Magnesium & Muscles

Which form of magnesium is most easily absorbed?

an elderly lady smiling at the camera while doing light exercise
When faced with shelves of magnesium supplements at your pharmacy or health food store, it can be confusing to choose which one is best for your body’s needs. They may look pretty much the same, but magnesium supplements really aren’t created equal. The most important consideration is whether your body can actually make use of it.

What is the bioavailability of different magnesium supplements?

Bioavailability refers to how easily a substance is absorbed by the body and can be readily used. On its own, magnesium has low bioavailability. To be used in a supplement, magnesium is paired with another substance such as a salt or an amino acid and this can have an impact on how effective it is in delivering its intended health benefits.

Magnesium oxide is a combination of magnesium and oxygen and is often used in lower cost supplements, either on its own or in multi-nutrient products. Magnesium oxide can provide a high level of elemental magnesium, making it look impressive on the label. However, its bioavailability is limited. In fact, in a comparative study of the bioavailability of magnesium supplements, magnesium oxide performed the worst.1

Magnesium citrate is magnesium combined with citric acid. Studies show that magnesium citrate has statistically higher bioavailability when compared to magnesium oxide making it a better choice.2

Magnesium diglycinate (or bisglycinate), has been found to be easily absorbed and transported to the bloodstream. It’s shown to be consistently better absorbed than other forms of magnesium, including magnesium oxide and magnesium citrate, making it an ideal magnesium supplement for everyday magnesium replenishment.3,4


What will happen if I choose a lower quality magnesium supplement?

If you’re not absorbing your magnesium supplement properly, you might not be getting the health benefits you desire, whether that’s assisting your energy levels, supporting your body during times of stress, or helping with the management of muscle cramps and mild spasms. Some forms of magnesium are also associated with digestive upset. Because of its low absorption rate in the intestine, magnesium oxide may lead to symptoms of digestive discomfort including diarrhoea. In fact, it is commonly used for its laxative effects.5


What are the benefits of choosing an easily absorbed form of magnesium?

Here at Ethical Nutrients, we use an exclusive and highly absorbed form of magnesium, Meta Mag® (magnesium diglycinate) in our magnesium tablets and powders. Meta Mag® is no ordinary magnesium. It’s superior absorption rate not only supports results but increases its tolerability reducing the risk of digestive upset associated with other forms of magnesium. With a high quality, superior magnesium supplement, you can be confident that the magnesium will be put to good use, working with your body to support healthy muscles, assist energy production, provide benefits during times of stress and help relieve symptoms of premenstrual tension (PMT) and menstrual pain.



  1. Blancquert L et al, 2019, ‘Predicting and testing availability of magnesium supplements’, Nutrients, vol 11, no 7, p 1663
  2. Kappeler D et al, 2017, ‘Higher bioavailability of magnesium citrate as compared to magnesium oxide shown by evaluation of urinary excretion and serum levels after single-dose administration in a randomized cross-over study’, BMC Nutrition, vol 3, no 7
  3. Hartle J et al 2016, ‘Development of a model for in-vitro comparative absorption of magnesium from five magnesium sources commonly used as dietary supplements’, FASEB Journal, vol 128, no 6
  4. Graff D 2000, ‘Bioavailability of magnesium chelazome’, Research Notes, vol 9, no 1, pp2-3
  5. Mori H 2021, ‘Magnesium oxide in constipation’, Nutrients, vol 13, no 2, p 421

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