True or false: Drinking too much coffee can cause a magnesium deficiency

Like a lot of people, I’m a big coffee drinker. Sometimes just the promise of a frothy oat milk latte is what gets me out of bed when it’s cold outside and I’d rather hit the snooze button. Which is why I wasn’t exactly thrilled when a friend told me my favorite morning ritual could be completely obliterating my magnesium levels.

Magnesium might not get as much press time as collagen or calcium, but the multitasking mineral has over 300 roles in the body. A few of the tasks in magnesium’s job description: helping with cognitive function, supporting the immune system, providing energy, keeping the heart strong, improving muscle function, and strengthening bones.

Women ages 19 and older should be getting between 310 and 320 milligrams of magnesium a day from their diet, and more if they’re pregnant. Some of the best sources of magnesium include leafy greens, nuts, soy, legumes, fruit, fish, and (score) dark chocolate. (There are lots of different kinds of magnesium supplements that can help you get your daily dose, too.)

However, coffee may not play so nicely with your bod’s magnesium supply. “There are a few very anecdotal studies that show that when you drink coffee, the intestinal lining actually has a drop in its ability to absorb magnesium,” says internal medicine and gastroenterologist Niket Sonpal, MD. He says that some researchers found that there was an association between people who drank lots of coffee and magnesium deficiency.

However, Dr. Sonpal says there are some caveats. Most importantly, coffee doesn’t directly cause a magnesium deficiency. “The coffee isn’t leeching the magnesium out,” he explains. “The coffee itself [may reduce] your intestine’s ability to absorb [magnesium], which over time can result in a magnesium deficiency.” Another thing to note: Many of these studies are small or performed on rats, so the relationship still needs more study.

“When it comes to coffee and magnesium, you shouldn’t worry about it, but you should be mindful of the connection.” —Niket Sonpal, MD

Despite the correlation, Dr. Sonpal says it’s really nothing to get too hung up on. “What I tell my patients who are coffee drinkers is that as long as your diet is generally healthy, you’ll get enough magnesium from your diet that it will balance out.”

Zandra Palma, MD, an integrative doctor at Parsley Health, agrees. “Coffee—or caffeine in general—is not the primary reason people become deficient in magnesium,” she says. (Phew!) She says that while it’s difficult for most women to get that 310 milligrams a day, it’s not because people are suddenly obsessed with Bulletproof coffee or oat milk lattes. “Because of modern farming practices, our soil is less nutrient rich than it used to be, which then means the plants and animals we eat have less nutrients.” (People are likely also not eating enough magnesium-rich foods in the first place.)

The only sure way to know if you’re getting enough magnesium—whether you’re a coffee drinker or not—is to get your levels checked via a blood test at the doctor’s, Dr. Sonpal says. He recommends anyone who drinks more than two cups a day of coffee get checked if they’re feeling concerned. According to the NIH, signs of a magnesium deficiency include muscle tremors, feeling weak, nausea, and loss of appetite.However, a lot of these symptoms are similar to having too much caffeine, Dr. Sonpal says, making it hard to pinpoint what’s going on—which is why he says it’s so important for people to get their levels checked if they’re experiencing these symptoms.

What Dr. Sonpal doesn’t recommend: Deciding to take a magnesium supplement on your own without talking to your doctor first. “Just like too little magnesium isn’t good, too much is bad too,” he says, explaining that a surplus can cause delayed reflexes, brain fog, and irregular heartbeats.

“When it comes to coffee and magnesium, you shouldn’t worry about it, but you should be mindful of the connection,” Dr. Sonpal says. As long as you’re generally feeling good, you can enjoy that cup of coffee worry-free.

While we’re on the subject, here’s the verdict on if coffee is good for you. And this is the whole deal on how CBD coffee works—because chances are it’s about to be on the menu of your favorite cafe.