A celebrity endorsement can sell a movie, cosmetics and, sometimes, a bogus health claim. When stars share personal health experiences or opinions, those messages can reach millions of people and spark real-world behavior change. A 2018 study found that an op-ed penned by Angelina Jolie about her BRCA testing and preventative mastectomy led to a “statistically significant increase” in BRCA testing and mastectomy rates among women who had not been previously diagnosed with breast or ovarian