Why Can’t We Drink Salt Water?

Most sports drinks, such as Gatorade, are designed to hydrate us even better than plain water because they’re loaded with electrolytes. Electrolytes are what we call various minerals essential to our basic life functions, including the two that make up salt — sodium and chloride.

We lose these minerals as we perspire (which is why sweat is so salty), so electrolyte drinks help replenish them in addition to quenching your thirst. But if salt is made of purely electrolytes, why can’t we just take in a mouthful of salt water to replenish our energy? After all, it’s common knowledge that you can’t drink seawater because, rather than rehydrate you, it dehydrates you.

So what makes the salt in Gatorade healthier than the salt in the ocean? The answer is quantity, not quality.

Everything in Moderation

While it would certainly make things easier when it comes to spending time out on the ocean, drinking seawater isn’t an option for humans. A pinch of salt in our blood is a good thing, but high salt content affects kidney function and can lead to high blood pressure, strokes, and heart attacks. 

Salt is composed of two elements: sodium and chloride. Among other roles, the elements are used by our nerves to communicate with one another, using it to send signals and impulses throughout our body. It’s also employed by our body to contract and relax our muscles, so we actually need it to move around. 

On average, we humans require around 500 mg of sodium each day for the element to properly do its job. When we consume salt through food, it’s diluted with the intake of freshwater that we drink directly or through water-based drinks and foods. This helps our kidneys remove any excess salt from the bloodstream through urine.

When you ingest too much salt in comparison to the amount of freshwater you’ve taken in, our kidneys struggle to remove the excess salt from your bloodstream. Even if you drink a lot of seawater, being unable to flush out the salt not being used by your body actually makes you more thirsty, not less.

And if you can’t get enough freshwater to bring your salt-to-water ratio down, water from other parts of your body, such as muscle tissue, will be used in an attempt to dilute it. Borrowing this water needed elsewhere in your body is what makes you dehydrated, which can cause sickness and even be fatal in extreme cases.

A Pinch of Salt

But if you’re thinking: “If salt is an electrolyte, then it should help with hydration, not make it worse,” here’s the difference. The salt you ingest during or after a particularly tough workout or a few hours spent in the sun typically comes through a water-based sports drink, snacks, or a meal.

These electrolyte solutions have a far smaller proportion of salt than seawater does, and the freshwater it includes also helps flush any excess sodium chloride from your blood. Electrolytes, whether from a sports drink or a banana, also help relieve symptoms of electrolyte imbalance (including brain fog, fatigue, irritability, and more), which can be caused when you lose too much electrolytes through sweat. 

That’s why it’s a good idea to pack a salty snack or your favorite Gatorade flavor alongside your largest reusable water bottle before working up a sweat at the beach. The ocean is for swimming, not drinking.