Dietary Magnesium


DarkChocolateMagnesium is the fourth most abundant mineral in the body and is essential for good health. Approximately 50% of total body magnesium is found in bone, with other half found predominantly inside the cells of body tissues and organs. Only 1% of magnesium is found in the blood.

Biological roles in the body: Magnesium helps to maintain normal muscle and nerve function, keeps heart rhythm steady, supports immunity, and helps keep bones strong. Dietary magnesium also helps regulate blood sugar levels and promote normal blood pressure, while it is also known to be involved in energy metabolism, protein synthesis and the bioactivity of vitamin D and other vitamins.

Deficiency: Specific deficiency syndromes are rare in humans, but lower than normal levels are commonly seen during micronutrient testing. Low levels can be an indicator of chronic poor intake of green vegetables, nuts, beans and fish, or could alternatively be a response to recent illness or medical treatments such as diuretics, antibiotics, painkillers and steroids, which can impair absorption or increase renal excretion. A number of chemotherapy agents can deplete magnesium (mg), particularly cisplatin, oxaliplatin and erbitux (cetuximab). If you are receiving these drugs, it’s advisable to make an extra effort to eat more food containing Mg. Very low levels can cause fatigue, insomnia, poor memory, muscular cramps, tremor, fasciculation’s, muscle weakness and an increased risk of nausea, low mood and peripheral nerve damage during chemotherapy. Severe deficiency can cause abnormal heartbeats (arrhythmia), prolongation of the QT interval, muscle spasms, delirium and hallucinations.

The RDA is between 320 – 420 mg/day. Optimal serum levels are between 0.7-1.0 micromols/l, while red cell magnesium levels should be between 2.1-3.0 mmols/l.

What foods provide magnesium? Real chocolate is one of the best sources of magnesium. The problem is that most chocolate products have high sugar content. Even dark chocolate varieties have a lot of added sugar, but there are some 100% chocolate brands available with no added sugar which can be bought on the internet from single plantations. These are very bitter, but to make them palatable, they can be broken up and mixed with fruit, making them both delicious and healthy. Fish such as halibut are good sources, while green vegetables such as spinach, kale, seaweed and spirulina are also rich in mg because the centre of the chlorophyll molecule (which gives green vegetables their colour) contains Mg. Some legumes (beans and peas), nuts and seeds, and whole, unrefined grains are also good sources of magnesium. Refined grains are generally lower in Mg as products are stripped of Mg-rich germ and bran when they are refined and processed. Tap water can be a source of Mg, particularly if from a “Hard” water area. In general, eating a wide variety of green vegetables, legumes, nuts, whole grains, as well as seafood, will easily help you meet your daily dietary requirement for Mg.

In summary, common sources of dietary magnesium include:

  • Dark chocolate with no added sugar (100g)- 150mg
  • Swiss chard, spinach (one cup) – 150mg
  • Pumpkin seeds (1/8th cup) – 150mg
  • Almonds and cashew nuts (30g) – 80mg
  • Halibut (60g) – 75mg
  • Soybeans (30g) – 75mg
  • Beetroot and  rocket salad leaves (30g) – 75mg
  • Black-eyed or black beans (½ cup) – 60mg
  • Kale, dark green cabbage (1 cup) – 60mg
  • Shredded wheat (2 biscuits) – 55mg
  • Yogurt, Kefir (1 cup) – 50mg
  • Oatmeal, instant, fortified (1 cup)-  50mg
  • Potato, baked with skin (1 medium) –  50mg
  • Peanuts (30g) –  50mg
  • Baked Beans, Kidney Beans ( ½ cup) – 50mg
  • Broad beans or peas (½ cup) – 50mg
  • Whole wheat cereal, branflakes (1 cup) – 45mg
  • Lentils (1 cup) – 40mg
  • Long grain rice (1 cup) – 35mg
  • Wheat germ (2 tablespoons) – 30mg
  • Avocado  (1 medium) – 30mg
  • Banana (1 medium) – 30mg