H2-Oh No! Study Challenges Beliefs on How Much Water Humans Need Daily

Water is an essential component of human life, and it is vital for the proper functioning of the body’s organs and systems.

[Mar. 23, 2023: Staff Writer, The Brighter Side of News]

Water is an essential component of human life, and it is vital for the proper functioning of the body's organs and systems. (CREDIT: Creative Commons)

Water is an essential component of human life, and it is vital for the proper functioning of the body's organs and systems. The human body is composed of approximately 60% water, and maintaining proper hydration is crucial for overall health and well-being. While the amount of water needed by each person can vary depending on factors such as age, gender, activity level, and climate, there is a general guideline for the amount of water that humans need to consume each day to survive.

The amount of water required by humans varies depending on factors such as age, gender, activity level, and climate. For example, a young child or an elderly person may require less water than an adult. Additionally, men typically require more water than women, and individuals who engage in strenuous physical activity may require more water than those who are less active. In hot and humid climates, the body loses more water through sweat, and therefore, more water intake may be necessary to maintain proper hydration.

The Institute of Medicine (IOM) provides general guidelines for the amount of water that individuals should consume each day. According to the IOM, adult men should consume approximately 3.7 liters (or 125 ounces) of water per day, while adult women should consume approximately 2.7 liters (or 91 ounces) of water per day. These recommendations include water intake from all sources, including beverages and food. However, they specifically noted that these guidelines are only general recommendations, and individual water needs may vary.

Now an international group led by scientists at the Shenzhen Institute of Advanced Technology (SIAT) in China found that the average daily water intake of a man in his twenties should be 1.5 to 1.8 liters, while it should be 1.3 to 1.4 liters for a female in the same age group.


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The study published in the journal Science described, for the first time, a set of equations to predict human water turnover, an indicator reflecting the amount of water used by the body each day.

The researchers investigated 5,604 participants from the ages of 8 days to 96 years and from more than 20 countries, using isotope-tracking methods.

They have found that a man aged 20 to 35 consumes 4.2 liters of water each day, while a woman aged 30 to 60 consumes 3.3 liters, with the water requirements dropping as he or she ages.

Since the metabolism and water exchange on skin can provide 15 percent, while food and drinking contribute half each of the remaining 85 percent, people are thus suggested to drink less than 45 percent of the total daily turnover, according to the researchers.

"The majority of people perhaps don't have to drink 8 glasses of water a day," said Zhang Xueying, co-first author of the paper and an assistant research fellow at the SIAT.

The total water input and output varies according to multiple factors, including body size, physical activity, air temperature, humidity, and altitude, according to the study.

"The equations can be applied to individuals around the world," said Zhang. "Just input his or her basic physiological indicators and the temperature and humidity he or she lives in."

However, people who lived in countries with a low human development index (HDI) had higher water turnover than people in high-HDI countries, she added.

The study marks the first step towards a personalized prediction of water requirements, said the paper's co-corresponding author John Speakman who works at the SIAT.

Factors that can affect an individual's water needs

Factors include:

  • Age: Young children and elderly individuals may require less water than adults.

  • Gender: Men typically require more water than women due to their larger body size and muscle mass.

  • Activity level: Individuals who engage in physical activity may require more water than those who are less active.

  • Climate: In hot and humid climates, the body loses more water through sweat, and therefore, more water intake may be necessary to maintain proper hydration.

  • Health status: Certain medical conditions, such as kidney disease or diabetes, can affect an individual's water needs.

It is important to note that the body's water needs can also vary depending on the type and amount of food consumed. Many foods, such as fruits and vegetables, are high in water content and can contribute to overall hydration. In contrast, foods that are high in salt or sugar can increase the body's water needs, as these substances can dehydrate the body.

Dehydration can have serious consequences on the body, ranging from mild symptoms such as dry mouth and thirst to severe symptoms such as dizziness, confusion, and even organ failure. Mild dehydration can usually be resolved by increasing water intake, but severe dehydration may require medical intervention.

Variation in human water turnover associated with environmental and lifestyle factors. (CREDIT: Science)

To ensure proper hydration, it is important to consume a variety of fluids throughout the day, including water, herbal teas, and low-fat milk. It is best to avoid sugary drinks such as soda, sports drinks, and energy drinks, as these can actually dehydrate the body. Additionally, alcohol consumption should be limited, as alcohol is a diuretic that can increase water loss.

It is also important to be aware of the signs of dehydration and to take steps to prevent it. Symptoms of mild dehydration include thirst, dry mouth, and darker urine, while more severe symptoms can include dizziness, confusion, and even organ failure. To prevent dehydration, individuals should drink fluids regularly throughout the day, particularly during periods of high physical activity or in hot and humid climates.

Anthropometric, Environmental and lifestyle factors affecting human water turnover. (CREDIT: Science)

In addition to beverages, certain foods can also contribute to overall hydration. Fruits and vegetables, for example, are high in water content and can help to maintain proper hydration levels. Examples of high-water fruits and vegetables include watermelon, cucumbers, oranges, and strawberries.

In summary, water is an essential component of human life, and maintaining proper hydration is crucial for overall health and well-being. While the amount of water needed by each person can vary depending on factors such as age, gender, activity level, and climate, there is a general guideline for the amount of water that humans need to consume each day to survive. By drinking fluids regularly throughout the day and consuming a diet that is high in water content, individuals can maintain proper hydration levels and prevent the negative consequences of dehydration.


Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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Joseph Shavit
Joseph ShavitSpace, Technology and Medical News Writer
Joseph Shavit is the head science news writer with a passion for communicating complex scientific discoveries to a broad audience. With a strong background in both science, business, product management, media leadership and entrepreneurship, Joseph possesses the unique ability to bridge the gap between business and technology, making intricate scientific concepts accessible and engaging to readers of all backgrounds.