Dear Ms. Swift:
I write to urge you to drop your endorsement of Diet Coke, which contains the artificial sweetener aspartame. I am glad that you are not promoting full-calorie Coca-Cola, which promotes diabetes, heart disease, obesity, and other health problems. But Diet Coke and other sodas sweetened with aspartame may raise consumers’ risk of cancer.
A prominent laboratory conducted three major studies of aspartame and found that it caused cancer in both rats and mice. In the two tests on rats, aspartame caused lymphomas, leukemias, kidney tumors, and breast cancer. A study in mice found that it caused liver and lung cancer. Scientists generally accept that if a chemical causes cancer in lab animals it likely increases the risk of cancer in humans.
While the Food and Drug Administration still considers aspartame to be safe, the Center for Science in the Public Interest urges consumers to avoid this chemical. We think it makes sense to take action to eliminate a likely cancer risk rather than wait for absolute proof that aspartame causes cancer in humans.
Your endorsement carries great weight with your millions of young fans. To the extent that your endorsement encourages them to begin drinking Diet Coke, or to drink more, your endorsement is likely increasing your fans’ risk of cancer. Even if the increase in risk is small, we question whether you would want to lend your name, image, and reputation to any product linked to any increased risk of cancer.
Clearly you have many options when it comes to selecting products to endorse, including video games, digital cameras, cosmetics, fragrances, jeans, milk, and sneakers. You have also generously lent your name and given your time and money to a long list of charities, including several prestigious children’s hospitals and many highly regarded cancer-related organizations. Aspartame does not deserve a place in your otherwise admirable portfolio.
On behalf of our 900,000 members, I wish you a healthy, happy, and prosperous 2015, and I thank you for considering my views.
Michael F. Jacobson, Ph.D.