When people are strong and reliable, we describe them as solid, yet the human body is about 60% water. Let’s face it: even the toughest among us is less like concrete, and more like a walking water balloon. Water is essential to most of our bodily functions, like carrying nutrients to our cells and keeping the brain sharp. The problem is that we’re constantly losing water through sweating, peeing, and breathing. We must do our part to keep the balloon full. We must drink fluids.
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Drinks are absorbed and retained better when paired with minerals commonly found in food like sodium, potassium, and chloride. It’s important to replenish these minerals, called electrolytes, during tough, lengthy exercise, as sweat ushers them out of the body.
Cue the electrolyte products. Commercials show our favorite pro athletes boosting their electrolytes with sports drinks, powders, and gels—with looks of deep satisfaction etched on their faces—but does the average person actually need these supplements?
Charge up hydration
Electrolytes are key to hydration, mainly because they enhance fluid retention. “Having more electrolytes can trigger more efficient fluid uptake from the gut,” says Kim Barrett, a gastrointestinal physiologist at the University of California, Davis and spokesperson for the American Gastroenterological Association.
Sodium is the most important electrolyte for staying hydrated. When it’s consumed, sodium hangs around the exterior of cells, where its positive electrical charge attracts water molecules into the bloodstream and tissues. Think of sodium-rich water encircling the cells as “the sea water we took with us” when our ancient ancestors left the oceans to live on land, says Craig Horswill, a professor of exercise and nutrition at the University of Illinois, Chicago. Electrolytes help ensure healthy hydration at the cellular level.
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A negatively-charged electrolyte, chloride, clings to sodium, supporting electrolyte balance, Horswill says. Other kinds, also found in food, prevent sodium levels from cresting too high, which could cause the body to retain excess water, straining the heart and kidneys. Potassium is an electrolyte that offsets sodium by getting the kidneys to filter its salty cousin from the bloodstream. “Sodium, chloride, and potassium are the primary ones to consider,” Horswill says.
If you rely only on plain water without replacing these electrolytes, you’ll start getting headaches and muscle cramps. Eventually, more serious health problems will develop, says Stavros Kavouras, a professor of nutrition and director of the Hydration Science Lab at Arizona State—like swelling of the brain.
He points to another benefit: people actually end up drinking more water when it contains electrolytes. Otherwise, we often drink too little. “One benefit of sodium is that it maintains the drive to keep drinking and reduces the risk of dehydration,” says Mindy Millard-Stafford, a physiology professor at the George Institute of Technology and director of the Exercise Physiology Lab.
Find the salty sweet spot
But how many electrolytes, especially sodium, do we need?
The normal range for sodium in the body is narrow: the minimum is 135 mg per liter of blood, with the max just a little higher at 145 mg. It’s rare for people to drop below the minimum, partly because electrolytes are so plentiful in food, and partly because light sweat contains relatively few electrolytes during casual exercise.
“Unless there are significant electrolyte losses during illness or heavy, prolonged sweating, most electrolytes can be replenished by a healthy diet,” Millard-Stafford says.
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It’s also “very challenging” to get too many electrolytes, Barrett says. But that doesn’t mean you should eat pickles all day, she adds, especially for those with hypertension. Some populations, including African-Americans, tend to have more salt sensitivity. Meanwhile, extremely high potassium levels can be toxic.
Who really needs electrolytes?
It turns out that electrolyte supplements, popularized through ads featuring sweat-drenched pro athletes, are mostly useful for…sweat-drenched pro athletes. But these supplements can also benefit us exercise-commoners in certain situations.
One example is people working outside throughout the day in high heat, such as construction workers, delivery drivers, landscapers, and farm laborers. “Workers exposed to hot environments for over two hours need to start replacing electrolytes,” says Hayden Hess, a professor of exercise science at the University of Buffalo. If they just drink water, “they’re essentially diluting the blood.”
In these conditions, guidance from the U.S. Centers for Disease Control and Prevention recommends having fluids every 15-20 minutes while prioritizing electrolytes—and this doesn’t necessarily mean downing sports drinks. Workers can refuel electrolytes with meals and snacks.
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Similar advice applies to lengthy leisure activities. When hiking for several hours on a warm day, for instance, “electrolytes could become important for maintaining optimal hydration,” Kavouras says.
