By Courtney Sperlazza, MPH
Reviewed by Emily Gonzalez, ND for Scientific Accuracy

Article at a Glance:

  • Magnesium is involved in tons of body processes. This makes magnesium deficiency difficult to identify because it looks like a lot of other conditions, from fatigue to memory problems.
  • Low magnesium is caused by factors like stress, medicines, alcohol consumption, certain medical conditions—and even our food.
  • Keep reading for magnesium deficiency symptoms, the causes of low magnesium levels and how to get more magnesium in your diet.

It’s hard to pinpoint magnesium deficiency as the source of your troubles when the mineral is involved in so many seemingly unrelated functions in your body. Think about it: If you haven’t pooped in three days, you’re snapping at your kids and you keep losing your car keys, would you think that all of those trace back to the same thing—let alone low magnesium?

We’re diving deep into what symptoms of magnesium deficiency can look like and what makes them happen in the first place.


First things first: Plenty of people don’t get enough magnesium in their diet and can benefit from adding more of it—but there’s a difference between not getting enough magnesium in your diet and true magnesium deficiency.

That’s one reason we can be grateful for kidneys: When dietary intake of magnesium is low, as it often is, the kidneys prevent magnesium from being excreted in the urine. This prevents true deficiency in most situations. Neat.

So, we’re really talking about the side effects of magnesium insufficiency—which is one of those things that tricks doctors. It looks like a lot of other conditions, since magnesium is involved in so many of your body’s processes. About half of the U.S. population is not getting enough magnesium in their diet. And if you’re insufficient, the effects can range from mildly annoying to serious.

If your magnesium intake remains too low for an extended period of time, here are the most common signs of low magnesium in the body that can start to appear:

  • Muscle weakness, aches and pains
  • Migraines
  • PMS
  • Irregular sleep patterns and insomnia
  • Heart irregularities
  • Anxiety and depression
  • Digestive trouble and constipation
  • Brain fog and memory problems
  • Loss of appetite
  • ADHD

The tricky thing is, you can have a magnesium insufficiency and display some of these symptoms, but you may have no noticeable symptoms at all. Ignoring the signs isn’t worth the gamble—especially when magnesium is one of the cheapest, most abundant supplements you can get.


Dietary intake of magnesium isn’t quite as simple as it was back in your great-great-grandparents’ time. With mono-cropping and soil depletion, your vegetables don’t take up as many minerals from the soil as they used to.

Natural spring water used to be a reliable source of minerals, too, but it’s way more likely you’re drinking filtered water from a bottle or your fridge. If you have public water, more than likely it contains fluoride, which depletes magnesium even further.

The good news is, magnesium supplements are super cheap and easy to come by. Once you find the type that’s right for you, you can feel the effects fairly quickly.


If you have low magnesium levels, you want to hang onto as much magnesium as you can. These things can work against you, depleting your body of magnesium and causing malabsorption:

  • Over-the-counter and prescription medicines: A wide range of medicines, like antacids, antibiotics, birth control pills, blood pressure medications (diuretics), stomach acid blockers (proton pump inhibitors) and more cut into your magnesium stores.
  • Chronic diseases: Crohn’s disease, kidney disorders, celiac disease, digestive disorders, type 2 diabetes, low stomach acid and other conditions can affect magnesium absorption and retention.
  • Alcohol consumption: Occasional drinks are fine, but regular alcohol consumption destroys your mineral stores, especially magnesium. You can tell drinking throws off your electrolyte balance because you wake up thirsty, puffy and bloated—all at the same time.
  • Stress: Stress kicks magnesium from the inside of your cells to the space outside your cells, which makes your kidneys excrete it faster. If you have stress here and there, you have enough magnesium to recover. But chronic stress tanks your magnesium, which is one of the reasons you want to manage your stress levels for everyday wellness. (Good news is, Bulletproof Zen Mode contains magnesium—plus a blend of adaptogenic herbs and nutrients—to support your body’s stress-busting abilities.)


You have two options to test your magnesium status: with the help of a health professional or at home.

If you’re wondering how to test for magnesium deficiency at home, start with an at-home blood test kit. Before making that commitment, it’s important to note that true deficiency isn’t the same as low magnesium levels, and blood tests for magnesium don’t always give you exact results.

