Taste: Surprising Stories and Science About Why Food Tastes Good (32 page)

Pliner’s next experiment required hiring “confederates” to act like test subjects, when in reality they were members of her research team. Each confederate was paired with an unsuspecting tester and the pairs were told to choose from a list of familiar, safe foods or unfamiliar, novel foods. The real test subjects were more likely to try new foods when they were paired with a confederate who modeled the behavior of choosing novel things—like nutria—over more familiar foods, like chicken or beef. You are more likely to do something if you see someone else doing it.

Nutria, by the way, are large semiaquatic rodents that were imported into Louisiana from South America for the fur-farming industry. They escaped (or were released) into the wild and have become destructive pests. In an effort to control the nutria population, the state of Louisiana tried to promote them as a source of protein. The state got the word out and put up websites with regional recipes to encourage capture and consumption of the critters, including Heart-Healthy
Crock-Pot Nutria, Nutria Sausage Jambalaya, and Nutria Andouille Sausage Gumbo. Yet even appropriate use of flavor principles couldn’t get the Louisiana public to eat wild rodents. Imagine New York taking this approach to deal with its rat problem.
Rat Reuben on Rye
does have a certain ring to it, though.

There is one day of the month when no matter how much salt I use, my food tastes bland. On this day I do not make any decisions in the lab at work. Instead I rely on a team of other people. When I cook dinner, Roger knows what’s up by simply watching me twisting the salt grinder as if I’m trying to wring it dry. Every woman has experienced something similar, whether it’s a craving, an aversion to a certain food, or a smell that simply nauseates her for no other reason than “It’s that time of the month.”

The most intensive study to date on women’s sensitivity to aromas throughout their menstrual cycle ran up against the fact that women have different cycle lengths with different hormones spiking at different times. After the authors normalized the data, they found a peak in the ability to detect smells at midcycle: in other words, around the time of ovulation. This was true of women both on and off birth control pills. They also found that olfactory sensitivity practically mirrors body temperature when plotted on a graph.

Women are in general both better tasters and better smellers than men, as has been proved in numerous studies in which women usually outscore men. Monell’s Johan Lundström says that this is due not to their superior anatomy, but to the fact that women pay better attention to the task at hand. But not all women are better tasters than all men. In your household, there might be a male HyperTaster who is much more sensitive to tastes than a female Tolerant Taster.

Everyone has a story of a wife, a friend, a sister, or a colleague who became so sensitive to odors when she was pregnant that she could no longer tolerate the offending smell at all. Sometimes, a woman even becomes intolerant of her spouse’s smell, which can be a harbinger of incompatibility and an impending split.

In one study, 67 percent of pregnant women said they’d experienced an increase in their sensitivity to aromas at least once during their pregnancy. Self-reported data are notoriously unreliable, and other studies that have tried to scientifically prove this finding have been inconclusive.

Whether or not pregnant women can smell more acutely than those who aren’t pregnant, you would think that they’d be able to know what it is they’re smelling. After all, they are the gatekeepers for their developing babies. If they can’t smell the difference between noxious fumes and baking bread, that poor child is in danger. But to date, no study has found that pregnant women show an overall, general increase in their ability to identify odors. In fact, in two different studies, pregnant women were on average less likely—or showed the same ability—to identify smells as did nonpregnant women. The one smell the pregnant women could identify more accurately in two different studies was clove.

Seventy-five percent of women report that some smells were less pleasant when they were pregnant. Some studies suggest that the unpleasantness—or disgustingness—of odors is strongest in the first trimester. This makes good sense, since a pregnant woman’s level of immunity drops during this period, making her more susceptible to toxins, illness, and disease. Bitter tastes are most intense and liked least during the first trimester. If a pregnant woman’s digusto-meter is very sensitive, she’ll be less likely to eat food that is dangerous to the baby.

In the second and third trimesters, bitter tastes are tolerated a little bit more (or hated a little bit less), as are the sour and salt Basic Tastes, and this change encourages women to ingest a more varied (read: healthful) diet.

