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RENEE MONTAGNE, host:

This is MORNING EDITION, from NPR News. I'm Renee Montagne.

STEVE INSKEEP, host:

And I'm Steve Inskeep. Good morning.

In "Your Health" on this Monday morning, we begin with salt. Most people know that consuming too much salt increases your risk of high blood pressure, heart attacks and strokes. Some people may not realize that laying off salt may be harder for some people than others. NPR's Allison Aubrey says one explanation lies at the tip of your tongue.

ALLISON AUBREY: I'm about to paint my tongue blue. Stick with me. I've got a Q-tip here in my right hand. And - well, it just takes a drop or two of this food dye. And on the phone with me is just the person who can explain this little experiment.

Professor JOHN HAYES (Food Science, Pennsylvania State University): My name is John Hayes, and I am an assistant professor of food science at Pennsylvania State University.

AUBREY: Hayes uses the blue food dye to determine just how intensely people can perceive tastes. I've just done it here in the recording studio, and I've got a little mirror I can look into. When it's actually done in the lab, Hayes uses fancy video microscopes to examine people's tongues.

Prof. HAYES: When we do that, we can just put a slip of plastic on their tongue, and they hold it there with their hands.

AUBREY: I'm actually holding my tongue now. What do I look for?

Prof. HAYES: So there's these little dots that you can see on the front of your tongue.

AUBREY: Little bumps called papillae. They house our taste buds. And here's the thing: It turns out that some of us have a lot more of them than others. In Hayes' most recent study, he recruited 87 healthy volunteers and examined an area of their tongues about the size of the head of a pencil eraser. Then he counted the number of papillae.

Prof. HAYES: We saw people had anywhere from about 12 to 40.

AUBREY: Wow. So some people have three times as many as others?

Prof. HAYES: Yes.

AUBREY: Which Hayes says was not a surprise. Scientists have long known about this variability. People who have lots of papillae have been dubbed supertasters for their ability to really perceive, say, the bitterness in arugula or the subtle sweetness of a pea.

But something new Hayes did learn in this study really surprised him. When he gave his volunteers salty foods, he figured that the supertasters wouldn't want too much of it.

Prof. HAYES: We had expected that the supertasters would need less salt.

AUBREY: Because past studies have shown that supertasters experience stronger taste sensations from lots of foods.

Prof. HAYES: So, for example, we know that they need less fat and sugar to get to the same amount of pleasure than a non-taster does.

AUBREY: But with salt, it turns out that the supertasters could not get enough. They choose higher-sodium foods than their non-supertaster counterparts, and it's not what Hayes expected. The surprise shows just how varied individual preferences can be, says food scientist Danielle Reed of the Monell�Chemical�Senses�Center.

Dr. DANIELLE REED (Monell�Chemical�Senses�Center): You can never go wrong when you try to carefully appreciate how individual differences might influence things like trying to comply with a low-salt diet.

AUBREY: So sticking with foods that may help keep the high blood pressure medicine and heart disease at bay is likely going to be much harder for some than others.

Allison Aubrey, NPR News.

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