The Science of Spit

image via Abracadebra

drool bib via Abracadebra



You could fill your bathtub a few times over with a typical year’s worth of saliva.
Each of us pumps out a liter or two of the stuff daily. Food photography, TV cooking shows, even the mere reading of menu descriptions can get us dribbling. 
That’s a lot of drool. 

Saliva is much more than just water.
Saliva is teeming with hormones, proteins, and enzymes. It keeps our teeth from rotting, heals wounds to our mouths and tongues, and controls the hordes of unhealthy microbes that find their way into our mouths. And it allows us to taste, swallow, and digest food.

It’s actually two different fluids. There’s a sticky, dense liquid that acts as a lubricant and turns everything we chew into a kind of paste, and a thinner, watery fluid that contains the enzyme amylase which breaks down carbohydrates and turns them into digestible sugars. Saliva contains just a trace amount of amylase, but it’s such powerful stuff that even a drop of it will break down all the starch you can throw at it. Spit into a soft, starchy food like mashed potatoes, put it aside, and in a matter of hours you’ll have a bowl of sugary liquid.

Saliva makes you think you’re hungry.
Drooling is an uncontrolled appetite response. We salivate at the sight, sound, and especially smell of tempting foods, and it triggers hunger signals from the brain and intestines, even when we’re not really hungry. It makes it harder to resist temptation, and really, it’s not likely that we’re drooling over rice cakes and celery sticks.

The key to successful dieting: control your drool.
People who struggle with diets tend to be big droolers. If they can resist temptations, eventually they’ll drool less and keep the hunger response from kicking in. Anyone who has ever tried to lose weight knows that the toughest part of any diet is just getting started; the drool data tell us that it gets easier if a dieter can push through the early days and reprogram their hunger response.

It’s not just about food.
Are you drooling over the new iPhone? That’s not just a figure of speech; we really do salivate for material goods. The results from two recent studies published in The Journal of Consumer Research reported increased saliva flow in subjects shown photographs of shiny new sports cars, cashmere sweaters, and piles of money. By contrast, they got dry-mouthed from images of office supplies.

This is all sounding very Pavlovian. Instead of a dog and a bell, we’re salivating reflexively over everything from grilled cheese sandwiches to touch screens. But we’re not simple stimulus-response machines. We are infinitely more complex with active internal lives and the capacity to ignore, resist, choose, and change.
We’re not immune to conditioning, but we can take charge of our drool.


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