Why Take a Magnesium Supplement

This is why everyone is *still* talking about magnesium

Feb 25, 2020

Magnesium: 12th on the periodic table and often last on our lists of nutritional concerns. Most would be surprised to learn it is involved in over 300 biochemical bodily reactions! With 60% of it found in bone, it is the world’s 4th most abundant mineral and is crucial to many of your body’s pivotal functions. The bad news: Stats Canada has confirmed that over a third of Canadians aren’t getting enough through diet alone, and a deficiency could lead to some unfavourable symptoms (see: cramps, high blood pressure, asthma, irregular heartbeat to start). Are you deficient? Should you consider supplementing? Here are some real reasons you should be keeping your eye on your intake.

Regulates blood pressure

Did you know that Canadian adults diagnosed with high blood pressure are 6 times more likely to be diagnosed with diabetes than those without? While lifestyle plays a significant role here, so does diet. Namely, magnesium intake. In a 3-month, double-blind, placebo-controlled trial of participants with hypertension, those who took magnesium supplements  lowered their systolic blood pressure by ~2mm of mercury (mm Hg), as well as their diastolic blood pressure by 1.8 mm Hg, compared to those who did not supplement.   

Responsible for muscle function (including your heart)

Yes, you read that right. Muscles need magnesium to contract; nerves need it to send messages. That also rings true when it comes to the most important muscle of all: your heart. Magnesium contributes to maintaining a healthy heartbeat and competes with calcium to relax your heart after it contracts, and it is that very interaction that helps to maintain a healthy heartbeat. When your magnesium levels are low, you leave room for calcium to overstimulate the heart, often resulting in an irregular heartbeat. Just like in the heart, magnesium acts as a calcium blocker to help your muscles relax. When you’re low on calcium, or experiencing hypocalcemia, your muscles go into overdrive, over-contracting and over-cramping/spasming/generally hurting. So the best bet? Balance. That’s why magnesium is often suggested to help calm muscle aches (and to help relax them at bedtime).

Used to make DNA

You wouldn’t know it by name, but magnesium is instrumental in creating, repairing and protecting both DNA and proteins! Refresher: DNA, or deoxyribonucleic acid (say that 3 times fast 😉) is a long, double-stranded molecule found at the core of our cells carrying the bulk of our genetic material. Magnesium is heavily involved here and even acts as a cofactor for DNA polymerase, an enzyme that repairs and replicates DNA.

Energy booster and mood regulator

Among the other wonders it performs, magnesium is also suspected to have its hands in the pot when it comes to mood and brain function. Magnesium activates ATP (adenosine triphosphate), which helps create energy in the body, helping it have an impact on mood and temperament. One study even found that people under 65 with low magnesium intake had a 22% greater risk of developing depression. While more research is needed here, it is suggested that magnesium could help curb depression, and has been shown as effective as some anti-depressants. On the lady circuit, magnesium has also been shown to improve mood, reduce water retention, and other PMS symptoms (like migraines)

Magnesium and menstruation

Let’s take a deeper dive on the PMS powers of magnesium. Turns out, a deficiency actually increases contraction in smooth muscles (i.e. cramps) and increases the levels of the inflammatory compounds responsible for period pains (what cripples many of us into the fetal). Magnesium has long been recommended to women experiencing the thrills of menstruation. Since it calms the nervous system, tempering headaches and moodiness, and helps to regulate stress-inducing cortisol, it’s no wonder its been dubbed the “miracle mineral”. 

Magnesium and pregnancy
Since magnesium helps to build and repair muscle tissue, a deficiency of it in pregnant women could lead to some very serious issues, including both preeclampsia and poor fetal growth. Since magnesium excretion through urination increases in pregnancy, soon-to-be-mums aged 19-30 should up their intake to 350 mg daily from the regular range of 310-320 mg. Bonus: some research suggests magnesium may help prevent leg cramps in pregnancy, so if you’re expectant and achy,  it would make good sense to consider adding more of it to your diet.


Did you know your body needs access to 10-20% more magnesium during exercise than when resting? That’s because we lose more nutrients when we sweat, namely sodium, chloride, potassium and, you guessed it: magnesium. Therefore, supplementing with magnesium has been said to improve athletic performance in athletes, the elderly and those suffering from chronic disease. And that doesn’t change in recovery! Magnesium helps release blood vessels and plays a key role in the regulation of blood sugar, including moving that same blood sugar into your sore muscles to rid them of lactate. Cramps are also caused by dehydration, which causes a mineral loss that can worsen muscle cramps. Ensuring you have enough electrolytes, including magnesium, while exercising can help temper muscle cramps. 

Not sure whether you’re deficient? Look out for these signs and signals:

  • Muscle weakness, spasms and/or cramping
  • Insulin resistance
  • High blood pressure
  • Irregular heartbeat
  • Low HDL
  • Tingling and numbness
  • Migraines

Where can you get it?

One of the most abundant minerals in the world, some of your favourite foods are the best sources. Here’s the skinny:

  • Pumpkin seeds: 46% of the RDI in a quarter cup (16 grams)
  • Spinach, boiled: 39% of the RDI in a cup (180 grams)
  • Swiss chard, boiled: 38% of the RDI in a cup (175 grams)
  • Dark chocolate (70–85% cocoa): 33% of the RDI in 3.5 ounces (100 grams)
  • Black beans: 30% of the RDI in a cup (172 grams)
  • Quinoa, cooked: 33% of the RDI in a cup (185 grams)
  • Halibut: 27% of the RDI in 3.5 ounces (100 grams)
  • Almonds: 25% of the RDI in a quarter cup (24 grams)
  • Cashews: 25% of the RDI in a quarter cup (30 grams)
  • Mackerel: 19% of the RDI in 3.5 ounces (100 grams)
  • Avocado: 15% of the RDI in one medium avocado (200 grams)
  • Salmon: 9% of the RDI in 3.5 ounces (100 grams)



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  • Iseri, L T, and J H French. “Magnesium: Nature's Physiologic Calcium Blocker.” American Heart Journal, U.S. National Library of Medicine, July 1984, www.ncbi.nlm.nih.gov/pubmed/6375330.
  • Jahnen-Dechent, Wilhelm, and Markus Ketteler. “Magnesium Basics.” Clinical Kidney Journal, Oxford University Press, Feb. 2012, www.ncbi.nlm.nih.gov/pubmed/26069819.
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  • Gröber, Uwe, et al. “Magnesium in Prevention and Therapy.” Nutrients, MDPI, 23 Sept. 2015, www.ncbi.nlm.nih.gov/pubmed/26404370.
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  • Office of Dietary Supplements - Magnesium. (n.d.). Retrieved from https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
  • Dominguez, J, L., Barbagallo, Mario, Fulvio, Bandinelli, … Luigi. (2006, August 1). Magnesium and muscle performance in older persons: the InCHIANTI study. Retrieved from https://academic.oup.com/ajcn/article/84/2/419/4881823

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