You've probably heard the food-world adage about how we shouldn’t consume oysters during months that don’t contain the letter 'R.' But does 'R' really stand for risk?

Technically, yes. Although, when it comes to eating commercially farmed oysters served in restaurants and sold in supermarkets, this old mnemonic can go out the window.

The idea of not eating oysters during months without an 'R' comes from the fact that the summer months are the prime breeding time for "red tides," or large blooms of algae that grow along the coast and have the tendency to spread toxins that can be absorbed by shellfish, including oysters. This is especially an issue for places with warm water temperatures, and eating locally raised seafood raises your risk of ingesting the toxins.

That said, commercially harvested seafood—which makes up a majority of the seafood sold in restaurants and supermarkets—is strictly regulated by U.S. law, which ensures it is safe to consume. Many restaurants often increase the size of their safety net by serving commercial oysters from cold-water climates during the months of May, June, July, and August.

So, while we wouldn’t recommend digging up your own oysters off the coast of Florida for a mid-summer backyard bake, there’s no reason to fear the product sold in stores or served in restaurants within U.S. borders any month of year, 'R' or no 'R.' But in case you prefer to play it safe, September is just around the corner.

A version of this article ran in 2013.