A registered dietitian nutritionist recently told me, “Probiotics are hot right now.” She’s not wrong: The number of adults in the U.S. taking probiotics or prebiotics—both of which are said to make your gut healthier—multiplied by four between 2007 and 2012, according to government data. Children use them too. A report from the National Institutes of Health says, “Probiotics or prebiotics were among the top three natural products used by children in 2012.”
[…]They could be dangerous for immunocompromised people
For a very small number of people, probiotics can be dangerous. Don’t worry: We’re talking one in millions. Specifically, we’re talking about immunocompromised people. These are individuals living with weak immune systems who are less likely to fight off some illnesses. People with HIV/AIDS or certain inherited diseases have weak immune systems. Additionally, transplant and cancer patients taking some types of immunosuppressive drugs have weak immune systems.
For these people, probiotics can be dangerous, Dr. De Latour explains. She says that the risk of harm is small but present enough to warrant caution. Preliminary research presented at the American Association for Cancer Research meeting this year also supports the idea that probiotics might be dangerous if you’re being treated for cancer. “Based on our early results, cancer patients and doctors should carefully consider the use of over-the-counter probiotic supplements, especially before beginning immunotherapy treatment,” senior author of this new research Jennifer Wargo, MD, said in a statement. That said, you should consult a doctor about the risks associated with probiotics if you have reason to believe your immune system isn’t as strong as it should be.