To limit sweet indulgences, chew, chew, chew

Chewing sugarless gum throughout the afternoon can significantly curb your cravings for sweet snacks. Gum chewing also makes people feel more energetic and alert through the p.m. doldrums than when they pass the hours gumfree. And when gum chewers do snack, they consume fewer calories than on gum-less days.

Or so concludes a new study, reported yesterday morning at the Experimental Biology meeting, in New Orleans. It was (surprise, surprise) funded by the Wrigley Science Institute, a four-year-old research arm of the famed Chicago-based chewing gum company. Needless to say, Wrigley is thrilled by the diet-reinforcing implications of the new study — and the suggestion of a brand new market for its products.

Paula J. Geiselman and her colleagues at the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge recruited 115 people (66 percent of them women). All were normal to overweight, 18 to 54 years old, and had chewed gum in the past. Each came to the Pennington lab after a standard breakfast on two different days.

On one of those days, the recruits were offered their choice of nine sugarfree chewing gums. And beginning one hour after receiving lunch, each participant was asked to chew gum for 15 minutes each hour — over three hours. After lunch on the other day, these participants wiled away the afternoon gumfree.

Roughly three and half hours after lunch, each volunteer was presented with 12 custom-selected snacks. Three were high in fat and sugar (such as blueberry muffins and chocolate-covered doughnuts). Three more were high in fat and starch, such as potato chips and croissants. Another trio were low in fat but high in sugar, such as fatfree chocolate pudding. The final options were low in fat and high in complex carbs, such as fatfree popcorn and baked chips.

Participants were invited to eat any and all of the proffered foods. And on the day that they had chewed gum, the recruits snacked on foods contributing an averages of 530 calories. Which was about 45 fewer calories than on the day they had spent the afternoon gumfree. Geiselman says the smaller snack reflected the participants eating some 60 fewer calories per person of sweet foods on their gum-chewing day.

Moreover, when polled hourly throughout the afternoon about any food cravings, the participants tended to report significantly less desire for sweets at every time period on their gum chewing day — the opposite of their responses on the gumfree afternoon. Meanwhile, cravings for starchy and salty foods grew over time and showed no correlation with gum.

After the session, I asked Geiselman whether there were any surprises in her findings. An earlier study (also Wrigley funded), she notes, found people snacked less after chewing gum. But in that trial, participants chose their gums of choice — some of which contained sugar. Moreover, the snacks they were later offered were all high in fat and carbs. In other words, especially energy-dense junk foods.

In her new study, Geiselman says, “we wanted to tease apart if [the gum chewing] had an effect on some particular type of macronutrient” — nutrition-ese for fat versus sugars or starches. “And that’s what we did — separate out the [offered] foods by type to see if the selection of any type would preferentially decrease.”

Also new in this study, as the afternoon wore on, participants reported “significantly lower energy levels than they did immediately after their lunch,” Geiselman says. Unless they had chewed gum. One those days, she says, “they maintained their energy levels. It didn’t decrease.” After gum chewing, participants also “maintained their feeling of alertness across the three hours” — a sharp departure from the day they didn’t chew gum.

So what’s happening? Geiselman doesn’t know, but points to another recent study (also funded by the Wrigley Institute) performed by Todd Parrish and his team at Northwestern University’s med school. It used functional magnetic resonance imaging to study brain activity during gum chewing. And she says it found gum chewing increased activity in areas of the brain associated with memory and emotional responses. So Geiselman says it would be interesting to use fMRI to probe for brain activity changes that might underlie satiety, alertness or the snack preference changes that she’s just observed.

Explains Wrigley consultant Gilbert Leveille, executive director of the Wrigley Science Institute, “We’ve funded a lot of studies looking at the specific (biological} effects of chewing gum. And coming out of these has been very clear data showing that chewing gum reduces stress. But the fMRI work is really exciting.”

Years ago, one Japanese fMRI study showed that chewing gum increased blood flow to the brain, Leveille says. “We’ve sponsored a study that was done by a Chinese investigator,” published about a year ago. “And it showed a 40 percent increase in blood flow to the brain.” More recently, Parrish has been funded “to help us try and interpret those data,” he told me. The current Northwestern study is using fMRI and electroencephalograms, which measure electrical activity in the brain, as people do complex, stressful tasks such as math problems.

“The important thing that such work shows is that chewing gum impacts the brain,” Leveille says. “What the relationship is in the brain to what [Geiselman] is observing, we don’t know. But it gives us a plausible mechanism to pursue.”

So what good is dropping 40 calories from an afternoon snack? Well, at an obesity session the day before, Caroline Apovian of Boston University noted that for each 10 fewer calories a day consumed — assuming exercise levels remain constant — an individual will shed a pound a year.

But for me, the most interesting finding was the putative energy/alertness advantages. Clever publishers might want to put packages of gum beside the office coffee pot to further perk up their overworked, sleep-deprived reporters.

Janet Raloff

Janet Raloff is the editor of Science News for Students, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer.

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