Throughout pregnancy, however, a woman’s reaction to aroma is heavily dependent on what she smells and is related to her own likes and dislikes.

One of the cruelest things about growing old is that our ability to smell almost inevitably degrades. Half of people between the ages of sixty-five and eighty lose some of their smell functioning. And more than 80 percent of those over eighty years of age have a compromised sense of smell.

I spoke to a group at lunch one day at the Senior Friendship Center in Sarasota, part of a network of nonprofit facilities that provide services to those over
fifty years of age, because I wanted to talk with older adults who were experiencing this loss. One woman just about broke my heart. She was slowly losing her passion for eating, which was devastating to her.

“What else do we have left?” she said wistfully of seniors like her who have started to lose their enjoyment for food. “We can’t drink because we’re on medication. We can’t dance because our bones have become brittle. We love to eat. And when that goes, it’s depressing. The only reason I eat is because I have to eat. And that scares me.”

Then she reached into her purse and pulled out a tangerine. “This I can taste,” she said, gripping the piece of fruit as if her life depended on it. Well then, use it, I told her. I asked her if she was enjoying her chicken with black beans and rice. She wasn’t. “I’m just chewing,” she said. So I told her that the next time she came for lunch, she should ask the cooks to cut a tangerine into wedges for her to squeeze over her meal. If something works for you, why not leverage it fully? That’s the takeaway. Figure out what works for you. Explore. Crank it up. Don’t just sit back and accept the loss.

Jennifer Stamps, a graduate student who works for Linda Bartoshuk at the University of Florida, studies olfaction and the brain. A few years ago, she was living next door to an elderly man who was in the early stages of Alzheimer’s disease. Stamps brought home the UPSIT, the University of Pennsylvania Smell Identification Test, one day and administered it to her neighbor. He scored 25 out of 40, a typical score for an Alzheimer’s patient who has started to lose his sense of smell.

About six months later, the neighbor told Jennifer that something was wrong. He could smell food while it was cooking, but once it was in his mouth, food just didn’t taste right. Everything “tasted” like salty cardboard. Jennifer pulled out the UPSIT again and retested him. Same score: 25 out of 40. On the surface, nothing had changed. But the UPSIT is a scratch-and-sniff test, meaning you don’t put anything in your mouth. It measures only nose-smelling. The neighbor had barely complained about his loss of nose-smelling, probably because it had occurred gradually, but over the past six months something different had happened. He had lost his ability to mouth-smell.

“When he lost his retronasal (mouth-smelling), it was very dramatic for
him. Very distressing. He lost thirty pounds in three months as soon as this happened,” said Stamps. “It had a much greater impact on him, on his health, on his well-being, pleasure for life. Everything. He got very depressed, lost a lot of weight. His cognition declined even more, and very dramatically, and his health just went down the tubes.”

Stamps was flummoxed. She asked Bartoshuk what she thought was happening. Why hadn’t the test captured this type of olfactory loss? Was it even possible to capture this?

“You haven’t caught it because it’s
taste
, Jennifer,” Stamps remembers Bartoshuk saying to her, meaning that she had missed this loss because she had been testing the functionality of the wrong sense.

Stamps tested her neighbor next time for taste, not smell, and found that the back of his tongue was completely useless for tasting; this meant that the glossopharyngeal cranial nerve was completely dead. Also gone were the areas of the tongue that connect with the left side of the chorda tympani facial nerve. His ability to mouth-smell disappeared when he lost some of his sense of taste. This is the same phenomenon that happened to Bartoshuk’s patient who had slashed her taste nerve by licking the inside of a metal can.

Stamps began to test people who had experienced partial flavor loss like her neighbor, asking them to rate the intensity of various foods by both nose-smelling and mouth-smelling. Foods with high levels of chemesthesis, or tactile burn, such as curry, mustard, vinegar, and garlic, seemed to be the most resistant to loss. Foods without a tactile component (such as grapes, butter, and apples) were most susceptible to loss.

