Gulp: Adventures on the Alimentary Canal (13 page)

Picture one of those little silver
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balls that cake decorators use. Strip away the metallic coating and soften the texture. You are now picturing the amassed bacteria in one milliliter of unstimulated saliva. Silletti put our samples in the centrifuge and spun cellular from noncellular. Some of what we are looking at is shed mouth cells, but most is bacteria—about a hundred million of them. More than forty species.

Yet never in my life has a cut or sore in my bacteria-crazy mouth become infected. As much as saliva is a bacterial cesspool, it is also an antimicrobial miracle—the former necessitating the latter. As a germ killer, saliva puts mouthwash to shame.
^†
Saliva has anti-clumping properties, which discourage bacteria from forming colonies on the teeth and gums. There are salivary proteins that retain their antimicrobial abilities even when they themselves are broken down. “And they may be even more effective than the whole protein of origin,” Silletti is saying. “It’s incredible!”

Saliva’s antimicrobial talents explain some of the folk medicine remedies that have been making the rounds since the 1600s. One 1763 treatise advocates applying “the fasting saliva of a man or woman turn’d of seventy or eighty years of age” to syphilitic chancres of the glans penis. As with the ancient Chinese
Materia Medica
prescription of saliva “applied below arms to counteract fetid perspiration,” one imagines—
hopes
—that an applicator other than the tongue was employed.

“It is a known observation among the vulgar that the saliva is efficacious in cleansing foul wounds, and cicatrizing recent ones, thus dogs by licking their wounds . . . have them heal in a very short time,” wrote the eighteenth-century physician Herman Boerhaave. He was correct. Wounds that would take several weeks to heal on one’s skin disappear in a week inside the mouth. In a 2008 rodent study, animals that licked their wounds healed faster than those that could not (because their salivary glands had been disconnected—a wound, alas, that even saliva cannot heal).

More than just disinfecting is going on. Rodent saliva contains nerve growth factor and skin growth factor. Human saliva contains histatins, which speed wound closure independent of their antibacterial action. Dutch researchers watched it happen in the lab. They cultured skin cells, scratched them with a tiny sterile tip, soaked them in the saliva of six different people, and clocked how quickly the wounds healed, as compared to controls. Other components of saliva render viruses—including HIV, the virus that causes AIDS—noninfective in most cases. (Colds and flus aren’t spread by drinking from a sick person’s glass. They’re spread by touching it. One person’s finger leaves virus particles on the glass; the next person’s picks them up and transfers them to the respiratory tract via an eye-rub or nose-pick.)
^*

The average person, of course, is oblivious to all this. With no more formal criteria than the number of Hollywood monsters featuring copious, pendant drool, you can make the case that saliva remains universally upsetting. And thus maligned, even in the medical community. There has long been an assumption among emergency medical personnel that human bites are especially likely to become infected and lead to sepsis—a potentially lethal systemic infection. “Even the simplest of wounds require copious irrigation and wound toilet,” warn the authors of “Managing Human Bites” in the
Journal of Emergencies, Trauma, and Shock.

Not so fast, says rival
American Journal of Emergency Medicine.
The article title says it all: “Low Risk of Infection in Selected Human Bites Treated without Antibiotics.” Only one out of the sixty-two human-bit patients who were not given antibiotics developed an infection. However, the authors excluded high-risk bites, including “fight bites” on the hands. Here it is the aggressor who gets the “bite”—when he splits open his knuckle on another man’s teeth. Fight bites
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tend to get infected, but it is the fault of the knuckle as much as the saliva. Relatively little blood flow reaches the tendons and sheaths of the finger joints, so the immune system has fewer resources with which to fight back. (Ear cartilage is similarly underserved by the vascular system, so if you plan on picking a fight with Mike Tyson, do practice good wound toilet.)

