Water has been dubbed the "forgotten factor" in our diets, but it's the most vital of nutrients. We can survive for days, even weeks, without food, but only two or three days without water. It's needed for so many functions in our body. Read up on why and how much we need.

Why we need water

Our body is made up of around 60 per cent water. Organs such as the brain and muscles contain as much as 75 per cent water but we tend to underestimate how important water is for us to function.

We need water to:

• transport nutrients around the body via the blood and lymph system
• remove wastes via the urine and faeces
• serve as a medium for the countless biochemical reactions that take place in the body
• moisten our food to facilitate chewing
• maintain body temperature - when we sweat, heat is released as the sweat evaporates which cools you down

Dehydration signs

A US study reported that significant numbers of people go about their lives in a state of mild dehydration. Dehydration occurs with only a 1 or 2 per cent loss of fluid but if left uncorrected its symptoms can be significant. Over a life time, insufficient fluid has been linked to kidney stones, urinary tract infections and bladder cancer.

Signs of dehydration

Mild

• Headache
• Feeling tired
• Light headed
• Skin loses its plumpness and becomes flushed

Moderate

• General weakness
• Rapid heart rate
• Inability to think clearly

Severe

• Muscle cramps
• Failing kidneys

Susceptibility - who to watch

Some groups are more at risk of dehydration than most. These include:

• small children
• breastfeeding mothers
• the elderly

Also other conditions may put you at risk of dehydration:

• very hot weather
• gastroenteritis
• diarrhoea
• vomiting
• extreme high-fibre diets

 THIRST is not a reliable guide to our fluid needs as we are usually dehydrated by the time we experience it.

Achieve hydration

If you follow the NRV (Nutrient Reference Values) guidelines, you will consume around 8 to 10 glasses of drink or about 2 L of total fluid each day. These guidelines will also:

• Moderate your intake of sweetened drinks such as soft drinks, cordial and sports drinks
• Encourage responsible alcohol consumption, as suggested by health authorities
• Limit caffeine (tea has about one-third to one-half the caffeine of coffee, although this is influenced by length of brewing)

The bottom line

Let's put this into practice now. Are you drinking enough each day? Here's how:

• Have a drink on your desk. Drink one glass of water every hour so you get through those 8 to 10 glasses over the day
• Carry a drink with you in the car or on outings
• Make it a habit to have a drink every time you take a break
• Encourage kids to drink - they are more susceptible to dehydration