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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
What’s the Difference Between Prison and Jail?
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Many people use the terms jail and prison interchangeably, and while both terms refer to areas where people are held, there's a substantial difference between the two methods of incarceration. Where a person who is accused of a crime is held, and for how long, is a factor in determining the difference between the two—and whether a person is held in a jail or a prison is largely determined by the severity of the crime they have committed.

A jail (or, for our British friends, a gaol) refers to a small, temporary holding facility—run by local governments and supervised by county sheriff departments—that is designed to detain recently arrested people who have committed a minor offense or misdemeanor. A person can also be held in jail for an extended period of time if the sentence for their offense is less than a year. There are currently 3163 local jail facilities in the United States.

A jail is different from the similarly temporary “lockup”—sort of like “pre-jail”—which is located in local police departments and holds offenders unable to post bail, people arrested for public drunkenness who are kept until they are sober, or, most importantly, offenders waiting to be processed into the jail system.

A prison, on the other hand, is usually a large state- or federal-run facility meant to house people convicted of a serious crime or felony, and whose sentences for those crimes surpass 365 days. A prison could also be called a “penitentiary,” among other names.

To be put in a state prison, a person must be convicted of breaking a state law. To be put in a federal prison, a person must be convicted of breaking federal law. Basic amenities in a prison are more extensive than in a jail because, obviously, an inmate is likely to spend more than a year of his or her life confined inside a prison. As of 2012, there were 4575 operating prisons in the U.S.—the most in the world. The country with the second highest number of operating prisons is Russia, which has just 1029 facilities.

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 Do Morticians Do With the Blood They Take Out of Dead Bodies?
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Zoe-Anne Barcellos:

The blood goes down the sink drain, into the sewer system.

I am not a mortician, but I work for a medical examiner/coroner. During an autopsy, most blood is drained from the decedent. This is not on purpose, but a result of gravity. Later a mortician may or may not embalm, depending on the wishes of the family.

Autopsies are done on a table that has a drain at one end; this drain is placed over a sink—a regular sink, with a garbage disposal in it. The blood and bodily fluids just drain down the table, into the sink, and down the drain. This goes into the sewer, like every other sink and toilet, and (usually) goes to a water treatment plant.

You may be thinking that this is biohazardous waste and needs to be treated differently. [If] we can’t put oil, or chemicals (like formalin) down the drains due to regulations, why is blood not treated similarly? I would assume because it is effectively handled by the water treatment plants. If it wasn’t, I am sure the regulations would be changed.

Now any items that are soiled with blood—those cannot be thrown away in the regular trash. Most clothing worn by the decedent is either retained for evidence or released with the decedent to the funeral home—even if they were bloody.

But any gauze, medical tubing, papers, etc. that have blood or bodily fluids on them must be thrown away into a biohazardous trash. These are lined with bright red trash liners, and these are placed in a specially marked box and taped closed. These boxes are stacked up in the garage until they are picked up by a specialty garbage company. I am not sure, but I am pretty sure they are incinerated.

Additionally anything sharp or pointy—like needles, scalpels, etc.—must go into a rigid “sharps” container. When they are 2/3 full we just toss these into one of the biotrash containers.

The biotrash is treated differently, as, if it went to a landfill, then the blood (and therefore the bloodborne pathogens like Hepatitis and HIV) could be exposed to people or animals. Rain could wash it into untreated water systems.

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

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