Frequently Asked Questions

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 litres.

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 on going 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.