Magnesium supplementation- skin or gut???

Magnesium seems to be the current trendy micronutrient that has stolen the spotlight from Vitamin D.

So what is all the fuss about?

Do we need magnesium? Hell yeah. Deficiency can lead to issues.

How much do I need? a 31-50 year old male has a recommended daily allowance of 420mg (see reference 4 below).

Source of magnesium? Mother nature:

  • 28 grams of dry roasted almonds give you 80mg of magnesium and a 1/2 cup of spinach gives a similar amount (see reference 4 below).

  • Oceans and rivers e.g. the Dead Sea.

Do I need to supplement? Good question and it will depend on the your quality of diet, medicines you take, general health etc.

Should I get my magnesium levels assessed? Difficult to do as no single test is really accurate on its own e.g. blood, saliva, urine.

How do I know if my levels are too low? Symptoms may include:

  • Weakness

  • Fatigue

  • Loss of appetite

  • Nausea

  • Vomiting

  • Numbness

  • Tingling

  • Muscle cramps

  • Change in heart rhythms

(see table within reference 1 below)

Supplement via skin or gut?

The current scientific evidence base is evolving and at present it is unclear so the debate and marketing rages on.

People in the skin camp (transdermal) promote sprays, lotions, creams, gels and Epsom salt baths. They suggests the skin allows for better absorption and less side effects.

People in the gut camp (oral) say that we know an oral supplement works and that there are issues with magnesium being absorbed via the skin. Does it actually get through? Some say hair and sweat glands help. How much to apply? For how long? If it does get into the blood then how much actually gets in? How clinically relevant is it?

Practical considerations:

In the study below, participants had to put 2 x 5 ml spoonfuls of magnesium cream on their torso and legs , once a day, at any time and had to leave it on for 3 hours i.e. no showering, washing (?sweating).

So have a think if this would work in your lifestyle.

What to do?

Seek professional medical advice.

If you do decide to supplement then:

  • check if the product states the concentration of elemental magnesium within it e.g. 10 sprays = 130mg of elemental magnesium

  • Check what is the form of the product i.e. spray, lotion, gel, tablet

  • Check what is the form of magnesium i.e. it is magnesium oxide, citrate, chloride, lactate, aspartate, sulphate, hydroxide


  1. Grober et al. (2017). Myth of reality - transdermal magnesium? Nutrients (9) 813. Accessed online PDF.

  2. Kass et al. (2017). Effects of transdermal magnesium cream on serum and urinary magnesium levels in humans: a pilot study. PLOS ONE.

  3. Engen et al. (2015) Effects of transdermal magnesium chloride on quality of life for patients with fibromyalgia: a feasibility study. Jounral of Integrative Medicine (13) 5:306-313.

  4. US Department of Health and Human Services. Link

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