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Why 'Supertasters' Can't Get Enough Salt

Most people know that consuming too much sodium can increase your risk of high blood pressure, heart attacks and strokes. But did you know that laying off the salt shaker is harder for some than others?

One explanation may lie at the tip of our tongues -- and in our genes.

The Experiment

According to the Mayo Clinic, 77 percent of the salt in the American diet comes from processed food. Here's a look at the salt content of some common grocery items -- some of the findings might surprise you. Keep in mind that the 2005 Dietary Guidelines for Americans say you should consume less than 2,300 mg of sodium per day, and the American Heart Association recommends less than 1,500 mg.

Rice: Boxed rice dinners might seem innocuous, even healthy. But Chicken Fajita Rice A Roni contains a whopping 1,000 mg of sodium per serving. That's nearly as much sodium as a McDonald's Big Mac, which has 1,040 mg. Other types of packaged rice aren't much better: Zatarain's New Orleans Style Yellow Rice has 930 mg and Near East Original Rice Pilaf has 780 mg.

Soup: Even soups that seem healthy can contain large amounts of sodium. Campbell's Vegetable Soup contains 890 mg of sodium per serving. Other soups fare better: Campbell's Healthy Request Tomato Soup clocks in with less than half that amount at 410 mg. Progresso Light Chicken & Dumpling soup has 345 mg for the same serving size. Point of comparison: A McDonald's Cheeseburger has 750 mg of sodium.

Salad Dressing: Considering they're associated with the ultimate health food, salad dressings have surprisingly high levels of sodium. Eating Right Light Ranch dressing is 310 mg a serving (2 Tablespoons), and Wishbone Balsamic Vinaigrette is 280 mg. To compare, McDonald's Medium French Fries have 270 mg, and Lay's Classic Potato Chips have 180 mg.

-- Whitney Blair Wyckoff

All you need for this experiment is a cotton swab and some blue food dye. Painting your tongue with a few drops of the dye is one way to gauge the density of papillae on your tongue.

"You can see these little dots on the front of your tongue," says food scientist John Hayes of Pennsylvania State University.

The little bumps are called papillae, and they're the structures which house our taste buds. People with lots of papillae usually experience tastes more intensely -- they've been dubbed "supertasters." For instance, they may sense a real bitterness in arugula or the subtle sweetness of a snap pea. So-called "non-tasters" are on the other end of the spectrum.

In a laboratory setting Hayes uses fancy video microscopes to examine people's tongues and count how many papillae they have. But at home you can use a mirror. That's what I did.

Hayes counted the number of papillae within a 6-millimeter area of the tongue, which is about the size of the head of a pencil eraser. And in his latest study, published in Physiology & Behavior, he found lots of individual variation.

"We saw that people had anywhere from 12 to 40 (papillae)," says Hayes. The research involved 87 healthy participants, ranging from supertasters to non-tasters. All the participants agreed to sample salty foods such as broth, chips, pretzels and cheese. Afterwards, they rated the intensity of taste and described their preferences. (Check out NPR's Richard Knox's blog post to read more about Hayes' experiments.)

Supertasters Like Salt

Scientists have long known about the wide variation in taste preferences among individuals. "People don't all live in the same taste world," Hayes says.

But one new finding from his study did surprise him.

"We had expected that the supertasters would need less salt," Hayes says, because past studies have shown that supertasters experience stronger taste sensations from lots of foods. "For instance, we know supertasters need less fat and sugar to get to the same amount of pleasure than a non-taster does."

But with salt it turns out that the supertasters couldn't get enough. They choose higher-sodium foods than their counterparts. For instance, they opted for -- and preferred -- higher sodium chips and cheeses.

This study illustrates the wide range in individual sensitivities when it comes to sensitivities and preference.

Still, Hayes says we shouldn't conclude that the density of our papillae is akin to genetic determinism. His take is that we all have free will and can choose what's healthy to eat. But when it comes to a low-salt diet, he says, "it's easier for some people to make good choices."

Oh, as for me? Turns out the density of my papillae wasn't so easy to measure. I definitely saw lots of bumps -- but they were too small to get a good count. If I really want to know, looks like I’ll have to make a trip to John Haye's lab -- and put my tongue under a microscope.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

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Transcript

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. Transcript provided by NPR, Copyright NPR.

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