Hacking Taste (encore)

Taste is the oldest of our five senses, and yet perhaps the least understood. It's far more complicated than salty versus sweet: new research is dramatically expanding our knowledge of taste, showing that it's intimately connected to obesity, mood, immunity, and more. In this episode, we get into the science of how taste works, why we taste what we do, and what makes supertasters unique. And finally, we hack our taste buds—for fun, but, in the future, maybe for health, too. (encore) Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Nicola Twilley?

  It's the season of giving and we have a little extra gift for you this week, an encore presentation of one of our very favorite episodes, Hacking Taste.

• 0:10Cynthia Graber?

  It's all about what we can taste and why, and whether we can tweak it, or, you know, hack it. And speaking of giving, don't forget, if you enjoy the show and if you're able to support it this year, it would mean the world to us.

• 0:23Nicola Twilley?

  And of course, a huge thanks from us to all of you who already support the show and help make it possible. Enjoy.

• 0:31Nicola Twilley?

  All right. One, two, three.

• 0:35Speaker 02

  Oh, it's like lemonade. This is weird. It's just like, what? Why is this so delicious?

• 0:42Speaker 02

  What the hell? Wait, what have you done to me?

• 0:50Cynthia Graber?

  Nikki and I were on tour with a show called Pop-Up Magazine. And during one of the rehearsals, a handful of the crew and performers let us put red pills on their tongues without having any idea what they were taking and what they were in for.

• 1:02Nicola Twilley?

  Hey, we're good people. And it's not like we didn't do it ourselves. But I must admit, it was amazing how easy it was to get people to take pills without telling them what they were.

• 1:13Cynthia Graber?

  We'll tell you what those pills were later on. But for now, what you need to know is that we were screwing with their taste buds.

• 1:19Nicola Twilley?

  That's right. This episode, we're going to get to the bottom of our sense of taste. How does it work? And how can we mess with it?

• 1:26Cynthia Graber?

  Why do we taste the things we taste? And can the answers to these questions help us hack taste to tackle some of today's biggest health problems?

• 1:33Nicola Twilley?

  You're listening to Gastropod, the podcast that looks at food through the lens of science and history. I'm Nicola Twilley.

• 1:38Cynthia Graber?

  And I'm Cynthia Graber. Gastropod is part of the Vox Media Podcast Network in partnership with Eater.

• 1:46Speaker 03

  You know that feeling when the holidays are here at Starbucks?

• 1:50Speaker 04

  Welcome in.

• 1:52Speaker 04

  Peppermint mucus for Holly and Ivy? Thanks.

• 1:55Speaker 03

  Yeah, that one. Together is the best place to be at Starbucks.

• 2:02Cynthia Graber?

  So this is kind of a broad question, but what is taste?

• 2:07Speaker 05

  Yep, that's pretty broad.

• 2:08Nicola Twilley?

  That's Robin Dando. He's an assistant professor of food science at Cornell University, and he specializes in the study of taste.

• 2:15Cynthia Graber?

  Taste is one of our five senses. You know the ones: sight, sound, touch, smell, and taste. So taste, like smell, is a chemical sense. Our taste buds are detecting chemicals.

• 2:25Speaker 05

  A taste bud sits just below the surface of your tongue. We have a few of them around the insides of our mouths as well, but most of them are concentrated in the tongue.

• 2:33Nicola Twilley?

  A taste bud looks kind of like a very tiny little yellow onion. It's a spherical clump of cells. It has a little bunch of root-looking nerves coming out the bottom, like at the bottom of an onion. And at the top, it has a little hole or pore.

• 2:47Speaker 05

  Where they branch these little fingers out into the world above the tongue, looking for these stimuli.

• 2:53Cynthia Graber?

  Those are like if you left the onion to sprout. Those little green shoots, they're like the taste bud fingers waving around on the surface of your tongue, waiting for a chemical stimulus.

• 3:03Speaker 05

  So a stimulus that's in solution, something that we either drink or something that we're consuming and is dissolved in saliva, can activate receptors on the very tips of these cells and cause a cell to light up and send a signal on towards our brain, saying that we detect something.

• 3:19Cynthia Graber?

  The taste buds catch chemicals in a liquid. That's part of what our saliva does. It takes everything in our food and transforms it into a liquid form.

• 3:27Nicola Twilley?

  Each of the cells at the tip of those little fingers is configured to grab onto different chemicals, chemicals that trigger the basic tastes.

• 3:34Speaker 06

  You know, you drink a Coke and a sugar molecule comes sweeping by and boom, it attaches itself to a sweetness receptor. And that activates a signal inside the taste cell in the tongue that goes into a nerve and goes into the brain and you'll recognize that it's sweet and it will feel sweet.

• 3:58Nicola Twilley?

  That's John McQuaid, the author of Tasty: The Art and Science of What We Eat. Just to be confusing, John's book is really about flavor more than just taste. In normal conversation, we tend to use taste and flavor interchangeably, but they're not the same thing.

• 4:12Cynthia Graber?

  As you might know, if you've listened to our flavor episode, flavor is much more complex than taste. It's the whole experience of eating a food. So it includes taste, but it's much bigger and it's influenced by many other aspects of a dish.

• 4:24Nicola Twilley?

  As you'll know, if you try to eat with a heavy cold, flavor has a lot more to do with smell than it does with plain old taste. Flavor depends on the aroma chemicals that are sensed in our nose. Also, you should listen to that. That episode, if you haven't, it's called Savor Flavor.

• 4:40Cynthia Graber?

