Drinking more water may have several health benefits, study finds

SAN FRANCISCO - A new study reveals that increased water consumption may result in several health benefits. 

Researchers at UC San Francisco analyzed 18 randomized clinical trials, with interventions in these studies consisting of a recommendation to alter the daily amount of water intake by a specific amount for a predefined period of time ranging between 4 days and 5 years, with the control groups mostly asked to maintain their usual intake habits.

The study, published on Nov. 25 in Jama Network Open, found that the majority of trials were associated with greater weight loss and benefits related to migraine prevention, urinary tract infections (UTIs) and diabetes control.

"For such a ubiquitous and simple intervention, the evidence hasn’t been clear, and the benefits were not well established, so we wanted to take a closer look," Benjamin Breyer, a researcher and co-author of the study, said in a statement.

Water intake associated with weight loss

Consuming additional water was associated with greater weight loss, ranging from 44%-100% more than control conditions.

FILE: A photo illustration of tap water in a clear glass drinking glass. (Credit: Ben Hasty/MediaNews Group/Reading Eagle via Getty Images)

Three of the studies documented greater weight loss in adult participants with an intervention of pre-meal water intake of approximately 500 mL. This suggests that pre-meal water intake may induce weight loss through stomach filling, leading to earlier satiety or by replacing high-calorie beverages. 

Water intake resulted in other health benefits

Water intake also resulted in 15 fewer nephrolithiasis events (or kidney stone events) per 100 participants over 5 years.  

Increasing water intake to achieve a daily urine output of 2000 mL or more after an idiopathic calcium stone was associated with significantly fewer stone events by more than half. This intervention was also associated with increased time to recurrence, suggesting that increasing water intake in healthy individuals decreases stone risk. 

Single studies reveal migraine prevention, diabetes control

Single studies also suggested benefits related to migraine prevention, urinary tract infections and diabetes control.

A pre-meal water intervention for a total of 1000 mL was significantly associated with improved fasting blood glucose (FBG) in patients with diabetes with baseline FBG between 220 and 230 mg/dL over an 8-week period. Meanwhile, adults with primary recurrent headaches also reported better quality of life after three months of increased water intake.

In women with recurrent UTIs and less than 1500 mL of fluid intake per day, increasing water intake by 1500 mL was associated with a reduced number of episodes and a longer duration between episodes.

The research authors noted that many of the findings were examined by single studies, and therefore, only limited evidence is available. They said the literature would benefit from further studies confirming the results, especially given the low cost and low adverse-effect profile of water.

"We know that dehydration is detrimental, particularly in someone with a history of kidney stones or urinary infections," Breyer continued. "On the other hand, someone who suffers from frequent urination at times may benefit from drinking less. There isn’t a one-size fits all approach for water consumption."

How much water to drink per day

Water is a major constituent of the human body and is considered an essential nutrient that cannot be sufficiently produced by metabolism. 

According to the National Institutes of Health, experts generally recommend drinking around nine cups of fluids a day for women and 13 cups for men on average. 

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But, according to Harvard Health, four to six cups is suggested for generally healthy people, but that amount differs based on how much water they take in from other beverages and food sources. 

Also, certain health conditions, medications, activity level, and ambient temperature can influence total daily water intake.