Even the “deathly drool” of the Komodo dragon, the world’s largest lizard, has likely been overstated. Theory holds that Komodo dragon saliva contains lethal doses of infectious bacteria, enabling the reptiles to take on prey far larger than themselves—wild boar, deer, newspaper editors. (
San Francisco Chronicle
’s Phil Bronstein spent several days on an antibiotic drip after a Komodo dragon attacked his foot during a behind-the-scenes visit at the Los Angeles Zoo in 2001 with his then wife, Sharon Stone.) Rather than having to tackle and kill their prey on the spot, the theory goes, the reptiles need only deliver a single bite and then wait around for the animal to die of sepsis. The scenario has not been documented in the wild, however. A team of researchers from the University of Texas at Arlington attempted a laboratory simulation, using mice as mock prey and, as predator, injections of bacteria from wild Komodo dragon saliva. The scientists found a high death rate among mice injected with a particular bacteria,
Pasteurella multocida
. However, Australian researchers point out that
P. multocida
is common in weakened or stressed mammals. They speculate that the dragons may have picked it up from their prey, rather than the other way around. Current thinking postulates a “sophisticated combined-arsenal killing apparatus,” featuring venom and anticoagulative agents that lead to shock. The latter would explain “the unusual quietness . . . of prey items.” Prey item Phil Bronstein was unusually
not
quiet.
^*
“I was pretty pissed.”

Though bacteria and general ropy grossness are probably to blame for saliva’s nasty reputation, it may in part be lingering fallout from the writings of Hippocrates and Galen, Western medicine’s most influential early (as in, triple-digit
A.D.
and
B.C.
) thinkers. Both believed sweat and saliva to be the body’s way of flushing away disease-causing impurities. Before scientists realized syphilis and malaria were caused by microorganisms, the diseases were treated by putting patients in “salivating rooms.” It was the same medically quaint principle that persists today in the form of taking a steam or a sauna to “sweat out toxins.” Only back then, the steam included vaporized mercury
^†
to coax more saliva from the patient. No one realized that excessive salivation is a symptom of acute mercury poisoning. The salivating room was a standard feature of hospitals in the 1700s. (As was, charmingly, the “apartment for lunatics.”) Patients were left inside until they’d generated six pints of saliva—about three times the amount most people produce in a day.

Not all cultures denigrate saliva. In ancient Taoist medical teachings, stimulated saliva—“the jade juice”—was said to nourish the qi, which boosts the immune defenses and, wrote one seventh-century Taoist, “puts a man beyond the reach of calamities.” Given this tradition of qi-nourishing saliva retention, why do I so often see old Chinese men spitting? Silletti points out that it’s not saliva being expectorated. It’s phlegm from the lungs or sinuses. They spit it out, she added, because they don’t care to use handkerchiefs or Kleenex. They think it’s disgusting that we collect the material in our hands.

For saliva-positive attitudes, there is no place like Greece. “Greeks spit on pretty much anything they want to protect from the evil eye or bless for good luck,” says Evi Numen. Numen is the exhibitions manager at the Mütter Museum,
^*
a collection of medical curiosities amassed by Thomas Mütter and housed today at the College of Physicians of Philadelphia. Though her job qualifies her to comment on most things bodily and disgusting, her salivary expertise derives from her upbringing. Numen is of Greek extraction. Greeks spit on babies. They spit on brides. They spit on themselves. Though no actual gob is launched. “Most people,” explains Numen, “say ‘
ftou ftou ftou
’ instead of actually spitting.”

The Greeks got it from the Roman Catholics, whose priests used to baptize with spittle. The priests got it from the Gospel of Mark—the bit where Jesus heals the blind by mixing dirt with his saliva and rubbing the mud on a man’s eyelids. “It’s an interesting passage,” former Catholic priest Tom Rastrelli told me, “because the writers of the gospels of Luke and Matthew, who used Mark as their source, redacted a line.” Mark had included a bit about a blind man opening his eyes and seeing what looked like trees walking around. In other words, the treatment was minimally effective. The miracle of Jesus bestowing rudimentary vision to the blind doesn’t have the same ring to it, so the line was cut.

