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By Brigid Chunn, BSc Registered Nutritionist

Magnesium is a mineral, needed by our bodies for energy production. It is involved in over 300 enzyme systems that regulate many biochemical reactions including muscle and nerve function, normal heart rhythm, blood pressure regulation and blood glucose control.

How much do we need?
The recommended daily intake (RDI) for women and men over 30 is 320mgs/day and420mg/day respectively. For both under 30 the RDI is slightly less.

Too much magnesium from food is not a problem in healthy individuals because the kidneys eliminate excess amounts in the urine, however high doses of magnesium from dietary supplements or medications can result in diarrhoea, nausea and abdominal cramping. For this reason t is recommended if taking a supplement not to exceed 350mg /day.

Do we need magnesium supplements?
While in healthy individuals magnesium deficiency is uncommon, those with gastrointestinal issues such as coeliac and Chronis disease, type two diabetes, or a diet high in refined or processed foods may be deficient.  Stress, high intakes of alcohol, protein, calcium or smokers may also have low levels. Aging may also lead to lower levels.

Many people may take a magnesium supplement for a specific reason such as …

  • Muscle cramps – magnesium supplements may help with this but more research is needed
  • Hypertension, cardiovascular disease and risk of stroke – current evidence from epidemiological studies shows that higher Mg intake, either dietary or via supplementation, is associated with a protection against major CV risk factors, however more research is needed. Studies have also found that magnesium supplementation lowers blood pressure. Diet, however, (namely DASH – dietary approaches to stop hypertension) which emphasizes vegetables, fruit, wholegrains, and low fat dairy with low sodium also has a significant decrease in blood pressure. Overall, the current evidence supports the importance of adequate dietary magnesium for lowering CVD risk. Increasing magnesium-rich foods in our diet including fruits, vegetables, legumes, nuts and whole grains for the prevention of chronic diseases is very important.
  • Diabetes – diets with higher amounts of magnesium are associated with a significantly lower risk of diabetes; possibly because of the important role of magnesium in glucose metabolism however there is no clear scientific evidence supplementation benefits people with diabetes who do not have underlying nutritional deficiencies. Again a whole diet may be a better option
  • Sleep – some evidence suggest a link between magnesium and sleep, however more research is needed.
  • Osteoporosis – Studies suggest that increasing magnesium intakes from food or supplements might increase bone mineral density in post-menopausal and elderly women.

If you feel you may be low or deficient, increase your intake of magnesium rich food. Magnesium is found in dark leafy greens, legumes, wholegrains, bananas, seeds and nuts.

In summary, healthy individuals eating a balanced whole food diet, should not be deficient in magnesium.  If taking a supplement check with your GP first to ensure you fare not having too much and that it doesn’t interfere with any other medications you may be taking.