Your body stores over half of its magnesium in the bones and soft tissues, which requires you to test your intracellular magnesium levels—not your serum magnesium (which is what an at-home blood test would do).

For the most accurate results, set up an appointment with your healthcare provider and ask for the magnesium RBC test. This test measures the amount of magnesium stored in your red blood cells, which gives you an indication of how much magnesium your body has in reserves in your bones and soft tissues.


If your results fall below 6.0 mg/dl, you’ll want to supplement. If they’re measured in mmol/L, multiply that number by 2.43 to get mg/dl, and see how close you are to 6.0. This is a functional level. Most labs report a “normal” range, but since everyone’s requirements can vary, work with your doctor to interpret your results.

It’s a good idea to check your vitamin D and calcium levels while you’re at it, since they all depend on each other for function and absorption. In fact, you could prevent osteoporosis by keeping these vitamin levels in check. (Supplementation with vitamin D is a great idea anyway because most people don’t get enough, but we digress.)


We’ve taken a look at what causes magnesium deficiency, and we’ve established that low magnesium can lead to a range of symptoms. But magnesium insufficiency can also affect your body in ways you might not expect, from mental clarity to muscle function. Keep reading to find out how low magnesium affect your body’s normal processes.


A lot goes on in your brain because of the intricate network of electrical wires in your neural tissues. Every thought and movement you make is formed from teeny electrical impulses, firing all day, every day across the billions of neurons in the brain.

Wavering moods, mental clarity, attention problems and anxiety seem like distinct conditions, but they all have a common thread: They signal that the mitochondria (the structures that power your cells) in your brain are struggling.

Turns out, the levels of magnesium determines how much energy your mitochondria make. The available energy in your brain determines:

  • How clearly you think
  • How intensely you can focus
  • How calm or anxious you feel
  • How happy you feel
  • How you respond to stress

Having adequate amounts of magnesium can help regulate your brain’s everyday function.


Your body relies on magnesium to help regulate your bowels, detox your liver and eliminate and produce hormones. When these processes don’t happen like they should, you can encounter some pretty gnarly symptoms.

When you eat, your food mixes with saliva and stomach acid to form what’s known as a bolus, a semi-solid lump of food that moves through the digestive system and gets broken down by various enzymes.

To move efficiently, it has to be soft, and to be soft, the bolus has to have sufficient water content. Magnesium draws water into the bowels and stimulates peristalsis, or the “waves” of muscle contraction that keeps everything moving.

Without enough magnesium, the bolus of food can be dry and stiff, which slows everything down and causes constipation.

Pro tip: Looking for ways to support healthy digestion, aside from dietary magnesium? Reach for the prebiotics in Bulletproof InnerFuel Prebiotic. Want a dose of collagen protein in an all-in-one gut health supplement? Bulletproof Gut Health Collagen Protein has you covered.


Premenstrual syndrome (PMS) points to an excess of estrogen. One of the main ways your body gets rid of estrogen is through the bowels. When your digestive system works well, your body produces and secretes estrogen at a good pace for your body. When things slow down with low magnesium intake, estrogen hangs out in your intestinal tract too long.

Whatever estrogen doesn’t leave the body in a timely fashion goes right back into the bloodstream and stacks on top of the estrogen you’re already producing.

If you’re constipated or have slow digestion because of low magnesium, you might also experience PMS relief by supplementing with magnesium.

Related: The Best Women’s Vitamins and Supplements in 2021


Not only does magnesium help keep you regular, but it is also crucial for detox in the liver, which also neutralizes excess estrogen.

In the liver, estrogen metabolites are converted to water-soluble molecules so you can get them out quickly. Without sufficient magnesium, this process slows way down.

Magnesium is also critical in your body’s production of sex hormones that balance estrogen, including progesterone and testosterone. On top of that, most sex hormones are manufactured when you’re snoozing, and good magnesium levels improve sleep.


Have you ever cramped up during a run, felt your eyelids twitching or taken a gasp from fluttering in your chest? It’s all from nerve cells getting over-excited and firing too much.

How and when nerve cells fire depends entirely on electrolyte balance—the concentration of sodium and potassium ions on either side of the cell’s membrane. A portion of electrolytes switch places when the nerve cell fires. Magnesium steps in when there are imbalances. When there’s not enough magnesium available, there’s no stopping an over-excited neuron, and no waking up a lazy one.

