1294g19g
Grande Frappuccino Blended Coffee, caramel, with whipped cream (Starbucks)43016g61g

Hints on cutting down (why decaffeinated drinks aren’t always the answer)

If you decide to give up or cut down on caffeine, you may experience withdrawal symptoms including fatigue, drowsiness, headaches, body aches and irritability. These negative effects will stop after a few days.

For heart health, and to minimise withdrawal symptoms, reduce your caffeine intake gradually, especially if you usually consume a lot. Try swapping one or two of your normal drinks with herbal teas, coffee alternatives (like Ecco or Caro), caffeine-free soft drink, or fruit juices. Substitute one drink per week until you are below the 200 mg mark.

Decaffeinated drinks

Decaffeinated beverages may not be the healthy alternative you’re looking for. A recent study published in Circulation: Journal of the American Heart Association found markedly elevated blood pressure and increased nervous system activity when occasional coffee drinkers drank a triple espresso, irrespective of its caffeine level.

The results suggest that something else in coffee – not caffeine – is responsible for cardiovascular activation. Coffee contains several hundred different substances.

However, some people find that if full-strength caffeine drinks affect them too adversely, decaffeinated versions can be a good alternative.

Drinking to your health – is coffee helpful or harmful?

Research into the impact of coffee on health is overwhelming: in the past few decades more than 19,000 studies have been conducted into this little bean! For a while, researchers had coffee and caffeine doomed to the dregs as far as health was concerned, but despite some drawbacks, for many people, a moderate amount of coffee may be more helpful than it is harmful.

The table below highlights a selection of some current study findings – the results of these studies are general and more research needs to be done.  If you have any specific questions, it’s best to discuss these with your doctor.

Health areaCoffee researchTo drink or not to drink? Current thinking:
ArteriesSmall doses, even as little as one cup of coffee, can cause temporary suffering of the blood vessel walls.In sensitive individuals, limit caffeine to 100mg a day.
Blood cholesterolOil compounds in unfiltered coffee (espresso and cafeteria style) appear to raise cholesterol.Drinking filtered coffee will not affect blood cholesterol.
CancerIFIC says claims linking coffee and caffeine to certain cancers are not supported by medical research.Keep to a healthy, well-balanced diet that may or may not include caffeine.
Colon cancerScientists recently discovered the presence of a highly active compound (methylpyridinium) in coffee that may prevent colon cancer.The anti-cancer compound is found in caffeinated, decaffeinated, and instant brewed coffees. Drink moderate amounts of any of these for the benefits.
DiabetesA recent Harvard study shows 6 cups of coffee a day dramatically reduces risk of Type 2 diabetes, particularly in men.If you choose to drink coffee, also eat well, exercise, and maintain a healthy weight as these approaches can prevent the onset of Type 2.
FertilityThere is very little evidence, but caffeine may affect the time it takes to get pregnant and increase risk of miscarriage or low birth-weight. May also affect sperm motility in men.Not enough evidence behind these suggestions. But if you have fertility complications, cutting out caffeine won’t hurt.
GallstonesA comprehensive 10-year Harvard study found that people who drink coffee are at a lower risk of gallstones.2-3 cups of caffeinated coffee a day may reduce the risk of gallstones by around 40%.
High blood pressure and cardiovascular diseaseSome studies associate caffeine with increased blood pressure, others say there is only a weak connection. There are few links between caffeine and heart attack or stroke.If you have an existing problem with high blood pressure – watch your caffeine intake. Keep it under 200mg a day.
Liver diseaseA 2004 study found those who drank more caffeine had fewer liver abnormalities. More research is needed.Limit caffeine to 200-250mg per day.
OsteoporosisExcess caffeine can increase risk of osteoporosis and fractures.If calcium intake is above 800mg a day there is little detrimental effect on bone density.
Parkinson’s DiseaseStudies have shown that coffee consumption can decrease risk of Parkinson’s Disease. However, women who are heavy coffee drinkers and have hormone replacement therapy are one and a half times more likely to develop PD than heavy coffee drinkers who don’t have HRT.3-4 cups of caffeinated coffee a day may decrease risk, but if you are having HRT talk to your doctor about drinking coffee.
PregnancyCaffeine does reach the fetus and may disrupt the developing baby’s rest periods. Newborns may experience caffeine withdrawal.Pregnant women should avoid caffeine.
Rheumatoid arthritisResearch suggests that an ingredient in coffee other than caffeine may contribute to rheumatoid arthritis.Four cups daily may increase risk of developing rheumatoid arthritis by 50%.
StressCaffeine is a stimulant. It increases heart rate, adrenaline, and stress levels.If your anxiety levels are up, keep your caffeine intake down.

References :

This article was compiled in consultation with Calorie King experts and in reference to the following sources:

Daniel S W Tan, ‘Coffee Consumption and Risk of Type 2 Diabetes Mellitus’,  Lancet, Volume 361: Issue 9358, pg 702

E.W. Karlson et al., ‘Coffee Consumption and Risk of Rheumatoid Arthritis’, Arthritis Rheum, Nov 2003, 48 (11), pp 3055-60

Eduardo Salazar-Martinez, MD, PhD et al., ‘Coffee Consumption and Risk for Type 2 Diabetes Mellitus’, Annals of Internal Medicine, January 2004, 140 (1), pp 1-8

T. Lloyd et al., ‘Bone Status among Postmenopausal Women with Different Habitual Caffeine Intakes: A Longitudinal Investigation’, American Journal of Clinical Nutrition, 1997, Volume 65, pp 1826-1830

Calorie King
CalorieKing's mission is to provide the best information, tools and education to Australians to help them conquer their weight.

CalorieKing is the brainchild of Allan Borushek, registered dietitian, co-found here at and author of "Allan Borushek's Pocket Calorie & Fat Counter", Australia's best-selling calorie counter for over 30 years.

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