 Caramel coloring may be the most widely consumed food coloring in the world. Unfortunately, its manufacture can sometimes lead to the formation of a carcinogen called methylmitazol, which was identified as a cancer-causing chemical in 2007. And so for the purposes of their Prop 65 labeling law, California set the daily limit at 29 micrograms a day. So how much cancer might caramel-colored soft drinks be causing? We didn't know until now. 110 soft drink samples were tested off-store shelves in California and around New York. None of the carcinogens was found in Sprite, for example, which is what you'd expect since it's not caramel-colored brown. Among sodas that were, the highest levels were found in Goya brand soda and the lowest in Coke products, about 20 times less than in Pepsi products. Interestingly, California Pepsi was significantly less carcinogenic than New York Pepsi, presumed because of the law in California. This supports the notion that labeling laws like Prop 65 can incentivize manufacturers to reduce foodborne chemical risks, rather than just wish they could all be California. To protect consumers around the rest of the country, federal regulations could be a valuable approach to reducing excess cancer risk. But how much cancer are we talking about? Johns Hopkins researchers calculated the cancer burden, an estimate of the number of lifetime excess cancer cases associated with the consumption of the various beverages. So at the average U.S. soda intake, with the average levels of carcinogens found, Pepsi may be causing thousands of cancer cases, especially non-California Pepsi products, which appear to be causing 20 times more cancer than Coke. Of course, no need for any of them to have any carcinogens at all, but we don't have to wait for government regulation or corporate social responsibility. We can exercise personal responsibility and just stop drinking soda altogether. Cutting out soda may reduce our risk of becoming obese and getting diabetes and fatty liver disease and hip fractures and rheumatoid arthritis and chronic kidney disease and maybe gout as well. In children, daily soda consumption may increase the odds of asthma five-fold and increase the risk of premature puberty in girls, raising the likelihood they start getting their periods before age 11 by as much as 47%. If you look at the back of people's eyes, you can measure the caliber of the arteries in their retina and the narrower they are, the higher the risk of high blood pressure, diabetes, and heart disease. If you do these kinds of measurements on thousands of 12-year-olds and ask them about their soda drinking habits, children who consume soft drinks daily had significantly narrower arteries. So the message to patients can no longer just be eat less, exercise more, it matters what you eat. Specific dietary advice should be to significantly reduce the consumption of processed food and added sugar, and to eat more whole foods.