Wary of the U.S. medical system? You are not alone. Turns out, nearly half of all American adults believe in some sort of health conspiracy theory, according to new research published in JAMA Internal Medicine and reported by Reuters.

For the study, scientists at the University of Chicago used online survey data from 1,351 adults and then weighted the numbers to represent the U.S. population. In the end, 49 percent of respondents said they agreed with at least one of six popular conspiracies.

Scientists say the most popular allegations by the American public included the idea that U.S. regulators prevent people from pursuing natural cures for their illnesses (37 percent agreed) and that vaccines can cause psychological disorders such as autism (20 percent agreed).

Other well-known conspiracy theories include the belief that a U.S. spy agency infected a large number of African Americans with HIV in the early days of the epidemic, the idea that genetically modified organisms (GMOs) are being used to shrink the human population, and that water fluoridation is a way for “the man” to drop dangerous toxins into the environment. Many respondents also believed that the U.S. government knows that cell phones cause cancer but is doing nothing about it.

“Science in general—medicine in particular—is complicated and cognitively challenging because you have to carry around a lot of uncertainty,” said J. Eric Oliver, PhD, lead author of the study. Many people, he said, believe these conspiracies because they are easier to understand than complex medical data.

However, he also acknowledged that these theories are far more widely known and endorsed than previously thought—and that this could have huge implications for medical providers.

People who believe these theories may be less likely to follow a prescription drug regimen and might be more flexible to alternative therapies. The study authors suggest that instead of writing off such patients as crazy, doctors and researchers should give them better information about health and science.

To read the Reuters article, click here.