Are Electrolyte Supplements Safe During Pregnancy?

I’m pregnant and like to work out and usually drink an electrolyte supplement with my water (LMNT, Nuun, etc.). Are these safe in pregnancy?
—Dehydrated mom

I feel like sodium and electrolytes are having a moment (maybe this is just because I spend many hours listening to podcasts about endurance exercise). In contrast to a more traditional view that more sodium is bad, the current messaging is that we might actually need more sodium than we think, especially if you’re exercising and sweating.

This last point is important. If you are largely sedentary, then consuming a lot of excess sodium may not be a good idea. It’s not obvious that it’s a bad idea — I think the literature linking sodium consumption to health is mostly correlation and not causation — but it’s also probably unnecessary. You’ll excrete the excess sodium in your urine.

electrolyte bottles placed in a shelf — Shayna Douglas / Unsplash

However, when we sweat — through exercise or other ways — we lose sodium. Depending on your sweat rate, this could be 1,000 milligrams an hour or more. When we rehydrate, we also need to replace that sodium (and other things — but really, sodium is the key). If you only drink water, your electrolyte balance can be off.

For athletes, this can show up as a “bonk”: that feeling when you just literally cannot go anymore. It can be more dangerous than that in extreme cases; this is an interesting article about search and rescue in the Grand Canyon, where the advice to drink water only has been replaced with the need to add salty snacks.

There are a number of ways to replace sodium, but the drinks you mention are among them. LMNT has 1,000 mg of sodium in a packet — it’s salty, although I will say I love it, especially the fizzy version. Nuun has 300 mg; Skratch, Gatorade, etc. all have some sodium as well.

What about pregnancy? Hydration is important in pregnancy, as is electrolyte balance, and there is no reason to think the advice above would be any different. If you’re not sweating, it may be less necessary. If you are, it’s a good idea! The one caveat is that if you have hypertension, it’s worth talking to your doctor. The links between salt consumption and hypertension in pregnancy are not airtight, but in some cases this would argue for more restrictions.