  And if you heard our episode called Crunch, Crackle and Pop, you'll also know that all sorts of other things can influence the flavor we experience. Sound is another one. Check out that episode, too.

• 4:49Nicola Twilley?

  Heck, check out our entire back catalog while you're at it. I say this without any bias, it's all great. But so taste is just one part of our experience of food. And on the surface, it seems super simple. I mean, really, kind of basic. The general consensus is that there are only five main tastes.

• 5:09Speaker 06

  Bitterness, saltiness, sourness, sweetness and umami. Umami being savoriness.

• 5:17Cynthia Graber?

  There are other tastes that scientists think we might be detecting, but those are still being argued over. So taste has two primary functions in humans. The first one, it helps us survive. Paul Breslin studies taste at Rutgers University and the Monell Chemical Sensors Center.

• 5:31Speaker 04

  Taste is really a gateway for the entire gastrointestinal tract and is a basis for making the determination whether you should eat it or not eat it. Is it nutritious? Is it toxic? Will this help sustain you if you eat it and that it has calories and nutrients and minerals? Or is it poisonous? And if you eat it, you'll die and that will end you right there with one meal.

• 5:55Nicola Twilley?

  So it's important. The second function of taste is kind of like an early warning system for your metabolism.

• 6:01Speaker 05

  When we take food into our mouths, it's one of our first encounters with that food. So to get our body ready to be able to digest it, we can't just have the food placed right in our stomach. It's not ready for it. So we have to have the right kind of gastric juices flowing inside of our stomach. We have to have some motility to actually be able to move the food down. Maybe if we're eating something very sweet, we're going to have to have our body prepared for that blood sugar hit with an insulin response.

• 6:33Nicola Twilley?

  Robin told us that your taste receptors will trigger all of these responses depending on what they detect. So your stomach and your pancreas and so on, they're all gearing up. Getting ready for what's about to hit them.

• 6:45Cynthia Graber?

  That response happens even if the food never makes it to your stomach. Scientists have studied this both in animals and in people. People swish around sweet solutions in their mouths and spit them out, and their bodies get primed for sugar. Your insulin goes up, for instance, even if you just put a piece of candy in your mouth and then spit it out.

• 7:01Nicola Twilley?

  So those are the two functions of taste, the conscious yes or no signal in our mouths and the unconscious metabolic response. But why these five major tastes? Why did we evolve to detect sweet, salty, sour, bitter, and umami?

• 7:16Speaker 06

  Humans are omnivores, so it benefits us to be able to taste as much as we can. Humans have lived in every environment on Earth. This has helped tune our sense of taste this way and that. That whole evolutionary background helps give us the great variety of taste abilities that we have today, and also accounts for the great variety of food that we eat in cuisine around the world.

• 7:43Cynthia Graber?

  John says that actually, pretty much all of the things our ancestors might have put in their mouths, plants and bugs and other animals, they all contain chemicals that fall within one or more of those five major tastes. But out of all of the potential foods we could eat, we have a particularly strong reaction to chemicals that trigger our sweet receptors.

• 8:01Nicola Twilley?

  Sugar is, in other words, fructose, glucose, sucrose. Those light up our sweet receptors and from there, our brains. And that makes sense. Sugar is the most concentrated source of calories there is, and we need calories to live.

• 8:15Speaker 06

  Scientists think that sugar is really a primordial pleasure experience. And sweetness, which is basically the experience of sugar, goes back to the dawn of complex life. So for 500 million years, life has been responding positively to sugar. So it's not surprising that humans do also. And really, it's largely out of our control, our reaction to it.

• 8:45Cynthia Graber?

  Salt is another one. We did an entire episode on salt, which, of course, you should also go listen to. All mammals need salt. To live, we can't make it, so we need to find sources of it in the environment. Makes sense that we'd be able to taste it.

• 8:58Nicola Twilley?

  And Paul told us salt also triggers a metabolic response, the way the taste of sugar triggers your body to produce insulin. In the case of salt, Paul has managed to show that your blood vessels will actually start relaxing a little if you swish salty water in your mouth, even if you spit it out. Your blood vessels know that to keep your blood pressure constant, you'll need to pull in more water to counterbalance that incoming salt, and they prepare accordingly.

• 9:24Cynthia Graber?

  The relationship between salt and blood pressure is actually quite complicated. Our episode on salt goes into this in much more depth.

• 9:30Nicola Twilley?

  But sugar and salt are tastes that we crave because they're things that we need. Sour is a little different. Very sour things don't taste good, which makes sense because strong acids damage our teeth and tissues. Some people say sourness evolved as a ripeness detector. And so we don't like really sour things because our body is telling us to hold off and wait until the fruit or berry or whatever is ripe and ready. But Paul pointed out that our response to sour is more complicated than straight up dislike.

• 10:01Speaker 07

  Obviously, we like mixtures of acid with with sugar.

• 10:05Cynthia Graber?

  Like lemonade, but even without sugar, sour flavors can still be appealing.

• 10:09Speaker 07

  People actually do like low levels of sour taste. People will put a twist into a glass of water or a glass of seltzer water.

• 10:16Cynthia Graber?

  Scientists aren't quite sure why we like these low level sour tastes. One theory is that sour points us to vitamin C. Most mammals can make vitamin C, but we humans can't. So it's crucial that we be able to detect the ascorbic acid in fruit that gives it that puckery taste. We need that vitamin C, but there are other places we find sourness appealing.

