Instead, experts suggest spacing out coffee and magnesium intake.
On social media, some people are suggesting adding magnesium to coffee, claiming it can offset the jitters, energy crashes, and anxiety that caffeine sometimes causes. While there's no evidence that it can do this, combining the two might have other effects.
In theory, the coffee-magnesium combination makes sense. is a stimulant and can leave people feeling wired, anxious, or even a little sick to their stomach if they're sensitive to it or have had too much. Magnesium, on the other hand, has relaxing properties and is often promoted for reducing anxiety and improving sleep.
However, while some clinical trials suggest that magnesium could have these effects, the benefits are generally small, Morgan Walker, MS, RD, LDN, sports dietitian and adjunct professor at Lebanon Valley College, told Health.
As for the claim that magnesium can cancel out coffee's stimulant effects, there's simply no scientific evidence to support it. "There is not enough research to say definitively that it can offset caffeine-induced jitters, tension, or sleep disruption," Walker said.
Plus, magnesium isn't absorbed for four to six hours, while caffeine typically takes effect within 30 minutes, noted Erin Barrett, PhD, senior director of scientific affairs at Shaklee, a supplement company.
Taking magnesium with coffee is unlikely to have any unique positive effects, experts said -- but there's a slight chance it could actually have a negative one: reducing absorption of the mineral.
Caffeine is a diuretic, meaning it helps your kidneys get rid of excess water and salt. "Some studies have shown temporary increases in urinary magnesium excretion after caffeine intake," Walker said. The effect is generally insignificant, she added, but could contribute to lower magnesium levels overall in people who consume large amounts of caffeine and don't get enough magnesium through their diet.
Mixing caffeine with certain types of magnesium -- such as magnesium sulfate, citrate, and oxide -- could also have you running for the bathroom, since both have a laxative effect, Barrett said.
For some people, getting more magnesium -- which helps balance fluid and support the nervous-system, muscle function, and energy production -- is necessary.
"Studies suggest that more than half of adults fail to meet the recommended daily intake of magnesium, and low intakes have been linked to an increased risk of obesity, type 2 diabetes, , osteoporosis, and other conditions," Walker said.
But given the potential negative side effects of combining magnesium with coffee, experts suggest spacing out intake instead.
Rather than starting with a supplement, both Barrett and Walker recommended first eating more magnesium-rich foods, such as:
And if you're experiencing coffee jitters, Barrett suggests simply reducing intake rather than turning to magnesium as a fix. "People can always give it a try and see if it works," Barrett told Health, "but my recommendation would be, if you're experiencing jitters, cut back on your caffeine."