January 23, 2014
There are many good reasons not to drink soda. Multiple studies have found that consumption of sugar-sweetened beverages, including sodas, increases the risk of obesity and related diseases like diabetes mellitus. Now a new study conducted by the Center for a Livable Future in collaboration with Consumer Reports magazine focuses on yet another risk, and one that applies to diet sodas as well as their sugary brethren: sodas that list caramel color as an ingredient also contain a potential carcinogen known as 4-methylimidazole, or 4-MEI for short. Drinking these sodas could increase your risk of cancer.
Distinct from the caramel found in many desserts, caramel color is produced by heating carbohydrates, sometimes in combination with ammonium compounds. When these compounds are used, 4-MEI can form and enter the food supply in sodas and other food and beverage products.
The National Toxicology Program of the U.S. Department of Health and Human Services has found clear evidence that exposure to 4-MEI caused lung cancer in mice as well as some evidence that it caused leukemia in female rats. The State of California has declared 4-MEI a carcinogen and has required that products that expose consumers to more than 29 micrograms (µg) of 4-MEI per day carry warning labels.
We tested 12 soda brands, including multiple Coke and Pepsi products, purchased in California and the New York area between April and December of last year. All samples of the 11 brands that listed caramel color as an ingredient contained some amount of 4-MEI. We did not detect 4-MEI in the twelfth brand, Sprite—not surprising since it does not contain caramel color. (For all results, see the Consumer Reports story released today.)
Both Coca-Cola and PepsiCo previously had pledged to lower levels of 4-MEI to avoid adding warning labels to products sold in California. Our results confirmed reports that Coca-Cola has lived up to this promise while PepsiCo still has work to do. If a California consumer drinks a single can (355 mL) of Pepsi One per day, our results suggest that he or she would be exposed to 39.5 micrograms per day.
While we cannot say that these levels violate California law, we believe they are too high, and Consumers Union, the advocacy arm of Consumer Reports, has asked the California Attorney General to investigate. (None of the samples we tested carried such a label.)
Today PepsiCo disputed our study and claimed that the average Pepsi One consumer drinks less than one-third of a can of Pepsi (about 100 mL) per day, which would mean daily exposure to 4-MEI in Pepsi One is less than a third of what we estimated it to be. If true, Pepsi One would not require a warning label.
PepsiCo told us that its estimate of Pepsi consumption is based on an analysis of data from the National Health and Nutrition Examination Survey (NHANES). While a detailed description of their methods was not provided, barring us from assessing this claim, it runs counter to analyses of soda consumption by independent experts. It also defies intuition—does the average consumer of Pepsi really drink just one-third of a can and leave the rest to spill? PepsiCo needs to reduce 4-MEI levels in its products.
Meanwhile, the Food and Drug Administration (FDA) should set national standards that compel all food and beverage companies to limit 4-MEI in products that contain caramel color. The agency should also require companies to specify whether caramel color listed as an ingredient is produced with ammonium compounds and therefore likely contains 4-MEI (Europe already does this). Consumers Union has petitioned the agency to do just that. Until then, the only way consumers can avoid exposure to 4-MEI in soda is to avoid sodas that contain caramel color.