The Functional Medicine Complete Guide to Magnesium: Symptoms, Sources, and Supplements

Most Americans don’t get enough magnesium from their diets, which can put them at risk for mood problems, fatigue, chronic pain, heart rhythm issues, and more. As a functional medicine doctor, I've seen how the right form of magnesium supplementation, combined with magnesium-rich foods, can transform my patients' energy levels and overall wellbeing.

In this blog, I'll discuss magnesium and the crucial functions it serves in our bodies. You'll learn why many Americans have insufficient intake of this key mineral; the symptoms linked to low magnesium; and how to boost your magnesium through foods. I'll also share how I determine which form of magnesium supplement works best to address the magnesium-related symptoms I see in my patients.

Why you might be at risk of low magnesium

Magnesium is a mineral that plays a key role in the chemical reactions occurring in our cells. It serves as a cofactor (helper molecule) for over 300 different enzymes.1 These enzymes help drive what I call the "chemistry of life" — the countless reactions that build strong teeth and bones, support our nervous system, and keep our bodies functioning optimally.^1-4 Without adequate magnesium and other mineral cofactors, these essential processes can't work efficiently.

Unfortunately, research shows that a majority of Americans aren’t getting enough magnesium from their diets,5 putting them at risk for magnesium deficiency and its wide-ranging health consequences.

Symptoms that are linked to low magnesium

Not getting enough magnesium can cause numerous health problems, but the symptoms are often vague and non-specific (meaning they could point to many different conditions). This makes it challenging for your medical team to identify magnesium deficiency as a root cause of your symptoms.

The initial symptoms may include poor appetite, fatigue, muscle cramps, muscle twitching, and muscle spasms — all of which are quite common and easy to confuse with the ways MS often presents.

Because these symptoms are so general, magnesium deficiency often goes undiagnosed for months or even years.¹

Brain-related symptoms linked to low magnesium

Low magnesium can contribute to mood problems, increasing the risk of anxiety, depression, and sleep disturbances.^4,6 If you're dealing with MS or other autoimmune diseases, this is particularly important since you already face higher rates of these challenges.

Magnesium deficiency is also associated with increased leakiness of the blood-brain barrier (the protective boundary that controls what substances can enter your brain).^4,6 For people with MS, this increased permeability can raise the risk of developing new inflammatory brain lesions and experiencing relapses.

Pain and magnesium

Magnesium has been used as adjunct therapy for people with a wide variety of neurological and psychiatric conditions, including chronic pain management.^1,6-9

Magnesium helps to regulate muscle contraction and relaxation. Without sufficient magnesium, your muscles struggle to relax properly, leading to increased muscle tightness, spasms, and chronic back and neck pain.

Magnesium also plays a role in how your nervous system processes pain. It works by inhibiting NMDA receptors (specialized proteins that can amplify pain signals).

In addition. magnesium is involved in modulating chronic pain by inhibiting N-methyl-D-aspartate (NMDA) receptors. This is particularly relevant for people with MS and other neurological diseases, where damage to spinal cord or brain tissue can lead to chronic pain that becomes amplified over time.¹⁰
Given the increased risk of bone thinning and fractures in MS, it’s critical to pay attention to your magnesium intake, not just vitamin D, K2, or calcium.

Heart symptoms and magnesium

If you've noticed heart palpitations or irregular rhythms, consider this — magnesium helps control the electrical impulses in your heart, playing an important role in regulating your heartbeat.

Without sufficient magnesium, there's a greater likelihood of abnormal electrical activity in the heart. This can lead to serious heart rhythm problems, including atrial fibrillation (irregular heartbeat) or, in severe cases, more dangerous cardiac events.^11,12 For these reasons, maintaining adequate magnesium levels is particularly important for overall cardiovascular health.

Food sources of magnesium

So how can you improve your intake of this important mineral? Start with green leafy vegetables. Magnesium is the central ion in chlorophyll (the green pigment in plants), making leafy greens one of nature's best magnesium sources.

Unfortunately, most Americans don't eat nearly enough green vegetables, which contributes to widespread magnesium deficiency.¹ The good news is that adding more greens to your diet can make a significant difference.

If you're concerned about oxalates (compounds that can contribute to kidney stones in sensitive individuals), I recommend focusing on kale, collards, parsley, lovage, and algae rather than spinach, Swiss chard, and beet greens. These lower-oxalate options provide excellent magnesium while also delivering calcium and other important minerals.

How to choose the right magnesium supplement for you

Many of my patients benefit significantly when they add a magnesium supplement to their routine, reporting more energy, better moods, and improved sleep. The key is choosing the right form based on your specific symptoms and health goals.

For digestive issues: Magnesium citrate

If constipation is your main concern, I often recommend magnesium citrate. This form isn't absorbed as well by your body, but that's actually the point — most of its effect comes from drawing water into your bowels and easing constipation.

For brain and neurological symptoms: Magnesium threonate

If you have neurological or psychiatric symptoms, you need a form of magnesium that can actually reach your brain. Magnesium threonate is the only form that reliably crosses the blood-brain barrier. ^13-15 I typically recommend magnesium threonate at bedtime for patients with brain-related symptoms.

When I work with patients, I do a thorough assessment of their symptoms and background so I can recommend the most effective form of magnesium supplement. I then monitor the magnesium levels in their red blood cells to see if they’ve reached optimal levels.

Given magnesium's critical role in brain function and muscle contraction, I want to make sure my patients have sufficient levels to support all those essential cellular reactions.

Summary

Most Americans aren't getting enough magnesium from their diets, putting them at risk for a wide range of health problems. If you're experiencing unexplained fatigue, mood issues, muscle pain, or heart palpitations, magnesium deficiency could be playing a role.

The best approach combines magnesium-rich foods — especially green leafy vegetables and algae — with the right supplement for your specific needs. For brain-related symptoms or chronic pain, I recommend magnesium threonate since it's the only form that reliably crosses the blood-brain barrier.

If you suspect magnesium deficiency might be affecting your health, consider working with a functional medicine practitioner who can assess your individual needs and monitor your progress through proper testing

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Citations

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