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Understanding the role of magnesium

What is magnesium?

Magnesium is a major mineral appearing in small amounts in the body within the bones, muscles and soft tissue. Magnesium is involved in many body processes such as; bone health, energy metabolism, enzyme activity, muscle contraction, blood clotting, blood pressure, lung function, heart function and immunity (Whitney, Rolfes, Crowe, Walsh & Crowe, 2017). As an electrolyte, Magnesium works closely with other electrolytes such as potassium, calcium and sodium. It helps to transport sodium and potassium across the cell membrane (Urden, 2018).

Dietary sources of magnesium

Magnesium occurs naturally in many plant and animal foods. According to the National Health and Medical Research Council (NHMRC, 2014a) most green vegetables, legumes, peas, beans and nuts are rich in magnesium, and is also found in some shellfish and spices. Despite this, Australians tend to consume below recommendations although severe deficiency is rare in developed countries.

According to the Food Standards Australia & New Zealand (FSANZ, 2019), seeds, cereals, grains, legumes, spices and even coffee contain magnesium. Excellent sources are listed in the following table;

(Whitney, et al., 2016) and (FSNAZ, 2019)

Recommended Daily Intake (RDI) and therapeutic dose

Infants <6 months

Magnesium for infants 0-6 months is ideally obtained from breast milk, with an Average Intake (AI) of 30 mg/day. Cow’s milk infant formula typically contains magnesium with lower bioavailability than breast milk. From 7-12 months, the AI increases to 75 mg/day as a food and breast milk (NHMRC, 2014a).

Children & adolescents

For children 1-3 year old the RDI is 80 mg/day, from 4-8 years old it is 130 mg/day. Boys and girls from 9-13 years old have the same RDI at 240 mg/day. From 14 to 18 years old the needs change between the sexes, with boys requiring 410 mg/day and girls requiring 360 mg/day (NHMRC, 2014a).


Men 19-30 years old have an RDI of 400 mg/day, from 31-70 years old it remains at 420 mg/day. Women require less at each life stage, from 19-30 years old they require 310 mg/day, from 31 to over 70 the RDI is 320 mg/day (NHMRC, 2014a).

Pregnancy and lactation

The RDI for pregnant women is 400 mg/day for teenage mothers, to 350-360 mg/day RDI for other groups and 310 mg/day RDI (slightly higher for older mothers, and significantly higher for teen mothers) (NHMRC, 2014a).

Therapeutic applications of magnesium

Therapeutic levels of magnesium can be used for cardiovascular issues, migraines, osteoporosis, premenstrual syndrome, pregnancy-related leg cramps, blood glucose, insulin sensitivity, attention deficit hyperactivity disorder (ADHD), and multiple sclerosis (Hechtman, 2019). Taking a magnesium supplement can help reduce muscle cramps, twitches and spasms, and may also help to promote calm and sleep (Fusion Health, 2020a).

Figure 1: Fusion Magnesium Advanced.

Each tablet contains 200mg of magnesium

(Fusion Health, 2020b).

Factors of insufficiency or excess

Magnesium absorption can be impaired due to various factors but the body is capable of adjusting to changing levels. Phytates in fibrous foods can inhibit absorption and excess protein intake can result in magnesium being secreted (NHMRC, 2014a). Magnesium competes for absorption with calcium in the gastrointestinal tract, which could lead to a deficiency issue (Urden, 2018).

Excess magnesium intake can occur through over-supplementation and so there is an upper level for intake of supplements (Whitney, et al., 2017). See appendix 1 for the full table of upper intake (NHMRC, 2014a).

Signs and symptoms of deficiency, excess and toxicity

Deficiency of magnesium is rare in developed countries and tends to only present in disease. In excess however, symptoms can include diarrhoea, alkalosis and/or dehydration (Whitney, et al., 2017). Signs and symptoms of deficiency can also include neurological and/or neuromuscular. Leading to anorexia, nausea, muscular weakness, lethargy, weight loss, muscular spasms (NHMRC, 2014a). With magnesium deficiency, the walls of the arteries and capillaries tend to constrict (Whitney, et al., 2017).

There is mixed information on whether supplementing with magnesium for muscle cramps is effective (Whitney, et al., 2017, p.446). However, Bioceuticals claims that their Ultra Muscleze® product, shown below, can help relieve muscle cramps (Bioceuticals, 2020a).

Figure 2: BioCeuticals Ultra Muscleze.

Each dose contains 280mg of magnesium

(BioCeuticals, 2020b).

Requirement of magnesium across the human lifespan

The average magnesium requirement is slightly higher for older adolescents than children due to the high growth experienced by this age group (NHMRC, 2014a). Magnesium requirements are higher in pregnancy and lactation as the mother transfers around 4.5mg/day of magnesium to the fetus. This can be obtained through a carefully planned diet, and there may not be a need for supplementation (Gluckman, Hanson, Chong & Bardsley, 2015). There is an even higher amount required by pregnant and lactating teens as they are potentially still growing themselves. Older pregnant and lactating women over 31 years old also require a higher amount of magnesium. Later in life, women need to be aware of signs of magnesium deficency as it can increase risk of postmenopausal osteoporosis (NHMRC, 2014a).


Adjusting magnesium intake and supplementation for each life stage can improve body function and avoid a state of insufficiency. Practitioners can tailor magnesium levels relevant for each patient and patients can seek the advice of a nutritionist, naturopath or integrative doctor for guidance on their magnesium requirements.


Bioceuticals. (2020a). Ultra Muscleze®. Retrieved from

Bioceuticals. (2020b). Ultra Muscleze® [Image]. Retrieved from

Fusion Health. (2020a). Magnesium Advanced. Retrieved from

Fusion Health. (2020b). Magnesium Advanced [Image]. Retrieved from

Gluckman, P., Hanson, M., Chong, Y., & Bardsley, A. (2015). Nutrition and lifestyle for

pregnancy and breastfeeding (First ed.) Oxford: Oxford University Press. Retrieved




Hechtman, L. (2019). Clinical naturopathic medicine (Second ed.). Chatswood, NSW:


NHMRC. (2014a). Magnesium. Retrieved from

Urden, L. (2018). Critical Care Nursing, Eighth Edition. Missouri, USA: Elsevier Inc.

Retrieved from!/content/book/3-s2.


Whitney, E., Rolfes, S., Crowe, T., Walsh, A., & Crowe, T. (2017). Understanding nutrition. (pp 384-409). Cengage Australia. Retrieved from


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