Sports drinks, she said, were designed to provide fluid and energy during exercise or physical labor, so they contain carbohydrates as well as electrolytes. “Electrolyte-infused waters can help maintain hydration but are not designed for improving exercise performance,” she said.
Although ingredients of sports drinks vary, those carbohydrates are often in the form of simple sugar. According to the U.S. Department of Agriculture, one popular sports drink, for example, has 79 calories, 140 mg of potassium, 299 mg of sodium and 21 grams (5 teaspoons) of total sugars per 12-ounce serving. Another sports drink has similar levels of sugars and calories but only 36 mg of potassium and 151 mg of sodium.
Although sugar can provide quick energy for an endurance athlete, most people are already getting too much, and the excess is linked to a variety of health problems. The AHA recommends limiting added sugar to 6% of total calories. For most women, that’s no more than 100 calories a day, or about 6 teaspoons. For men, it’s 150 calories a day, or about 9 teaspoons.
Meanwhile, some electrolyte waters contain only traces of minerals, while an electrolyte powder pack might be mostly sugar, along with sodium and potassium.
Rosenkranz said that some people, including pregnant women and people with kidney disease, need to be particularly cautious about taking in electrolyte supplements. Those conditions, as well as some blood pressure medications, can affect electrolyte balance. People in those categories should talk to their doctor and have their electrolyte levels checked.
“If you are taking electrolyte drinks, supplements or tablets, please be careful of not always assuming that more is better,” Rosenkranz said. Overuse of electrolyte drinks can be a problem, she said. Excess electrolytes can lead to heart rhythm issues, fatigue, nausea and more. “Interestingly, a lot of the same symptoms of getting too much can look like getting not enough.”