• 10:35Speaker 07

  And in the case of eating virtually anything that's fermented, whatever that may be, whether it's dairy being processed into cheese or cucumbers being processed into pickles, what have you, there's acid being generated by bacteria. Or in the case of yeasts, if you're making wine or beer. And we seem to like that low level of acidity, a little bit of sourness is pleasing to us.

• 10:58Nicola Twilley?

  Our taste for that fermented sour, that could be beneficial in evolutionary terms, too. We all know that our gut microbes appreciate fermented foods, so perhaps our sour taste receptors were guiding us towards that, too.

• 11:11Cynthia Graber?

  That sour, now on to another complicated taste, bitter. And yes, we've done an entire episode on bitter as well.

• 11:18Nicola Twilley?

  You really have made a lot of episodes.

• 11:20Cynthia Graber?

  Which is a good thing. It means we could just tell you all to go listen to them. But bitter is a weird one. We have more bitter receptors that can taste more bitter compounds, maybe hundreds of compounds, if not more. That's more than for any other taste.

• 11:32Nicola Twilley?

  Things that taste bitter often contain chemicals that are toxic to us, at least in large doses. Most people in most cultures around the world will not and do not eat anything that's very strongly bitter. It's an evolutionary response to avoid poisons. But for foods that are only mildly bitter, it's a different story. Sometimes we even seek them out.

• 11:53Cynthia Graber?

  Paul told us that in the real world, almost all the food that's good for us also has low levels of toxins, otherwise known as bitter flavors. We learn to enjoy, maybe even crave, some bitterness so that we can get at all the other great nutrients in those bitter plants. And Paul says there's another evolutionary reason we might like bitter. Almost all medicines taste bitter, too, so our ancestors might have developed a taste for self-medicating.

• 12:16Nicola Twilley?

  The fifth and final major taste is umami, and it's the most recent addition to the canon. A Japanese chemist proposed that umami should join sweet, salty, sour, and bitter back in 1908. But it wasn't really recognized as a distinct taste with its own unique chemical triggers until 1985.

• 12:34Cynthia Graber?

  You may have heard of the main chemical trigger for umami that the Japanese scientists had isolated from seaweed broth. It's called MSG or monosodium glutamate.

• 12:42Nicola Twilley?

  If you translate umami from Japanese, it means a pleasant savory taste. And it's a really mild taste compared to sugar and salt and bitter. Umami never gets very strong, and we don't even like it by itself. So why can we taste it?

• 12:58Cynthia Graber?

  The first thing you need to know is that glutamate primarily comes about through a transformation of protein. As protein breaks down, it's transformed into amino acids and ribonucleotides, and together, this is what gives you glutamates.

• 13:10Speaker 07

  Savory taste is about tasting amino acids and ribonucleotides together as a cocktail.

• 13:16Speaker 07

  So it kind of begs the question then, when are we going to be exposed to pure free amino acids and free ribonucleotides together at the same time? And really, the only times you're going to experience those is when a food is being broken down. It's somehow decomposing. And there's really only three ways that that happens.

• 13:40Nicola Twilley?

  Fermentation, drying, and cooking.

• 13:42Cynthia Graber?

  You'll find lots of awesome umami flavors in cooked meats or Parmesan cheese or, yes, seaweed broth.

• 13:48Nicola Twilley?

  And when you taste umami, you're actually detecting predigested protein. Although that doesn't sound that nice, it's really good news for your body. You need those amino acids from protein to build cells.

• 13:59Cynthia Graber?

  Delicious predigested proteins. But really, all these stories we've just told you about why we taste what we taste and why we've come to enjoy these tastes, these are just theories. We don't know exactly what our ancestors were tasting. It's impossible.

• 14:12Nicola Twilley?

  But you can find some clues for how evolution has shaped taste by looking at other animals and what they can taste, like, for example, cats. Cats are carnivores, they don't eat their veggies, and all they have left is an umami receptor.

• 14:27Cynthia Graber?

  Penguins and dolphins and whales and lots of other sea mammals also have a poor sense of taste. John says they've lost a lot of taste receptors over evolutionary time.

• 14:35Speaker 06

  It may be because they're just swallowing fish whole, so they don't really have a need to taste them. Most of the taste experience occurs in when you're chewing something. So there's a lot of that in the animal kingdom where certain animals, you know, they don't need to taste something, and so it falls into disuse and kind of is evolutionarily filtered out.

• 14:55Nicola Twilley?

  And there's been plenty of time for that filtering to happen because the sense of taste is incredibly ancient.

• 15:02Speaker 06

  It goes back to the origin of complex life on Earth. Because once you have complex life, which is more than just single cells floating around, which have multicelled creatures, they have an inside and an outside. And the outside has to detect what is food and what isn't food.

• 15:22Speaker 04

  So it goes back at least 500 million years.

• 15:25Nicola Twilley?

  And this is why animals that live in the water still have taste receptors in what might seem like strange places. In a lot of fish, taste receptors aren't just in their mouths. Tom Finger is a professor at the University of Colorado School of Medicine who studies taste, and a lot of his work has focused on fish.

• 15:40Speaker 04

  So the taste molecules are dissolved in the water and they can swim around and detect taste because the taste molecules are contacting the surface of their skin. So catfish, for instance, have taste buds scattered across their whiskers and the whole body surface.

• 15:54Nicola Twilley?

  Turns out, we are more like catfish than you might think, because we have taste receptors outside of our mouths, too. They show up in a lot of the tissues that interact with these external molecules in our environment. So in us, the equivalent of catfish whiskers is the lining of your gut.

