Magnesium - Information and Sources

Magnesium is the fourth most abundant mineral in the body. Most is found in bone, but there are also high amount in cells of tissues and organs. Magnesium is involved in a huge amount of biochemical reactions in the body, including helping to maintain normal muscle and nerve function, keeping heart rhythm steady, supporting a healthy immune system and keeping bones strong. Magnesium also helps to regulate blood sugar levels, promotes normal blood pressure, and is known to be involved in energy metabolism and protein synthesis.

Dietary magnesium is absorbed in the small intestines and its metabolism is closely linked to calcium. Magnesium is excreted through the kidneys.

Magnesium deficiency is characterised by progressive muscle weakness, neuromuscular problems, heart problems and eventual death. Adult males should aim for 300mg per day, females 270mg per day.

Green vegetables contribute a good proportion to magnesium intake because the chlorophyll, which gives greens their green colour, contains magnesium. Wholegrain cereals are also great sources, but refined grains are low in magnesium as refining removed the magnesium rich germ and bran, so some cereal products are fortified with magnesium. Tap water can also be a source of magnesium but the amount varied according to supply; 'hard' water contains more magnesium than 'soft' water.

  • Spinach (130g) – 45mg
  • Muesli (95g) – 95mg
  • All-bran (45g) – 95mg
  • Bran Flakes (45g) – 60mg
  • Shredded Wheat (2 biscuits) – 55mg
  • Weetabix (2 biscuits) – 48mg
  • Special K (35g) – 19mg
  • Porridge oats (100g) – 18mg
  • Wheatgerm (2 tbsp) – 35mg
  • Wheat bran (2 tbsp) – 45mg
  • Wholemeal bread (1 slice) – 55mg
  • Granary bread (1 slice) – 40mg
  • Brown rice (50g) – 55mg
  • Almonds (25g) – 80mg
  • Cashew nuts (25g) – 75mg
  • Peanuts (25g) – 50mg
  • Peanut butter (25g) – 50mg
  • Mixed nuts (25g) – 65mg
  • Soya beans, cooked (100g) – 63mg
  • Kidney beans (50g) – 75mg
  • Chick peas (50g) – 65mg
  • Baked beans (200g) – 62mg
  • Potatoes, baked with skin (150g) – 48mg
  • Banana – 45mg
  • Avocado – 25mg
  • Halibut (85g) – 90mg
  • Natural yoghurt, low fat (150g) – 45mg
  • Plain dark chocolate (100g) – 100mg
  • Milk chocolate (100g) – 100mg