The myth Dispelled

Frequently Asked Questions


Q. Does either coffee or caffeine cause cancer?
A. No. In 2007 the World Cancer Research Fund published a comprehensive evaluation of over 7000 published studies and found no strong association between drinking coffee and cancer.

Q. I have seen some reports that suggest coffee drinking is associated with an increased risk of cancer – why is this?
A. In 1991 the International Agency for Research on Cancer classified coffee as being associated with cancer of the bladder. However, since that date, numerous studies have been published which show insufficient evidence to link coffee consumption with the development of cancer.


Q Is it true to say that coffee drinking is protective against some forms of cancer?
A. Studies have shown that coffee drinking appears to be protective against the development of cancer at some body sites, particularly the liver and the lower bowel.

Q. Can I continue to enjoy my coffee without being concerned about the development of cancer?
A. Yes. Coffee does not cause cancer and when consumed in moderation, it may be enjoyed as part of a healthy diet and lifestyle.



Q: Is it true that coffee protects against Type II diabetes?
A: At this stage it would not be appropriate to conclude that coffee protects against Type II diabetes, however, epidemiological research to date suggests coffee may have a protective effect.

Q: How may coffee protect against Type II diabetes?
A: The exact cause and effect has yet to be identified. There are several hypotheses and research into the possible mechanism of protection is ongoing at several research centers.


Q: Does all coffee have the same effect?
A: Both caffeinated and decaffeinated coffee has been shown to be associated with a reduced risk in onset of Type II diabetes.

Q: How much coffee would a person need to derive any beneficial effects?
A: Research papers vary in the amount of coffee recorded at which the effect was seen. Most research papers that have been published on this subject suggest that positive effects are observed at consumption levels of three to four cups of coffee per day.


Q. Is coffee stimulating?
A. Caffeine, found naturally in coffee, is a mild central nervous system stimulant.

Q. I have heard that coffee leads to better physical performance, is this true?
A. Yes. Several published research papers over many years have shown that caffeine in coffee is an ergogenic aid – ergogenic means 'something that can increase muscular work capacity'.


Q. How long does the beneficial effect last?
A. Once consumed the effect of caffeine will be experienced after about 20 minutes and can last for several hours.

Q. How much coffee do I need to drink to experience this effect?
A. The amount is relatively small, with benefits on performance being seen after one large cup of coffee containing approximately 90 mg of caffeine.
Q. How does coffee help to boost my physical performance?
A. Whilst the beneficial effect is well documented in scientific literature, the exact mechanism of action is not yet fully understood.

Q. I had heard that coffee is a diuretic and that I should avoid coffee and other caffeine containing drinks before or during exercise – is this good advice?
A. It is not necessary to exclude caffeine containing beverages from your diet before or during exercise. There is no evidence to support caffeine restriction on the basis of impaired thermoregulation or changes to hydration status at levels less than 300 – 400 mg per day, equivalent to 3 to 4 regular size cups of coffee a day.


Q. So is it fair to say that the 3 to 4 cups of coffee I enjoy can be part of a healthy diet and lifestyle – whether I exercise or not?
A. Yes. Coffee drinking in moderation is safe and can be an enjoyable part of a healthy balanced diet.




Q. Is it true that drinks containing caffeine will cause our bodies to lose even more water than normal?
A. No. Despite what you may have heard or read, there is no evidence to support this claim. In fact, a moderate intake of coffee and other caffeinated drinks does not lead to dehydration and may contribute to daily fluid intake.

Q. What happens if you drink 3-4 cups of coffee a day – is urine output increased?
A. Evidence shows that regular consumers of caffeinated drinks, including coffee, have a higher tolerance to the mild diuretic effect, so the overall long term effect on hydration is very similar to water.

Q. How much water do we loose on average per day?
A. The normal average daily water loss is around 2500 ml of which urine accounts for approximately half. About 800 ml of water is lost through the skin and most of the remainder is from the lungs. This will of course vary, and in extreme conditions of heat and exercise, daily fluid loss may exceed 10 liters.


