Do we really need eight glasses of water a day?

Do you make sure to get your eight glasses of water a day? After all, it’s been touted as the way to get great skin, detox toxins, and help you lose weight. But a recent editorial in the British Medical Journal claims that your efforts may be a waste.

Dr. Margaret McCartney, a Scottish general practitioner, wrote in the journal that efforts to get people to drink more water are unnecessary because drinking eight or more glasses daily hasn’t been shown to have positive effects on our health — and could cause some people harm by overworking the kidneys and lower sodium levels in the blood. She points out that campaigns to get in those eight glasses — or two litres — are often sponsonsered by companies that own bottled-water brands and clearly have a vested interest in our fluid-consumption choices.

But McCartney has her detractors, as well. One of them is Thomas Sanders, a nutrition professor at King’s College London, who pointed out that McCartney’s editorial is just that — the opinion of one physican, not supported by peer research. Sanders said that some people, including the very young and the elderly, need to watch fluid intake carefully to prevent dehydration, and that discouraging water consumption could just make people drink more of other, unhealthy beverages, like soda.

However much we really need to take in, we do need to be properly hydrated — water makes up 60 percent of our bodies, and it’s necessary for functions like transferring materials to and from our cells and keeping our nasal passage and throat hydrated. Drinking fluids other than water can also count towards your daily total — coffee and tea are made with water, after all, and it’s also a key component of many fresh juices. Getting your recommended intake for fruits and vegetables is another way to make sure you’re avoiding dehydration.

So how much water do we actually need to drink? The Mayo Clinic says that differs for each of us, depending on factors like our age, size, exercise levels and general health. Mayo still recommends eight to nine eight-ounce glasses a day, however; people who spend time out in heat or exercise will need more. And how do we know if we’re getting enough fluids? If you’re not thirsty, and you’re expelling about six cups of light-coloured urine daily, you’re probably good.