The Salt
9:59 am
Mon October 15, 2012

A Nose Tuned In To Bitter May Help Stave Off Sinus Infection

Supertasters are the Olympic athletes of gastronomy, able to detect subtle differences in flavors that other people never register. That talent may make for more than a discriminating palate, though. It may also warn them about attacking germs, and help them defend themselves against sinus infection.

This notion isn't as bizarre as it may seem. Bitter tastes have long been considered a danger signal in foods, warning about potential toxins in potatoes and other vegetables. If the potato's bitter, don't eat it.

Supertasters' exquisite sensitivity to bitterness and other flavors is caused by genetic variations that give them amped-up taste receptors. About 25 percent of people are supertasters, while another 25 percent are "non-tasters", barely able to detect bitterness. The rest of us fall somewhere in between. (NPR's Richard Knox says that supertasters may crave salt as a way to mask intensely bitter tastes.)

But it turns out that receptors for bitterness aren't just on our tongues. They're also in our gut, lungs, and nasal passages. The gut receptors have been linked to cholesterol metabolism, and the lung receptors help control mucus production. And the nose?

Those nose receptors surely must add to a gourmet's experience with the sharp tang of a ripe Gorgonzola. But Noam Cohen, a head and neck surgeon at the Philadelphia VA hospital who spends his days operating on people with sinus infections, thinks the receptors are part of the immune system. "Maybe these bitter taste receptors are there as an early detection system," he told The Salt. "And maybe if you have the wrong genetics they won't kick in."

Cohen got curious about taste receptors in the nose while worrying about why a small number of his sinus patients never got better after surgery. Were they susceptible to infection in some way that most of the patients, who recovered completely, were not?

So he and his colleagues at the University of Pennsylvania, where he's an assistant professor of otolaryngology, and at the Monell Chemical Senses Center in Philadelphia, tested tissue samples from the noses of his patients.

In the laboratory, they exposed the samples to a chemical produced by Pseudomonas aeruginosa, a bacterium that's a common cause of sinus infections.

They found that the taste receptors from the patients who were supertasters responded strongly to the bitter taste of the chemical, which bacteria produce to communicate with each other. People who lacked the genes to taste bitterness didn't respond at all.

When the supertasters' receptors were exposed to the bacterial chemical, they did two things that Cohen thinks show they're helping fend off the bacteria: They activated cilia, tiny hairs that sweep germs out of the nose, and increased production of nitric oxide, which kills bacteria.

"If you are a supertaster you have an inherently strong defense in your nose to these organisms," Cohen says.

The scientists tested just one type of bitterness receptor against one bacterium. But the nose holds dozens of different bitter taste receptors, and they are hoping that the other receptors are there to detect and fight other pathogens. "Are there others that protect against Staph. aureus? MRSA?" he says.

Now, there's a big caveat. This all happened in a lab, not in real life, so there's no guarantee that this is how it works in human noses. But Cohen is hoping that if it holds true, a simple taste test could be used to screen patients with sinus infections. Even better would be if the system could somehow be amped so that non-supertasters could get the germ-fighting benefits, too. "That's what we're hoping."

Cohen's work was published online in the current Journal of Clinical Investigation.

So, supertasters: are you healthier than everyone else in the office? Happily free of sinus infections?

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.