What is magnesium?

Learn about magnesium, a mineral required by the body for a variety of processes. Discover why we need it, what it does and which foods are a rich source of magnesium.

Bowls of sunflower and pumpkin seeds

Magnesium is an extremely important mineral that is required by the body to maintain optimal health. It is one of the most abundant minerals in the body and is absolutely essential for the regulation of hundreds of biochemical reactions.  

It is also responsible for several physiological systems that maintain cardiovascular and metabolic health. It is absorbed along the entire intestinal tract, but the sites of maximal absorption occur in the small bowel, in particular the jejunum and ileum.

Always speak to your GP or healthcare provider before taking a new supplement or if you are concerned about nutritional deficiencies.

Why do we need magnesium?

Approximately 60% of magnesium is locked inside the skeletal system, making it significantly responsible for bone strength and health. The remainder is utilised in soft tissue cells including the liver, muscles, heart and kidneys and the fluid inside these, known as intracellular fluid.

It is inside this fluid where magnesium's role flourishes – it participates in more than 300 biochemical reactions with significant roles in protein synthesis, calcium homeostasis, vitamin D formation and muscle contraction. Magnesium is also essential for regulating heart rhythm and blood glucose levels and it also supports immunity.  

Brown rice in a pile

How much magnesium do we need and what are the effects of consuming too much?

Daily UK recommendations of magnesium for men and women are 300mg and 270mg respectively. According to recent figures, 11% of women and 16% of men are magnesium deficient. The reason for this is thought to be due to the increased intake of processed foods.

Too much magnesium from food does not pose any problem for healthy people as any excess would be excreted by the kidneys in urine. However, taking high dose magnesium supplements or medications may often cause gut problems such as diarrhoea, nausea or stomach cramping. It is recommended not to exceed a daily intake of 400mg.  

Which foods are good sources of magnesium?

Magnesium is found in green leafy vegetables such as spinach, wholegrain bread, brown rice, dairy products, almonds, cashews, peanuts, sesame and sunflower seeds, meat, seafood and fish.

Cashew chicken in a bowl

Recipes rich in magnesium

Cashew chicken
Thai pork & peanut curry
Spinach rice
Japanese-style brown rice

More on vitamins and minerals

Five nutrients every woman needs
Vital vitamins
What is vitamin B12?
The best sources of vitamin C
Am I getting enough vitamin D?


This article was published on 18th June 2019.

Emer Delaney BSc (Hons), RD has an honours degree in Human Nutrition and Dietetics from the University of Ulster. She has worked as a dietitian in some of London's top teaching hospitals and is currently based in Chelsea.

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

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