• 16:10Speaker 07

  So anything that's still in your stomach is not really in you. You're sort of like a giant doughnut. There's a hole running all the way through you from mouth to anus, and anything inside that is, in some sense, not really in you. So you have taste receptors throughout your GI tract, going all the way from your mouth through your intestines.

• 16:27Nicola Twilley?

  Paul says these likely have an anticipatory role, like the ones in our mouths do. The taste receptors in our digestive system, they also help prime the body for the nutrients that are about to be absorbed into our bloodstream. And that's not all.

• 16:39Speaker 07

  There are also taste receptors in what I would call regulatory organs or metabolic organs. And that would include the pancreas, the liver, fat tissue, the thyroid, and the brain. And what they're doing, we really don't know. But it's a safe bet that in a species like ours, that they're extremely important.

• 17:02Nicola Twilley?

  Back in Colorado, Tom has been working on figuring out what some of these receptors on other parts of our body do. And he says by calling them taste receptors, we're kind of missing the point.

• 17:13Speaker 04

  So the taste receptors, actually from the standpoint of biology, you can think of them as just tools. And they're tools for detecting chemicals. So the body can use these tools anywhere. And because we give them the name taste receptors, we're confusing function with the role in biology.

• 17:31Nicola Twilley?

  One of Tom's projects has been to figure out what the heck taste receptors are doing in our noses.

• 17:37Cynthia Graber?

  Turns out, these receptors detect chemicals put out by a harmful bacteria in the air that we breathe, and then tell our body to mount an immune response. Like in our mouths, the nose taste receptors are just chemical detectors.

• 17:48Nicola Twilley?

  So that's how taste works and how it evolved. And now, here's the cool part. As we learn more about taste, we can start to hack it, for fun, but maybe also for help.

• 17:58Cynthia Graber?

  But before we tell you how to mess with your friend's taste buds at your next dinner party, this week's sponsors.

• 18:05Cynthia Graber?

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• 18:21Nicola Twilley?

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• 18:39Nicola Twilley?

  So one of the many intriguing things about taste is that although it's one of our oldest senses, it was kind of ignored by science for a long time.

• 18:46Speaker 06

  It's much easier to study the detection of light, for example, or sound, because these are sort of shared experiences. Whereas an experience of taste or smell also, which are both components of flavor, is a subjective experience. And so, basically, once science tried to wrap its arms around this, it failed. And so, a lot of scientists kind of gave up.

• 19:14Cynthia Graber?

  And it's not just that it's hard to study. We also ignored taste because scientists and philosophers have looked down on it for thousands of years. John says the ancient Greeks considered it the lowest and grossest of the senses.

• 19:26Speaker 06

  There's a historical tradition in Western culture that makes taste and smell, particularly taste, second-class senses, because they're tied to eating, which is a kind of a base

• 19:41Speaker 06

  Activity, devouring stuff, putting stuff in your mouth, chewing it. You know, it's what animals do. And of course, we're animals, but it wasn't considered a higher sense.

• 19:52Nicola Twilley?

  Still, throughout history, people had theories about how many tastes there were and how the tongue detected them. But until really quite recently, most of what we knew about taste was wrong.

• 20:03Cynthia Graber?

  The most enduring myth of the past century, and it's one that you might have even learned when you were a kid. It's a myth known as the tongue map. And we can lay the blame for this mistake at the feet of Edwin G. Boring.

• 20:13Speaker 06

  He was an influential 20th century psychologist.

• 20:18Nicola Twilley?

  And he decided to write the definitive book on the history of the senses, A Big Tome. And while Mr. Boring was researching the taste section of his book.

• 20:27Speaker 06

  He came across this study that had been done. This was, I think, in the 40s, he was writing this. And he came across a study that had been done about 30 years earlier by a German scientist that looked at the sensitivity of the tongue to different tastes. And this study showed that depending on where you were on the tongue, the sensitivity to these tastes differed, sometimes by a little, sometimes by a little bit more.

• 20:54Nicola Twilley?

  You know, like one part of the tongue was more sensitive to sweetness. Another part was slightly more sensitive to salt. The German scientist published his data in the early 1900s. And then decades later, Boring drew on that data to draw his graph.

• 21:07Speaker 06

  But it was an exaggeration. The original data, you know, there are very limited differences. And suddenly now there are huge differences in this graph.

• 21:15Nicola Twilley?

  Because Boring was so influential, this tongue map idea spread through the scientific community.

• 21:21Speaker 06

  And then pretty soon that morphed into maps of the tongue that showed clearly demarcated areas, you know, like on a geographical map where it was a clear border. It's like the tip of the tongue tastes sweet and the back is bitter.

• 21:37Cynthia Graber?

  Soon, these maps swept popular culture as well.

• 21:40Speaker 06

  And they appeared in textbooks and they were used in children's scientific experiments in elementary schools and kind of became the conventional wisdom that different. Parts of the tongue were anatomically devoted to different tastes.

• 21:56Cynthia Graber?

  So Boring was totally wrong, but scientists didn't figure out just how the tongue works, how the taste receptors work, until quite recently. And that's because of a much better understanding of genetics.

• 22:06Nicola Twilley?

  Back in 2000, John actually visited scientists at the NIH when they were first isolating taste genes.

• 22:13Speaker 06

  Essentially, they were looking for a needle in a haystack.

• 22:17Cynthia Graber?

  They knew what taste receptors were, and they knew that there were genes to express them, but they didn't know how to match the two.

