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Where Did the 8 Glasses of Water A Day Myth Come From?

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By Chris Gayomali

We have all been told at some point that proper hydration requires us to consume eight glasses of water a day. That works out to about two liters, which is an awful lot of fluid, considering the average human stomach (when unexpanded) is about the size of a balled fist.

But health researchers have refuted the eight-glasses-a-day claim as a silly myth riding a wave of flimsy scientific literature. In fact, many of the groups behind the public push for over-hydration have been exposed as having — surprise! — monetary interests in the fluid industry.

For example: In a 2011 article published in the British Medical Journal, Margaret McCartney debunked the eight glasses a day myth and noted that one water advocacy group in Europe, Hydration for Health, is not only sponsored by, but was actually created by food giant Danone. Under the company's expansive culinary umbrella? Volvic, Evian, and Badoit bottled waters.

Set aside the entangled interests of Big Bottled Water, and you'll see that study after study continues to show that the human body is remarkably resilient when it comes to quenching our thirst. Saharan nomads, for example, are capable of subsisting on very little water for days at a time in one of Earth's most hellish climates, as was first noted in 1976 by anthropologist Claude Paque.

You and I, on the other hand, may get a bit cranky in our air-conditioned offices if we forget to visit the water cooler for a morning, but it's highly, highly, highly improbable that we'd shrivel and die at the dusty hands of the dehydration monster. Consider all the other stuff we consume. Despite the widely held notion that tea and coffee dehydrate us, they actually count toward our overall water intake, says Dr. Stanley Goldfarb, a nephrologist (kidney researcher) at the University of Pennsylvania. Even though we're told it's important to drink eight glasses of water a day, "there's no evidence that benefits health in any real way and it really represents an urban myth," says Goldfarb. Even something like, say, a baked potato, is 75 percent water.

So where exactly did this eight glasses of water a day voodoo come from? The very idea of a "minimal water requirement" is actually a fairly recent notion that first appeared in dietary guidelines published in 1945 by the Food and Nutrition Board of the National Academy of Sciences. The academy spuriously suggested that "2,500 mL [2.5 liter] of fluid should be ingested on a daily basis," although a primary clinical study was never actually cited.

The idea may have been at least partly put forth by Frederick J. Stare, an influential 20th century nutritionist and founding chairman of the department of nutrition at the Harvard School of Public Health. (He passed away in 2002 at age 91.) Stare was one of the first to recommend that humans consume six or so 12-ounce glasses of water a day.

Since then, researchers have begun to see eight glasses a day as an overestimate (especially considering our diets), but there are still advocates pushing for eight glasses of pure water or more. Those proponents include Dr. Fereydoon Batmanghelidi, a medical practitioner in Virginia who claims that a lack of water is responsible for many preventable diseases. Water, after all, is still good for us. Recent studies have suggested that adequate hydration may not only give our cognition a boost, but goes a long way toward keeping chronic kidney disease at bay.

As for how much we should be drinking, there is unfortunately no hard and fast rule. (Sorry!) And when you include all the other stuff we munch on or guzzle throughout the day, we actually consume more than the recommended two liters. A 1995 Australian survey found that the diet of average adults provides more than enough daily fluid: Women take in about 2.8 liters a day, and men consume 3.4 liters a day.

Research suggests that drinking water when you start to feel thirsty is sufficient should you desire to continue existing. Clearly, it's all relative, as when you feel thirsty will be different if you're drenching yourself in spin class or spinning in your cushy chair at work. As with most things, it's probably best to listen to your body before proceeding accordingly.

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Big Questions
Why Do Fruitcakes Last So Long?
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Fruitcake is a shelf-stable food unlike any other. One Ohio family has kept the same fruitcake uneaten (except for periodic taste tests) since it was baked in 1878. In Antarctica, a century-old fruitcake discovered in artifacts left by explorer Robert Falcon Scott’s 1910 expedition remains “almost edible,” according to the researchers who found it. So what is it that makes fruitcake so freakishly hardy?

It comes down to the ingredients. Fruitcake is notoriously dense. Unlike almost any other cake, it’s packed chock-full of already-preserved foods, like dried and candied nuts and fruit. All those dry ingredients don’t give microorganisms enough moisture to reproduce, as Ben Chapman, a food safety specialist at North Carolina State University, explained in 2014. That keeps bacteria from developing on the cake.

Oh, and the booze helps. A good fruitcake involves plenty of alcohol to help it stay shelf-stable for years on end. Immediately after a fruitcake cools, most bakers will wrap it in a cheesecloth soaked in liquor and store it in an airtight container. This keeps mold and yeast from developing on the surface. It also keeps the cake deliciously moist.

In fact, fruitcakes aren’t just capable of surviving unspoiled for months on end; some people contend they’re better that way. Fruitcake fans swear by the aging process, letting their cakes sit for months or even years at a stretch. Like what happens to a wine with age, this allows the tannins in the fruit to mellow, according to the Wisconsin bakery Swiss Colony, which has been selling fruitcakes since the 1960s. As it ages, it becomes even more flavorful, bringing out complex notes that a young fruitcake (or wine) lacks.

If you want your fruitcake to age gracefully, you’ll have to give it a little more hooch every once in a while. If you’re keeping it on the counter in advance of a holiday feast a few weeks away, the King Arthur Flour Company recommends unwrapping it and brushing it with whatever alcohol you’ve chosen (brandy and rum are popular choices) every few days. This is called “feeding” the cake, and should happen every week or so.

The aging process is built into our traditions around fruitcakes. In Great Britain, one wedding tradition calls for the bride and groom to save the top tier of a three-tier fruitcake to eat until the christening of the couple’s first child—presumably at least a year later, if not more.

Though true fruitcake aficionados argue over exactly how long you should be marinating your fruitcake in the fridge, The Spruce says that “it's generally recommended that soaked fruitcake should be consumed within two years.” Which isn't to say that the cake couldn’t last longer, as our century-old Antarctic fruitcake proves. Honestly, it would probably taste OK if you let it sit in brandy for a few days.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
What's the Difference Between Stuffing and Dressing?
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For carbohydrate consumers, nothing completes a Thanksgiving meal like stuffing—shovelfuls of bread, celery, mushrooms, and other ingredients that complement all of that turkey protein.

Some people don’t say “stuffing,” though. They say “dressing.” In these calamitous times, knowing how to properly refer to the giant glob of insulin-spiking bread seems necessary. So what's the difference?

Let’s dismiss one theory off the bat: Dressing and stuffing do not correlate with how the side dish is prepared. A turkey can be stuffed with dressing, and stuffing can be served in a casserole dish. Whether it’s ever seen the inside of a bird is irrelevant, and anyone who tells you otherwise is wrong and should be met with suspicion, if not outright derision.

The terms are actually separated due to regional dialects. “Dressing” seems to be the favored descriptor for southern states like Mississippi, Tennessee, South Carolina, and Georgia, while “stuffing” is preferred by Maine, New York, and other northern areas. (Some parts of Pennsylvania call it "filling," which is a bit too on the nose, but to each their own.)

If “stuffing” stemmed from the common practice of filling a turkey with carbs, why the division? According to The Huffington Post, it may have been because Southerners considered the word “stuffing” impolite, so never embraced it.

While you should experience no material difference in asking for stuffing or dressing, when visiting relatives it might be helpful to keep to their regionally-preferred word to avoid confusion. Enjoy stuffing yourselves.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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