Human World

Water, water, everywhere, but which to drink?

Heat waves, they’re so hot right now. Weather reports are starting to sound like a broken record of broken records, and it appears the northern U.S. is aiming to outdo the south in triple digit temperatures. But it’s hard to beat Texas, where I presently reside. When other states’ sidewalks are hot enough to fry eggs, ours can roast an entire turkey in less than five minutes.

Because I don’t drive, my daily commute involves two 30-minute bike rides in the blazing Texas sun. Coworkers express concern for my physical wellbeing, some insisting that I need to “drink something with electrolytes.” I often wonder if people pushing these beverages on me have any idea what an electrolyte is, or are just parroting copy they read on a billboard. There’s a dizzying volume of competing hydration options wedged between the beer and soda racks. It all seems like a bit of overkill. Can’t we just drink water?

What exactly are electrolytes?

Purveyors of sports drinks are proud of their electrolytes, but less eager to explain what the hell they are. Clearly electrolytes must be complex, almost magical ingredients that can be created only at the high tech laboratories of products containing the suffix “ade”. Right? (Warning: rhetorical question, do not attempt to answer.)

Actually, it’s pretty basic science. Electrolytes are ions (i.e., atoms or molecules that carry an electrical charge) in a solution*. These can be acids, bases or dissolved salts. Here’s an example: the salt sodium chloride (NaCl) is a neutrally charged solid. Throw it into water and it dissolves into the ions sodium (Na+) and chloride (Cl). Instant electrolytes. Btw, NaCl is table salt, and it makes up the bulk of the electrolytes found in sports drinks. A liter of Gatorade contains about half a gram of sodium.

Sodium is also the primary electrolyte lost through sweating. While perspiration composition (and rate) varies between individuals, according to the American Dietetic Association (ADA) the average is about one gram of sodium per liter of sweat. Sweating also expels a lesser amount of potassium, and even smaller quantities of magnesium, calcium and chloride.

Do I need a special beverage to replenish electrolytes?

That depends. Are you running a marathon? Does your job involve welding, or tarring roads, or perhaps fighting forest fires? Are you fasting or otherwise unable to eat solid food? If you’re nowhere close to any of these scenarios, you can probably pass on the sports drinks.

It’s not that you don’t need electrolytes. Electrolytes are great. The body uses these ions to power muscles and fire neurons. (Remember learning about the sodium potassium pump in Biology? No? Well, I assure you it exists.) But unless you’re partaking in strenuous exercise for long periods of time in hot weather, you’re not really hemorrhaging electrolytes.

Additionally, you don’t need to re-acquire them exclusively in beverage form. Food also supplies ions. Most people in developed countries are in greater danger of consuming too much sodium than too little. It’s redundant to down a bottle of technicolor salt water if you’re going to eat plate of French fries an hour later. The other predominant ion ingredient in sports drinks – potassium – can also easily be procured from food (bananas, spinach… hey, even potatoes are high in this mineral.)

It’s important to remember that the electrolytes in many sports drinks also come with a dose of added sweeteners and artificial colors, two things most of us can do without. A proposed beverage guideline published in 2006 in the American Journal of Clinical Nutrition advised that water can be guzzled with wild abandon, while sports drinks should be “consumed sparingly, except by endurance athletes”. Despite being heavily marketed to the general public, sport drinks are really designed for athletes. The rest of us are flattering ourselves if we think we need something beyond water after an air-conditioned 45-minute workout. But if you still feel compelled to drink your electrolytes, I’ll try to work with you…


Have you considered mineral water? Since minerals include salts, mineral waters can contain some of the same sought-after electrolytes found in sport drinks, albeit often in lower doses. You’ll want to have a look at the label though, as the mineral content varies considerably between brands. A 2001 paper published in the Journal of General Internal Medicine examined the mineral concentrations in various water sources. They found that while some mineral waters contained less than half the sodium of commercial sports drinks, others packed in twice the amount (over 1g/L).§

Even tap water, it turns out, contains some electrolytes, but this too varies from source to source. So-called “hard water” contains more minerals than soft water. At the time the study samples were taken, residents of Boston and Chicago were getting almost no sodium in their tap water, while the faucets in El Paso, TX were spewing out up to 160mg per liter (0.16g/L, compare that to 0.45g/L in Gatorade… about a third).