Q. Is dehydration harmful to health?
A. Severe dehydration is detrimental to health; it is associated with less efficient functioning of the heart and kidneys and generally makes us feel unwell. Doctors also agree that ongoing mild dehydration also has a negative effect on our general well-being.

Q. How much do we need to drink?
A. Fluids are an important part of our daily diet and to maintain our body's water balance we should be drinking in excess of on average 1.5 litres of various fluids throughout the day, and may include caffeinated drinks such as coffee. This amount will need to be increased to around 2-3 litres in hotter weather, during and after exercise, when working in very hot conditions, or when experiencing high body temperatures associated with a fever. In these circumstances we need to top up fluid levels on a regular basis.


Q. Are caffeine containing drinks the main cause of dehydration during the heat of summer?
A. No. The main factors affecting water loss from our bodies are surrounding air temperature and humidity. If the temperature increases we are likely to sweat more and this loss is greater still if we undergo prolonged exercise in a warm environment.

Q. So, what makes us thirsty?
A. We are consciously stimulated to drink when our blood volume falls and there is a rise in the concentration of sodium in the blood. This regulatory mechanism is rather insensitive and we may already be slightly dehydrated before we are prompted to drink. The sensation of thirst is often also reduced in elderly people, so they may not always drink enough to replace normal fluid losses.

Q. Where do we get caffeine from in our diet?
A. Caffeine is naturally occurring in coffee, tea, chocolate and cocoa and is added to cola and “energy” drinks. Caffeine is also present in some over-the-counter cold remedies and pain relief products.

Q. Is caffeine the active component in coffee influencing liver function?
A. Caffeine does have a role to play, but there are other active substances, including the diterpenes; Cafestol and Kahweol and the antioxidants, which are thought to have a beneficial effect on liver function.

Q. Does drinking coffee permit us to drink more alcohol without the risk of developing liver cirrhosis?
A. No. All medical advice makes clear that excessive alcohol consumption is detrimental to health. Adults, who choose to consume alcohol in moderation, should be aware of the recommended advice for safe consumption. Even though scientific research suggests that coffee drinking may have a beneficial effect on liver function, the risks associated with excessive alcohol consumption are not counter balanced by coffee consumption.

Q. I have heard that the effects of alcohol can be different for women than for men. Is coffee effect different according to gender?
A. Generally, the physiological effect of coffee drinking does not differ between the sexes, however, some groups – pregnant women, smokers, or women taking hormone replacement therapy do metabolize caffeine in a different time scale to those in the general population.

Q. How many cups of coffee should I drink to assist my liver function?
A. Although the research results are based on typical amounts of coffee consumption, it is too early to make recommendations concerning levels of coffee intake that may be protective for liver function. Drinking coffee in moderation is perfectively safe and can be enjoyed as part of a healthy diet and lifestyle.

Q. Are the effects similar when drinking espresso, filter, or instant coffees?
A. Studies on the effects of coffee and liver function have been conducted in relation to various types of coffee preparation including; filtered, instant and espresso coffee.

Q. Are the effects of decaffeinated coffee on liver function as beneficial as those of regular coffee?
A. Currently there are no published studies specifically investigating the effects of decaffeinated coffee and liver function.

Q. I usually drink my coffee with milk and sugar. Can I also benefit from the effects reported for black coffee?
A. There is no evidence from published studies to indicate that the addition of milk and/or sugar or their absence, affects the benefits associated with coffee and liver function.

Q. Does drinking coffee prevent the risk of developing Parkinson's Disease?
A. Research shows an inverse relationship between coffee drinking and the development of Parkinson's disease, with the exception of women undergoing hormone therapy. The mechanism of action for this effect has yet to be fully identified.