T
HE
D
UTCH, BY
tradition, are a dairy-farming people. Adults drink milk with dinner. A town will have a shop devoted entirely to cheese. The national dish of the Netherlands, sighs Silletti, is
vla
: custard. I have been staying in the home of food scientist René de Wijk, the world’s foremost expert on the science of semisolids like
vla
. Upon hearing this, Silletti immediately, as though it were a matter of medical urgency, invited me over for home-cooked Italian food.

Silletti is lactose-intolerant and, as concerns Dutch cuisine, just generally intolerant. “Everything is based on milk,” she says, arranging sundried tomatoes for a plate of antipasto.

Silletti’s home is a twenty-minute drive from Germany, where the supermarkets sell a decent range of Italian products. She regularly travels across the border to stock up. I don’t blame her. The supermarket near de Wijk’s house sells things like gorte pap—buttermilk barley porridge—and Smeer’m, a kind of spreadable cheese vileness. I’d go home with a cucumber and some peanuts because I wanted something real, something with crunch, something that didn’t sound like a gynecology exam. There was an entire aisle devoted to
vla.

“The Dutch and their
vla
. . .” Silletti speaks it like a curse word. “For me it’s not food. You don’t need teeth
or
saliva!”

Oddly, the cluster of Wageningen-area universities and research facilities known as “Food Valley” is the home of the foremost expert on the physics of crunchy food, as well as a man who knows more about chewing than anyone else in the world. I am meeting them both tomorrow, at the Restaurant of the Future. This is a cafeteria at Wageningen University where hidden cameras allow researchers to gauge how, say, lighting affects purchasing behavior, or whether people are more likely to buy bread if you let them slice it themselves. Silletti says she won’t eat there.

“Because of the cameras?”

“Because of the food.”

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Except possibly Irwin Mandel. Mandel was the author of a hundred papers on saliva. A winner of the Salivary Research Award. The subject of a lush tribute in the
Journal of Dental Research
in 1997. The editor of the
Journal of Dental Research
in 1997. Mandel did not go so far as to write the tribute himself. That was done by B. J. Baum, P. C. Fox, and L. A. Tabak. Having three authors means no one man can be blamed for the sentence “Saliva was his vehicle and he went with the flow.”

*
I can vouch for this. I once toured the refrigerator at Hill Top Research, where odor judges test the efficacy of deodorizing products like mouthwash and cat litter. The president at the time, Jack Wild, was looking for the malodor component of armpit smell, which I had asked to sample. He kept opening little jars, going, “Nope, that’s dirty feet, no, that’s fishy amines” (vaginal odor). I asked him which is the worst. “Incubated saliva,” he said without hesitating. “Both Thelma and I got dry heaves.” I don’t recall Thelma’s title. Whatever she did, she deserved a raise.

*
Less high-tech than it sounds. Subjects leaned over and spat into the machine every two minutes. A slight improvement over the earliest collection technique, circa 1935: “The subject sits with head tilted forward, allowing the saliva to run to the front of the mouth . . . and drip out between parted lips.” A photo in Kerr’s monograph shows a nicely dressed woman, hair bobbed, hands palm down on the table in front of her, forehead resting in a support. An enamel basin is positioned just so, to catch the drippings.

*
But nothing compared to crow droppings. According to Harper, the traditional purification ritual for the Brahmin polluted by crow feces is “a thousand and one baths.” This has been rendered less onerous by the invention of the showerhead and the crafty religious loophole. “The water coming through each hole counts as a separate bath.”

*
Or, as of 2007, an adult. Egyptian scholar Ezzat Attiya issued a fatwa, or religious opinion, extending breast-milk-son status to anyone a woman has “symbolically breastfed.” For convenience’s sake, drivers and deliverymen could, by drinking five glasses of a woman’s breast milk, be permitted to spend time alone with her. In the ensuing ruckus, another scholar insisted the man would have to drink directly from the woman’s breast. Which is crazier: that Saudi courts, in 2009, sentenced a woman to forty lashes and four months in prison for allowing a bread deliveryman inside her home, or the notion that she might have avoided punishment by letting him suckle from her breast? The woman was seventy-five, if that helps you with your answer.