And then there’s coconut water. With the enthusiasm people have for this stuff, you’d think it contained illicit drugs, but allegedly it’s just the clear liquid found inside young coconuts (as opposed to the thick coconut “milk” sold in cans, which is really an emulsion made from coconut meat). I wrote about coconut water for one of my earliest Blogus scientificus posts and found that it had an electrolyte composition that was somewhat the reverse of sweat, i.e., more potassium and less sodium. But given the high sodium content of the American diet, that may actually be an advantage. Plus it doesn’t contain ingredients like “Red 40” and “Yellow 6.” You should note, however, that while you can get coconut water with no added sugar, it still harbors a fair bit of naturally occurring sugar.

Navigating uncharted waters

Not content to add salts and sugars to water, beverage makers are constantly striving to give consumers even more ingredients. Energy drinks offer caffeine (why anyone would prefer the taste of Red Bull to coffee I’ll never understand) others offer vitamins (not especially useful given that you can get already get vitamins in sugar-free pills… or food even, if you’re feeling traditional.) But by far the creepiest thing I’ve heard of in this realm are drinks promising psychological benefits – relaxation, better sleep, increased mental acuity – through the addition of ingredients like hormones and neurotransmitters. These dubious potions are classified as “dietary supplements” and can thus evade the stricter FDA regulations imposed on over-the-counter and prescription drugs.

Yet there are some worrisome components going into such beverages. Many of the sleep/relaxation concoctions contain the neurotransmitter precursor 5-HTP (5-hydroxytryptophan). The body uses 5-HTP to synthesize serotonin, a neurotransmitter involved in mood and targeted by a class of antidepressants (SSRIs). Is this really something we want floating around in our water? At best, it does nothing. Simply producing more neurotransmitter does not guarantee that it will be released in greater quantities in the brain (neurotransmitters need to reach receptors near the synaptic cleft between neurons to actually do anything useful). At worst, it supplies psychoactive drugs in unknown doses to people who may not need them.

Some of these products (such as iChill and Dream Water) are sold as 2.5 ounce shots. The small bottle may at least remind consumers that they’re ingesting something more akin to a pill than a drink. But Neuro Sleep – one of a series of Neuro drinks cheerfully packaged in Gatorade-esque colors – comes in a 14.5 ounce bottle, which seems like an invitation to drink it like ordinary water. (Also, am I the only one who thinks it’s a bad idea to consume almost half a liter of liquid right before going to bed?)

With the popularity of these beverages increasing, scientists are starting to express concern. A March 2012 editorial in Nature Neuroscience warned of the dangers of indiscriminate consumption of poorly tested ingredients, and urged improved regulation and labeling of such products. But the Internet assures us that, despite what these lab-coated killjoys might think, brain-tampering drinks get an enthusiastic seal of approval from a more important demographic – celebrities. Have a look. If the sight of Kim Kardashian and Paris Hilton clutching bottles of Neuro drinks doesn’t make you run screaming back to tap water, then I don’t know what will.

A matter of taste

While it’s reasonable to avoid beverages with excessive caffeine, sugars, and the laundry list of crazy crap in Neuro drinks, there’s something to be said for drinking what tastes good, or at least not awful. Taste, after all, influences consumption. One benefit of electrolyte rich beverages (including coconut water) is that their saltiness maintains a sensation of thirst, so you’re likely to drink more of them. If you hate water but are okay with Gatorade, I not going to come over there and knock the bottle out of your hand. Though you might consider diluting it a little. In our sugar saturated world, we’ve acclimated so much to sweetness that plain water now seems hopelessly bland. It’s too bad, because for ordinary daily hydration, water is still the best option. I’ve found I can coax myself into drinking more water simply by adding fresh lemon juice to it. You wouldn’t think it would make such a huge difference, but it does. In fact, we should probably just go ahead and start adding lemon to our municipal water systems. In the utopian future, kitchen faucets will have three knobs – hot, cold, and lemon.

* While electrolytes are typically dissolved in liquids, they can also exist in solid form.

I’m using an empty bottle of Gatorade G2 orange-strawberry (generously provided by a friend) as my reference, but obviously there are other sports drinks out there, so ingredients may vary.

Don’t confuse mineral water with spring water or distilled water, both of which are typically low in dissolved minerals. And while we’re here, let me also preemptively address your concerns about carbonated beverages and their potential effect on calcium levels. The link between carbonated drinks and low bone density is strongest with colas (implying that caffeine or some other cola component, rather than carbonation, may be the real issue.) If you’re still worried, you can always buy the non-carbonated mineral water.

§ The study only looked at sodium, calcium, and magnesium. They didn’t bother with potassium, which is a shame since, as we discussed, potassium is second after sodium in terms of electrolytes lost to sweat.

July 19, 2012
Human World

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