• 22:22Speaker 06

  And basically, through kind of a sieve-like process, they managed to isolate a sweetness receptor and match it with its DNA code in the genome.

• 22:36Nicola Twilley?

  The scientists were working with rats, but fortunately, the human gene and receptor for sweetness is pretty similar.

• 22:42Speaker 06

  So once they had that, finding the human version of it was quite easy. And once you have that, you can begin to experiment. You can make copies of sweetness receptors yourself, put them in a Petri dish, and see how they react to different substances, to sugar, to artificial sweeteners, et cetera, et cetera.

• 23:02Nicola Twilley?

  And from there, you can begin to understand how the sensation of taste is triggered, how it's sent to the brain, and ultimately, how we perceive it.

• 23:10Cynthia Graber?

  One thing scientists have figured out is that, as we said, Boring was wrong. Every taste bud on our tongue has multiple receptors, and those pick up many different tastes. It is absolutely not true that one section of the tongue is dedicated to sweet. There may be slight differences in sensitivity, but everything is being sensed everywhere.

• 23:28Nicola Twilley?

  But we're not all sensing it exactly the same. There are pretty significant individual differences. And where they come from? That's something that Linda Bartoszuk has been trying to get a handle on for decades. She's a professor at the University of Florida and kind of a legend in the taste world.

• 23:45Speaker 03

  Well, it all started when we were doing work in New Haven, Connecticut.

• 23:49Speaker 04

  And we were working on the first genetic known taste was to something called PTC. It was a bitter compound and it was known since the 1930s that some people couldn't taste it. So I was working on that problem. And we decided that the methods that had been used on the problem up to then were very old fashioned. And we were going to do something more modern. We were going to actually see how bitter this compound was, not just whether you could taste it or not, but how bitter it was. Well, it turns out the variation was simply enormous. And some of the people got such incredibly intense bitter taste from this that we started calling them supertasters.

• 24:28Cynthia Graber?

  Yes, Linda is the one who coined the term supertasters. A lot of listeners have asked us to do an episode on supertasters.

• 24:34Speaker 04

  Supertasters are people who experience particularly intense taste sensations. The most intense taste sensations that are experienced by any people, those are supertasters.

• 24:46Nicola Twilley?

  Once Linda and her colleagues identified this group and started studying them, they quickly realized that it's not just bitter PTC that supertasters taste more intensely. It's everything.

• 24:56Speaker 04

  Yes, it is. Sweet is more intense to supertasters by about a factor of two or three.

• 25:02Cynthia Graber?

  There is actually a continuum. It's not a yes or no, supertaster or not. Linda herself is in the not category. She's on the non-tasting end of the taste spectrum, but a lot of people fall somewhere in the middle.

• 25:13Nicola Twilley?

  Most scientists estimate that roughly a quarter of us are what they call non-tasters, about a quarter are supertasters, and the rest are sort of medium.

• 25:21Speaker 04

  Part of it has to do with how many taste buds you have. Taste buds are on the human tongue in structures called papillae. And fungiform papillae are the ones on the front of the tongue. If you under magnification, they look like little button mushrooms on your tongue. And supertasters have many, many more of these than people like me do.

• 25:39Cynthia Graber?

  We decided to test some of these things out when we were on tour with Pop-Up Magazine, and we've got the results after the break.

• 25:47Speaker 03

  Support for the show comes from Google Gemini. You know that moment when curiosity strikes? You're exploring a new city with the family and a sculpture catches your daughter's eye. What is that? Who made it? With Gemini, you can snap a picture and get a fully interactive breakdown of its history, architecture, and even hidden secrets. Gemini is built for moments like that. Whether you're learning something new, solving a problem, or looking for your next favorite thing, Google Gemini is here to help. Download Gemini, Google's AI app, or visit gemini.google.com to learn more.

• 26:26Cynthia Graber?

  First, we wanted to find out who could taste PTC. We got a whole group of people in a back room in one of the theaters and told them to put a piece of paper on their tongue.

• 26:35Nicola Twilley?

  Why are you nervous?

• 26:36Speaker 02

  Because I don't really know what I said yes to at this point, so I don't know what's about to go down.

• 26:45Speaker 02

  It's definitely not drugs. I'm a role model, so I hope it's not like drugs or anything.

• 26:49Nicola Twilley?

  I don't know if it was peer pressure or what, but they all did it. They put these slips of paper on their tongues without even knowing what it was.

• 26:56Speaker 02

  Just put it on the tongue.

• 26:57Nicola Twilley?

  Yeah.

• 27:00Nicola Twilley?

  It's paper for me. Really? I totally taste it.

• 27:04Speaker 02

  It tastes really terrible. It tastes bitter. It's really bitter. It's paper for me.

• 27:08Nicola Twilley?

  It's paper for you, too?

• 27:09Speaker 02

  Yeah. I have a very, very bitter, gross taste in my mouth. It tastes like aspirin or something.

• 27:13Nicola Twilley?

  Yeah, it tastes exactly like aspirin. I totally agree. Oh, Tim, you look like you're in pain. Yeah. It's dreadful. In our little group, we had four bitter tasters. Cynthia, Tim, Jeff, and pop-up boss Doug McGray. I had a little bit of a bitter aftertaste, but not enough to scrunch up my face like those guys.

• 27:32Cynthia Graber?

  One of our fellow contributors, Kelly Carter, she didn't taste anything. Neither did another couple of the pop-up crew, Tina Antolini and Anita Badajo. No bitterness, just paper.

• 27:41Nicola Twilley?

