Staying hydrated—and knowing how best to do it—is more important than ever.
This summer’s excessive heat isn't just a hot spell, but rather a taste of what we can expect from climate change, says Ashley Ward, director of the newly opened Heat Policy Innovation Hub at the Nicholas Institute for Energy, Environment & Sustainability at Duke University: “This is not your grandmother's heat.”
To beat it, many of us now carry around water bottles, ready to quench a thirst at a moment’s notice. And on social media, videos about how best to stay hydrated can rack up millions of views.
But do we really need to down a gallon a day to stay healthy? And does your water need minerals, alkalinity, or salt to really hydrate you?
The important role of salt
The human body is upwards of three-quarters water. Most of it is absorbed by our cells; the rest lubricates muscles and tissues and generates saliva. Any noticeable loss of body moisture upsets the balance that keeps us healthy, alert, and alive.
The recommended daily intake, for a normal adult, is up to eight to 12 cups of water daily, according to the Mayo Clinic, but research published last year suggests that advice doesn’t take into account the water you absorb by eating certain fruits and vegetables like watermelon and cucumbers, or lifestyle factors like physical activity.
The more we sweat, the more water—and salt—we lose.
Salt helps maintain fluid balance through osmosis, which regulates the amount of water in the cells. Without sodium, cells could shrivel from dehydration.
The salt in our bodies is also important because it contains electrolytes—minerals such as sodium, potassium, and chloride—that carry an electrical charge through the blood and body fluids, keeping hydration at a healthy level.
Most professionals agree that electrolyte-enhanced drinks are valuable because they replenish the potassium and salt lost through sweat, but before you add salt to your water, keep in mind that most of us get the recommended amount of sodium in our diet.
But if you’re healthy and don’t have known heart problems, a sprinkling of salt in water won’t harm you and may help keep you hydrated. The type of salt doesn’t matter. The recent popularity of unrefined Himalayan, or pink, salt is based on the slightly higher number of minerals it contains. To replenish lost salt, it doesn’t take much—one-quarter teaspoon will do—and any salt-containing energy bar or snack also replaces lost electrolytes.
And water isn’t the only hydrating drink you can reach for—studies show that cow’s milk is more hydrating than plain water. Milk can slow the loss of fluid in the stomach, which helps maintain hydration over a longer time span, and it also contains those needed electrolytes.
Other additives and enhancements found in bottled water have become popular but aren’t proven to keep you any more hydrated than water from the tap.
Alkaline water, for instance, has a higher-than-average pH value that makes it less acidic, but to prevent dehydration, medical professionals say that the amount of water you drink—not pH levels—is more hydrating.
Studies are ongoing on the effects of alkaline water on athletic performance, and recent research has found potential benefits for the general public. According to the Arthritis Foundation, one study suggests that alkaline water with an 8.8 pH “permanently neutralized stomach acid”; another study showed promising benefits to bone density.
Dangers to drinking too little—and too much
Beware of false narratives that your body will tell you when it's thirsty, says Josh Beaumont, former trainer for women’s soccer at Arizona State University.
“That’s too late to really hydrate. Especially now in the hotter climates, we’re already in a bit of a dehydrated state,” he said, but cautions against just, “…slamming water. There's only so much water that the stomach and gut can absorb.”
It is also important to know which medications can interfere with the body’s natural ability to hydrate. Those that make the heat more dangerous include certain anti-depressants, diuretics, and blood pressure medicine, which can interfere with kidney function and electrolyte levels. People with diabetes, which already increases the need to urinate, need to closely monitor fluid intake.
In extreme cases, drinking too much water can create a condition known as hyponatremia, which is a response to a lack of salt. Hyponatremia is most often found in the elderly and among those who have kidney disease. But people can and do drink too much water, most recently a 35-year-old mother of two from Indiana.
According to news reports, she was “severely dehydrated” after a day of boating and drank 64 ounces of water in 20 minutes, way beyond the body’s capacity for absorption. She died from water toxicity, which caused the brain to swell and cut off its own blood supply.
How hydration keeps us cool—and safe
On a hot day, you may notice that your blood vessels seem closer to the surface of your skin or even swollen on your arms. That’s because the hypothalamus, the part of the brain responsible for keeping body temperature in homeostasis—is directing more moisture into the blood stream to help cool down the body’s surface as it sweats.
Be aware of your body and mindful of the circumstances. For example, if you stop sweating, that’s a bad sign, because the body is conserving the little fluid it has to keep blood pumping to your muscles.
At the cellular level, any substantial decrease in water going into the body—and the increase going out via sweat—triggers the hypothalamus gland in the brain to send out its own heat alarm. The first alarm hits the kidneys, which are instructed to stop withdrawing water from the blood. The end result, and a clue that something’s amiss, is infrequent urination.
The dropping levels of water in the blood makes blood pressure drop and the heart rate to spike. Throughout, the body is doing what it can to minimize the loss of this precious fluid.
Eventually, your internal temperature begins to rise because the body is incapable of cooling itself off. At that point, drinking water won’t help, warns Beaumont. First, the exterior body needs to be cooled down immediately with damp cloths, cold compresses, and ice packs. Emergency rooms in Phoenix have even brought in body bags filled with ice to revive the heat-stricken.
If you experience mild dehydration, without the above symptoms, rest in the shade or indoors with air-conditioning or fans; take a shower or pat down with a damp cloth to cool the body; and slowly drink water, plain or with electrolytes. “Chugging” water can intensify the imbalance between the body and its electrolytes, and it is hard on the stomach.
It can take upwards of an hour to fully recover.