Are you drinking too much water?by Dr. Sarah Brewer
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iVillageThe answer is probably no. Yet recent media reports of water intoxication have left many iVillagers confused over how much water they should be drinking a day. Dr Sarah Brewer advises on how to keep your fluid intake healthy
Water is more important to our health than most people realise. During an averagely active day in a temperate climate such as the UK, we lose around 2.5 litres of fluid from our body, either through the lungs as water vapour, through the skin as sweat, or through the kidneys as urine. A small amount is also lost through the bowels. If you take vigorous exercise or visit a hot country, it is easy to lose twice this amount. Athletes in hot climates may lose as much as 10 litres of fluid per day.
The body normally maintains a fine fluid balance. As long as we replace our daily water losses through adequate drinking and eating, excess fluid passes into your circulation and is usually filtered out by the kidneys. If you are slightly dehydrated, you will pass less urine than normal. This is because your body will carefully conserve its water stores and also trigger sensations of thirst.
Ideally, we need to drink at least two litres (eight glasses) of pure water per day, in addition to other fluids, such as alcohol, tea, coffee and soft drinks. Children should drink approximately half this amount, depending on their age. Although we should ideally drink at least eight glasses of water a day, only 10% do so. Over half the population only drink between one and four glasses of water a day, and this can lead to dehydration.
Dehydration is a common cause of tiredness, poor concentration, reduced alertness, recurrent headaches and mood changes. It can also lead to constipation, kidney stones, and even a blood clot, heart attack or stroke, as it increases the thickness and stickiness of blood.
It's important to not wait until you feel thirsty, as thirst receptors are a poor judge of how fluid deficient you are, and you are already significantly dehydrated the time you feel a craving to drink. Aim to drink fluids regularly throughout the day rather than just drinking when you feel thirsty.
High temperatures can quickly lead to dehydration, so drink plenty of water in summer months or when visiting hot climates. If exposure to heat is excessive, it can also lead to heat stroke - this is because increased humidity stops sweat evaporating from the skin to cool the body. To help prevent this, acclimatise yourself to hot weather slowly by spending gradually longer periods of time in the heat, before returning to cooler shade - full acclimatisation can take up to three weeks. Avoid strenuous exercise, wear loose, lightweight clothes, and drink plenty of fluids. Cool off in a shower whenever possible.
However, even water intake requires moderation: recent media reports have focussed on people who have drunk too much water, which can overwhelm the kidneys and lead to swelling of the brain. Water intoxication can cause symptoms of headache, dizziness, nausea, confusion and, in extreme cases, can lead to coma and death, although this is rare. Certain drugs, including illegal ones such as ecstasy, can trigger drinking excessive amounts of water. It can also be caused by health conditions that affect water balance, such as kidney failure, liver cirrhosis, and uncontrolled diabetes. Drinking excessive amounts of water can also have a psychological cause when it is known as psychogenic polydipsia.
Most people will come to no harm if they stick to drinking two to three litres of fluid per day. If you are concerned about your fluid intake, seek medical advice.