Stamps is now using this knowledge to test whether adding an Irritaste to foods will help those with taste loss get more aroma from their foods. Her secret ingredient is cayenne pepper. She hypothesizes that adding the tactile burn of capsaicin at a level below which it is detectable may increase mouth-smelling and, therefore, overall flavor perception and ultimately the enjoyment of food. The cayenne stimulates the touch nerve that gives the olfactory system the input it’s not getting from the taste nerves.

A woman with Parkinson’s disease visited the University of Florida’s memory disorder clinic complaining of flavor loss. Stamps gave the woman a full taste and smell work-up, which showed dramatic smell loss. Then Stamps gave the patient her untested “cure,” dosing grape jelly with increasing levels of cayenne pepper, all of them at a level that was below what the patient could detect.

To set the baseline, Stamps served the patient plain grape jelly. The woman
said she got a musty flavor, but that was it. When she tasted the first, lowest concentration level of cayenne-and-grape-jelly concoction, the patient said the same thing. Musty, but that’s about it. At the next higher concentration, she looked straight at Stamps and yelled, “Grape! I got grape!” as she experienced exactly what Stamps had hoped. The right amount of tactile stimulation (from cayenne pepper) had kicked this woman’s flavor perception into gear.

“We don’t know how or why—if it’s tricking the trigeminal nerve into carrying the olfactory information, or what,” said Stamps. “I have no idea how it’s working. But it is.”

The Parkinson’s patient got teary-eyed and emotional upon experiencing the simplicity of grape jelly again for the first time. She had tasted a glimmer of hope in what she thought would be a depressing, downward spiral into flavorlessness. Stamps gave the patient a list of Irritastes and told her to “go play” at home in her kitchen. The woman left Stamps’s office as giddy as a child on her way home from the toy store.

Oral health can also affect older people’s ability to taste. When you age, you produce less saliva then you do when young, so you’re less able to moisten foods. Eating crunchy or dry foods—pretzels, rice cakes, and croutons—is less appealing. Of course, in order to even bite into a pretzel without effort or pain, you need a healthy set of teeth and gums or you’ll have difficulty chewing. Without chewing, you can’t release the volatile aromas from food. Chewing gives you more of everything the more you chew it: basic tastes, aromas, textures. The University of Connecticut’s Valerie Duffy has found that older women with dentures had more complaints that they were not experiencing food fully than those with their own healthy teeth and gums.

According to Richard Doty, director of the Smell and Taste Center at the University of Pennsylvania Medical Center, people who already are genetically prone to Alzheimer’s disease turn out to have a ninefold higher risk when they also report problems with their sense of smell. Also, substances from the environment can enter through the nose and reach the brain, triggering diseases such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jakob. The best way to avoid this type of nasal exposure is to avoid the toxins that cause harm in the first place. Doty recommends avoiding herbicides, pesticides, and heavy metals, and getting
treatment for infections immediately. This is good advice in general, though we know very little about these devastating diseases.

If you or a loved one suffers from a diminished sense of smell or taste, there are a few things you can do. It’s likely that someone with diminished senses has already started salting his food more heavily or adding more sugar to coffee—the first, most logical reactions. If you wanted to get more flavor from your food, you’d add more salt. The problem, though, is that most older adults, especially those with hypertension or diabetes, don’t need more sodium or calories.

Taste is much more resilient to the effects of aging than smell. It’s likely that the sense of taste is fine, so they’d be better off squeezing tangerines or lemons over their food, as I told the woman in Sarasota to do, than adding more of the Basic Tastes. What they are really craving are aromas, which citrus fruits have in spades. Using aromatic citrus probably won’t harm an older person’s health and won’t add calories, sodium, sugar, or guilt. Buy fresh lemons and serve a wedge with everything from already-dressed salad to subtle foods such as potatoes or rice. You can also start playing around with cayenne or other hot peppers. Be cautious, though, as many hot sauces contain sodium, although when used sparingly, the level tends to be minimal. Try smoked peppers, which add almost no sodium or calories. You can probably find ground chipotle chiles at your grocery store and a multitude of other dried chile powders at Hispanic markets.