Can Drinking Soda Increase Your Risk of Cancer?

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If you are a soda drinker, it may be time to rethink your drink.  An advocacy organization has brought to light some studies which indicate that the caramel coloring used in dark soft drinks and some foods are known to be carcinogens in mice and rats.  The Center for Science in the Public Interest has asked the US Food and Drug Administration to ban the chemicals.

Dark colas, such as Coke and Pepsi, use a coloring that is manufactured through a chemical reaction between sugars, ammonia, and sulfates.  According to CSPI Executive Director Michael Jacobson, these reactions produce two carcinogens:  2-methylimidazole (2-MEI) and 4-methylimidazole (4-MEI).  Studies by the National Toxicology Program have identified these two chemicals as causing cancer in animals – specifically of the lung, liver, thyroid, and blood (leukemia).

California has added 4-MEI to its list of carcinogens and is pursuing legislation that would require a product with levels higher than 16 micrograms per person per day would require a warning.  Jacobson says some sodas have levels eight times higher than that.  A 12-ounce can of cola contains up to 130 micrograms, according to CSPI.

Clear sodas such as Sprite do not contain the caramel coloring.

Jacobson has petitioned the FDA to ban the artificial colorings, which have no nutritional or preservative value, and move toward natural colorings such as from beets or carrots.

Of course, every story has two sides, and this one is no exception. The American Beverage Association contends there is no evidence showing that 4-MEI causes cancer in humans.  Take the case of saccharin, which carried a warning level for years because it caused bladder cancer in rats.  However, it was later discovered that rats respond to saccharin differently than humans, and over time, an increased risk of cancer was not found to occur in humans.

Even if future studies find no risk in humans, excessive intake of soda is still concerning for other health reasons.  First, regular soft drinks can contribute a significant amount of calories to the diet.  Obesity is rampant now in our country, with over two-thirds of Americans over their ideal body weight.  Excess body weight increases the risk for heart disease (the number one killer of American adults), diabetes, respiratory problems such as sleep apnea, and some types of cancer including those of the colon and pancreas.

But diet soda may be no better.  In a study appearing in the American Journal of Clinical Nutrition, investigators evaluated data from more than 84,000 women and 43,000 men regarding soda intake and risk of stroke. The authors found that “Greater consumption of sugar-sweetened and low-calorie sodas was associated with a significantly higher risk of stroke.”

The bottom line for health is to decrease the amount of soft drinks you consume, whether regular or diet, brown or clear, and increase your intake of water.  After all, as Dr. Jennifer Ashton says to CBS News, “our bodies are about 60% water, not 60% soda.”


Bernstein AM et al. Soda consumption and the risk of stroke in men and women. American Journal of Clinical Nutrition 2012 May; 95(5): 1190-99

Center for Science in the Public Interest. FDA urged to prohibit carcinogenic “caramel coloring.” 2011 Feb 16