Why You Probably Need More Magnesium


Magnesium is one of the most important minerals for long-term good health. It’s need for over 600 enzyme reactions making it vital for just about every metabolic process in the body. It also mans the pumps that control how salts move in and out of cells and is essential for nerve conduction, muscle relaxation, healthy bones and energy production. Good intakes are even associated with longevity, yet lack of magnesium is one of the most common mineral deficiencies.

Diet should always come first

Magnesium is found in nutrient-dense wholefoods such as nuts and seeds (especially pumpkin seeds, Brazil nuts, almonds and cashews), dark green leaves (eg spinach), beans (especially soy and lentils), fish (especially mackerel), dried fruit (especially figs) and wholegrains such as quinoa, millet, Bulgur wheat and brown rice. Chocolate and drinking water in hard-water areas are also important sources for some people.

Once processed, however, much of the magnesium is stripped out of wholefoods so that white flour and rice contain significantly less then brown versions, for example. Magnesium absorption is also decreased by the consumption of excess dietary fat, alcohol, salt, phosphoric acid (found in canned fizzy drinks) and coffee.

The EU recommended daily intake is 375mg magnesium per day for adults but few people achieve this. Average magnesium intakes within the UK are around 323 mg for males and 228mg for females. And, according to the National Diet and Nutrition Surveys, almost one in eight adults aged 19-46 (13%) obtain less than the lower reference nutrient intake (LRNI) for magnesium which puts them at risk of deficiency symptoms – a figure that rises to one in four (25%) adults aged 75 and over. 

Magnesium status is not easy to assess unfortunately as half our total magnesium is stored within our bones and half inside our cells. Very little – less than one third of one percent – circulates in blood serum so that magnesium status must be assessed by measuring the amount inside our red blood cells. That makes deficiency symptoms one of the best indicators that you would benefit from increasing your magnesium intake.

Deficiency symptoms

Lack of magnesium can lead to a wide range of common and troublesome symptoms including constipation, insomnia, fatigue, weakness, muscle cramps, numbness and tingling, anxiety, loss of appetite, poor co-ordination, palpitations and abnormal glucose control.

Research involving over 536,000 people found that those with the highest magnesium intakes (whether from food or supplements) were 22% less likely to develop type 2 diabetes than those with the lowest intakes, for example, and every 100 mg per day increase in magnesium reduced the risk by 14%.  

Magnesium deficiency also contributes to the development of hypertension, cardiovascular disease, kidney and liver disease, migraine, recurrent bacterial infections, premenstrual syndrome, osteoporosis and possibly erectile dysfunction (due to lack of nitric oxide). The full list is quite staggering.

After taking other confounding factors into account, people with the highest magnesium serum levels appear to have a 48% reduced likelihood of developing  hypertension than those with the lowest magnesium levels. And, when magnesium supplements were given to people with resistant high blood pressure (that was not responding to medication) their blood pressure measurements reduced by an astonishing average of 18.7/10.9 mmHg. 

Magnesium has such wide ranging, beneficial effects throughout the body, especially in the circulation (lowering blood pressure, reducing abnormal blood clotting, promoting blood vessel dilation and protecting against abnormal heart rhythms and heart failure) that research involving almost 533,000 people found that the risk of cardiovascular events was 15% lower in those with the highest dietary magnesium intake and 33% lower in those with the highest blood levels of magnesium.

Functions of magnesium

Understanding of magnesium function remains relatively modest and the EU have only authorised 10 claims relating to magnesium function – that it:

  • Reduces tiredness and fatigue
  • Contributes to electrolyte balance
  • Contributes to normal energy-yielding metabolism
  • Contributes to normal muscle function
  • Contributes to normal functioning of the nervous system
  • Contributes to normal psychological function
  • Contributes to normal protein synthesis
  • Contributes to the maintenance of normal bones
  • Contributes to the maintenance of normal teeth
  • Has a role in the process of cell division.

Take-home message

If you are feeling tired and fatigued or burned out, a magnesium supplement may help. If you are troubled by constipation, then a magnesium supplement taken at night will promote bowel movements and encourage a ‘magnesium movement ‘in the morning.

I used to experience frequent ectopic heart beats which only resolved once I started taking a daily magnesium supplement – and as a medical nutritionist I like to think my diet is relatively healthy.

Supplements typically supply a dose of 375mg per day. Intakes above 400mg per day can have a laxative effect – not always a bad thing. If you are susceptible to this effect, then a great way to boost your magnesium levels is to absorb it through your skin by adding a handful of magnesium flakes to your bath water, or by using a magnesium skin oil.

All in all, magnesium is one of my favourite supplements, and one I make sure to take every night. 

NB See your doctor if you have persistent tiredness or other symptoms. Occasionally, lack of energy is a sign of health problems that need further investigation and treatment. 


About Dr Sarah Brewer

QUORA EXPERT - TOP WRITER 2018 Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 60 popular self-help books and a columnist for Prima magazine.

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