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The Wonders of Saliva

It protects our teeth, fights infection and is sorely missed when absent. Scientists are fascinated by its medical potential.

January 21, 2002|ROSIE MESTEL | TIMES MEDICAL WRITER

Saliva is a humdrum liquid, the stuff of giggles, dribbles and schoolyard grossness. It's hardly something to take seriously--until, that is, you lack it. When your glands no longer pump out a normal and robust 2 to 3 pints daily, then you'll come to appreciate spit for the wondrous substance it is--one that does far more than render food slimy and digestible.

Saliva, science has revealed, is much more than water. It is packed with proteins that help control the teeming hordes of microbes in our mouths. It is stuffed with substances that make our spit stringy, stop our teeth from dissolving and help heal wounds. It is brimming with a plethora of hormones and other chemicals revealing anything from whether one smokes to whether one is stressed.

Thus it's no wonder that trouble starts brewing when mouths dry out. Cavities blossom like flowers in spring. Tongues become sore and fissured, and breeding grounds for yeast. In a spit-depleted world, speaking and swallowing are challenges, eating a cracker is the height of recklessness and you wake up with your tongue glued to your mouth.

Such indignities will be more frequent in future years because the number of saliva-depleted people stands to rise, experts predict. Tens of thousands of Americans receive radiotherapy for head and neck cancers each year--a treatment that can permanently damage salivary glands. Maybe a million have dry mouths because their immune systems are attacking their own glands in a disease known as Sjogren's syndrome.

But an increasing number of people (25 million by some estimates, and more to come as the population ages) get dry mouths as a side effect of more than 400 of today's medications--taken for depression, high blood pressure and more.

A small band of scientists is fighting back.

Armed with a deep knowledge of saliva gleaned over decades, this cadre--which jocularly refers to itself as the "salivation army"--is working to create better artificial salivas to keep mouths wet and protected and find new drugs to help saliva flow more freely. They're trying to repair salivary glands with gene therapy--even to build an artificial gland to implant in the mouth.

And their vision goes far beyond simply mending the mouth. Just as leech saliva gave us anticoagulants, researchers hope that our very own spit may yield new antimicrobial drugs to help battle germs. Or that sick people's salivary glands can one day be coaxed to make hormones that are needed for their bodies to heal.

"The field's quite exciting--we're entering a new phase," says Lawrence Tabak, a longtime saliva scientist and director of the National Institute of Dental and Craniofacial Research. "People are trying to translate what they've learned from nature into things that are going to improve patients' health. To me, that's the most exciting thing possible--to take these great, basic science discoveries and translate them into tangibles."

Tangible breakthroughs on the saliva front can't come too soon for Nancy Ross-Flanigan, 52, a Detroit area writer who's been pretty much spitless for 11 years, ever since her salivary glands were blitzed during radiotherapy for tongue cancer.

Nothing, she says, prepared her for just how dry things would be.

"I just assumed--well, everybody has dry mouth when they get nervous or something--that's what I thought it would be like," she says. "That you could still talk. You could still eat. You wouldn't have to be putting something in your mouth all the time to have any moisture."

But her mouth ended up so dry it wouldn't yield spit even when doctors tried milking her glands with a suction cup stuck inside her cheek. Unless she sipped water every few minutes, her mouth gummed up, her throat got scratchy, she croaked, and then she choked. Life's most humdrum events became tinged with new drama.

She learned to favor slimy pastas and soups after a series of spectacular restaurant choking incidents--and a time, on a lunch date, when a wad of bread wedged fast under her lip, bulging it out like a chipmunk's cheek.

She experimented with a long stream of over-the-counter mouth moisturizers that her friends jocularly referred to as "I Can't Believe It's Not Saliva!" She tried a drug to stimulate her glands. It left her saliva flow almost unchanged but sent other bodily secretions into overdrive, drenching her with sweat in the grocery store or office.

Today, Ross-Flanigan uses over-the-counter pills that coat her mouth with slime--but mostly she just totes water everywhere. She carries it in sundry bottles, plastic jugs and on a pouch on her back when she rides out (not quite as wild and free as she'd like) on her Harley motorcycle.

It is far from ideal. Water isn't slick like saliva, so her mouth gets dry and sore. Sinister scenarios color her fantasies of overseas travel: "I think, 'Gee, what if I get captured by terrorists and they won't let me have my spit bottle?'"

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