Just as a car's radiator needs to be topped up with water to make sure the car runs properly, we need to make sure that we are hydrated to stay well. We lose water from our bodies through sweating, urinating and breathing.
Even though fluids aren't classed as nutrients, they are still an important part of our diet. Fluids play a crucial role in maintaining the functions in our body, from simple things like lubricating our eyes for blinking, to removing toxins from our body. This isn't surprising when water makes up two-thirds of our body weight.
If we become dehydrated then we may suffer from headaches, lack of concentration or become confused and irritable. In severe cases it can be fatal. We're already dehydrated by the time the sensation of thirst sets in so it's important to keep hydrated to prevent us from getting to this point. Another sign of being dehydrated is having darker urine and passing less when we go to the toilet.
How much water we need depends on age, our diet, what activities we are doing and what the temperature is like. In moderate climates such as the UK, we should aim to drink around 1.2 litres each day, which is around 6-8 cups of fluid. When the weather is warmer and/or we have been doing physical exercise we should aim to drink more.
Water is a good source of fluid, but it's not the only one, you can also drink milk, fruit juices, soft drinks, tea and coffee.
Caffeinated drinks can act as mild diuretics. Diuretics can make us lose fluids from our body as they cause us to wee, and stronger versions are sometimes used in medicines. A single caffeinated beverage is unlikely to have a diuretic effect - in fact, this is a common myth. Caffeinated drinks are fine as one of our sources of fluids, but we should also have other types of drinks. Alcohol also has a diuretic effect, which can be much greater than that of caffeinated drinks. The effect depends on the strength of the drink, for example, a shandy will have less of a dehydrating effect than whisky. Therefore, if we drink too much alcohol, we could be dehydrating rather than hydrating ourselves! So try to drink water alongside alcoholic drinks to lessen this effect.
It's also wise to avoid having lots of sugary fizzy drinks, squashes or sports drinks as they can be high in calories and sugar, which can contribute to weight gain and tooth decay.
It's best to hydrate with water as it's calorie and sugar free, or fruit juices with a meal as they count as one of our 5-a-day or even a glass of milk, which contains many beneficial nutrients especially for children.