Go get a snack. Now take a bite. Now chew. Chew some more. And some more. In fact, chew it for 10 minutes, until it’s entirely liquid.

We’ll wait.

Now swallow.

Such thorough mastication was prescribed by Horace Fletcher, founder of the early-20th-century Fletcherism movement. He argued that people could absorb double the nutrients in food if it was chomped into oblivion. (Bonus: He also held that those who adhered to the regimen would produce poop with “no more odor to it than there is to a hot biscuit.”)

“I wouldn’t want to sit down with Fletcher … or any of the autointoxication weirdos,” says author Mary Roach. Her latest book, “Gulp. Adventures on the Alimentary Canal,” covers the mechanics of what we put in our body and how it gets out. (Those “autointoxication weirdos” believed that fecal matter poisons the body. They were into “internal baths.”)

Roach’s books go down easy (so to speak), combining science with plain language and humor. Her prior work, “Packing for Mars,” dealt with something very few readers will actually experience: how scientists are preparing humans for long-term space travel. Now she’s returned to the quotidian science of earthbound people.

“With ‘Packing for Mars,’ someone had to imagine themselves in that position,” Roach says. “I think it’s so much easier to relate to something that’s right inside you as you read.”

Perusing “Gulp” while eating may not be the best idea. We can assure you at least one lunch was abandoned while reading about Alexis St. Martin. After being shot in a manner that made the inside of his stomach visible from the outside, he became the subject of multiple experiments in which his doctor shoved food into the stomach and watched what happened.

“I would love to sit down with St. Martin,” Roach says. “No one cared about his side of it. He was a professional stomach — that’s how he got paid. What a weird life that man had.”

Even though Roach spent a lot of time researching some unappetizing subjects, she’s pretty un-gross-out-able. With one exception.


“Surprisingly, the chapter that was the most difficult for me, in terms of how icky it was, was the unstimulated part of the saliva chapter,” she says.

Stimulated saliva is what you get when you’re presented with a big bowl of chili (assuming you like chili). Unstimulated saliva is the kind that’s always in your mouth. Try this: Don’t swallow for one minute. Now spit out what’s accumulated. That’s the stuff Roach can’t stand.

“It’s this mucoid, thick, ropey saliva,” she says. “Even for me it was a little … yyyyyeahhh,” she says. “My curiosity generally trumps any sense of disgust or revulsion, but that’s a particularly unpleasant thing.”

Her hatred for the viscous extends to food. “I have a problem with gumbo with okra in it, because that stringy stuff looks like unstimulated saliva,” she says.

So, when you invite Roach to dine with you (she’ll be in town Saturday), don’t serve gumbo. In exchange, she promises to be a hit at your dinner party: “I will share all these facts. I will start many arguments about whether men or women have worse gas. Rent me out.”

In and Out

Six interesting facts to digest from ‘Gulp.’ (See illustration above.)

1. Nose:  Eighty to 90 percent of tasting is actually smelling. Food scents are picked up by your internal nostrils (in the back of the mouth, go figure), a process called “retronasal olfaction.”

2. Mouth: Saliva has antimicrobial power. In ancient China it was used to fight body odor, and a 1763 medical treatise recommended it as a treatment for syphilis in men. (Don’t try it.)

3. Stomach: If you die while eating, your stomach will continue to digest your last meal. It can also eat through itself, leaking its contents into the body cavity. A warm climate enhances the effect.

4. Small Intestine: Early colonic irrigators were so forceful they could shove fecal matter out of the large intestine into the small intestine (the wrong direction), where it would be absorbed into the body. This is bad.

5. Large Intestine: During a colonoscopy, doctors blow air or carbon dioxide into the colon in case they need to remove a polyp. This keeps electricity from the tools from igniting any hydrogen or methane inside the patient.

6. Rectum: When James Garfield was shot, his doctor ordered him fed with a “nutrient enema” consisting of beef, egg yolk and whiskey. Garfield died. The doctor submitted a bill for $25,000.

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