  You can try this at home. I ordered the PTC paper off Amazon, and it was kind of amazing how different all our reactions were.

• 27:48Cynthia Graber?

  So not everybody who tastes PTC is automatically a supertaster, but Linda says it's the first step. You have to be able to taste it. Then supertasters tasted super intensely. Supertasting is much more than this initial bitter compound we first discovered. It happens to all tastes. But is there some biological utility that that made were supertasters the originals? And there was a mutation that made the rest of us? I don't I don't know. That very interesting question. But my picture of this, I think about the Neanderthals wandering around, or maybe the first humans of our type wandering around. And by the way, women are more likely to be supertasters than our men. And that gives you a clue.

• 28:31Cynthia Graber?

  So maybe when they moved into new territory, the chief sent his wife out to check out the local plants and see were if they were OK. And if she didn't die, they were safe. But you'd want a supertaster to do that because the supertaster would taste the bitter more intensely, and bitter is a signal for poison.

• 28:51Nicola Twilley?

  This ability to taste PTC, it's really interesting. It evolved independently in humans and in our closest relatives, chimps. That implies that having some of your population as bitter tasters has an evolutionary advantage for the species as a whole. Otherwise, it wouldn't persist in humans over time like this, and it wouldn't pop up separately in other species.

• 29:12Cynthia Graber?

  Tasting PTC or not seems to be largely governed by one gene. Being a supertaster is more complex. Linda suspects multiple different genes contribute, although she hasn't identified them yet. But there are patterns in the population as to who is likely to be a supertaster or a non-taster. For example, Caucasians have the fewest supertasters. And men have fewer supertasters than women. And this led one of my postdocs to say white men can't taste. But I told her she couldn't say that because it's politically incorrect. What's funny is that all three of the white guys backstage at Pop Up could taste bitter. And remember, that's the first step towards being a supertaster. But the two African American women couldn't.

• 29:52Nicola Twilley?

  While our group was awesome, it wasn't exactly statistically significant. But so PTC strips are the first step. The next step in diagnosing whether you're a supertaster or not is to count your taste buds. This involved dying your tongue blue. And funnily enough, our Pop Up buddies didn't want to do that before the show. I don't blame them. I made Jeff dump a teaspoonful of blue food coloring on his tongue, and he looked really funny. I think maybe you gave him a little. We maybe overdid it. At least you overdid it on Jeff. It was a test run. That's what husbands are for.

• 30:29Cynthia Graber?

  We didn't read the instructions. There are instructions for this experiment online. We thought you just squeezed out some dye on your tongue and looked to see what stuck and what didn't, because blue dye doesn't stick to taste buds. But it's a little more complicated than that. So after Jeff spent many minutes swishing out blue water, we decided to tackle this more scientifically back at home. We found instructions at Scientific American. We'll link to it on our website.

• 30:50Nicola Twilley?

  So it turns out we're both basically average, at least when it comes to this. And actually, this is not a bad thing.

• 30:57Speaker 06

  Now, supertasters are going to be a little bit fussier than other people because they're going to notice bitter whenever it's present. And there are going to be foods they don't like, like leafy, green vegetables that tend to be bitter. So there'd be perhaps an advantage to non-tasting if you were in an environment with a lot of bitter compounds that are safe. But what if you're in an environment with a lot of bitter compounds that are dangerous? Now, the supertaster has the advantage.

• 31:24Cynthia Graber?

  Supertasters generally don't eat as many vegetables, so they seem to be at a higher risk for colon cancer. But they also tend not to drink and smoke as much, so they're apparently at lower risk for head and neck cancer.

• 31:34Nicola Twilley?

  Swings and roundabouts. But all you supertasters out there, you can stop patting yourselves on the back.

• 31:40Speaker 06

  In some sense, it was a poor choice of name because super implies something special, great. I'm delighted that I am not a supertaster. It just means more intense. And the truth is, I look around at extreme supertasters, and I don't think they're having as much fun with food as I am. Let me qualify that one step. We have looked at the pleasure that supertasters and others get from food. And if you look at the favorite food of a supertaster, they really love it. And you look at something they don't like, they absolutely

• 32:13Speaker 04

  We hate it. Though the supertaster experiences a much larger hedonic range of extremes to like and dislike. I'm sort of more in the middle. I like a lot of things, but not terribly much. The supertaster may like fewer, but the ones he or she likes, they get tremendous pleasure from. Now, that's interesting. For example, chefs tend to be supertasters, more of them than you'd expect by chance. And does that have something to do with the pleasure they get from their favorite foods? We don't know. I'd like to see somebody study that who knows cuisine more than I do.

• 32:48Nicola Twilley?

  This phenomenon of supertasters getting more pleasure from their favorite food, given how central food is to our pleasure circuits overall, this has really interesting implications beyond food.

• 32:59Speaker 04

  I mean, are supertasters kind of a different group? Are they hedonically more volatile? Do they get more pleasure from a lot of things? That's a real possibility. We just don't know yet.

• 33:10Cynthia Graber?

  This question of pleasure is a really complicated one. Whether or not you're a supertaster is only one factor in whether or not you're deeply enjoying your meal. For example, research Linda's done shows that overweight people get more pleasure from their food than thin people.

• 33:23Nicola Twilley?

  And that's complicated, too, because that brings us to the connection between our sense of taste and obesity. We live in a world where sugar is everywhere, but we're built to love sweets so intensely.

• 33:34Speaker 06

  The signal for sugar is, you know, give me more sugar.

