Magnesium: The Mineral Doing More Than You Think
45% of Americans are magnesium deficient. But it’s essential for a reason. This mineral has a big job description!
by Caylin Cheney, Advanced Registered Nurse Practitioner
This post is the second in a new series here on the blog where I walk through individual supplements — what they are, what the evidence actually shows, and whether I think they're worth your time and money. The first one covered creatine. Next up: magnesium.
Key Takeaways
Magnesium is an essential mineral involved in hundreds of processes throughout your body, from muscle function to sleep to mood regulation.
Many people don't get enough through diet alone, but deficiency and excess both come with distinct symptoms worth keeping an eye out for.
Not all magnesium supplements are the same — different forms are better suited to different goals, from sleep support to digestion to muscle recovery.
The best way to know if you actually need to supplement is to talk it through with your provider, ideally with labs to back up your care plan.
Magnesium might be the supplement I get asked about most after creatine. In fact, Google searches for “magnesium” are up 30% over the last year, with a lot of chatter driven by wellness trends on social media.
It's marketed for everything from better sleep to less anxiety to fewer muscle cramps. Some of that is well-supported by the evidence and some of it is oversold. Let's walk through what magnesium actually does in your body, how to know if you need more of it, and how to choose a supplement if you do.
What is magnesium?
Magnesium is an essential mineral, meaning your body needs it to function but can't produce it on its own, so you have to get it through food or supplements. It's the fourth-most abundant mineral in your body, and most of it is stored in your bones and soft tissue, with only a small amount circulating in your blood at any given time.
But despite how important it is, something like 45% of Americans are magnesium deficient.
What role does magnesium play in our bodies?
Magnesium is a mineral that our bodies use in hundreds of different ways – and because it’s involved in so many processes, having too little or too much of it can cause lots of different problems.
And it’s not just us! Plants use magnesium as an essential part of photosynthesis to turn sunlight into energy. So it makes sense that our bodies use it for so many vital purposes, as well.
For example, magnesium plays a role in these functions (and more!):
Sleep regulation, via its role in calming the nervous system
Muscle and nerve function, including muscle relaxation and contraction
Energy production at the cellular level
Blood sugar regulation and insulin sensitivity
Blood pressure regulation and cardiovascular health
Bone structure and density
Because it touches so many systems, low magnesium can contribute to things like fatigue, poor sleep, muscle cramping, and mood changes without always presenting as an obvious single issue with an easy solution.
How much magnesium do I need and where can I get it?
Recommended daily intake varies by age and sex, but most adults should shoot for 310–420 mg of magnesium per day, with needs slightly higher during pregnancy.
Many Americans aren't hitting that target. Most people get around 250–350 mg of magnesium a day from food, depending on their age, sex, and what they eat. That's usually 50–100 mg short of what they're supposed to get, but sometimes more.
It's not a dramatic shortfall, but it's part of why mild, low-grade magnesium insufficiency is so common and so easy to miss.
What foods are rich in magnesium?
Magnesium is available in a wide variety of foods, so many people can close that gap through diet alone. Here's roughly how much you'd get from common sources:
Pumpkin seeds (1 oz, about a small handful) — 156 mg
Spinach, cooked (1 cup) — about 157 mg
Almonds (1 oz, about 23 nuts) — 80 mg
Black beans, cooked (1 cup) — about 120 mg
Quinoa, cooked (1 cup) — about 118 mg
Avocado (1 medium) — about 58 mg
Dark chocolate (1 oz) — about 50 mg
Salmon, cooked (3 oz) — about 26 mg
A day that includes a handful of pumpkin seeds or almonds, a cup of cooked spinach, and a serving of black beans, for example, gets you well over half of the daily target before you've even thought about supplementing with a magnesium powder or pill.
I always recommend eating a diet rich in veggies, whole grains, and whole foods like these no matter what, so adding these into your diet if you’re not already getting them is a great idea!
What are the symptoms of a magnesium imbalance?
Low magnesium can show up as muscle cramps or twitches, fatigue, weakness, irritability, poor sleep, headaches, or in more significant deficiency, irregular heartbeat and numbness or tingling. Mild deficiency is fairly common and often goes unnoticed because the symptoms are so nonspecific.
Too much magnesium from food alone is extremely rare, since your kidneys are good at clearing excess. It's much more likely to happen from supplementation, particularly at high doses. Symptoms of excess typically start with gastrointestinal upset (nausea, cramping, and diarrhea) and in more serious cases can progress to low blood pressure, irregular heart rhythm, or confusion. This is more of a concern for people with impaired kidney function, since the kidneys are what clear excess magnesium from the body.
Do I need a magnesium supplement?
This is where I always encourage patients to loop in a provider rather than guessing. A standard blood magnesium test only reflects a small fraction of your body's total stores, so it isn't a perfect tool, but combined with a conversation about your diet, symptoms, medications, and health history, it gives us a much clearer picture than symptoms alone.
Certain things can increase your risk of low magnesium, including a diet low in whole foods, high alcohol intake, gastrointestinal conditions that affect absorption (like Crohn's or celiac disease), type 2 diabetes, and certain medications. If any of that sounds like you, it's worth bringing up at your next visit.
There are so many options! What kind of magnesium supplement should I take?
If you and your provider decide supplementation makes sense, you'll also discuss which form makes sense for your needs. Here are a few options:
Magnesium chloride – most often used to treat magnesium deficiency as diagnosed by bloodwork
Magnesium glycinate — well absorbed and gentle on the stomach; the best option for sleep and anxiety support
Magnesium citrate — well absorbed, but has a laxative effect at higher doses, which makes it a good option for constipation relief
Magnesium oxide — a common supplement but not as well absorbed by the gut as other forms. It’s often used for heartburn, as a laxative, or for chronic migraines rather than for correcting deficiency
Magnesium sulfate (like Epsom salt) — often used topically, via baths or sprays, though absorption through skin is less well established in the science
As with any supplement, it’s better not to make it guesswork! The form, dose, and whether you need it at all really does depend on your individual health picture, and taking the wrong form, or an unnecessarily high dose, can just trade one uncomfortable symptom for another.
Should I use magnesium creams and sprays?
Topical magnesium — the oils, lotions, and sprays you rub onto your skin — has become popular, especially for muscle soreness and sleep. I’ll be honest, the evidence supporting meaningful magnesium absorption through the skin is thin. A few small studies suggest some magnesium may be taken up this way, but nothing close to the level of research we have behind oral supplementation, and there's no good data showing it reliably raises magnesium levels in the body the way a capsule or powder does.
That doesn't mean these products are useless. Some people genuinely find that a magnesium spray or an Epsom salt bath (magnesium sulfate) helps them relax or ease sore muscles. But that benefit may have more to do with the massage, the warm water, or the ritual of winding down than with magnesium crossing into your bloodstream. If it's part of a routine that helps you relax before bed and you’re not breaking the bank, there’s no harm in enjoying it.
Overall, what I don't recommend is relying on topical magnesium as your main strategy if you're trying to correct a deficiency. For that, food and oral supplementation are still where the evidence is strongest.
When I was pregnant and having trouble sleeping, part of my bedtime routine was using the Calm brand magnesium in a warm drink to wind down. So that’s another option to help wind down your day with magnesium!
The bottom line
Magnesium is essential for almost every function of our bodies, and it's common enough for people to fall a bit short that it’s a great thing to discuss with your provider.
Magnesium is usually part of a more comprehensive treatment plan rather than a magic pill! If you're dealing with symptoms that make you wonder about your magnesium levels, bring it to an upcoming visit so we can look at the full picture together.
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