The Sweet Science: How Our Brain Reacts To Sugary Tastes

"Sweetie," "Sugar," and "Honey." There's a reason we call our loved ones flavor-derived nicknames. "We're all born liking sweet tastes," says Dr. Alexei B. Kampov-Polevoi, a professor of psychiatry at the University of North Carolina Chapel Hill. "It's kind of the yardstick for all pleasures." But what does it mean for food to taste sweet? And how does that taste affect our brains and our bodies?

The desire for sweetness is hardwired into humans--give babies a little sugar on their lips and they'll smile. That's because up until the advent of artificial additives, sweet flavors signified calorie-dense foods. "If you're sitting there on the savanna and trying not to be eaten by something else, you want to be able to make a quick decision about what's good to eat," says Steven Munger, an associate professor of Anatomy and Neurobiology at the University of Maryland. A sweet snack indicated that not only was it probably not poisonous, it also would provide ample energy. While we can't blame everything on our prehistoric ancestry, the desire for sweetness is well-rooted in primitive genetics.
"All mammals - mice, dogs, humans—with the exception of cats, use the same types of genes and genetic mechanisms to detect sweet flavor," says Munger. (Cats have since mutated so that they no longer have the gene for detecting sweet food).

Still, some people crave sweetness more than others: women are more likely than men to have a preference for sweet food, a fact that's somehow tied to hormones. "During the menstrual cycle, the mood as well as the desire to eat sweets can fluctuate," says Dr. Kampov-Polevoi. "That indicates that sex hormones are involved."
Children, as well, are more drawn than adults to like sweet foods, which makes sense. "Things that I loved as a child just taste so obnoxiously sweet to me now," says Danielle Reed, a member of the Monell Chemical Senses Center in Philadelphia. Her research showed that as children grew, their preference and liking for sweet foods decline. The research indicates that the desire for sweetness is linked to stages of development. "When you're growing you need the [extra] calories, and when you stop growing you don't," says Reed.

Whether one like the taste of sugar a little or a lot, sweet foods react with everyone's brains in the same way--by producing a rush of chemicals, including dopamine, which creates an opiate-like effect. "In Sweden, sweet-tasting foods like sugar solutions are used as anesthetic to do minor surgeries," says Dr. Kampov-Polevi. Sugar water is also used in the US on babies for minor procedures like blood draws. It's also a go-to staple for recovering addicts, who find that binging on sugary snacks can sometimes help fight the urge to drink.

No matter how you get your sugar fix, the brain reacts the same: whether your source is artificial sweeteners, high fructose corn syrup, or fructalose. "A sugar is a sugar is a sugar," says Barry Popkin, professor of global nutrition at the University of North Carolina. (At one point, researchers thought that artificial sugars may make the body even hungrier, since they offer a sweet taste with no calories, leaving the body wanting more. That has proven not to be true, says Popkin.)

How we consume that sugar, however, does make a difference. Humans do all process sweetness in beverages differently than sweetness in food - that is, by barely responding to it at all. Though our brains associate the taste of sugar with calorie dense food, drinking highly sweet beverages doesn't impact our caloric impact. When test subjects consumer eat 500 calories of sugar-rich food, says Popkin, they're likely to eat 500 fewer calories sometime during the day. Not so with sweet beverages. Even when researchers stir in spoonfuls of sugar into a regular glass of water, subjects still fail to compensate for those extra calories elsewhere.

That's trouble. An increase in sugary beverages has translated into a two-thirds to three-fourths increase in overall calorie consumption over the last 20 years, says Popkin. We can speculate about what this means for our waistline--some studies claim that the rise in American obesity can be directly linked to the rise in inexpensively produced soft drinks - but we are less sure about other long-term implications.

What's also unknown is the long-term effect of eating sweet foods over a lifetime. Americans are currently living in what could be called the Sweetest Generation: our access to sweet and sugary foods, especially beverages like soda and juice, is at an all-time high. "For the past 1000 years, it's mostly been breast milk followed by water," says Popkin. Now, we get about twenty percent of our calories from sugary drinks, a number that's skyrocketed in the past 20 years. We're eating more sugary foods than ever, and researchers are still unsure of the consequences.

"If you consume caffeine over time, you habituate to it, and it has a different effect," says Popkin. "With drug use, you habituate to a certain amount of drugs and need more over time. When it comes to sweetness, we don't understand the long-term effect." We do know that we love sweets - and that the country is sweeter than ever. But in this case, being sweet may not be a good thing.