Overhydration: How much water is too much?

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The dangers of dehydration are well documented - severe loss of water and liquids in the body can lead to an imbalance of electrolytes, which can result in low blood pressure, unconsciousness and even stroke. Moreover, with the adult body made up of approximately 60 per cent water, our cells and organs need it to function properly. But, did you know that water intoxication or overhydration (drinking more water than your body can process) can be equally dangerous as well?

A new study published in the European Journal of Nutrition suggests that both dehydration and overhydration can impair cognitive abilities in older women. Hence, as per the report, it is best to identify a ‘sweet spot’ of hydration for healthy cognitive functions, wherein older adults focus on their hydration levels by paying a close watch on ensuring adequate water intake to avoid dehydration, and that electrolytes are balanced to avoid overhydration.  

Dangers of overhydration

Overhydration does not just affect older people. It is possible for athletes and those who spend a lot of hours exercising outdoors, especially in warm temperatures, to overhydrate as well. This happens when you drink more water than your body can hold in, for fear that you may get dehydrated. This, however, can prove harmful as the kidney can only process around 20-28 litres of water per day and 0.8 ml-1. litre per hour - anything beyond that can cause waterlogging in the body. In the case of younger children, older adults or those with kidney problems the threshold is even lower.

Excess water intake can cause the cells to swell up and can lead to cerebral oedema or accumulation of water in the brain. Symptoms include headaches, fogginess, nausea or vomiting. At a more severe level, water intoxication can cause difficulty in breathing, confusion, double vision and increased blood pressure. The body also needs a healthy amount of electrolytes such as sodium in the bloodstream to help the cells hold on to water and the brain function properly. Excess hydration dilutes this sodium, leading to a condition called hyponatremia where the body holds too much water and sodium levels drop (less than 135 mmol/L). This affects the normal functioning of the brain, and, at a basic level can lead to headaches, confusion, appetite loss, loss of focus and lethargy. When severe, overhydration leads to rapid brain swelling, seizures and can even result in coma and death.

Signs of overhydration:  

The quantity of water that you take and the time frame within which you drink water matters. Though it is not easy to reach a state of water intoxication, you may start to see the symptoms if you have consumed more than 3 litres of water in a few hours. One of the signs to look out for is the colour of your urine - contrary to the general belief that clear urine is a healthy sign, the fact is that transparent urine often means that you have consumed more water than your body needs. You need to ideally aim for transparent yellow/pale straw colour urine.

Further, your urine count also matters - the average healthy adult would urinate 6-8 times a day. If you notice that you are urinating more frequently and this is affecting your work, you may need to consider cutting down the fluids.

Other symptoms include nausea and vomiting, headache, confusion or disorientation.

How much should you drink?

While we have all heard about how we should aim for eight glasses of water a day, the fact is that this number should be adjusted depending on the climate, your weight, the medications you are taking, the kind of work you do and how active you are. A good rule of thumb is to drink water when you are thirsty and avoid overdoing it. Sip small amounts of water and phase it out across the day, ensuring that you stay within the prescribed daily limit.

Your hydration also does not need to come from water alone. A 2015 study published in the American Journal of Clinical Nutrition revealed that a number of drinks, which included milk, tea and orange juice were, in fact, more hydrating than plain water. As per the study, there are certain elements in a beverage, which includes its nutritional level, and the presence of diuretic that can help determine how hydrating it is. Experts also recommend that athletes and others who exercise for more than an hour in the heat should ideally consume sports drink to ensure that sodium levels are in check.