Overhyped: “Electrolyte packets hydrate you faster than water.”

Overhyped

Evidence confidence Moderate

The short answer

Electrolyte packets have not been shown to get water into your body faster than plain water.

What this means for you

For everyday drinking, plain water does the job, and a packet has not been shown to get water into you faster. A packet as salty as a rehydration solution helps your body keep a little more of what you drink, which matters most after hours of heavy sweating, when you need to replace salt as well as water. Liquid I.V.'s "faster" promise rests on its own testing.

Your next step

Drink water for everyday hydration, and save electrolyte drinks for long, sweaty activity.

Who should be careful?

Safety note: Electrolyte packets add sodium. Too much sodium may raise blood pressure in some people and can cause a serious buildup of fluid in people with heart failure, liver cirrhosis or kidney disease. Adults with high blood pressure are advised to keep sodium to 1,500 mg a day or less.

Talk to a healthcare professional if: you are vomiting or have diarrhea and cannot keep fluids down, or you have high blood pressure, heart failure, kidney disease or liver cirrhosis, or you have been told to limit salt or fluids.

Why this confidence?

Small controlled trials show that some drinks, including milk and medical rehydration solution, help the body keep more fluid than water, but keeping more fluid is not the same as absorbing it faster. A university lab test found extra salt did not make water reach the blood any faster, and no independent study has tested a packet's speed; the trials are small, short and partly industry funded, so confidence is moderate.

The facts

Electrolyte packets have not been shown to get water into your body faster than plain water. Drinks as salty as a medical rehydration solution, and milk, do help your body hold on to a bit more of what you drink, about 10 ounces more out of about 34 ounces (1 liter) over 4 hours in one lab test. That extra matters most after long, heavy sweating.

The bigger picture

Liquid I.V. says its packets give "faster hydration than water alone" and are "over 30% faster at 3 hours." That number comes from a study by a lab whose director sits on the company's science advisory board. So far it is out only as a short conference summary, and the company lists the full report as a manuscript still in preparation. Its other study, run with a member of its science advisory board, measured how much fluid people kept, not speed. In a university lab test of 20 men, raising the salt in a sugary drink from none to a high level did not change how fast its water reached the blood. A drink with a little sugar (3%) got its water into the blood slightly faster over the first hour than a drink with no sugar (about 7% more by the lab's tracer measure), while more sugar (6% or 9%) slowed it down. Neither group tested plain water. That study was funded by GlaxoSmithKline Consumer Healthcare. In a separate trial, 72 healthy men at rest each drank about 34 ounces (1 liter) of different drinks. A medical rehydration solution and milk led to about 10 ounces less urine over 4 hours than water (about 35 versus 45 ounces), but a sports drink with less salt did no better than water. That trial measured how much fluid stayed in the body, not how fast it got there. For comparison, the rehydration solution in that trial had about 1,260 mg of sodium per liter. One Liquid I.V. lemon lime stick has 500 mg of sodium and is meant for 16 ounces (about half a liter) of water, which is close to that level.

Do electrolyte drinks help you rehydrate after heavy sweating?

Yes. In a lab study, 6 men who sweated off about 2% of their body weight in the heat drank 1.5 times what they had lost. With a nearly salt-free drink, they were still about 23 ounces short 5.5 hours later, and with a drink about as salty as a sports drink, about 12 ounces short. With the two saltiest drinks, about as salty as a medical rehydration solution or more, they ended up about even. The more salt the drink had, the more of it the body kept.

Sources (5)

“Electrolyte packets hydrate you faster than water.”

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