In fact, this debate is more about the perspective of the problem.
Many studies have linked drinking more water with health, but critics usually think that the data of such studies are insufficient, the conclusions are uncertain or not widely applicable.
For example, a study of nearly 48,000 men published in the New England Journal of Medicine in 199 showed that the risk of bladder cancer decreased by 7% for every glass of water people drank every day. Other studies have found that the more water you drink, the less likely you are to develop colon polyps with precancerous characteristics. A study of 20,000 Adventists in California, published in the American Journal of Epidemiology, found that women who drink at least five glasses of water a day are 465,438+0% less likely to develop fatal heart disease, and men are 54% less likely than those who drink only two glasses of water a day.
Henry, a physiologist at Dartmouth Medical College? In a groundbreaking article published in the American Journal of Physiology in 2002, Walding discussed the above studies and concluded that these studies could not support the general recommendation that everyone should drink eight glasses of water a day, but only applied to those who were known to have certain diseases. Six years later, Dr. Valding said, I haven't seen any scientific report to refute my conclusion.
Similarly, in an editorial in April, the Journal of the American Society of Nephrology refuted the conclusion of small-scale research that drinking water can increase heat production (burn calories), reduce migraine attacks and accelerate skin blood circulation. The editorial reiterated Dr. Valding's conclusion that there is no clear evidence that drinking more water is good for health. However, the editorial added, we also admit that there is no clear evidence that drinking more water is not good for health.
This makes researchers in this field feel quite frustrated. Judy, a scientist at Children's Hospital and Research Center in Oakland, California? Jodi Stookey said that there is enough data to show that we should collect more data. Stookey's research found that replacing sugary drinks with water can help female dieters reduce their overall calorie intake (while low-calorie drinks seem to stimulate their appetite). Her research also found that women who use four popular diets and drink at least one liter of water a day lose weight faster than women who drink less than one liter of water, no matter what diet the latter adopts.
It seems impossible to find causality from the accidental association obtained in this kind of research. When asked about diet or drinking water, participants' memories are not always very accurate. So, what kind of research can meet the skeptics' requirements for evidence? The April editorial of Journal of American Nephrology Society pointed out that only large and expensive randomized trials can clearly answer these questions. Given that water can't be patented, such an experiment seems impossible.
Urologists do agree that drinking more water can reduce the recurrence rate of kidney calculi. However, it is not clear whether water can prevent kidney calculi. Stanley, a kidney expert at the University of Pennsylvania Health System and one of the authors of this editorial? Goldfarb said that 4% to 5% of the population suffers from kidney calculi, so it is unrealistic to suggest that everyone drink eight glasses of water every day.
Dr goldfarb also refuted the idea that drinking more water can improve the functions of various organs, because organs can't keep water. He said, you can't leave these eight glasses of water in your body. They will eventually be released. Dr. goldfarb pointed out that the human body has a complex self-regulation system, which can automatically eliminate anything that is not needed. He said, but this does not mean that the human body can excrete more toxins; The same toxin is only diluted in more water.
Experts also believe that the human body's demand for water will vary greatly: if you are attending the US Open instead of sitting in front of the computer in the air-conditioned office, you will definitely need more water. However, most nephrologists, as well as the National Academy of Sciences, believe that thirst alone is enough to guide the body's drinking water demand. Dr. goldfarb said that thirst is one of the most powerful motivations in the human body, far exceeding sex.
In fact, this is also the focus of debate. Born in Iran, Dr Fereydoon Batmanghelidj praised the benefits of drinking water in two books. He said that it is "the greatest tragedy in the history of medicine" to adjust the amount of drinking water by thirst. He and other water lovers believe that when people feel thirsty, they are already dehydrated. This camp believes that the human body needs about two liters of water a day to replenish lost water, excluding other drinks, especially caffeine drinks.
A large number of government officials have suggested agreeing to the principle of drinking two liters of water, but this includes a lot of water in solid food itself. Dr. Valding said that even a piece of white bread contains more than 30% water.
Nevertheless, some weight loss experts firmly believe that drinking more water can help people feel full and keep less fluid. Some experts even admit that the benefits of drinking more water may be both metabolic and behavioral.
Karen, chief scientist of Weight Watchers, a professional weight loss company? Karen Miller-kovac said that if your usual habit is to put a bowl of popcorn or peanuts on the table, a sip of water will satisfy you and keep your hands and mouth busy. Weight Watchers suggests drinking six glasses of water every day.
Some marathoners have died from drinking a lot of water quickly. Dr. goldfarb said that the human body can only absorb about 946 grams of water per hour at most, and if it exceeds this limit, the brain will expand dangerously. Another danger is hyponatremia, where the sodium level drops sharply, but this is also rare in healthy people. Dr. goldfarb said that drinking eight glasses of water a day "is unlikely to be harmful to the human body, but it is extremely unlikely to bring you all the benefits claimed by traditional ideas."
However, some supporters say they have all the evidence they need. Manhattan lawyer Theo? Robbins said, I feel better when I drink a lot of water every day. I have fewer headaches, more energy and more concentration, which are all important.