Too much firing, and magnesium will slow down ion exchange. When there aren’t enough nerve impulses, magnesium will kickstart the exchange process.

Every muscle in your body depends on magnesium to keep this system working properly. If you experience any of the following signs, you might need more magnesium for your nerves and muscles to play nicely together:

  • Heart rhythm irregularities, palpitations or “flutters” also known as arrhythmias in the medical world
  • Muscle spasms
  • Muscle cramping
  • Restless leg syndrome
  • Twitching eyelids, lips or skeletal muscle
  • Nightly leg cramps, especially in pregnancy

Symptoms like these can have a root cause other than magnesium deficiency, and some conditions are serious and require medical attention. Always run your concerns by your doctor and get their medical advice before making any changes.


Increasing magnesium intake can be as simple as eating more magnesium-rich foods, trying out topical options or taking a supplement. For a general rule of thumb, the recommended dietary allowance (RDA) of magnesium for women is about 320 mg of magnesium per day and about 420 mg per day for men.

It’s pretty tough to get too much magnesium or magnesium toxicity from food. However, some forms of magnesium used in supplements can cause GI upset and diarrhea. Don’t go over 350 mg per day of magnesium specifically taken from supplements—that’s the established upper tolerable intake.

The good news: A magnesium supplement up to 350 mg per day is enough for men to reach that RDA (and definitely help women get to the RDA).


Dietary magnesium comes from various animal and plant-based foods, which makes it easy to fit into any type of diet. Here are a few foods with high magnesium content:

  • Seeds, such as pumpkin and chia
  • Nuts like cashews and almonds
  • Green vegetables, especially leafy ones like spinach
  • Legumes including black beans, kidney beans and edamame
  • Salmon
  • Chicken breast
  • Bananas
  • Potatoes
  • Whole grains
  • Tap, mineral, and bottled water (depending on the brand and source)

Pro tip: Foods that contain magnesium and tryptophan offer a dual-angle approach to enhancing mood and mental clarity. Tryptophan is a precursor to serotonin, the brain chemical that makes you feel happy, focused and calm. Eat foods with both tryptophan and magnesium to support your mood and get a mental boost, such as dark chocolate, salmon, spinach and avocados.

Some of these foods don’t fit into every diet—you’re not eating whole grains on keto, for instance. It’s a good rule of thumb to get as much supplementation through your diet with the foods you do eat, and to fill in the gaps, use a magnesium supplement.


Some forms of magnesium absorb through the skin, which makes topical magnesium effective for muscle relief. For muscle cramps or spasms, spray on magnesium oil, which isn’t actually oil at all. It’s magnesium chloride, which feels slippery because it’s slightly more basic than water.

Another topical solution: Take a bath with epsom salts, which are magnesium sulfate crystals. How much you’ll absorb depends on how deficient you are and your body’s other nutrient levels, particularly vitamin D.

Pour 1-2 cups of epsom salts into your bath a couple times a week to get a boost, and drink plenty of water when you’re done soaking.


If you don’t have time for a bath, magnesium supplementation could address certain magnesium deficiency symptoms. There are 10 or so more common types of magnesium supplements on the market, and they have slightly different applications. For example, magnesium threonate supports memory and brain function, while magnesium citrate is great for muscle relaxation.

You may also notice magnesium in supplements combined with other essential nutrients for targeted support. That’s what you get with Bulletproof products—science-backed blends of ingredients to help you feel and perform your best.

Sleeping problems? Have a soothing night cap with Bulletproof Sleep Collagen Protein, which combines magnesium citrate, chamomile and melatonin to give you a more restful slumber.

Feeling stressed? Bulletproof Zen Mode provides a mixture of magnesium citrate with adaptogenic herbs to keep you feeling tranquil, calm and focused.

Try a few different magnesium formats—powders, capsules or baths—to find what works for you, and pay attention to how you feel. Because magnesium regulates hundreds of processes in your body, it’s a mineral supplement worth looking into. Magnesium is a safe supplement to experiment with to see if it helps you feel like the best version of you.

What other essential nutrients are you missing? Check out the best supplements that almost everyone should take.