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Magnesium: What You Need to Know

By Ying Wang, BSc. Pharm. RPh.

Magnesium symbol on blue background

Magnesium is one of the most essential nutrients for maintaining good health. It is the fourth most abundant mineral in the human body and is required for the proper function of all of the body’s cells and organs.

More than half of our magnesium (~60%) is found in our bones. The rest (~30 to 40%) is found in our muscles and organs. Only 1% of our total magnesium circulates within our bloodstream.

Why is magnesium so important for optimal health? 

Magnesium is fundamental in countless processes that keep the body running smoothly. This is because magnesium is a cofactor in the myriad of chemical reactions that keep us alive. 

Enzymes are proteins that facilitate these chemical reactions—whether that’s breaking down food for fuel, or metabolizing toxins before they can do harm. For over 300 of these enzymes, magnesium is an essential partner.

One such reaction, perhaps the single most important, is the production of cellular energy. Every time a cell produces a unit of energy, called adenosine triphosphate (ATP), the ATP molecule must bind to magnesium in order to be biologically active. 

In short, magnesium is required for any process in the body that requires energy! In addition to cellular energy, magnesium is also responsible for stabilizing and repairing our DNA, regulating the way our nerves conduct signals, and ensuring that muscles relax after contraction. 

How do I know if I’m getting enough magnesium? 

Given that magnesium has such a crucial role to play in nearly all functions of the body, it comes as no surprise that a deficiency in magnesium can manifest in symptoms big and small, from head to toe.

Conditions associated with magnesium deficiency include: fatigue, headache, low mood and/or anxiety, poor sleep, muscle cramping, acid reflux, constipation, high blood pressure and high cholesterol, poor insulin sensitivity, osteoporosis, and more.

 human body diagram showing magnesium deficiencies

Magnesium is found in many whole food sources, such as leafy green vegetables, nuts and seeds, and legumes.

However, since magnesium is found in small quantities over a large wide variety of foods, it can be a challenge to consume enough magnesium through diet alone.

In Canada, more than 40% of adults over 30 do not meet the daily recommended intake of dietary magnesium: about 300mg/day for women, and 400mg/day for men.

In addition to poor dietary intake, many of us have risk factors for increased magnesium depletion: chronic stress, alcohol and caffeine use, poor dietary absorption, and drug induced depletion, just to name a few. 

If you are taking long-term medications, your pharmacist is a great resource for checking if any of your medications might be contributing to magnesium depletion.  

One complicating factor to assessing for magnesium deficiency is that testing for such is difficult. This is because lab testing evaluates the amount of magnesium in the bloodstream, called serum magnesium. 

However, only 1% of the body’s magnesium is found in the blood. This means that magnesium levels in the blood might not reflect true magnesium levels in the body; your serum magnesium levels might read normal, even when your total body’s magnesium levels are low. This means that diagnosing low magnesium requires a careful assessment of your whole-body symptoms, and risk factors for magnesium depletion, as well as lab values. 

So it’s always best to work with your healthcare provider.

Should I be taking a magnesium supplement? 

In addition to correcting or preventing magnesium deficiency, there are many other reasons why taking a magnesium supplement may benefit your overall health. Here are some other evidence-based benefits of magnesium supplementation: 

Preventing against cardiovascular disease 

Studies have linked a higher intake of magnesium to reduction of plaque build-up in the arteries, and a lower risk of heart attack and stroke. Taking supplemental magnesium seems to slightly lower blood pressure. Magnesium may also help to reduce the “bad” cholesterol (LDL) while raising the “good” cholesterol (HDL). 

Fighting type-2 diabetes   

Higher dietary magnesium has been associated with lower risk of developing type-2 diabetes. In patients who already have type-2 diabetes, supplemental magnesium may also decrease fasting blood sugar, and improve insulin sensitivity. 

Preventing recurrent migraine headaches 

Magnesium supplementation can help to reduce the frequency and severity of migraines. Migraine headaches can be debilitating. They are often treated with anti-pain medications—but overusing anti-pain medications can, in itself, cause even more headaches. Magnesium can play a crucial role in breaking this feed-forward cycle. 

Reducing chronic pain 

There is emergent evidence to support the use of magnesium in chronic pain management, particularly in nerve pain. Chronic pain is multifactorial and complex, but one of the key players in the pain pathway is the activation of the NDMA receptor. Magnesium acts to block this receptor, and in doing so, interrupts the pain signal.  

Improving insomnia 

Studies show that taking supplemental magnesium can help to improve sleep onset and sleep quality, particularly in older adults. 

Maintaining bone health 

We often talk about the importance of calcium when it comes to bone health, but research shows that magnesium is also essential in maintaining bone mineral density, preventing osteoporosis, and reducing fracture risk. 

In fact, one study showed that higher magnesium intake or supplementation reduced risk of osteoporotic fracture by 34%. 

It is important to note that there is such a thing as taking too much magnesium. Excessive magnesium supplementation can cause side effects, and can even be unsafe. 

People with low kidney function are less able to excrete excess magnesium, and thus are at higher risk of magnesium toxicity, which can be dangerous to the heart. Discuss with your healthcare provider whether magnesium supplementation is right for you. 

Which magnesium supplement is the best choice for me? 

There are many forms of supplemental magnesium, and not all are made equal. Here are the different types of magnesium supplements available, and how they may best be used:

Magnesium citrate 

This form of magnesium is bound to citric acid, a large molecule with mild laxative effects. While well-absorbed, magnesium citrate can cause loose stools, especially at higher doses. This is a great option for those looking for general magnesium supplementation, who might also suffer from occasional constipation. 

Magnesium oxide 

Magnesium oxide is poorly absorbed in the gastrointestinal tract. As such, it will not be as effective for increasing magnesium levels. It is, however, a highly effective antacid and laxative. 

Magnesium bisglycinate (glycinate) 

Magnesium bisglycinate is well-absorbed and less likely to cause loose stools compared to magnesium citrate and oxide. Additionally, glycine is an amino acid that also functions as a calming neurotransmitter in the body—hence, this form of magnesium is particularly useful in promoting sleep. Magnesium bisglycinate is a great option for those not requiring a laxative effect, while still providing optimal magnesium absorption. 

Magnesium taurate 

Taurine is an amino acid that, when bound to magnesium, minimizes the laxative effect that magnesium may otherwise cause. Taurine in itself may also be beneficial for cardiovascular health. Hence, magnesium taurate may be beneficial in those taking magnesium for its heart health benefits. 

Magnesium L-threonate 

This form of magnesium is unique in that it crosses the blood-brain barrier. Within the brain, magnesium may be beneficial for improving anxiety, depression and cognition.  

Ying Wang, BSPharm, RPh is a compounding pharmacist and pharmacy manager at Pure Integrative Pharmacy in Vancouver. She completed her degree in Bachelor of Pharmacy at the University of British Columbia. Her practice focuses on preventive medicine by integrating the best of conventional pharmacy with supplements, lifestyle management, and nutrition.