This article delves into a systematic review published in JAMA Network Open by researchers from the University of California, San Francisco, and Weill Cornell Medicine. It explores the impact of increased daily water intake on physical health. The findings reveal that drinking more water can not only aid in weight loss but also reduce the risk of kidney stones, and potentially improve conditions like headaches and diabetes. Moreover, pre-meal water consumption proves more effective than random drinking. This review provides a comprehensive understanding of the benefits of water intake, emphasizing its significance in maintaining good health.
In our daily conversations, "drink more water" has seemingly become a universal and perfunctory phrase. Whenever someone is feeling unwell, a woman is experiencing discomfort during her menstrual period, or someone is determined to embark on a weight loss journey, this simple piece of advice often slips out. As time goes by, it has lost its original warmth and turned into a thoughtless exchange in social interactions. However, in today's modern society filled with carbonated beverages and bubble teas, this overlooked phrase actually carries significant scientific power. Recently, the release of a significant research achievement has compelled us to reevaluate this seemingly ordinary glass of plain boiled water.
A team of researchers from the University of California, San Francisco, and Weill Cornell Medicine published a highly valuable study in JAMA Network Open, a prestigious medical journal, delving deep into the impact of increasing daily water intake on physical health. The study employed the rigorous method of randomized controlled trials (RCTs) with the aim of scientifically evaluating the correlation between daily water consumption and health outcomes.
The researchers were like explorers in the vast ocean of knowledge, conducting extensive searches in three authoritative databases: Pubmed, Web of Science, and Embase. The search spanned from the inception of these databases to April 6, 2023. Centering around the two core themes of "water intake" and "health-related outcomes", they were like searching for treasures in the vast sea of literature, retrieving a total of 1,464 relevant studies. Subsequently, through a strict screening process, similar to carefully selecting precious gems, only 18 RCTs studies that met the criteria were finally included in this evaluation, truly picking the best from the best.
The median sample size of this study was 48 participants, ranging from 14 to 631 participants, ensuring that the study had a certain degree of representativeness. In terms of the intervention measures, the researchers required participants to change their daily water intake within a scheduled time frame, with the intervention period varying from as short as 4 days to as long as 5 years. The control group was mostly required to maintain their usual water intake, thus forming a scientific comparison.
Figure 1: Research flow chart
Regarding the popular topic of weight loss, 4 studies specifically evaluated the impact of increased water intake on the weight changes of overweight/obese participants. The results of 3 of these studies were truly inspiring. Compared with the control group, overweight/obese participants who persisted in drinking 1,500 milliliters of water before meals for 12 weeks to 12 months showed a more significant degree of weight loss, which was 44%, 87%, and 100% higher than that of the control group, respectively. This implies that, without the additional pain of exercise and dieting, a glass of water before meals may well become a powerful assistant for those trying to lose weight, easily helping to reduce body weight.
For diabetes patients, controlling blood glucose is of utmost importance. 2 studies focused on the impact of increased water intake on fasting blood glucose levels. Among them, a study by Sedaghat et al. selected 40 newly diagnosed type 2 diabetes patients as the research subjects. The results showed that there was a significant difference in the average fasting blood glucose (FBG) changes between the intervention group and the control group. The FBG in the intervention group decreased by an average of 32.6 mL/dL, while that in the control group increased by 5.3 mL/dL. This indicates that appropriate increase in water intake may provide a simple and effective auxiliary method for diabetes patients to control their blood glucose levels, helping them better manage their own blood glucose.
There are many people who often suffer from headache problems, and 2 studies evaluated the impact of increased water intake on recurrent headaches. As early as in a study conducted in 2012, the researchers studied 102 adults with primary headaches. The results showed that when the daily water intake reached 1,500 milliliters and continued for 3 months, it could improve the score of the Migraine-Specific Quality of Life Questionnaire (MSQL), which was 4.5 points higher than that of the control group. This means that for headache patients, drinking more water may be a simple way to relieve headache symptoms and improve their quality of life, without the need for complex treatment methods.
Urinary tract infections are also a common health problem. 3 studies evaluated the impact of increased water intake on urinary tract infections and overactive bladder. One of the studies, which focused on 140 premenopausal women with urinary tract infections, found that compared with a daily water intake of less than 1,500 milliliters, increasing the water intake to 1,500 milliliters was associated with a decrease in the number of urinary tract infection episodes. This shows that maintaining an adequate water intake can, to a certain extent, prevent urinary tract infections and help women better maintain the health of their urinary system.
Patients with kidney stones often suffer a great deal, and 2 studies explored the relationship between increased water intake and the risk of kidney stones. The research found that increasing the daily water intake to 2,000 milliliters could significantly reduce the recurrence rate of kidney stone patients. Within 5 years, there were 15 fewer events per 100 participants, and it could also prolong the time between stone recurrences. This undoubtedly brings new hope to kidney stone patients. By simply adjusting their water intake, they can effectively reduce the risk of the disease recurrence.
Figure 2: Association between increased water intake and five major health issues
In addition, some studies have also explored the relationship between drinking more water and diseases such as chronic kidney disease and hypertension. However, unfortunately, these studies did not detect any obvious association between increased water intake and these diseases. Nevertheless, the researchers clearly pointed out that more high-quality studies need to be carried out in the future to further comprehensively evaluate the impact of water intake on specific health conditions, providing more accurate evidence for medical research and health guidance.
This study can be regarded as the most comprehensive systematic review evaluating the benefits of interventions related to changing daily water intake. The study clearly indicates that drinking more water has a positive promoting effect on weight loss in adults, especially when drinking water before meals, the weight loss effect is more significant. In addition to this, drinking more water also has many other benefits, such as controlling blood glucose, alleviating migraines, reducing the recurrence of urinary tract infections, and decreasing the number of kidney stone attacks.
Water, as a safe and easily accessible substance, is undoubtedly an excellent strategy for "weight loss". However, it is particularly important to note that water intake should also be appropriate. According to the "Dietary Guidelines for Chinese Residents", men and women in China should drink at least 1,700 milliliters and 1,500 milliliters of water per day, respectively. Excessive water intake may lead to adverse consequences such as "water intoxication". Therefore, while enjoying the health benefits brought by drinking more water, we should also rationally grasp the amount of water intake and achieve scientific water consumption.
Health is no trivial matter, and water intake is a significant topic. From now on, stop treating "drink more water" as a perfunctory phrase and turn it into practical actions. Quickly share this important health knowledge with those you care about around you and remind them to use cups of warm plain boiled water to nourish a healthy body!
Hakam N, Guzman Fuentes JL, Nabavizadeh B, et al. Outcomes in Randomized Clinical Trials Testing Changes in Daily Water Intake: A Systematic Review. JAMA Netw Open. 2024;7(11):e2447621. Published 2024 Nov 4.