Another example is training for a long-distance race in hot weather. “Beyond two or three hours, the electrolyte imbalance starts to become an issue, and supplementing becomes important—or you could just salt food a bit more,” Kavouras says. Research shows that when fluid loss results in overall body mass dropping by just 2%, sports performance starts to decline, and the risk of heat illness rises.
With shorter exercise—say 30 minutes to an hour—you may not need any electrolyte supplements. Your levels won’t change much, Kavouras says. “You’ll complete your electrolyte needs by eating regular foods.”
Salty sweaters, beware
Some people need to replenish electrolytes more than others. “Whether replacing them is warranted depends on the individual, particularly with salt-loss sweat,” Millard-Stafford says.
People vary widely in how much they lose—from 200 all the way up to 1,800 mg of sodium per liter of sweat. One study found that 20% of runners were salty sweaters. A separate but related issue: how much you sweat overall. “The worst combination is if you’re a salty sweater and a heavy sweater,” Kavouras says. Those who perspire salty and heavy may have large electrolyte losses with shorter workouts, making supplements more important. Commercially available tests can determine your sweat type.
Another individual difference is how much salty food you regularly consume. Most people in the U.S. consume too much (up to 2,300 mg of sodium is recommended per day, yet the average of American clocks in at 3,400), negating the worry that they’re not getting enough electrolytes. . However, certain diets such as raw vegan and the MIND diet contain far less salt, perhaps justifying an electrolyte supplement.
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Kids are vulnerable to dehydration. They often don’t consume enough fluids, and about 20% drink no water. During hot exercise, a sports drink with electrolytes could help. Research has found that kids given a low-sugar drink with electrolytes consume more liquid compared to kids given water. “They prefer the taste,” Kavouras says.
A supplement could also help people exercising in warm conditions for the first time in a while, Horswill says. “As we get heat-adapted and fit, the body does a better job of reabsorbing sodium rather than losing it in sweat.”
When in doubt, listen to your body. You may get cramps or feel lightheaded when you’re becoming dehydrated. Another measure is what’s happening in the bathroom. Light yellow urine suggests optimal hydration with balanced fluid intake and electrolytes.
Optimize your electrolytes
When exercising for hours at a time, options abound for boosting electrolytes, such as drinks, powders, and salty snacks like rice crackers.
The best type comes down to personal preference. “They all get into your system with the same end results, once they’re in your intestine and dissolved,” Barrett explains. An advantage of the drinks is that they deliver both electrolytes and fluids. “The pills and gels are more portable, but you’ve still got to get the fluid into the body,” Barrett says.
Supplements can vary widely in their ingredients, Hess says. Many sports drinks have significant sugar content for refueling energy, while providing fewer electrolytes than what’s lost through sweating, Horswill says. He suggests aiming for a supplement with more electrolytes: around 1,150 mg of sodium per liter.
And go easy on the sugar. Electrolyte supplements with lower sugar levels “help transport fluids into the blood” for better absorption, Hess says. Up to 14 g of sugar per 8 oz. is optimal for quick fluid absorption during and right after exercise, according to Horswill. Even less, about 7 g, could be ideal if the supplement includes only the glucose form of sugar.
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Amino acids, the building blocks of protein, also seem to support hydration when combined with electrolytes. More research may reveal whether sugar or amino acids make the better hydration partner for electrolytes, Millard-Stafford says. For now, “a complete fluid replacement beverage would ideally contain electrolytes, sugar, and maybe amino acids,” Hess says. Pedialyte, for example, provides a good ratio of sugar to electrolytes, experts say.
Some sports drinks have caffeine, which could deplete electrolytes since caffeine is a diuretic, increasing urination in theory. But caffeine has this effect only at high levels: more than 400 mg, Millard-Stafford says. Moderate intake of tea and coffee, below 400 mg of caffeine, are as effective for staying hydrated as water, she adds.
Combining different beverages throughout the day works well for hydration, especially if they naturally contain electrolytes. Coconut water is an option with electrolytes and low sugar that may support hydration, according to some studies. However, because coconut water is higher in potassium than sodium, it could be less hydrating than typical sports drinks when exercising, Horswill says.
Millard-Stafford points to low-fat milk, which offers electrolytes, carbs, and amino acids. However, “milk could cause gastrointestinal distress during exercise,” Barrett notes. It does a body good for replenishing electrolytes after exercise.
The perfect electrolyte potion probably hasn’t been alchemized just yet. “I wouldn’t be surprised if we come up with a new recipe for optimal hydration in a few years,” Kavouras says.