Q. How much coffee do I need to drink to help protect me from developing Parkinson's Disease?
A. Studies have shown that regular caffeine consumption may be protective against the incidence of Parkinson's. Higher amounts of coffee consumption (four or more cups per day) were found to reduce the risk of developing Parkinson's in male participants, whilst women with the lowest risk consumed moderate amounts of caffeine (one to three cups of coffee per day or, about 100-300 mg/day) and had never used post-menopausal hormone replacement therapy.

Q. Have scientists recently discovered the protective effects of drinking coffee and Parkinson's Disease?
A. No. The first study to indicate the possible effects of drinking coffee and reducing the risk of Parkinson's was published in 1968. Since then many studies have shown similar results, which all suggest that coffee in moderation may reduce the risk of developing Parkinson's in men and women not taking post-menopausal hormone replacement therapy.

Q. Is it safe to drink coffee during pregnancy?
A. Yes. Scientific studies have shown that moderate coffee consumption whilst trying to conceive, during pregnancy and whilst breast feeding is perfectly safe.

Q. How much coffee is safe to drink during pregnancy?
A. The majority of scientific studies suggest that caffeine intake of 300 mg or less per day (approximately 3 regular sized cups of coffee) is safe. Most women are drinking less coffee during pregnancy due to nausea or aversion to coffee.
The UK Food Standards Agency recommends 200 mg of caffeine or two cups of coffee per day for women whilst trying to conceive and during pregnancy and lactation. Similar advice is provided by the US based charity, March of Dimes. ; It remains to be seen whether this precautionary point of view will be endorsed by scientific bodies around the world.

Q. I've heard that drinking coffee during pregnancy can cause a miscarriage?
A. Research does not indicate that moderate caffeine or coffee consumption increases the risk of miscarriage. Scientific research has shown that an increased level of a hormone which exists in a normal pregnancy is associated with coffee aversion and lower levels of hormone were not. As a result caffeine/ coffee are commonly – misunderstood to be associated with miscarriage.

Q. What about the effects of drinking coffee on fetal development and birth weight. Is my baby at risk if I drink coffee?
A. The vast majority of scientific research has found that maternal consumption of coffee and caffeine, in moderation, is not associated with increased risk of congenital malformations, or birth defects in foetuses. Research also has not found a relationship between moderate coffee intake and impaired foetal growth.

Q. How much coffee should I drink to stay awake?
A. Research shows that taking a 30 minute break from driving and drinking one to two cups of coffee (providing about 150 mg of caffeine), and then taking short nap of 15 minutes, is the most effective way of alleviating driver fatigue.

Q. How long before the caffeine in a cup of coffee takes effect?
A. Up to two cups of coffee can increase alertness for several hours, but it takes on average 20-30 minutes to take effect. It is recommended to drink a cup of coffee at the beginning of a break and before taking a nap. On a long journey the advice is to take a break every two hours.

Q. Can coffee help sober you up if you drink alcohol?
A. A common myth, but not true! Coffee will not reduce the effects of alcohol nor does it increase your ability to break down the alcohol you drink.

Q. Does eating a bar of chocolate have the same effect as drinking coffee, as it also contains caffeine?
A. A 50g (2oz) bar of milk chocolate contains around 40 mg of caffeine whereas an average cup of coffee contains 80-150 mg of caffeine – the amount needed to alleviate tiredness

Q. I'm told that playing the car radio very loud or singing is actually all I need to keep me awake. Is that correct?
A. Sadly no. Such actions may even distract a driver from being as aware of their sleepiness and poor driving.

Q. Is coffee more beneficial to alertness at certain times of the day?
A. Most sleep related accidents happen when the body's circadian rhythm or natural clock, is at its low points: between 2.00 and 6.00, and mid afternoon between 14.00 and 16.00. However drinking one or two cups of coffee at any time when feeling sleepy will be effective in helping to keep you alert

Q. I am about to set off on a long distance holiday and will be doing most of the driving when we arrive after the flight. What advice would you give me?
A. Even if you have had sufficient sleep, jet lag will often cause daytime drowsiness so long distant driving should be avoided after a lengthy flight and when suffering from jet lag
Follow the basic principles of safer driving - don't drive if you are feeling drowsy. The only safe thing to do is to take a break - stop driving, drink one or two cups of coffee and take a nap for about 15 minutes.

