Basic water needs vary from person to person, study finds
Water needs vary greatly from person to person, fluctuating between one and six liters of water per day.
Basic water needs vary greatly from; person to person, shattering once and for all the entrenched myth that we should all drink at least eight glasses of water a day to stay healthy, says a new international study.< /p>
Researchers have measured for the first time how much water is actually expended and then replaced each day by thousands of humans.
They studied 5,600 people from 26 countries, ranging in age from 8 days to 96 years. They found that daily averages fluctuated between one liter and six liters of water.
This allows for the very first time to paint a real portrait of human water consumption, commented Professor Stéphanie Chevalier, from the School of Human Nutrition at McGill University.
“This is immense quality data that is not approximate. We have real data to then build recommendations based on all their analyses, so for that, it's very interesting.
— Stéphanie Chevalier, McGill University School of Human Nutrition
This study would be the first ever not to rely on participant-provided information to measure their water intake, which can generate data of questionable utility. Instead, the new research objectively measured how long the subjects took to pass out water that had been added with oxygen and hydrogen isotopes to make it detectable in their urine.
< p class="e-p">More than 90 researchers contributed to this work. They found that, among their subjects, water replacement peaked in their twenties for men, and was fairly stable for women between the ages of 20 and 55. Newborns, however, come out on top, replacing an average of 28% of the water in their bodies every day.
All other things being equal, men replace about half a liter more water each day than women.
If this study is not revolutionary in the world of nutrition, we can hope that it has at least the effect of reminding people that the myth of eight glasses of water a day does not x27;is nothing but a myth, Ms. Chevalier said.
“When I read this, my hair always curls a bit because I think, how can you think that, for example, an 80-year-old old lady who weighs 50 kilos should drink eight glasses of water, the same amount as a big guy of 30 who works on a construction site outside all day?
— Stéphanie Chevalier, from the School of Human Nutrition at McGill University
Generally, Chevalier said, people are recommended to consume one milliliter of water per day for every calorie burned. In other words, an individual who expends 2000 calories in a day should also drink two liters of water.
Researchers have also found an association between water consumption and the UN Human Development Index of the participants' country: the lower the country's index, the higher the water consumption, possibly because it are frequently hot countries where air conditioning is non-existent and whose inhabitants must work very hard physically to survive.
The authors of the study point out that, in the face of With climate change and ever-increasing human population, more and more people are at risk of not having enough clean water to meet their needs. They therefore consider that their results could help to more accurately predict the water needs of the population.
The conclusions of this study were published by the journal Science< /em>.