Magnesium: What Does It Do and Should You Supplement?

What does magnesium do?

Magnesium is involved in over 300 enzymatic functions in the body, meaning that it is a crucial mineral for almost every system in the body. It plays a role in protein synthesis, muscle and nerve function, blood glucose control, blood pressure regulation, energy production, oxidative phosphorylation, glycolysis, structural development of bones and synthesis of DNA and RNA and is required for conducting nerve impulses, contracting muscles, and even the heart beat itself. Put simply, we need adequate magnesium to enjoy good health.

That's why it's so unfortunate that magnesium deficiency has become extremely, extremely common (many esteemed experts estimate about 70% of the world population!). So how can you tell if you're one of the many people who would benefit from increasing your magnesium intake?

I've listed some of the most common symptoms below, but there are many, many more given how broad the roles of magnesium are (remember, it's involved in over 300 enzymatic processes!):

  • low mood/depression
  • anxiety and nervousness
  • poor memory and concentration
  • facial twitching
  • high trigylcerides
  • weight gain
  • PMS
  • heart palpitations
  • fatigue
  • constipation
  • blood sugar imbalance
  • high cholesterol
  • insomnia
  • restless leg syndrome
  • muscle cramps
  • irritability and mood instability

We know that magnesium deficiency plays a role in cardiovascular disease/hypertension, type 2 diabetes, osteoporosis, and migraine headaches, and many in the health community suspect that it also plays a role in the development of a number of other diseases. I can tell you that from my own clinical experience, magnesium deficiency seems to be involved in many other pathologies, including the development of neuropsychiatric imbalances. In any case, given the diverse roles that magnesium plays within the body, maintaining adequate levels is obviously necessary for optimal health.

Unfortunately no exceptionally accurate and satisfactory tests currently exist to measure levels of magnesium. While serum magnesium concentration is the most commonly used test, serum levels may not in fact reflect overall magnesium stores as only 1% of total magnesium resides there. Another 50-60% exists within the bones, and most of the rest in the soft tissues of the body. So you can still be magnesium deficient even if your blood tests appear normal. As is always the case, it is best to go by your symptoms and how you feel in general.

Should you take magnesium supplements?

I use magnesium supplementation frequently in my practice. For anyone who is at high risk for deficiency (e.g. those with GI disease, diabetes, cardiovascular disease, alcoholism, those over 50 years old, those who eat very few leafy greens), it's a no-brainer, but I have noticed that more and more people who don't fall into the high-risk category show signs of sub-optimal magnesium stores. Why? Our bodies burn through magnesium when we are under stress. Given that our modern day lives seem to be characterized by mental, physical, and environmental stress, most of our magnesium stores have been depleted!

I suggest that anyone with, or at high risk for, any of the diseases that have been definitively shown to be related to magnesium deficiency (e.g. diabetes, cardiovascular disease, asthma, and migraines) supplement. And I believe that anyone with sleep disturbances, depression/anxiety, cognitive dysfunction, and stress intolerance would benefit greatly from supplementation. 

If you are unsure whether you need more magnesium, you can start by increasing your intake of magnesium-rich foods and see how you fare. Good food sources of magnesium include leafy green vegetables (especially spinach and chard), pumpkin seeds, almonds, black beans, dark chocolate, figs, cashews, salmon, yogurt/kefir, avocado, banana, and coriander. It's important to note that only about 30 - 40% of dietary magnesium is actually absorbed into the body, and many people - even those who eat plenty of these foods - still require supplementation to restore adequate magnesium levels. So if your symptoms persist, then it's worth trying supplementation for a period of time.

What kind of magnesium supplement should you take?

Magnesium supplements come in several forms with varying degrees of absorption. I tend to favor magnesium glycinate in my practice as it is well absorbed and very well tolerated. For people with constipation/anyone who is using the bathroom less than once per day, I recommend taking magnesium oxide to address the constipation piece in addition to magnesium glycinate to increase magnesium stores in the body.

No adverse effects have been documented from the ingestion of magnesium by any food sources, but toxicity can occur with supplementation if you are consistently taking very high doses. The most common symptom of excessive magnesium supplementation is diarrhea, and longer term elevated serum levels of magnesium can result in hypotension (low blood pressure). As always, it's best to use supplements under the care of a nutritionally-focused healthcare provider.

Now tell me... Do you take magnesium supplements? Have you noticed any differences since starting?