Though some believe carbonation can help alleviate upset stomach and constipation, carbonated water isn’t necessarily any better or worse for you, nutritionally, than still water. It depends on the waters in question.

“The perfect water would be rich in magnesium and calcium and low in sodium chloride,” says Roberta Anding, director of sports nutrition at the Texas Medical Center, and a dietitian for the Houston Texans football team. According to a study in the American Journal of Medicine, that means more than 48 milligrams of magnesium and 85 milligrams of calcium per liter, and fewer than 195 milligrams of sodium per liter. Just because water has bubbles, either because they’ve been forced in by the manufacturer or because they occurred naturally from a spring, doesn’t mean it also contains more or less of certain minerals than still water.

Many believe carbonated water contains higher sodium levels than still. This isn’t true. Sometimes it does, sometimes it doesn’t. Oftentimes, you can find out how much sodium your carbonated water has by reading the label. The FDA doesn’t require manufacturers to list levels, but many do. (If your fizzy water came from Europe, it definitely will, as required by EU law.) If the water you’re drinking contains a lot of sodium, it can contribute to high blood pressure. But it may also have health advantages. A 2004 article in the Journal of Nutrition found that fizzy waters with higher sodium levels reduced cholesterol levels and the risk of cardiovascular problems in postmenopausal women.

The studies don’t differentiate between soda water, seltzer water, club soda, or any of the other names under which carbonated water is sold. This is probably because those terms have no legal meaning. The only type of carbonated water the FDA has a standard for is sparkling water. It must come from its source naturally carbonated (though carbonation that’s lost during processing can be added back artificially). Other kinds of carbonated water might be naturally or artificially carbonated, and may or may not have added minerals.