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Why Is Cranberry Juice Good For UTIs?

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A mental_floss staffer who shall remain nameless asks, “Why is cranberry juice good for treating UTIs? I will not tell you why this question had been on my mind.”

Bacterial infections in the urinary tract and its organs are pretty common, especially in adult women, and more than seven million cases are reported by doctors every year. Among women who get one, about a third will experience them recurrently.

A popular folk remedy for the infections is cranberry juice. How the juice relieves UTIs, and even if it actually does help, isn’t entirely clear. Research on its effectiveness for UTI prevention has produced mixed results, and studies assessing the use of cranberry juice in UTI treatment are few. The strongest evidence available for prevention is among adult women with previous UTIs. In this group, results repeatedly show about a 50% reduction in disease recurrence with regular juice consumption. In elderly and pediatric patients, and some patients with bladder problems, the effect is less pronounced.

A caveat made in many of the prevention studies is that the cranberry juice’s effects seem to be dose-dependent, and that the amount a person would need to drink daily to have a real preventative effect is more than what most people are willing to drink. In some studies, as many as half of the participants withdrew before the studies' completion, suggesting that prolonged, regular guzzling of cranberry juice is too much to bear, either because of stomach aches, the calorie load, or adverse interactions between the juice and certain medications.

Overall, the evidence suggests that cranberry juice helps prevent UTIs. But how?

The Compound Equation

Cranberries contain quinic, malic, and citric acids, and for a long time researchers thought that the acidity of this mix had a bacteriostatic effect that kept bacteria from reproducing and gave cranberry juice its usefulness. Further studies showed that the amount of acid in the juice and the low amounts that people would tolerate drinking weren’t enough for the acid to do much good, though. More recent research suggests that the juice’s real benefit is that certain compounds in it keep bacteria from setting up shop in the urinary tract.

E. coli and other common UTI-causing bacteria have hairlike appendages called fimbria that they use to adhere to the walls of the urinary tract. A few different studies have found that two compounds in cranberries—fructose and proanthocyanidin—inhibit bacteria’s fimbria from sticking to anything, preventing the bacteria from colonizing and multiplying. The compounds' antiadherent effects start within two hours after someone drinks cranberry juice and persist for up to 10 hours after ingestion, keeping an infection from taking hold.

Other research has found that cranberry juice additionally alters and increases certain thermodynamic properties of bacteria in the urinary tract—including the amount of energy that that they have to expend before they can attach to tissue—creating an energy barrier that they can’t overcome, and therefore preventing them from latching on. If the bacteria can’t stick to the walls of the urinary tract, then they’re vulnerable to being flushed out and away by urine.

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Big Questions
How Long Could a Person Survive With an Unlimited Supply of Water, But No Food at All?
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How long could a person survive if he had unlimited supply of water, but no food at all?

Richard Lee Fulgham:

I happen to know the answer because I have studied starvation, its course, and its utility in committing a painless suicide. (No, I’m not suicidal.)

A healthy human being can live approximately 45 to 65 days without food of any kind, so long as he or she keeps hydrated.

You could survive without any severe symptoms [for] about 30 to 35 days, but after that you would probably experience skin rashes, diarrhea, and of course substantial weight loss.

The body—as you must know—begins eating itself, beginning with adipose tissue (i.e. fat) and next the muscle tissue.

Google Mahatma Gandhi, who starved himself almost to death during 14 voluntary hunger strikes to bring attention to India’s independence movement.

Strangely, there is much evidence that starvation is a painless way to die. In fact, you experience a wonderful euphoria when the body realizes it is about to die. Whether this is a divine gift or merely secretions of the brain is not known.

Of course, the picture is not so pretty for all reports. Some victims of starvation have experienced extreme irritability, unbearably itchy skin rashes, unceasing diarrhea, painful swallowing, and edema.

In most cases, death comes when the organs begin to shut down after six to nine weeks. Usually the heart simply stops.

