Magnesium Glycinate Brands on Amazon

NOW has continued testing supplements on Amazon by lesser-known brands with this round on Magnesium Glycinate.

Magnesium Glycinate has become a very popular form of Magnesium and we tested 16 total samples. NOW discovered that almost all other brands tested failed to include the chelated magnesium form, as claimed on the label. Magnesium chelates, such as magnesium bisglycinate or glycinate, have excellent water solubility and lack a laxative effect. The fully reacted chelates are better absorbed and more expensive than other forms and thus, are at risk for substitution with lower quality material, such as magnesium oxide and magnesium carbonate, simply blended with glycine.

Various magnesium glycinate products, including two manufactured by NOW, were purchased on Amazon and subjected to testing at our in-house lab, as well as at Eurofins contract laboratory. First, total magnesium content was determined by analyzing the samples using Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). To determine the levels of water-soluble magnesium glycinate, the same ICP-OES technology was used, but instead of acid digestion, a gentle water extraction was applied to all samples. Twelve out of 16 tested products met the label claim when we tested total magnesium content. However, only NOW products met the label claim, when we looked at the soluble (chelated) form of magnesium, suggesting that other brands use non-soluble forms of magnesium in place of the more expensive chelated form. Glycine was also detected in all samples, although the soluble magnesium results clearly suggest that glycine was not (or not entirely) bound with magnesium. Unfortunately, it is known in the industry that many brands either knowingly or unknowingly simply blend glycine with magnesium oxide or carbonate and then label the product as “Magnesium Glycinate”. The difference is that the improperly labeled product is much lower cost and is not a fully reacted or bonded chelate. The results are summarized in the table below.

Additionally, it seems some brands mislabel intentionally in order to get higher label potency claims. Deal Supplement brand claims 750mg of “Magnesium Glycinate” per capsule, while legal labeling should list the elemental dose of Magnesium and not the total weight of a RDI ingredient. Other brands that mislabel in this same way include: Innate Vitality, Naturebell, Terranics and ZYY Nutrition. Most brands label Magnesium Glycinate properly, such as below:

Magnesium (as Bisglycinate)…..125mg or Magnesium (from Glycinate)…..125mg 
Or Magnesium 200mg (from 2,000mg Magnesium Bisglycinate) as NOW does for full disclosure of total and elemental mineral weights.

We intentionally did not test most brands that claimed to use Albion Minerals**, which are known to be high quality and specialists in fully reacted Magnesium Glycinate. Magnesium Bisglycinate Chelate powder from Albion Minerals/Balchem contains 10% elemental magnesium. This is why it takes 2,000mg of Magnesium Bisglycinate powder to yield 200mg of elemental Magnesium in NOW brand. Some brands such as Toniiq claim that their Magnesium Glycinate is 20% elemental, but this can only be achieved by using Magnesium and Glycine that are not fully reacted/bonded together. NaturaLife appears to be labeled properly with 18% elemental Magnesium potency with Albion as the source, but this also is a blend – “buffered” - in order to reach the higher potency claim. So NaturaLife is accurate because they include “Magnesium Oxide” in the side panel of ingredients, but also deceptive since the front panel only lists Magnesium Glycinate. Horbaach brand seems to accurately label their side panel as: Magnesium 240mg (from 1,330mg Magnesium Glycinate Chelate – Magnesium Bisglycinate Chelate, Magnesium Oxide). But this is also deceptive since the front panel claims 1,330mg per serving and the side panel states that Magnesium is only 240mg. This form of Magnesium Glycinate contains a blend with Magnesium Oxide and claims to be made “with chelated minerals”, but not 100% chelate.

Test Results December 1, 2022