Caffeine is a natural stimulant found in tea, coffee and cocoa. These plants grow in the tropics or sub-tropics and use caffeine as a natural pesticide to kill insects — fortunately this is not the outcome for most human consumers of tea, coffee and cocoa. Caffeine is also added to sweetened energy drinks and a wide range of pain relief and gym workout supplements. There have been mixed reports on how caffeine affects health. This is due to the research study design (type and amount of caffeine and other lifestyle and health factors studied), as well as genetic differences between people.
Caffeine is metabolised (broken down) by the liver. It would take about 40 hours to completely metabolise 200mg of caffeine, however we only feel the affects of caffeine for about 4–6 hours after consumption.
We all metabolise caffeine differently due to:
- Our genes — we can be slow or fast metabolisers
- Exposure — our tolerance for caffeine increases over time
- Other compounds — foods and medications can slow down the metabolism
How caffeine affects health
The reported positive and negative affects of caffeine from research studies are often by association, not causation. This is why researchers are unable to say “drinking coffee will decrease your risk of diabetes”. This can be frustrating because all you want to know is should I drink more or less coffee! Putting such frustration and confusion aside, it is important to understand that research in any field rarely makes a ‘big discovery’ that proves or disproves a relationship in health. Our knowledge about how food and nutrients and components of food grows incrementally.
And my advice is assess your own health requirements and be mindful of how caffeinated foods and beverages affect you.
- Increases alertness and keeps us awake (this can be a disadvantage too)
- Pain relief in sore (inflamed) joints and muscles
- Increases endurance during long distance sporting events
- Increases our motivation and productivity
- May prevent or delay Alzheimer’s disease and Parkinson’s disease
- Delay and interrupt sleep
- Shakiness or ‘the jitters’
- Addiction, which can lead to the risk of overdose
- Withdrawal headaches
- May increase blood pressure
- Interferes with heart rate and contraction for people with existing heart conditions
Health recommendations for caffeine
There is currently no Australian or internationally recognised recommended daily intake level for caffeine. However, increased anxiety levels have been found in children consuming 95mg caffeine per day and in adults at levels of 210mg/day. The American College of Obstetricians and Gynecologists advise pregnant women to have less than 200mg of caffeine per day. The caffeine content of common drinks and foods are tabled below.
Caffeine content of drinks and food
|Caffeine content (mg)
|10-50/ 250ml cup
|Instant coffee (1 teaspoon)
|60-80/ 250ml cup
|Espresso and percolated coffee
|60-120/ 250ml cup
|Cola soft drinks
|57-77/ 600ml bottle
|Caffeinated energy drinks
|10/ 50g bar
|20/ 50g bar
Caffeine levels from Food Standards Australia New Zealand and the Australian Drug Foundation
What is the verdict on drinking coffee and health?
The most commonly consumed food source of caffeine is coffee. In Australia, the consumption of coffee has doubled in the past 30 years. It is unknown whether this increase is of a health concern. Scientific research is building a picture about the possible benefits and risks related to coffee drinking
- Possible benefits: decrease the risk for premature death, developing type 2 diabetes, liver cancer and some types of prostate cancer.
- Possible harm: increase the risk for developing lung cancer and high blood pressure.
As mentioned above, there are genetic differences between individuals in how they metabolise caffeine. It is proposed that fast metabolisers of caffeine may experience health benefits from the naturally occurring antioxidants in coffee, if they keep their coffee consumption to less than 2–3 cups per day. This potentially explains why research studies conducted in different populations have produced conflicting results about the impacts of coffee on health.
Due to the varying affects of roasting coffee on antioxidant levels, drinking coffee is not recommended as your main source of antioxidants. Coloured fruits and vegetables offer a wide range of antioxidants and provide a number of health benefits.
There is still more for us to learn about the health affects of drinking coffee. I suggest a lower consumption of coffee — no more than one per day — especially if you have high blood pressure or you are using coffee to boost your energy levels. Tricking your body into feeling more alert is not a long-term solution for your health and wellbeing.
If you are interested in knowing whether you are a fast or slow metaboliser of caffeine have your genes tested for caffeine metabolism. The test is very simple and involves a mouth swab.
I believe we should ban caffeinated energy drinks
The addition of caffeine to drinks is currently being reviewed in Australia. There have been cases of caffeine toxicity from consuming caffeinated energy drinks. The reported side effects include heart palpitations, extreme anxiety and restlessness, tremors and shaking. There have also been deaths caused by the overconsumption of these drinks. I do not recommend the consumption of caffeinated energy drinks.
Eastern Medicine view of caffeine
The Eastern view of caffeine is that it shouldn’t be consumed on a daily basis. Ayurveda and Traditional Chinese Medicine (TCM) describe that we are born with a reserve of life force energy (Qi), and through our lifestyle choices we either enhance or deplete this reserve. Caffeine, whilst being a stimulant, appears to provide us with additional energy, but the processes required to metabolise caffeine deplete our reserves of Qi. This leads to initial feelings of lethargy and longer-term health problems related to deficient Qi, for example drinking coffee is believed to deplete kidney function and interfere with the female reproductive system.
What’s best for you?
I suggest that you monitor the affects of caffeinated foods and beverages on your mental and physical health. If you currently enjoy a morning cup of coffee, with no side effects, then continue to do so. Tea also contains caffeine and I will be exploring the health benefits of drinking tea in an upcoming post.