Americans’ soda habit poses a public health threat, thanks to caramel coloring added to many dark beverages, a Johns Hopkins researcher says.
While the potential downsides of too much soda are hardly new news, a recent study published in the journal Plos One states that it’s the first peer-reviewed study to assess soda drinkers’ exposure to 4-methylimidazole or its associated cancer risk.
This byproduct, also known as 4-MEI, is a potential carcinogen formed during the manufacturing of some kinds of caramel coloring, according to a press release from Johns Hopkins University’s Bloomberg School of Public Health.
“Soft drink consumers are being exposed to an avoidable and unnecessary cancer risk from an ingredient that is being added to these beverages simply for aesthetic purposes,” says senior study author Keeve Nachman, director of the Food Production and Public Health Program at the Johns Hopkins Center for a Livable Future. “This unnecessary exposure poses a threat to public health and raises questions about the continued use of caramel coloring in soda.”
The study
The new research builds on data collected in 2013 and 2014, when the Center for a Livable Future partnered with Consumer Reports to analyze the concentration of 4-MEI in samples from sodas purchased in California and the New York metropolitan area, including New Jersey and Connecticut.
Researchers also incorporated data on beverage consumption from the U.S. Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey, and data on population characteristics from the U.S. Census Bureau
Twelve sodas were analyzed. Sprite, which does not contain caramel coloring and was not found to have a measurable concentration of 4-MEI, was dropped after initial analysis. The other 11 drinks are:
- 365 Everyday Value (Whole Foods’ house brand) Dr. Snap (regular)
- A&W root beer (regular)
- Brisk lemon iced tea
- Coca Cola (regular), Diet Coke, Coca Cola Zero
- Dr. Pepper (regular)
- Goya Malta
- Pepsi (regular), Diet Pepsi, Pepsi One
The findings
The sodas with the highest average concentrations of 4-MEI across all samples were Goya Malta (945.5 micrograms per liter), Pepsi One (246.9) and Pepsi (183.6).
Those with the lowest were regular Coca-Cola (11.7), Coke Zero (10.3) and Diet Coke (9.8).
The drinks that scored the highest for exposure to 4-MEI, as measured in what’s called the lifetime average daily dose, were generally the same drinks that scored highest for concentration of 4-MEI.
For example, under average exposure conditions, Malta Goya, followed by the three Pepsi beverages and Dr. Snap, were associated with the highest lifetime average daily doses. The Coca-Cola varieties were associated with the lowest.
The findings for cancer risk “mirrored” those of exposure, as the study put it.
Proposition 65
The federal government does not currently limit the amount of 4-MEI that manufacturers can add to foods and drinks, according to Consumer Reports.
However, California has instituted limits. In 2011, the state labeled 4-MEI a carcinogen under its Safe Drinking Water and Toxic Enforcement Act of 1986, also known as Proposition 65. A product sold in California that falls into that category must be labeled with a cancer risk warning if the product exposes consumers to more than 29 micrograms of 4-MEI per day on average.
That’s why researchers purchased soda samples from California and a separate region, and 4-MEI concentrations did vary for some drinks, with the California samples associated with lower levels.
“It appears that regulations such as California’s Proposition 65 may be effective at reducing exposure to 4-MEI from soft drinks, and that beverages can be manufactured in ways that produce less 4-MEI,” Nachman says. “An FDA intervention, such as determining maximum levels for 4-MEI in beverages, could be a valuable approach to reducing excess cancer risk attributable to 4-MEI exposure in the U.S. population.”
Federal food label laws
Not all dark beverages contain 4-MEI, but Consumers Reports says shoppers can’t tell the difference, thanks to federal food labeling laws overseen by the U.S. Food and Drug Administration.
Manufacturers use four different kinds of caramel coloring, some of which contain 4-MEI. Federal law does not require manufacturers to specify which kind of coloring they put into a soda, however.
That means the ingredient lists on drinks containing any caramel color can identify the additive by name or categorically, such as “artificial coloring.”
To learn more about food labeling laws, check out When Foods Go ‘Natural’ — Does That Really Make Them Healthier?
Of course, the FDA does not currently consider 4-MEI an immediate public health risk.
“Based on the available information, FDA has no reason to believe that there is any immediate or short-term danger presented by 4-MEI at the levels expected in food from the use of caramel coloring,” the agency’s website states.
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