What is magnesium?

Magnesium is a mineral found in abundance in the body, naturally in many foods, and added to other food products. Magnesium is a cofactor for many enzyme systems that regulate protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. It is also required for energy production, oxidative phosphorylation and glycolysis. Magnesium contributes to the structural development of bone and is required for the synthesis of DNA. More than half of the body’s stored magnesium is found in the bones, with some also found in soft tissues and blood.

Magnesium levels in the body are controlled by the kidneys, which excrete about 120 mg of magnesium into the urine daily.1

How much do I need?

For males 19-30 years of age, Health Canada recommends 400 mg per day of magnesium.

For males 31 years of age and older, Health Canada recommends 420 mg per day of magnesium.

For females 19-30 years of age, Health Canada recommends 310 mg per day of magnesium.

For females 31 years of age and older, Health Canada recommends 320 mg per day of magnesium.2

How does magnesium affect my health?

Some studies show that people who consume a diet higher in magnesium have a lower risk of some types of heart disease and stroke. However, these individuals may also consume other foods which are contributing to these positive effects.

People with higher amounts of magnesium in their diets tend to have a lower risk of developing type 2 diabetes. Magnesium helps to break down sugars in the body and can reduce the risk of insulin resistance.

Magnesium is also important for maintaining healthy bones. Individuals with higher magnesium intakes have a higher bone mineral density, which reduces the risk of bone fractures and osteoporosis.3

Which foods contain magnesium?

In general, foods containing dietary fibre provide magnesium and 30-40% of dietary magnesium is absorbed by the body. Green leafy vegetables, nuts, seeds, and whole grains are good sources. Choose whole grains rather than refined grains because the refining process removes the nutrient-rich components of grains, which also substantially lowers magnesium content.

  • tempeh – 116 mg per ¾ cup
  • almonds – 80 mg per 1 oz
  • spinach – 78 mg per ½ cup
  • black beans – 60 mg per ½ cup
  • lentils – 52 mg per ¾ cup
  • peanut butter – 49 mg per 2 tbsp
  • brown rice – 42 mg per ½ cup cooked
  • oatmeal – 36 mg per 1 packet
  • kidney beans – 35 mg per ½ cup
  • banana – 32 mg per fruit
  • avocado – 22 mg per ½ cup1,4

Am I at risk of magnesium deficiency?

Magnesium deficiency is characterized by loss of appetite, nausea, vomiting, fatigue, and weakness. Extreme deficiency can cause numbness, tingling, muscle cramps, seizures, personality changes and an abnormal heart rhythm.

Magnesium deficiency due to low dietary intake in otherwise-healthy people is uncommon because the kidneys regulate magnesium levels in the body. If the body is low in magnesium, urinary excretion of magnesium is limited. Habitually low intakes or excessive loss of magnesium due to certain health conditions, chronic alcoholism, and/or the use of certain medications can lead to magnesium deficiency.

Certain groups in the population may be more susceptible to magnesium inadequacy due to low consumption or medical conditions that reduce magnesium absorption or increase losses in the body. These groups include:

  • people with gastrointestinal diseases – Crohn’s disease, celiac disease, and regional enteritis
  • people with type 2 diabetes
  • people with alcohol dependence
  • older adults1

Do I need a magnesium supplement?

As mentioned earlier, magnesium deficiency in healthy individuals is uncommon. Consult with your physician if you are concerned about your magnesium status.

Health Canada recommends all individuals stay below 350 mg per day of magnesium from supplements and medication only. Magnesium supplement intake above this amount can cause diarrhea, nausea, and abdominal cramping. Extremely high intakes can cause an irregular heartbeat and even cardiac arrest.2,3


  1. National Institutes of Health – Office of Dietary Supplements. (2020, March 24). Magnesium – Fact Sheet for Health Professionals. Retrieved from https://ods-od-nih-gov.subzero.lib.uoguelph.ca/factsheets/Magnesium-HealthProfessional/
  2. Health Canada. (2006, June 29). Dietary Reference Intakes. Retrieved from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-elements-dietary-reference-intakes-tables-2005.html
  3. National Institutes of Health – Office of Dietary Supplements. (2020, March 24). Magnesium – Fact Sheet for Consumers. Retrieved from https://ods-od-nih-gov.subzero.lib.uoguelph.ca/factsheets/Magnesium-Consumer/
  4. Dietitians of Canada. (2016, June 10). Food Sources of Magnesium. Retrieved from https://www-pennutrition-com.subzero.lib.uoguelph.ca/viewhandout.aspx?Portal=UbY=&id=JMbrXAM=&PreviewHandout=bA==

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