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Controlling your caffeine

Aging, Diets, General Nutrition, Mens Health, Mental Health, Pregnancy, Sleep & Stress, Womens Health, Healthy Eating, Breastfeeding / Lactation
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Are you unable to kick start your day until you’ve had your first caffeine fix? Caffeine is one of the most widely consumed stimulants in the world so you are not alone if you depend on caffeine to wake you up and kick start the central nervous system. 

In this blog we explore how much caffeine is 'reasonable' as part of a healthy diet, and some insights into where caffeine is added to help you better manage your daily intake.

Natural sources of caffeine include:

  • Coffee
  • Tea – The amount of caffeine varies with the type and variety of tea leaves and the strength of the brew. It is noteworthy to mention here that even green tea, unless decaffeinated, also contains caffeine.
  • Cocoa – The seed of the cocoa pod is used to make cocoa powder and chocolate products. Higher the cocoa content in chocolate, higher is the caffeine content
  • Kola nuts – The seed of the kola nut is consumed as a nut or as a tea
  • Guarana – a plant with high levels of natural caffeine. Seed of this plant is used in snack bars and beverages like Red Bull etc.

 Caffeine is also added in several other consumables like:

  • Cola-type soft drinks
  • Energy or Sports drinks
  • Energy shots
  • Energy bars
  • Medications like cough syrups
  • Weight loss aids like slimming pills

Caffeine has a stimulating effect on central nervous system, heart, blood vessels and kidneys. The effects of caffeine vary from person to person depending on their weight, state of health and the amount of caffeine consumption. Caffeine is known to produce the following effects:

Positive Effects: People consuming caffeine have shown improved performance and efficiency, enhanced sensory activity, increased alertness and concentration and decreased fatigue. This partly explains why people get addicted to coffee or other caffeine containing beverages for them to perform and function better.

Negative Effects: Caffeine intake may also result in:

  • Rise in body temperature
  • Increased palpitations
  • Anxiousness
  • Nervousness
  • Restlessness
  • Sleeplessness
  • Involuntary shaking

Safe Limit for Caffeine

Currently, there is no safety limit such as Acceptable Daily Intake (ADI) or Recommended Dietary Intakes established for caffeine intake. However, 3mg / kg of body weight has been accepted as the recommended limit of caffeine daily intake for adults.  

Generally speaking, 400mg per day or less is considered an acceptable dose of caffeine and have not shown any adverse effects in healthy adults.


Average Caffeine content of some Foods and Drinks

Food Item

Serving Size


Instant Coffee

250 ml Cup

60-80 mg

Percolated coffee

250 ml cup

60-120 mg

Decaffeinated coffee

250 ml cup

5 mg

Tea (depends on the type and strength of the brew)

250 ml cup

10-50 mg

Green Tea (loose leaves)

250 ml cup

32 mg

Chocolate Drinks

250 ml cup

30-60 mg

Milk Chocolate Bar

100 g

20 mg

Dark chocolate Bar

55 g

40-50 mg


375 ml can

35-47 mg


Energy Drinks

Most energy drinks contain caffeine and sugar as major ingredients, with other ingredients such as Taurine (an amino acid) and Guarana. Energy drinks which contain high amounts of Caffeine and Gaurana, often claim to boost energy and sports performance although clinical evidence for the claim have not been clearly established. Energy drinks are not recommended to children and pregnant women because of their high caffeine and sugar content.

Caffeine content of Energy Drinks commonly available in Australia

Name of the Drink

Caffeine (mg)/250 ml of the drink


78 mg

Rockstar energy drink

135 mg

Red Bull

80 mg

Fuel Cell*

750 mg


80 mg

Red Eye

80 mg

Cintron energy enhancer

105 mg

Smart Energy

50 mg

* Has been taken off the shelves because of its very high caffeine content.

Quick Bytes

  • Caffeine is easily and readily absorbed in the body and has marked physiological effects on the human body
  • There have been mixed messages about caffeine and its possible diuretic effect – that is you urinate more after drinking them increasing your risk of dehydration. However, recent research shows this is not true and it only applies with high caffeine intake (approx. 600+mg of caffeine p.day) . Therefore the fluid you get from tea and coffee will actually contribute to you fluid intake for the day and help keep you hydrated. This is especially important for the elderly who often struggle to meet their fluid intake needs. 
  • Pregnant women should limit their daily caffeine intake to 3 cups of instant coffee/1 cup of express coffee/4 cups of tea/ 375ml of cola beverage, as recommended by Food Standards Australia New Zealand. High intakes of caffeine during pregnancy increases risk of miscarriage and birth defect in baby
  • Energy drinks contain higher amount of caffeine and sugar than cola drinks. Therefore,  not recommended for pregnant women and children
  • A FSANZ Expert Working Group concluded that children (aged 5-12 years) showed increased anxiety levels with  caffeine doses of about 95mg/day (2 cans of cola). Other symptoms include irritability, difficulty to sleep or stomach upsets
  • Like any other stimulants, caffeine also has withdrawal symptoms such as persistent headache, tiredness, poor concentration, irritability and anxiety. Therefore, it is advisable to cut down caffeine intake gradually to enable the nervous system adapt..
  • Heavy doses of caffeine intake for longer periods may increase the risk of  osteoporosis, high blood pressure, ulcers, severe insomnia, panic attack and confusion


Share your experiences: 

How much caffeine are you consuming and how does it affect you? Share your experiences below. 


References and Useful Links:

Caffeine - Food Standards Australia New Zealand. 2012. Caffeine - Food Standards Australia New Zealand. [ONLINE] Available at: http://www.foodstandards.gov.au/consumerinformation/caffeine/. [Accessed 23 March 2012].

Caffeine - Drug Prevention & Alcohol Facts - DrugInfo. 2012. Caffeine - Drug Prevention & Alcohol Facts - DrugInfo. [ONLINE] Available at:http://www.druginfo.adf.org.au/drug-facts/caffeine. [Accessed 23 March 2012].

Caffeine | Better Health Channel. 2012. Caffeine | Better Health Channel. [ONLINE] Available at: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Caffeine?open. [Accessed 23 March 2012].

Caffeine | Dietitians Association of Australia. 2012. Caffeine | Dietitians Association of Australia. [ONLINE] Available at: http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/caffeine/. [Accessed 23 March 2012].