Does Your Magnesium Glycinate Contain Magnesium Oxide?

Something Isn’t Adding Up: Does your Magnesium Glycinate also contain Magnesium Oxide?

Magnesium is one of the most used natural health products for good reason, it does so many beneficial things. It relaxes tight muscles, calms nerves, widens blood vessels and reduces inflammation just to name a few. From a physiological perspective, it is one of the key lynch pins of your cellular energy production so it is no surprise it has so many applications. To learn more about why magnesium is such a common deficiency click here.

Being a practitioner that uses magnesium with most of my patients I wanted to clarify a few, very important, points that recently have come to my attention regarding magnesium products and the increasing amount of elemental magnesium. Below is a summary of the different forms of magnesium and the % of magnesium in each form.

Magnesium Form% MgDescription and SummaryKey Clinical Uses
Mg oxide58%Commonly used in OTC laxativesLaxative
Mg citrate11%Commonly used form – good absorption but still can be laxativeLaxative, general magnesium support
Mg (bis)glycinate11-14%Amino acid glycine has calming effect on nervesInsomnia, restless legs, anxiety, muscle spasm
Mg malate11%Malate increases energy production inside cellFibromyalgia, muscle pain
Mg aspartate7%Aspartate helps transport fats inside the cellChronic fatigue
Mg taurate8.8%Normalizes electrical activity across membranes in heart and brainCardiovascular disease, Arrhythmia
Mg orotate7.2%Orotic acid also increases the formation of RNA and DNA, which can help repair damage to heart cells, improve stress tolerance and therefore improve functionHypertension, Congestive Heart Failure, Mitral valve prolapse, Stable angina, Blood vessel elasticity
Mg theronate8.1%Studied to penetrate past the blood brain barrierBrain injuries, cognition, memory, focus

To read more about magnesium and the different forms check out my article about different types of magnesium

One of the most popular forms is magnesium glycinate. Recently, I have noticed that several magnesium glycinate products claim to contain 200mg of elemental magnesium. We obviously want higher amounts of elemental magnesium but this immediately raised some red flags because dosage calculations just don’t add up.  As you can see in the above chart, the percent of elemental magnesium for magnesium glycinate is 11-14%. If you consider that the maximum you can fit into the standard capsule (largest 00 veggie cap) is 850mg, this means the maximum elemental magnesium would be 100-120mg.

 You are probably asking how is it possible to get 150 or 200mg of magnesium glycinate per cap? The label clearly states magnesium glycinate as the only medicinal ingredient. The only plausible answer is it’s NOT pure magnesium glycinate. What else is it then? The likely culprit is magnesium oxide, with a much higher percentage (58%) of elemental magnesium, could be combined with magnesium glycinate to inflate the “total elemental magnesium content” on the label. While adding magnesium oxide to magnesium glycinate is not going to harm a person, it may increase the likelihood of having loose stools without increasing magnesium levels effectively. Further, these blended forms are rarely labelled clearly on products, meaning consumers are led to believe that are getting a pure form of magnesium glycinate. Sometimes magnesium oxide is listed as a non-medicinal ingredient (which also is a sneaky way of not fully disclosing it) or it is not listed at all.

There are 2 possible explanations for this problem. Either a supplement company is aware and has decided to exclude it on the label or the raw material supplier is mislabeling the product and the supplement company is unaware of this fact. The second scenario has even led to a lawsuit in the United States where suppliers were found to be selling magnesium glycinate which included oxide in a proprietary form that is labeled as a “chelated” form of magnesium. The trouble with a proprietary form is that manufacturers don’t have to disclose all the ingredients. In the case of the lawsuit mentioned the blended form of magnesium contained mag glycinate, mag oxide, maltodextrin, citric acid and silica. Supplement companies in this case were unaware of the misidentification as it would not be reflected on the certificate of analysis (a lab test that checks the ingredients and contamination. Either way, neither reason is an acceptable excuse.

 How is this allowed to happen? For regulatory bodies, such as Health Canada (Natural Health Product Directorate NHPD), this sort of violation is lower on the priority list for dealing with complaints as there is no imminent health threats, i.e. allergen potential or adverse reactions. As far as the regulatory bodies are concerned, the company has a license to sell magnesium and is selling magnesium. The form of the magnesium is considered to be nuance. The concern speaks to a larger issue in the natural health product industry. Consumers of natural health products have a right to knowing exactly what is in a product they are purchasing. Cutting corners to make more money or being ignorant about what’s in a product they are selling is no longer acceptable. This is exactly what gives the whole industry a bad name when investigations and media outlets uncover shady ethics and adulterated products. As an industry that is still evolving its standards and that has been riddled with scrutiny for efficacy and safety, it benefits the entire industry when supplement manufacturers thoroughly vet their suppliers for medicinal and non-medicinal ingredients and then clearly communicating that with their customers.

What can you do? Start to understand how to read supplement labels. Check the non-medicinal ingredients and look for magnesium oxide. Beware formulations that contain ingredients that explicitly state modifications like “buffered” magnesium glycinate. This can be code for “mixed with something” that you might not want. I would also be wary of doses of magnesium glycinate above 125mg. As a savvy consumer, you have a right to hold your supplement company accountable so you can trust them with your health.


Coudray C, Rambeau M, Feillet-Coudray C, Gueux E, Tressol JC, Mazur A, Rayssiguier Y: Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg- depleted rats using a stable isotope approach. Magnes Res 2005;18:215–223.

Copeland et al v. Albion Laboratories, Inc.; Seeking Health, LLC; and Designs for Health, Inc., Case No. 15-cv-585, W. D. WA.

About The Author

You might also like to read