Magnesium absorption has been a confusing issue for many years now and has been the subject of a lot of debate.  But some advanced research in the past couple of years has shed light on why the picture has been confused with its findings of wide individual variation in Magnesium uptake, with some persons taking up some sorts better than others, while other persons absorbed different types better.  This has led to more recent Magnesium products tending to be a “mixed source” type where the Magnesium is provided in several different forms, in the hope that this will make it useful to a wider range of individuals.

As a lot of people take Magnesium for cramp and soft tissue pain, or as a muscle-relaxant to help sleep, it is often quite apparent what works and what doesn’t.  This is as opposed to some other minerals that are taken much more on faith.  You therefore may be able to determine your personal efficacy by trying different forms and seeing for yourself what works best.  The table below provides some general guidelines.

Common forms of Magnesium supplement and their bioavailability

Highly Bioavailable Generally well absorbed Least well absorbed
Magnesium L-lactate


Magnesium citrate


Magnesium phosphate


Chelated magnesium amino acid compounds


Magnesium chloride


Magnesium oxide


Supplement formulas often contain a combination of Calcium and Magnesium. With these types of supplements a ratio of around 1:1 is ideal.  Magnesium absorption may be suppressed if the ratio of Calcium to Magnesium is much higher than this.

Vitamin B6 (pyridoxine) supports magnesium absorption and an adequate intake of this nutrient is important to ensure optimal benefit from a magnesium supplement.

Recommended daily magnesium intake

310 to 420 mg is the adult recommended daily intake from all sources (supplements plus food sources).  Actual optimal intake will vary somewhat according to age, sex, weight and other variables.

Contraindications / Side Effects

Caution is strongly advised for individuals with impaired kidney function as magnesium supplementation can contribute to excessively high plasma concentrations.  In these circumstances, or if pregnant or breastfeeding, check with a health professional prior to use.  Diarrhoea is a possible side effect at high doses as this is how the body rids itself of excess unabsorbed magnesium.

Magnesium supplementation is generally very safe and not likely to cause any problems for most people.

This article was written by the specialists at HealthPost. Learn more about Magnesium.

How to choose the best Magnesium supplement, 5.0 out of 5 based on 1 rating


  1. Ava says:

    Hi. How can I tell whether the magnesium/calcium is 1:1. The tablets I’ve purchased show magnesium oxide-heavy at 440g, magnesium phosphate at 175mg, calcium ascorbate dihydrate at 50mg, vitamin B6 at 50mg, vitamin D3 at 100 and manganese amino acid chelate as 40mg? Thanks, Ava

    VA:F [1.9.17_1161]
    Rating: 3.5/5 (4 votes cast)

Post a Comment