• 33:38Nicola Twilley?

  And that was totally fine back when we encountered sugar very, very rarely, in fresh berries, maybe, if we were lucky, and wild honey. Now, of course, we have sugar at our fingertips day and night. Robin Dando, he's a food scientist at Cornell. He's been studying the connection between taste and obesity for a few years now.

• 33:57Speaker 05

  It's a cruel joke, really, that we've been put together to just go after things like sweet and fat and to really like them. We're programmed to want this in high quantities. We're programmed to kind of put on weight for the hard winter that might be coming because that, evolutionarily, that means that we might stick around for longer. So it's kind of a cruel joke now that this isn't really a problem anymore, but we're still programmed the same.

• 34:23Cynthia Graber?

  Robin's been studying the sense of taste in mice. One thing he's found is that as the mice become obese, they lose taste buds and he thinks there's a connection.

• 34:31Speaker 05

  Now, a couple of caveats in there, of course. One is that these are mice, these aren't humans. But as I say, it's a strong indicator. And then two is, does losing a handful of taste buds actually do enough to change a person's eating habits? Again, we don't know that for sure. We're looking into both of those questions right now.

• 34:52Cynthia Graber?

  So we don't know for sure, but you can easily imagine that if somebody has fewer taste buds, they might be getting less sensation from their food.

• 34:59Speaker 05

  So if that level of reward is decreased, then there are a couple of obvious things you could do to combat that. One is you could just eat more. And the other is you could eat more intensely tasting stimuli. So more intensely tasting usually isn't going to mean higher calories. So if that's the case, then that when somebody starts to put on weight, they lose taste buds, they are driven to consume more, then that means that they're going to put on more weight, lose more taste buds and be driven to consume more again. So it's kind of a dangerous positive feedback loop that we think could have something to do with the obesity epidemic that we're living in right now.

• 35:41Cynthia Graber?

  Supporting his hypothesis that gaining weight reduces taste sensation and that losing weight might bring it back, Robin says there's some evidence that people who lose weight quickly after gastric bypass surgery are more sensitive to taste afterwards.

• 35:53Nicola Twilley?

  He's also found that there are hormone receptors in your taste buds, too. They're picking up on circulating hormones like leptin, which signals us to feel full. Those hormone levels change in obese people, too, so that could also be affecting their experience of taste.

• 36:08Cynthia Graber?

  And so maybe in the future, there'll be a way to use these taste-related phenomena to help people lose weight.

• 36:13Speaker 05

  So there are lots of issues that happen with the body when someone becomes obese. And this would only be one of them. But if there is a portion of the process of becoming obese that could be attributed to the taste buds, then we'd really be interested in trying to kind of put that right, to kind of hack the taste bud to make. Do things that we want people to do in terms of food choice, then I think that's a really exciting idea.

• 36:40Nicola Twilley?

  This is all just speculation right now. We don't know enough to start hacking our taste buds to try to reverse obesity. But we do know that our sense of taste can be manipulated and changed for all sorts of reasons.

• 36:53Cynthia Graber?

  Like, take pregnant women. All of a sudden, things that used to taste good are suddenly disgusting. They throw up more frequently. Basically, their hormonal changes are making them more sensitive to potential toxins, more sensitive to bitter flavors. Children are the same. They're really sensitive to bitter when they're young. These are two super vulnerable groups. So it makes sense, from an evolutionary perspective, that they reject bitter and potentially poisonous foods.

• 37:16Nicola Twilley?

  What you eat, your culture, your memory associations, that has a really strong impact on your sense of taste, too. John told us about a group of indigenous Peruvians who are all PTC bitter tasters. But where they live, one of the staple foods that they rely on is this really, really bitter potato relative. And so they seem to have reset their bitter taste perception, lowered it to the point where they can all eat and enjoy this potato, even though their genes would seem to indicate otherwise.

• 37:45Cynthia Graber?

  So even if you are genetically sensitive to PTC, it doesn't mean you can't learn to enjoy bitter flavors. I taste PTC pretty strongly, and I love bitter. Other tastes can be reset, too. We humans are really malleable. Robin told us about research showing that if you start eating food with less salt or less sugar in it, you become more sensitive to salty and sweet foods.

• 38:04Nicola Twilley?

  There's even some evidence that your mood affects how things taste. Robin's been working on this, too.

• 38:10Speaker 05

  So our model was, we set up a stand at the hockey game at Cornell. If you're interested in sports and going to Cornell, then you're probably going to the men's hockey game.

• 38:22Cynthia Graber?

  He found that enthusiastic fans, whose team won, their food tasted better. But if the team lost, there went that delicious hot chocolate, not so delicious anymore.

• 38:31Nicola Twilley?

  And this makes sense, because there are those hormone receptors in the taste bud. And one of the hormones they pick up on is serotonin. Serotonin levels are connected to happiness versus depression. So there's lots of interesting New science happening here, too.

• 38:45Speaker 05

  There is a group that looked at SSRIs. So these are selective serotonin reuptake inhibitors. So probably around about the most prescribed type of antidepressant in the country. And found that indeed, people do start to perceive tastes, particularly sweet taste, as being different when they have a lot of these antidepressants inside of their body.

• 39:07Cynthia Graber?

  All of this mood and antidepressant research, the taste bud sensitivity and obesity research, all of this might help scientists hack our taste buds in the future to improve our health. But there are some fun ways to hack our taste buds today. Nikki had the chance to try something that I am super curious about.

• 39:21Nicola Twilley?

