According to scientists, the generally accepted requirement to drink eight glasses of water a day may be too high for our actual needs. Given that about half of our daily water intake comes from food, researchers estimate that we only need 1.3 to 1.8 liters of water a day instead of two.
Previous work in this area relied on surveys of small numbers of human samples, but now more than 90 scientists around the world have collaborated to measure water conversion using a different technique. A study was conducted with 5,604 people between the ages of eight days and 96 from 23 different countries.
Participants drank moderate amounts of water enriched with the element deuterium, which is naturally found in the human body and is completely harmless. The rate at which deuterium disappears from the body was then measured; This revealed how fast the water in the body was circulating.
The analysis, published in the journal Science, showed that those who live in hot and humid environments and at high altitudes, as well as athletes, pregnant and lactating women, need more water because their water cycles are higher.
One of the authors, Professor John Speakman of the University of Aberdeen, said the water cycle does not equal drinking water needs: “Even if a man in his 20s has an average water cycle rate of 4.2 liters per day, he does not need to drink 4.2 liters of water every day. ”
About 15 percent of this value reflects surface water exchange and the water produced from metabolism: “The actual water intake required is about 3.6 liters per day. Since most food also contains water, a significant amount of water is taken up just by eating it. This study shows that the common recommendation that we should all drink eight glasses of water is probably too high for most people in most cases.”
There is no harm in drinking 8 glasses of water a day, however; but in most cases it is not necessary. “Calculations show that a typical middle-aged man may need to drink about 1.6 to 1.8 liters per day and a typical woman of the same age about 1.3 to 1.4 liters per day. For people in their eighties, about 1.1 liters a day is enough. “But it depends a lot on what kind of food they eat. For example, if they drink a lot of soup, it will be enough for them to drink less water.”
Speakman does not neglect to emphasize that beverages such as tea, coffee, sodas, and juice are also included in the daily collection, but there are other things in them that may not be healthy.
Co-author Dale Schoeller, of the University of Wisconsin-Madison, said: “Science has never supported the old eight-cup thing as an appropriate guide because it mixes the total water cycle with the water from beverages, and most of your water comes from the food you eat. It’s the best study we’ve ever done to quantify how much water they actually consume on a daily basis – the key factors driving the water cycle – and the water going in and out of the body.”
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