What is Magnesium Used For in the Body?

Magnesium – The Under-appreciated Mineral
Why I recommend supplementing with magnesium

A long and detailed article?

Magnesium is an essential mineral that is implicated in over 300 biological processes.It is the 4th most common mineral in our entire body.

Every single cell in your body requires it to function. Most people are deficient in magnesium. Due to modern farming practices, the soil is depleted (up to 80-90% mineral depletion), and we only absorb 30-40% of magnesium from food, and up to ~20% from supplements.

The longer the time that lapses between when the food is harvested and consumed, the greater the nutrient loses. Furthermore, you can lose some during the cooking process. Phytates decrease absorption. There are also nutrient interactions: mag and calcium complete for absorption.

What is Magnesium Used For in the Body?

Vital Functions:

– Metabolic health: Required to make and use insulin, promotes healthy mitochondria
⁃ Cardiovascular function: blood pressure, muscle and nerve function, inversely related to coronary artery calcification, prevention of heart attack

– Mental health: treatment resistant depression, anxiety, apathy; low mag kills nerve cells and can cause brain damage, regulation of the hypothalamic-pituitary-adrenal (HPA) axis
⁃ Hormonal health: clears excess estrogen, optimizes progesterone, production of thyroid hormones

What is Magnesium Used For in the Body?
The importance of magnesium in the body

⁃ Energy production; helps to metabolize carbs, fat and protein
⁃ Bone health
⁃ Protein and gene synthesis (DNA, RNA, glutathione)
⁃ Nervous system regulation
⁃ Converts thiamin into active form
⁃ Enhances uptake of B6
⁃ Required for Vitamin D absorption, synthesis, and utilization
⁃ Anti-inflammatory
⁃ Helps with migraines
⁃ Sleep, dreams (melatonin production)

Symptoms of deficiency of magnesium
⁃ Muscle contractions/pain/spasms/weakness
⁃ Irritability
⁃ Tachycardia, Arrythmia
⁃ Insulin resistance
– Fatigue
– Hypertension
– Difficulty sleeping, dreamless
– Heart attack
– Constipation
– Severe morning sickness
– Calcified arteries (mag deficiency can cause calcium to accumulate in arteries)
⁃ Urinary frequency
You lose magnesium with caffeine intake, alcohol, high salt intake, stress, medications, sweating, supplement intake (i.e. Vitamin D), to process refined carbohydrates, alternating hot and cold temperature, diabetes, etc.

Most deficiency is asymptomatic, and symptoms are often confused for something else. Standard lab work does not capture deficiency, and there is only 1% in the blood, the rest is in tissue and bone. Thus, to maintain adequate blood levels (homeostasis), the body pulls from bone.

If you are interested in testing: How is magnesium listed on a blood test?


🔷IV Mg load test
🔷Mononuclear blood cell Mg.
🔷Oral Mg load test
🔷Hair content
🔷Bone (coccyx)
🔷Ratio of ionized Mg to total
🔷Ionized Mg levels
🔷Urinary or fecal

See the challenges encountered in the diagnosis of magnesium status here

I am very particular about supplementation, using a food first approach, but magnesium is non-negotiable for me. I don’t even believe you need to waste your time/money/energy on testing your levels (because deficiency is so widespread and increasing has many benefits without being toxic) unless you are trying to determine something specific (i.e. for certain medical purposes, ensuring you are absorbing the supplements, etc. + need specific expensive tests.

You can take a combo formula, or you can opt for the classic magnesium glycinate; there are many formulations, but I recommend avoiding citrate and oxide, both poorly absorbed/due to where they are absorbed in the intestine via passive diffusion, likely to causes loose stools – if you are constipated, this is a safe remedy.

Because of how much magnesium is required in the body, how difficult it is to get enough, and how easily we lose it, I recommend supplementing orally, as well as using magnesium chloride topical skin spray which absorbs well into bloodstream.

An Epsom salt bath is also considered a topical solution. Ensure you are looking at the elemental magnesium (the actual amount of the mineral; however; you will not absorb all of this as I have mentioned before).

Always cross-reference with any meds you are taking for contraindications. You can take it all at once, however, if you spread it out througout the day, i.e. 1 capsule 3x/day you will optimize absorption.

The top food sources of magnesium are: nuts/seeds (#1), leafy greens and some organ meat such as heart, other foods have a modest amount, such as avocado (44mg/c), dairy, fatty fish & meat, vegetables, legumes.

It takes very careful planning and substantial intake to even meet the RDA of 310-320mg for women and 400-420mg of men, and remember, that the RDA is really the minimum. Also remember that food is depleted, so standard references for the nutrient content is not reliable.

Most do not meet the RDA; it is very difficult to do so without supplementation. Especially for those who eat 1-2x/day. Unlike other vitamins and minerals, there is no set upper tolerable limit for magnesium, except for supplements, which demonstrates how safe/non-toxic it is.


Valeria, RD, MPH



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