  It was when I was over in London.

• 39:23Speaker 06

  Hi, my name is Emma Zhang, and we are at the Mixed Reality Lab in City University, London. So we have this device over here, which is a small device, which you can put in your mouth, and you will feel a virtual taste sensation.

• 39:42Nicola Twilley?

  Basically, there are these two silvery plates hooked up to a set of wires, and you put the tip of your tongue in between them, which I did. And then Emma electrocuted my tongue. All right, here goes.

• 39:54Speaker 06

  Yeah.

• 39:58Nicola Twilley?

  Oh, my God. That was ridiculous. Can I do it again? The taste she sent me was super sour. This is how it works.

• 40:05Speaker 06

  So for example, when we put something on our tongue, the chemicals will translate into an electrical signal in our brain. And what we're doing here is to reproduce those electric signals. So you will feel the same taste as if you're biting a lemon.

• 40:26Nicola Twilley?

  The idea that Emma and her colleagues have is that you could build this kind of digital taste into culinary. So your ice cream, say, would taste sweeter on an electric spoon. I don't really know that I would sign up for getting my tongue electrocuted on a regular basis, though.

• 40:41Cynthia Graber?

  Doesn't sound so much fun to me either, but I'd love to try it once someday. There's another way to trick your taste buds. We used a pill. It's an extract from a tropical African fruit called a miracle berry. What you do is you take the pill and slowly let it dissolve and coat your tongue. We handed them out to everyone in the dressing room, then we handed them slices of lemons and limes.

• 41:00Speaker 06

  My new favorite food is lemon and pills.

• 41:04Cynthia Graber?

  I'm gonna eat this whole lemon. Why didn't we get more lemon? Oh my god, this lime is amazing. Everyone was just sticking whole chunks of lemon and lime into their mouths like they were apple slices. And then we moved on to something that's already pretty sweet: strawberries.

• 41:18Nicola Twilley?

  This is my worst nightmare. Everything is sweet.

• 41:23Speaker 02

  Whoa, this is intensely, intensely sweet.

• 41:26Cynthia Graber?

  Oh my god, it's way too sweet for me.

• 41:28Speaker 02

  Candy, too much candy. It's been dipped in sugar.

• 41:31Cynthia Graber?

  Kind of disgusting. It's a strange day when strawberries are so sweet that we're calling them disgusting. So Lynda says scientists don't know exactly how miracle berries work, but here's the leading theory. There's a protein in the fruit that has sugar molecules on it. The protein attaches to your tongue with the sugar just out of reach. Then if you eat something acidic, like a lemon, your taste buds pucker and they access the sugar molecules too. So the lemon now tastes like it's been coated with sugar.

• 41:59Nicola Twilley?

  We didn't stop at fruit, though. We tried beer and olives and blue cheese, too. The olives, which I love olives, they were just pure salt, completely inedible. And the blue cheese was too salty and not funky and actually a little bit sweet.

• 42:15Cynthia Graber?

  So that means that the scientific theory maybe doesn't quite explain it all because if it's a protein with a sugar molecule attached, why would bitter and salt get so much more intense? Mystery's left to solve.

• 42:26Nicola Twilley?

  This is another one you can easily try at home. We have a link to buy miracle berry pills on our website. Just be aware that if you go out to lunch afterwards, like I did, your sandwich will taste disgusting.

• 42:37Cynthia Graber?

  Lynda says the effect lasts from about 15 minutes to about an hour and a half, depending on how strong your saliva is.

• 42:43Nicola Twilley?

  So hacking your taste buds is possible. It works. But can we use it to achieve our health goals?

• 42:49Cynthia Graber?

  There's some evidence that this doesn't work as intended. One way many of us hack our taste buds on a regular basis already is by consuming artificial sweeteners. These are non-sugar chemicals that trigger our sweet taste receptors, but our bodies don't get any calories from them. Scientists have been showing that replacing sugar with artificial sweeteners isn't helping people lose weight. In fact, with artificial sweeteners, people might actually be eating more. Maybe because our bodies are primed for sugar, but we're not getting those calories. And that triggers a whole set of reactions.

• 43:19Nicola Twilley?

  You know, and we should pay more attention to that. And by the way, that could be true of everything we do. For example, when you make acids taste sweet with miracle fruit, the body's expecting sugar. If we were really eating a lot of it, would that have consequences? It probably would. We ought to keep an open mind about that. Because when we come up with these things, it's not nice to trick Mother Nature. She sometimes has her ways of getting even. And it's very, very important to try to think of how things could go wrong. That's our job as scientists. So we need to be careful. But this uncertainty? This is what makes the science of taste really exciting. It's still such an open field. Robin told us that scientists are still trying to figure out exactly how sour works, for example.

• 44:04Nicola Twilley?

  And there are lots of scientists trying to show that we have more than five basic tastes.

• 44:08Cynthia Graber?

  It's funny. Taste is one of the oldest tools we have to make sense of the world and one of the least well-understood.

• 44:16Nicola Twilley?

  Thanks this episode to all the people we spoke with. John McQuade, Linda Bartoszuk, Paul Breslin, Robyn Dando, Tom Vanger, Emma Jong. We have links to their books and research on our website.

• 44:26Cynthia Graber?

  And a huge thanks to our partners, Tim and Jeff, and our friends and colleagues who are on tour with us with Pop-Up Magazine. The backstage taste hacking was ridiculously fun, and you all were great sports.

• 44:35Nicola Twilley?

  We'll be back with a brand new episode for your listening delight next week.

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