As a retired high school track and field athlete, it was physically impossible to go a day without drinking water. Let alone all 64 ounces, eight 8-ounces (8 x 8) of it. One coach after another would entail the same basic instruction in their pre-race speeches, “Remember drink half of your body weight in ounces.” All this time it wasn’t because I was an athlete that I needed to drink this much water. Rather a worldwide rule.
To this day, I still find myself drinking practically just as much water as I have been for the last 4 years, minus the competitive sport participation. It made me think. Everyone’s actually supposed to drink this much? Is the eight 8-ounce glasses of water a day recommendation somehow mean that water, in general, is good/healthy for you?
First and most commonly known fact is that more than half of the human adult body is water. This goes to say that water will remain the most recommend beverage to consume, but it doesn’t have to mean it’s the only source of hydration. BMJ’s authors, Aaron E. Carroll and Rachel C. Vreeman, of two paperbacks on medical myths wrote about the statement that people should drink at least eight 8-ounce glasses of water a day. The myth busters went to seek the science contradicting correlation to causation of water to our human body.
They claimed that many people have been following this recommendation from the 1945 Food and Nutrition Board. However, easily ignored what read, “Most of this quantity is contained in prepared foods.” In fact, Frederick Stare, a nutritionist, referred to the same 8×8 recommendation of water by pin pointing it “in the form of coffee, tea, milk, soft drinks, beer”, fruits, vegetables, etc. Besides, contrary of many stories told, drinking extra water doesn’t mean extra health benefits. A number of failed studies concluded that “drinking more water doesn’t keep skin hydrated, healthy, or wrinkle free”. But hey, if you still have that mentally engraved into your healthy lifestyle at least there’s one clear benefit of water: it’s calorie-free.
To make sure this wasn’t an outlier study merely made off two authors’ book, I searched through a bit more and found two studies. In one of Heinz Valtin’s articles from his American Journal of Physiology, cited professional journals even state “by the time a person is thirsty that person is already dehydrated”. Having regretfully experienced this time after time, wishing I would’ve drank more water as it made the scorching sun feel more painful than those countless laps around the track.
However, the data above consists of “normal aging, illness-associated of dehydration in elderly, and diagnostic/therapeutic interventions”. It’s important to consider “the amount of water differs considering what people eat, where they live, how big they are, and what they’re doing”. This graph furthers that point, as “the threshold for release of vasopressin (promote kidney’s retention of water and increase blood pressure) is lower than thirst and constant needs for water balance are met by changes in plasma vasopressin and changes in creatinine flow”. Disappointedly, as “evolutionarily” developed as we are, we’re intaking fluid to “compensate for a chronic water deficit we don’t even have”. Within a prospective study on daily fluid intake, a longitudinal analysis in kidney function and long-term mortality measured 3858 men and women aged 49 years and older residing in Australia through a food frequency questionnaire. “In about 13 years, 1127 deaths, 580 of which cardiovascular deaths, occurred and repeated creatinine measurements from fluid intake to never have been correlated with the all-cause or cardiovascular mortality”. Both studies’ results demonstrate again that there is no formal recommendation of water for more benefits. Not only that, but the recommendation could be harmful, both in dangerous low sodium levels, exposure to pollutants, and simply making many feel guilty for not drinking enough.
Therefore, there are some randomized controlled trial studies to find benefits as well, accepting a few specific cases. For instance, in a 10-year study of 48,000 men, Michaud and his coworkers concluded “the incidence of urinary bladder cancer was significantly reduced by high fluid intake”. The authors calculated within the range to conclude “the risk of bladder cancer decreased by 7% for every additional 240 ml of fluid”. Similar correlations have been reported for “colorectal cancer“, many known “risk factors for tumors”, and preventing the recurrence of “some kinds of kidney stones“.
In evaluation, here’s another part to consider: possible effects driven by confounding variables would mean that not all of these studies were randomized trials. Either those who drink water, opposed to those who don’t, or not even be due to water at all. Keeping in mind the studies that found these effects, “the threshold was significantly below eight 8-ounces of water”.
About now is when the wondering begins again: If there’s any evidence at all, that more or less water is better, given that there doesn’t seem to be any downside to or not to hydrate? Back in Arizona, every summer we’re swamped with news media reports warning that dehydration is dangerous and also worldwide. Attaching these claims under scrutiny leads to the evidence that obsessing about reaching some water goal to be healthy every day is unproductive. As long as the people in this country live longer than ever before, with arguably “more access to beverages than any other time in history”, it’s hard to say that all this water is customarily good for you.