Spit really shines!

Health: Saliva proves to be a surprisingly valuable, versatile substance -- just ask those who have lost it.

March 10, 2002|By Rosie Mestel | Rosie Mestel,Special to the Sun

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.

Such indignities will be more frequent in the future 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 mouth 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 refers to itself as the "salivation army," is working to create better artificial salivas to keep mouths wet and protected and to 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. Researchers hope that our very own spit may yield new antimicrobial drugs to help battle germs.

"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.

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 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."

Today, Ross-Flanigan uses over-the-counter pills that coat her mouth with slime -- but mostly she just totes water everywhere. It is far from ideal. Water isn't slick like saliva, so her mouth gets dry and sore.

Few people suffering from dry mouth are quite as desiccated as Ross-Flanigan. But they can still run into nasty trouble, says saliva expert Mahvash Navazesh, associate professor and chairwoman for oral medicine and oral diagnosis at the University of Southern California's school of dentistry.

She holds up slides depicting raw tongues white with yeast, teeth brown or black with decay on their ridges as well as at or under the gumline, where decay is usually rare.

"I don't think people are paying enough attention," she says. "Because of that, dentists are usually doing damage control."

Drug companies continue to neglect the dry mouth arena, saliva researchers say, because they don't see much money in it. And artificial salivas have fared no better than tap water in most clinical trials. It's time, experts say, to bring more science to bear.

A handful of researchers have established that human saliva is filled with hundreds of useful chemicals, floating around with millions of bacteria, viruses, yeast and skin cells.

They've been busily investigating such proteins, and finding that some are important for maintaining oral health.

There are long, sticky, stretchy proteins called mucins that are studded with carbohydrates, giving saliva its stringiness so it nicely coats the teeth and gums. Mucins also stick to bacteria that cause tooth decay and gum disease, interfering with their ability to colonize teeth and helping our immune cells attack them.

Other proteins -- with names such as peroxidase, lysozyme, lactoferrin and histatin -- as well as our own antibodies also wreak havoc on bacteria and fungi.

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