About water

Water is an indispensable element of life, and its role in how the body works is of the greatest importance. In addition to its structural role (the body of an adult contains on average 60 % water, of which 35 % is intracellular and 25 % extracellular), water has the job of carrying substances necessary for cellular activities or removing toxins from the body.

The body takes in water through liquid food, but also through solid food (whose degree of hydration varies; cucumbers, for example, contain 90 % water). Without water, a person cannot survive longer than 3-4 days, since water is excreted every day through urine, sweat, breathing and digestion.

For good hydration, a person with little physical activity needs 8–10 glasses of water a day, although the amount also depends on the kind of effort or the ambient temperature. Poor hydration leads to a build-up of toxins, an overload on the kidneys and malfunctions of the whole body (we feel more tired than usual).

A large part of the water enters the body through eating solid food, another part through drinking beverages, but a small part also arises from the burning of food in the body. It is known that burning 100 g of proteins produces 41 ml of water, burning 100 g of lipids produces 107 ml of water and burning 100 g of carbohydrates produces 55 ml of water.

There is normally a balance between the intake and the excretion of water, known as the water balance, in which the intake and the excretion are equal. A range of nervous and humoral regulating mechanisms help to maintain this balance. Water is lost through the kidneys (1300 ml), the airways (300 ml), the skin (750 ml) and the faeces (150 ml).

There are certain situations in which the excretion of water from the body increases and, in proportion to these losses, an increased intake of water is necessary. This happens during intense physical effort and at raised ambient temperatures.

The body regulates its temperature with the help of water. When it is exposed to high temperatures, it draws water out through sweating and so ultimately cools the skin. That is why hydration is very important on hot days; water losses have to be made up so that the working of the body is not impaired. The first signs that it is dehydrated are dizziness, a dry mouth, blurred vision or palpitations.

Water has no calorie value, and it is recommended that it be drunk at a temperature between 20 and 30 degrees so as not to disturb the digestive process, namely half an hour before or an hour after a meal. Fruit or vegetable juices cannot replace water, and it is recommended that they be drunk in combination with water in order to lower their glycaemic value.