Q. I often have to drive a long distance after I finish my shift at work. What advice would you give me?
A. Most sleep related accidents happen when the body's circadian rhythm or natural clock, is at its low points: between 2.00 and 6.00, and mid afternoon between 14.00 and 16.00. So be particularly vigilant if you are driving at these times and be very aware of the signs of sleepiness. If you are aware of any signs of being tired when you are a driver, the only safe thing to do is to take a break - stop driving, drink one or two cups of coffee and take a nap for about 15 minutes.

Q. How do I know if I am risk?
A. There are a number of warning signs that drivers should heed as signs of sleepiness:
- Constant yawning
- Tired or sore eyes or going out of focus
- Difficulty in keeping your head up
- Poor lane discipline
- Slow reactions
- Lack of concentration or day dreaming
- Erratic speed
- Difficulty in remembering the last few miles or kilometers
If you are aware of any of these when you are a driver, the only safe thing to do is to take a break - stop driving, drink one or two cups of coffee and take a nap for about 15 minutes.

Q: Is it true that the caffeine in coffee can help increase levels of alertness and attentiveness?
A: Yes. Many well-conducted studies demonstrate the effects of caffeine in coffee and other beverages and increased alertness.

Q: Can drinking coffee lead to better work performance?
A: Yes. As the caffeine in coffee helps enhance alertness and attentiveness, this can lead to better performance at work.

Q: What about mood, I have read somewhere that caffeine improves mood, is this true?
A: Yes. Caffeine impacts positively on alertness and performance, and this in turn can help elevate overall mood.

Q. Is the post lunch dips a true phenomenon? If so does coffee help?
A. Our bodies experience/have what is known as a 'circadian rhythm', often referred to as our body clock. The circadian rhythm goes through highs and lows throughout the day, and one of the lows is in the early afternoon – this
has been called the 'post-lunch dip' though in actual fact has nothing to do with lunch. The caffeine in a cup or two of coffee is sufficient to increase your levels of alertness and by doing so to keep you going through the afternoon.

Q: Is it true that coffee can reduce driver tiredness?
A: It is well documented that a couple of cups of coffee and a short nap are the most effective method of alleviating driver fatigue. Many road accidents occur as a result of a driver falling asleep at the wheel so yes, coffee may be improve road safety. Road safety organisations advise drivers to pull over, drink one or two cups of strong coffee and take a 15 minute nap.

Q: If caffeine is a stimulant, how will I have a short nap after drinking 2 cups of strong coffee?
A: The stimulant effects of caffeine take about 15 – 20 minutes before they are noticeable, so you have your nap and then wake feeling revived, as the caffeine will be working.

Q. Will coffee help me 'recover' from jet lag?A. Following a long plane journey, the caffeine in one or two cups of coffee can help you to remain awake/alert when you reach your destination until it is time for bed. Coffee is also a good source of fluid so it will help keep you hydrated which will also ease the feelings associated with jet lag.

Q. I don't understand how coffee can be stimulating, as I often enjoy relaxing with a cup of coffee?
A. Both are true. The effect of coffee depends on several things. When you are not quite awake, as may happen when you are getting up in the morning, the caffeine in coffee will raise your level of alertness. When you are already alert and active, it may over stimulate you and in some cases, the body responds to that state by dampening down its own metabolism. That would explain why coffee might relax you. The other relaxing effect of coffee is the psychological effects resulting from giving your body and mind a “treat” by having a coffee break.

Q. I don't drink coffee for the effects of caffeine. I just like it for its warmness, taste and flavour?
A. Most people drink coffee primarily because they enjoy the warmth, the aroma and the taste of a nice cup of coffee. The stimulating effect is usually a much appreciated plus. At times when the stimulating effect is not desirable, decaffeinated coffee is an enjoyable alternative beverage