liquids for life

Key points

• Water is the most abundant constituent of the human body and regular fluid intake is essential for our bodies to work properly.
• The amount of fluid needed varies between people and according to age, time of year, climatic conditions, diet and levels of physical activity.
• We can obtain our fluid requirements from a number of sources such as water and other drinks, as well as from the food we eat.
• Dehydration can impair physical performance, and in extreme cases can be fatal.
• The sensation of thirst is not triggered until there is a water shortage in body tissues, so it is a good idea to drink before you get thirsty. Extra attention should be given to children and the elderly who may not recognise the sensation of thirst so easily.
• Water may be described as ‘hard’ or ‘soft’ depending on the amount of dissolved calcium and magnesium it contains.

Water
Although water is not a nutrient in the classical sense, human beings would be unable to survive without it. Over half the human body consists of water and it is essential for the correct functioning of virtually all living cells. Water is made up of hydrogen and oxygen atoms and is sometimes called H2O.

Why Is Water Good For Us?
Water is essential for our bodies to work properly.  Water (and fluid in general) has many functions in the body.

• It acts as a lubricant for joints and eyes
• It helps us swallow
• It provides the medium in which most reactions in the body occur
• It acts as a cushion for the nervous system and helps get rid of waste
• It helps to regulate body temperature.

How Much Water Do We Need?
The amount of water (and other fluids) that we need to drink each day varies from person to person, depending on age, time of year, climatic conditions, diet and the amount of physical activity we do. 

Health professionals recommend at least 1.5 to 2 litres (6-8 cups) of liquids a day in temperate climates.

We can get our fluid requirements from a number of sources. It is not necessary to only drink ‘pure’ water, although this is a good choice. Like everything else we consume selection depends on personal preference and availability. Other drinks like squash, fruit juices, tea and coffee contribute to our daily requirements too. People often forget that some of our fluid requirements come from the food we eat, not just drinks. Roughly a third of an adult’s daily fluid intake is supplied by what is eaten rather than what is drank.  Fruit and vegetables provide most of this additional fluid but small amounts come from bread and dairy products for example.

© British Nutrition Foundation