Why Do Beans Make You Fart?

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Beans, beans, the musical fruit. The more you eat, the more you toot. But don't blame your flatulence on the poor legumes directly. The blame lies instead with the loads of little critters teeming in your gut.

Once you mash a bowl of barbecue baked beans into a fine mush in your mouth and stomach, it moves along to the small intestine. This organ is basically a molecular chop shop, where digestive enzymes strip your meal down for whatever bits and pieces your body can use and break them into smaller components that are more easily absorbed. Proteins get broken down into peptides and amino acids, fats into fatty acids and glycerol, and some carbohydrates into simple sugars. These are then absorbed through the intestinal wall to become fuel for your body.

This process isn’t so smooth with beans.

Their natural sweetness comes from a group of sugars called oligosaccharides (some of the more common ones in beans are raffinose and stachyose, which sound like rejected Musketeers). These sugars are hulking, awkward molecules. They’re far too big to slip though the intestinal wall on their own, and our guts’ enzymatic tool kit doesn’t have the right stuff to break the big things apart into more manageable pieces. So the sugars get a free ride though the small intestine. No one messes with them, and they move on into the large intestine intact.

Here their journey comes to a halt when they’re greeted by some of your closest friends, the 700+ species of bacteria that call your lower gut home. Fully capable of handling the big meal and never ashamed to have at your leftovers, the bacteria dig into the sugars. As they eat, their metabolic activity produces gases, hydrogen and methane among them. All that gas accumulates and eventually escapes your body as a fart, which may or may not be blamed on the dog.

Not all organisms have this problem with oligosaccharides, and some fungus species possess the right enzymes to break them down. These enzymes are easy enough to extract, and are often turned into gas-relieving supplements. Beano, the most well-known example, is made with the enzyme alpha galactosidase, derived from the fungus Aspergillus niger. Pop a tablet in your mouth before dinner, and the enzyme will snap those big sugars apart into handy little sugars like sucrose, glucose and fructose, giving you things your body can use and keeping you from giving a performance attributable to the musical fruit.

Today we're answering 20 big questions like this one. We'll plan more days like this, so if you have something you're dying to know, leave us a comment or tweet @mental_floss with the hashtag #bigquestions.

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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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Why Does Asparagus Make Your Pee Smell Funny?
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The asparagus has a long and storied history. It was mentioned in the myths and the scholarly writings of ancient Greece, and its cultivation was the subject of a detailed lesson in Cato the Elder's treatise, On Agriculture. But it wasn't until the turn of the 18th century that discussion of the link between asparagus and odorous urine emerged. In 1731, John Arbuthnot, physician to Queen Anne, noted in a book about food that asparagus "affects the urine with a foetid smell ... and therefore have been suspected by some physicians as not friendly to the kidneys." Benjamin Franklin also noticed that eating asparagus "shall give our urine a disagreeable odor."

Since then, there has been debate over what is responsible for the stinky pee phenomenon. Polish chemist and doctor Marceli Nencki identified a compound called methanethiol as the cause in 1891, after a study that involved four men eating about three and a half pounds of asparagus apiece. In 1975, Robert H. White, a chemist at the University of California at San Diego, used gas chromatography to pin down several compounds known as S-methyl thioesters as the culprits. Other researchers have blamed various "sulfur-containing compounds" and, simply, "metabolites."

More recently, a study demonstrated that asparagusic acid taken orally by subjects known to produce stinky asparagus pee produced odorous urine, which contained the same volatile compounds found in their asparagus-induced odorous urine. Other subjects, who normally didn't experience asparagus-induced odorous urine, likewise were spared stinky pee after taking asparagusic acid.

The researchers concluded that asparagusic acid and its derivatives are the precursors of urinary odor (compared, in different scientific papers, to the smell of "rotten cabbage," "boiling cabbage" and "vegetable soup"). The various compounds that contribute to the distinct smell—and were sometimes blamed as the sole cause in the past—are metabolized from asparagusic acid.

Exactly how these compounds are produced as we digest asparagus remains unclear, so let's turn to an equally compelling, but more answerable question:

WHY DOESN'T ASPARAGUS MAKE YOUR PEE SMELL FUNNY?

Remember when I said that some people don't produce stinky asparagus pee? Several studies have shown that only some of us experience stinky pee (ranging from 20 to 40 percent of the subjects taking part in the study, depending on which paper you read), while the majority have never had the pleasure.

For a while, the world was divided into those whose pee stank after eating asparagus and those whose didn't. Then in 1980, a study complicated matters: Subjects whose pee stank sniffed the urine of subjects whose pee didn't. Guess what? The pee stank. It turns out we're not only divided by the ability to produce odorous asparagus pee, but the ability to smell it.

An anosmia—an inability to perceive a smell—keeps certain people from smelling the compounds that make up even the most offensive asparagus pee, and like the stinky pee non-producers, they're in the majority.

Producing and perceiving asparagus pee don't go hand-in-hand, either. The 1980 study found that some people who don't produce stinky pee could detect the rotten cabbage smell in another person's urine. On the flip side, some stink producers aren't able to pick up the scent in their own urine or the urine of others.

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