 If you had to name the greatest medical advance of the past two centuries, what would you pick? Smallpox vaccine jumped to my mind until I realized it was discovered back in the 1700s. The British Medical Journal compiled a list of 15 contenders, but which would take the crown? Would it be anesthesia? Kind of nice to be asleep during surgery. Would it be antibiotics? One of the 15 may be surprising, the medical marvel that was water with sugar and salt. The discovery that sugar and salt were absorbed together in the small intestine was potentially the most important medical advance of the century, because it opened the way to oral rehydration therapy, which is to say simple packets of sugar and salt in the right ratio that could be added to water to save the lives of children losing electrolytes through severe diarrhea from diseases like cholera. I mean, here we just hook you up to an IV, give you intravenous rehydration therapy, but cheap, easy oral rehydration saved millions, and millions of children's lives every year, such that UNICEF can now put out reports like this to help finish the job. It only costs pennies, though. If only there was a way to sell salty sugar water for $2 a bottle. Sports drinks are a multi-billion dollar industry fueled by Coke and Pepsi, and even drug companies are now getting in on the action. Researchers went online to see what kind of hydration advice people were getting. Pop quiz, true or false. Fluid consumption during exercise should be based upon thirst. Is that a true or false statement? Fluid consumption during exercise should be based on thirst. Get a piece of paper, write down your answer. All right, ready? Next question, electrolyte intake is not generally necessary during exercise. Keeping score? True or false. Dehydration is not generally a cause of exercise-associated muscle cramping. And last one, exercise-associated muscle cramping is not generally related to electrolyte loss. And the answers are true, true, true, and true. If you said false to any of them, you're wrong. But in good company, 93% of top websites got the first question wrong, 90% got the second question wrong, 98% got the third question wrong, and they all got the last one wrong. And to make matters worse, those websites that would generally be perceived as being more trustworthy by the public, like medical or professional organizations, appeared to do no better. So you shouldn't feel bad if you got any wrong. No wonder athletes often have misunderstandings about proper hydration during exercise. Doesn't dehydration hurt performance? Surprisingly, when they looked at triathletes, they didn't see a correlation between dehydration and marathon finishing times. In fact, some that lost the most water actually had among the fastest times, as has been noted in other studies. Your body's not stupid. It will tell you when you need to drink. There's now ample evidence that we can just drink to thirst, and you do not have to drink your electrolytes. But wait, if you're sweating and just drink pure water, aren't you risking washing out too much salt, too much sodium, and ending up with exercise-associated hyponatremia, too little sodium? That's caused by drinking too much of anything, water, or sports drinks. One of the high-profile cases of a high school athlete who died from it drank two gallons of Gatorade. So how do we prevent such deaths? Simple, we drink according to thirst. So these, you know, don't wait until you feel thirsty statements. You here may actually be doing more harm than good. We've known this since the early 90s, but it was ignored. The American College of Sports Medicine instead started telling athletes they should drink as much as tolerable during exercise, and what followed was an epidemic of cases of hyponatremia. Commercial interests may play a role in delaying the acknowledgement of these findings for decades. Now, the current ACSM statement no longer says that, in fact, emphasizing how dangerous it can be to drink too much. But they still plug sports beverages as sometimes preferable to water. Hmm, I wonder who these authors are. Funding received from the Gatorade Sports Science Institute, or on the Gatorade Sports Science Institute Speakers Bureau. Gatorade Science Institute, more Gatorade, a quick step over to the Coca-Cola Company, and then back to Gatorade. So anyways, which of the 15 medical marvels won, by the way, was it oral rehydration to prevent death from cholera, or antibiotics to kill off the cholera bugs? No. Our greatest medical miracle over the last two centuries was sanitation, preventing the cholera from getting into our drinking water in the first place.