Here’s What’s Actually Going to Happen to You if You Eat Super Old Butter

There are some fridge staples I run out of on the reg. It seems like I’m always buying eggs or another half gallon of oat milk. But butter on the other hand, sits in my fridge for literally months on end. Maybe it’s because I don’t make Bulletproof coffee every morning and I’m not much of a baker, but it takes me forever to run out of the stuff. Which made me wonder: When does it reach the point when it’s not safe to eat anymore?

I did some digging and tapped an expert to find out. Apparently, there are a lot of people out there who have ancient butter in their fridge, including this person who put four year old butter on her baked potato. Fortunately, scientists have actually studied this. They meticulously monitored butter kept in the fridge and found that it can last about six months with no gross bacteria growing on it and no changes in texture or flavor. In another study, scientists found that after 10 months, there actually still wasn’t enough harmful bacteria on refrigerated butter to lose any sleep over it. So it turns out when kept in the cold, butter can last for a long damn time.

But what happens when you’re like the lady who ate four-year-old butter? Will it leave your stomach, er, churning? (Sorry! Sorry!) The first thing to know: Don’t panic—old butter can’t kill you. “Butter is a special type of food,” says Benjamin Chapman, PhD, a professor and food safety extension specialist at North Carolina State University and the host of the podcast Food Safety Talk. Dr. Chapman explains that since butter is structured with the fat on the outside and the bulk of water on the inside, the fat serves as a protective layer of sorts, preventing bacteria to form. “The microbes that we’re concerned about when it comes to food safety need water to grow,” he says. “It won’t grow on fat.” If you have salted butter in your fridge, Dr. Chapman says you’re even more in the clear. “Microbes don’t like salt,” he says, saying they’re less likely to grow in foods with a high concentration of the mineral.