Most of us know that sugary, calorie-laden beverages are terrible for our health. But what might happen if you constantly drink soda instead of water? One real-world case study presented in Athens, Greece, at the European Heart Rhythm Association meeting, examined such an extreme case, according to a story reported by LiveScience.

In Monaco, a small country near southern France, a 31-year-old woman was taken to the hospital after she mysteriously fainted. She had no family history of heart or hormone problems. But when doctors tested her heart’s electrical activity, results showed she had long QT syndrome. The condition causes an erratic heartbeat. What’s more, her blood tests revealed that she had dangerously low potassium levels. After doctors questioned the woman, they learned that since the age of 15 she’d drank no water, just soda—two full liters of cola each day, for all those years.

Researchers who evaluated this case also reviewed similar reports. According to the scientists, too much sugary cola can cause excess water to enter the bowels and lead to diarrhea and potassium loss. In addition, high amounts of caffeine in soda can increase urine production and decrease the body’s ability to reabsorb potassium.

Potassium is an essential mineral that regulates the heartbeat. Low levels in the body may cause heart rhythm problems, such as the palpitations this woman experienced. “One of the take-home messages is that cardiologists need to be aware of the connection between cola consumption and potassium loss,” said Naima Zarqane, MD, a cardiologist at Princess Grace Hospital Centre in Monaco.
But there was some good news for this patient: After one week of not drinking soda, her potassium levels and heart activity returned to normal.

Researchers said they wanted to pursue further studies to check whether heavy-duty cola drinkers have lower potassium levels than those who don’t drink the sugary soda.
Wondering what soft drinks are good for you? Here’s a list of the top five beverages to support a healthy lifestyle.