In conversation with the BBC, Prof. from the University of Aberdeen. John Speakman says that calculating 2 liters of water per day is due to a small inaccuracy.
Speakman explains it this way:
“The water we should drink is the difference between the total water we need to digest and the amount of water we get from what we eat.
“The way to estimate how much food people consumed was to ask people how much they ate.
“The estimate was inaccurate because people underreported and underreported how much they ate, so the amount of water needed was also exaggerated.”
People with a fast water turnover drink more water
The research was led by the University of Aberdeen in Scotland.
For the new research, scientists around the world collaborated and covered a large population.
Researchers worked with 5,604 people aged 8 days to 96 years from 23 different countries.
Using a method called the stable isotope technique, scientists have replaced the hydrogen molecule in the water people drink with its stable isotope, deuterium (heavy hydrogen).
Deuterium is a completely harmless element in the human body.
To find out how quickly water is digested in the body, they examined how quickly the extra deuterium was excreted.
Accordingly, people with fast water turnover drank more water.
The research found that those who live in hot and humid environments and at high altitudes, as well as athletes, pregnant and breastfeeding women, have rapid water cycles.
The most important factor in the water cycle was the amount of energy the body burned. The highest values were observed in men aged 20-35, with an average of 4.2 liters of water per day.
This amount decreases with age, to an average of 2.5 liters per day for men in their 90s.
While the average turnover of women aged 20-40 is 3.3 litres; this figure dropped to 2.5 liters by age 90.
“The amount of water needed for daily consumption is 3.6 liters. Since many foods already contain water, a significant amount of water is provided by eating food alone.
Amount of water extracted from food
Prof. “Since many foods already contain water, a significant amount of water is provided by simply eating it,” says Speakman.
Prof Speakman says that the water cycle does not directly imply the amount of water to drink.
“Even a man in his 20s does not need to drink 4.2 liters of water. 15 percent of this value is water produced by the exchange and metabolism of the body’s surface water.
“This study shows that the general recommendation that we should all drink eight glasses of water is probably too high for most people in most cases, and that a ‘one-size-fits-all’ water intake recipe is not supported. by this data.”
The scientist also says the research is a big step forward in predicting people’s future water needs.
Because drinking too much water can also come at a significant cost.
Prof Speakman says “Clean drinking water is not free” and adds:
“If 40 million people drink on average half a liter more water than they need every day, then you are unnecessarily drinking the extra 20 million liters of water that we need to supply and convert into urine.
“There are costs associated with that.”