A scene from Bud Lite's 2019 Super Bowl ad. Source: Anheuser-Busch

Anheuser-Busch used one of its Super Bowl ads to shame Bud Light rivals Miller Lite and Coors Light for using corn syrup to brew their beers, but dietitians say the sweetener isn't all that bad when used in the fermentation process. In the 60-second commercial, an order for corn syrup inadvertently shows up at the wrong castle. The Bud Light king takes an arduous journey up mountains and across the sea to deliver it to the Miller Lite and Coors Light castles, which both use corn syrup in their brewing processes. The ad prompted backlash from corn grower industry groups and Millers Lite and Coors Light, who are both owned by MillerCoors, the U.S. subsidiary of Molson Coors. Added sugars, especially high-fructose corn syrup, have come under intense scrutiny fueling an obesity epidemic that has left nearly 40 percent of U.S. adults obese.

Molecular difference

While corn syrup sounds pretty close to high-fructose corn syrup, it's actually quite different on the molecular level, Margaret Slavin, an associate professor in nutrition and food studies at George Mason University, told CNBC. Corn syrup is essentially corn starch that has been mostly broken down into single glucose molecules. To make high-fructose corn syrup, scientists use enzymes that change about half of those glucose molecules into fructose. The result is a sweeter substance that's cheaper to produce than regular sugar.

Miller Lite and Coors Light use corn syrup to feed yeast in the brewing process. Yeast eats sugar, in this case corn syrup, and turns it into alcohol and carbon dioxide. Anheuser-Busch uses rice to feed the yeast when brewing Bud Light. Rice takes a little bit longer to digest because corn syrup is pre-digested, since the enzymes break it down, Slavin explains. The end result for both? Beer. "I'm a little surprised at (corn syrup) being used in advertising in such a way," said Slavin, a registered dietitian. "I think it's more playing on consumer hot topics and concerns than on a particular scientific concern whether or not they're using sugar or rice or some other refined grain to feed the yeast."

Consumer fears

Nicole Lund, sports dietitian at NYU Langone, said one of her clients came in Monday asking her what she thought about the commercial and the implication that consumers should stay away from beer made with corn syrup. He said one of his friends prefers Coors Light and was a little nervous about drinking it. Like Slavin, Lund says the ad plays into consumer fears about high-fructose corn syrup and weight gain. Our bodies store whatever they haven't used for energy. Added sugars are typically found in foods we tend to overeat, like soda or candy, so they commonly get stored as fat, she said. However, it's not really an issue when sugars get mostly stripped out during the beer-making process, she said. "With a lot of these trendy things, you have to take a step back and decide how big of an issue it is to your life, but for the most part, that's probably not somebody's biggest issue," Lund said. "Especially if they're drinking six beers a day, it would probably be more about the quantity than which beer they're choosing."

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