(Here is a detailed medical report of the longest known fast: 382 days.)

This post originally appeared on Quora. Click here to view.

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Big Questions
Why is Friday the 13th Considered Unlucky?
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Today, people around the globe will feel uneasy about getting out of bed, leaving their homes, or going about their normal daily routines, all because of a superstition. These unfortunate folks suffer from “paraskavedekatriaphobia,” a common neurosis familiar to us all: the fear of Friday the 13th. But just where did this superstitious association come from, and how did it catch on?

The truth is that no one is absolutely sure where the idea that Friday the 13th is unlucky originated. Donald Dossey, the founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina, suspects the fear can be traced back to a Norse myth about 12 gods who had a dinner at Valhalla—the fabled hall where legendary Norse heroes feasted for eternity after they died—that was interrupted by a 13th guest, the evil and mischievous god Loki. According to legend, Loki tricked Höðr (the blind god of winter and son of Odin, the supreme god in Norse mythology) into shooting his brother Baldr (the benevolent god of summer who was also a son of Odin) with a magical spear tipped with mistletoe—the only substance that could defeat him. Thus the number 13 was branded as unlucky because of the ominous period of mourning following the loss of such powerful gods by this unwanted 13th guest.

For whatever reason, among many cultures, the number 12 emerged throughout history as a "complete" number: There are 12 months in a year, 12 signs of the zodiac, 12 Gods of Olympus, 12 sons of Odin, 12 labors of Hercules, 12 Jyotirlingas or Hindu shrines where Shiva is worshipped, 12 successors of Muhammad in Shia Islam, and 12 tribes of Israel. In Christianity, Jesus was betrayed by one of his 12 Apostles—Judas—who was the 13th guest to arrive for the Last Supper. Surpassing the number 12 ostensibly unbalances the ideal nature of things; because it is seen as irregular and disrespectful of a sense of perfection, the number 13 bears the stigma of misfortune and bad luck we know today.

WHY FRIDAY?

Friday joins in the mix mostly because all of the early accounts of Jesus’s crucifixion agree that it took place on Friday—the standard day for crucifixions in Rome. As Chaucer noted in The Canterbury Tales, "And on a Friday fell all this mischance." Yet perpetuating Friday as an unlucky day in America came from the late 19th-century American tradition of holding all executions on Fridays; Friday the 13th became the unluckiest of days simply because it combined two distinct superstitions into one. According to the Oxford University Press Dictionary of Superstitions, the first reference to Friday the 13th itself wasn’t until 1913. (So despite actually occurring on Friday, October 13, 1307, the popular notion that the Friday the 13th stigma comes from the date on which the famed order of the Knights Templar were wiped out by King Philip of France is just a coincidence.)

The repercussions of these phobias reverberated through American culture, particularly in the 20th century. Most skyscrapers and hotels lack a 13th floor, which specifically comes from the tendency in the early 1900s for buildings in New York City to omit the unlucky number (though the Empire State Building has a 13th floor). Street addresses sometimes skip from 12 to 14, while airports may skip the 13th gate. Allegedly, the popular Friday the 13th films were so-named just to cash in on this menacing date recognition, not because the filmmakers actually believed the date to be unlucky.

So, is Friday the 13th actually unlucky? Despite centuries of superstitious behavior, it largely seems like psychological mumbo jumbo. (One 1993 study seemed to reveal that, statistically speaking, Friday the 13th is unlucky, but the study's authors told LiveScience that though the data was accurate, "the paper was just a bit of fun and not to be taken seriously." Other studies have shown no correlation between things like increased accidents or injuries and Friday the 13th.)

And Friday the 13th isn't a big deal in other cultures, which have their own unlucky days: Greeks and Spanish-speaking countries consider Tuesday the 13th to be the unluckiest day, while Italians steer clear of Friday the 17th. So today, try to rest a little easy—Friday the 13th may not be so unlucky after all.

Additional Source: 13: The Story of the World’s Most Popular Superstition.

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