Maybe you became a brussels sprouts convert in your late teens. Or perhaps you were addicted to the sweet stuff — specifically, candy — as a kid, only to grow out of it later. It might have taken until adulthood for you to start craving bitter foods and drinks like sautéed kale or a martini with olives.
It’s a familiar story, right? Although we all have our own unique preferences, most of us gravitate towards sweeter things and avoid bitter-tasting foods when we’re children, then develop more complex palates as adults — and our tastes often shift again in our later years.
Sure, it’s a given that we like different foods at different points in our lives. But what’s perhaps less understood is why our tastes change as we get older.
“These senses [of taste and smell] change during development, but the brain is also plastic, and it learns; we perceive these flavors with our brain,” says Julie Mennella, a biopsychologist at the Monell Chemical Senses Center in Philadelphia. “One of the biggest times these senses change is during childhood. The research is showing that [children] really live in different sensory worlds.”
Understanding Our Sense of Taste It’s not just our taste buds that tell us whether we like a particular food. When we sink our teeth into, say, a crisp apple, our brains must then process a dizzying array of sensory and neurochemical signals to help us decide whether we want to take another bite. Our taste buds, found on the tongue, roof of the mouth, esophagus and at the back of the throat, respond to five fundamental stimuli — sweet, sour, salty, bitter and the more-recently-discovered umami. But those flavors are just part of the story.
“A great example is to plug your nose while you’re eating and chewing, and you’ll just experience taste,” says Mennella. “But once you unplug your nose, you’ll experience the odors in foods that hit the olfactory receptors from the back of the mouth.”
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Our memories are also deeply connected with taste. (Just ask Marcel Proust, whose bite into a tea-soaked madeleine famously whisked him away on a mental reminiscence.) Scientists have even found a direct link between the part of the brain responsible for taste memory and the region responsible for encoding the time and place we experienced that taste, according to a study published in The Journal of Neuroscience in 2014.
“Flavor is what ties us to our past and provides a sense of identity,” says Mennella. “And it allows foods to provide us with comfort. These are really powerful senses.”
Flavor Preferences in Childhood It turns out, a penchant for sweet and salty foods when we’re children may be hard-wired into our basic biology. From an evolutionary perspective, says Mennella, sweetness is nature’s shorthand for high-calorie foods, while salty flavors signal the presence of a much-needed mineral. That’s because until relatively recently in human history, children needed every scrap of energy they could find to survive until adulthood. As a result, their palates evolved towards energy-rich foods.
Sweet vs Bitter“If given their choice, they’d probably eat a lot more sweets, because it’s just the biology of it all,” says Mennella. “They’re really seeking out that energy source. We didn’t evolve in an environment that had low-calorie sweeteners that provide sweetness with no energy or refined sugars.”
On the other hand, we tend to steer clear of bitter-tasting foods as children. In fact, some researchers think that kids have a hypersensitive sense of taste — particularly when it comes to bitterness. Much like sweetness is nature’s alarm bell for caloric density, bitter flavors act as a biological skull-and-crossbones, protecting us from ingesting potential toxins during childhood.
“Bitter is often a signal for things that could be poisonous or that we should be wary of,” says Mennella. “But that’s not to say that you can’t learn to like bitter foods once you know that they’re safe.”
These food preferences may begin before birth, as well. For starters, women often become more sensitive to bitterness during pregnancy. A mother’s diet can even directly impact her unborn child. Thanks to ultrasound scans, scientists have observed fetuses grimacing in the womb when their mothers consumed a kale capsule, according to a 2022 study in Psychological Science.
Why Do Taste Buds Change?As we march through childhood and into adolescence, our senses lose that ultra-sensitivity to certain flavors. And as our bitter sensitivity — and preference for sweet and salty — diminishes, we become bolder and less picky, broadening our tastes through exposure and experience. It’s during this period that we might find we actually like once-despised foods like beets and broccoli.
“We’re omnivores, so we’re open to a wide variety of foods,” says Mennella. “I think that learning is always there.”
Another shift happens when we move into middle age. That’s when the roughly 10,000 taste buds we are born with begin to stop growing back. These taste receptors are titans of cellular turnover, dying off and regrowing about once every 10 days. Starting in our 40s and 50s, however, they simply don’t regenerate at the same frequency. This means that we have fewer taste buds sending sensory signals to the brain.
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That’s not the only factor that can make foods taste blander over the years. Our sense of smell starts to diminish as we age, too, since our olfactory receptors also stop regenerating as rapidly. Still, Mennella cautions that these sensory changes can be quite subtle — and are often unique to a particular odor or flavor.
“It’s not like all of the odors are decreasing,” she says. “It could be one; maybe you’re not as sensitive to rose, but just as sensitive to the [aromas] of garlic. […] It’s not a homogenous loss.”
What Else Changes Our Sense of Taste? It’s important to note that aging isn’t the only thing that can dull our sense of taste. Some medications, including those used to treat high blood pressure, can alter how your taste buds perceive certain chemicals. Viral infections and illnesses that target the upper respiratory system can also reduce your sense of smell, and by extension taste.
“These senses got a lot of attention during the COVID pandemic,” says Mennella. “They were the canaries in the coal mine and some of the first warning signals of the infection of the virus. Foods just don’t taste the same.”
For most of us, these senses typically return over time. But there are still plenty of people who continue to struggle with a loss of sense and taste from COVID-19. According to a 2022 survey, about 15 percent of people who experienced a loss of smell due to the illness still had problems six months later — about 9 million people in the U.S. alone.
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Source : Discover Magazine