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The label-maths test every magnesium buyer should know
This magnesium label promises 384mg. Its listed ingredients add up to roughly 254mg.
A 130mg gap between what a label lists and what it claims. Here is the arithmetic, the industry practice most likely behind it, and the label we think every magnesium should carry.
By Logan KingFounder, NF Supplements · 8 minute read
Label maths
Batch lab reports
Magnesium glycinate
UK magnesium labels
Exhibit A · the arithmetic
130mg unexplained
Nutrition Geeks Magnesium 3-in-1
1,000mg glycinate =
≈130mg elemental
400mg malate =
≈60mg elemental
400mg citrate =
≈64mg elemental
Approximate elemental total from the listed forms
254mg elemental
Elemental claim printed on the bottle384mg
This calculation uses approximate elemental values of 13% for glycinate, 15% for malate and 16% for citrate. Exact assay values depend on the ingredient specification, but the listed amounts do not reconcile with the 384mg claim on that basis.
The problem wasn’t that the two numbers were different. It was that they didn’t reconcile.
Compound weight and elemental magnesium are different measurements. That is normal. But one still has to account for the other.
This label lists 1,000mg of glycinate, 400mg of malate and 400mg of citrate. Together, those quantities provide approximately 254mg of elemental magnesium.
The label claims 384mg.
That leaves roughly 130mg of the claimed 384mg elemental magnesium unaccounted for by the three quantities listed on the label.
So where does the other 130mg come from?
The most likely answer is an industry practice called buffering.
Here is why we think so. Take away the malate and the citrate, and the glycinate is left to supply 260mg. From 1,000mg of glycinate, that is 26% magnesium. Pure magnesium glycinate tops out at about 14%. It cannot get there on its own.
Something much richer in magnesium has to be making up the difference. In this industry, that something is usually magnesium oxide. Around 217mg of it would close the gap. It gets blended in to lift the number, while the front of the pack still says “glycinate”.
Only the brand or a lab test can say for certain what is in that bottle. But buffering is no secret inside the trade. It is a label trick, and it leaves shoppers thinking they are buying something they are not.
You can run the same sum on any bottle in your cupboard.
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- Dosage
- Heavy metals
- Microbiological
Why would a brand put oxide in a glycinate bottle?
Because it is cheaper, and it makes the number on the front bigger. Most shoppers have never heard the word “buffering”. Here is how it works.
Swap in the cheap stuff
Oxide costs far less than glycinate. Every gram swapped in cuts the brand’s costs. More profit for them. Less of what you paid for.
A little oxide. A much bigger number.
Oxide is about 60% magnesium. Glycinate is about 13%. Gram for gram, oxide pushes the number on the label up more than four times as fast.
Print the big number. Keep the oxide quiet.
The number on the front goes up. “Glycinate” stays on the label. If the oxide isn’t named—or hides behind the word “buffered”—the buyer never knows.
Big number. Less absorbed.
The label counts every milligram the same. Your body doesn’t. Studies suggest oxide is absorbed less well than glycinate. So the extra milligrams you paid for are the ones you’re least likely to absorb.
A bigger number on the label. Not necessarily more magnesium in you.
✓What the brand gains
- A bigger number on the front
- A cheaper product to make
- More profit—or a price that undercuts the real thing
- “Glycinate” still on the label
✕How you’re short-changed
- Less of the magnesium you thought you were buying
- A number padded with magnesium you’re least likely to absorb
- What you don’t absorb stays in your gut—that’s why oxide is used as a laxative
- And unless the label says so, no way to tell
A 2021 systematic review found that inorganic magnesium formulations appear less bioavailable than organic formulations.https://pubmed.ncbi.nlm.nih.gov/34111673/
Magnesium oxide is widely used as an osmotic laxative, typically at higher doses than a buffered supplement contains.https://pubmed.ncbi.nlm.nih.gov/33525523/
Nobody buys magnesium glycinate hoping part of it is oxide. If it is in the capsule, it should be on the label.
So we made the magnesium label we wanted to see.
Exhibit B · the same test applied to NF
0mg unexplained
NF Magnesium Bisglycinate
2,600mg bisglycinate =
338mg elemental minimum
Magnesium malate =
0mg elemental
Magnesium citrate =
0mg elemental
Magnesium oxide =
0mg elemental
Declared elemental minimum
338mg elemental
Elemental minimum accounted for by the declared form100%
We apply the same arithmetic to our own label that raised the question at the top of this page.
The 338mg is a declared minimum—not a ceiling. Finished batches may test above it. Every approved batch must meet or exceed that minimum specification.
But label maths only shows what should be present. So we also send every finished batch for independent testing before it ships.
See the proof for yourself.
Every batch of NF Magnesium goes to an independent laboratory for three reports: dosage, heavy metals and microbiological. Scan the QR code on your bottle and you can open the reports for the exact batch in your hand. Here is the most recent one.
