Many of us take the label on our supplements at face value. If the label says “Magnesium Bisglycinate”, for example, we naturally assume we’re getting just that: Magnesium Bisglycinate. But are we really?

Buffered Magnesium

Many magnesium supplements are buffered with magnesium oxide, even if they state another form of magnesium on the main label, such as magnesium citrate, magnesium bisglycinate, magnesium malate, etc. This may be done for two reasons: 

(1) Magnesium oxide is inexpensive so it is used as a filler to make the supplement more cost effective

(2) It raises the amount of elemental magnesium in each capsule due to its small size. (Other forms of magnesium take up more space inside the capsule resulting in a lower amount of elemental magnesium per dose.)

But wait, isn’t getting more elemental magnesium per capsule a good thing? It is, but only if you’re able to absorb that magnesium. Magnesium oxide tends to have a low absorption rate, with one study finding that as little as 4% of the magnesium in magnesium oxide is absorbed by the body. Magnesium oxide is often used as a laxative for this reason (a lot of it is flushed out through the bowel) and can often lead to diarrhea and digestive discomfort. 

Here’s where it gets tricky: some companies will list magnesium oxide as a non-medicinal ingredient; others will list it as “buffered magnesium”, while some companies may not list it at all. Some magnesium manufacturers genuinely do not know that magnesium oxide is lurking in their product if their supplier didn't disclose that information to them. Others may take a chance on the unlikelihood of getting caught. The guidelines for ingredient disclosure in many places are murky at best, and there is often little oversight. 

What can you do to ensure your supplement doesn’t contain magnesium oxide? Look for the amount of elemental magnesium listed for each capsule on the label: if it has a high dose of elemental magnesium (around 120mg or higher per capsule), it is likely buffered with magnesium oxide. We have a related article that discusses how to determine if your magnesium bisglycinate supplement contains magnesium oxide here.

Fillers and Excipients

If you look closely at the ingredients label, you will often see a “Non-medicinal Ingredients” list. This typically includes a number of agents that are used to ensure smoother processing, extend shelf life, improve taste and appearance, or make the capsule (when applicable) appear fuller. These are called fillers and excipients. The question is, how much of these chemicals are in each capsule, and are these ingredients harmful? The answer isn’t cut and dry.

Here’s a list of the types of fillers and excipients commonly used in supplements:

• Binding agents: These are used to hold the supplement together, and are typically found in capsules and tablets.
• Flow enhancers and lubricants: These are used to prevent supplement ingredients from clumping together during the manufacturing process. These are used to help ensure a faster process, and therefore lowers the cost of the supplement.
• Fillers: These add bulk to supplements if there’s any danger of the capsule appearing only partially full. 
• Preservatives: These ingredients are used to extend the shelf life of supplements.
• Colours: These improve the appearance of supplements.
• Sugar and artificial sweeteners: These improve the taste of liquid and chewable supplements.

There are a number of fillers and excipients used in many magnesium supplement brands, but perhaps the most common is magnesium stearate. Magnesium stearate is often used as a flow agent to ensure the manufacturing process runs smoothly by keeping the ingredients from clumping together or sticking to the machines. Is magnesium stearate safe? One study from 1990 found that stearic acid – the acid carrier the magnesium is bound to in magnesium stearate – may act as an immunosuppressant on T-cells; however, magnesium stearate itself is generally considered safe for use. That said, studies show it may be an allergen, which is something you might want to keep in mind when shopping for a magnesium supplement.

Many magnesium supplements also contain a binder and bulking agent made of refined wood pulp. This can appear on the label as cellulose, microcrystalline cellulose, hypromellose, etc. These binders may cause digestive discomfort including gas, bloating and increased stool production, so those with sensitive digestive systems will want to proceed with caution if you see these ingredients listed on your supplement label.

Every magnesium supplement label is different, and some contain more fillers and excipients than others. It’s important to note that not all fillers and excipients are harmful, but you certainly don’t need them. We believe simple is best: If you see a host of medicinal and non-medicinal ingredients listed on the label that you don’t recognize, be sure to compare it with other brands to see which is the most straightforward.

The ITL Health Difference

We talk a lot about our products being 100% pure – it’s a fact we are very proud of as a supplement manufacturer. All of our products are made without any magnesium oxide, binders or excipients, save for the stevia extract we use in our flavoured MAG365 products. While it would be more cost effective for us to do so, we believe you should only get what you think you are getting: a pure product that adds to your health and wellness.