How much water do you drink in a day? It is set for several reasons

Are you drinking enough water?

The question seems like it should be answered directly – the specific amount of water that you need to drink every day to fight dehydration.

But the rate and manner in which the human body absorbs and excretes water is not as universal as you might expect. Studying more than 5,000 people living in 23 countries and ranging in age from 8 days to 96 years, the researchers found that the turnover of water in the human body varies widely depending on individual physical and environmental factors.

The event, on Nov. 24 Sciencesuggest that the idea that a person should ideally consume eight 8-ounce glasses is not a one-way solution to peak hydration.

Even within calculations, “individual variability could be huge,” says biomedical engineer Kong Chen, director of the metabolic research program at the National Institutes of Health Clinical Center.

Yosuke Yamada, a physiologist at the National Institute of Biomedical Innovation, Health and Nutrition in Japan, and colleagues used a stable isotope of hydrogen known as deuterium to study the movement of water through people’s bodies. Drinking water accounts for half of the total water intake by humans, with the rest coming from food. Simply measuring the amount of water a person drinks in a day is not enough to accurately estimate water turnover or body water used daily.

The researchers found that men aged 20 to 30 and women aged 20 to 55 had the highest water turnover. These numbers varied significantly according to humidity, altitude, latitude and physiological factors, as if a person were an athlete. For men and women, the low end of water turnover averaged around 1 to 1.5 liters per day and the high end averaged around 6 liters per day.

But the findings in the study aren’t a road map for how much water individuals should drink every day in some populations, Chen says. “There are a lot of complicated relationships that need to be tempered,” he said. But the data raise several questions about the effects of particular environments on raw water.

“The most unexpected finding is that people who live in poor countries … , or countries with a lower human development index, have a higher turnover of water,” says Yamada. Even when the researchers adjusted for climate, body size, gender and other factors, people living in low-HDI countries — which for this study included Ghana, Kenya, Nigeria and Tanzania — still had higher water turnover rates than high-income people. HDI countries include Belgium, Japan and the United States. The researchers suggest that the disparity is moderated by the frequent use of indoor climate control in wealthier countries.

Water turnover rate could also represent a significant marker of an individual’s metabolic health. Ten percent of the total water in the human body is lost every day through metabolic processes occurring in our cells. For people with less access to safe water, this loss is also a “huge issue,” says Yamada.

More than 2 billion people in the world do not have access to safe drinking water and that number is projected to grow, according to a 2018 United Nations report (SN: 8/16/18). Hopefully, the research will help people around the world fight against drought in the face of water scarcity, Yamada says.