Only with considerable effort could I find/figure out all that follows. It’s not that hard, but there seems to be a gap in the (easily accessible) internet. This may help fill it.
As a gentle sleep aid, suppose your doctor recommends you take 200 milligrams of magnesium glycinate. Or, suppose you read a recommendation of just that in a newsletter from a well-known neuroscientist. Following this advice is not as simple as you might think.
First, let’s get straight that, putting aside how it is phrased, this is a perfectly reasonable recommendation. Recommended daily allowances of magnesium for anyone other than young kids is in the hundreds of mg; it is quite common that people do not reach these levels through diet; and servings of foods can include many dozens to about 100mg of magnesium. Daily magnesium supplementation up to a 350mg is considered safe for adults, perhaps higher in consultation with a health care provider.
OK, so what are the problems? In short, there two significant communication issues.
The first is that when someone makes such a recommendation (and the internet is full of them), they almost certainly do not mean what it sounds like they mean. When someone says to take “200mg of magnesium glycinate” they really mean “take 200mg of magnesium in the form of magnesium glycinate.” Or, to be even more precise, they mean “take 200mg of elemental magnesium, delivered as a constituent of the compound magnesium glycinate.”
How do I know they mean this? First, there’s what I wrote three paragraphs above. Recommended daily allowances of magnesium are in the hundreds of mg of magnesium not magnesium glycinate (or some other compound of magnesium). As I will explain below, the difference is large. Only by ignorance or sloppiness can one confuse one with the other.
Second, there are many studies that are clear on this point. They examine magnesium for sleep and discuss doses in the hundreds of mg of elemental magnesium, some taken as magnesium glycinate, others as some other magnesium compound (e.g., magnesium citrate, magnesium oxide).
This is an important distinction. Each magnesium glycinate molecule contains one magnesium atom and two glycine molecules (this is why it is also called magnesium biglycinate, the “bi” meaning two). So, the mass of a number of magnesium atoms is less than the same number of magnesium glycinate molecules, by about a factor of 7. Thus, if you follow the advice “take 200mg of magnesium glycinate” literally (meaning you buy and consume as directed a supplement that offers 200mg of the magnesium glycinate compound per serving), you will be taking less than 30mg of elemental magnesium (200/7 is not quite 30). Based on what I’ve already conveyed above, that’s not enough to do anything. You’re way under-dosing.
(If anything about the preceding paragraph is confusing, think of it this way: imagine a special cherry that has as its pit elemental magnesium. Suppose the pit has a mass of 1 (units irrelevant). The pit is surrounded by cherry fruit composed of biglycinate with a mass of 6. The total mass of a cherry, with pit, is 7. Suppose your doctor said you should eat a mass of 210 of these magnesium-pitted cherries (and to eat the pits too, not spit them out), but she really meant that you should eat 210 magnesium pits. If you follow her instructions, you’d eat 30 cherries (210/7 = 30). In doing so, you’d only get 30 mass units of magnesium (30 pits), a far cry from 210!)
OK, so we’re clear that everyone on the internet, in doctor’s offices, and everywhere else should stop saying “take 200mg of magnesium glycinate” and start saying “take 200mg of magnesium in the form of magnesium glycinate” (or something even clearer than that). Good.
Here’s communication issue number two: The supplement market is not adequately regulated. This allows manufacturers to put all kinds of confusing stuff on their labels. This includes:
- Not clearly indicating the mg of elemental magnesium, only writing the mg of the compound of which it is a constituent. So, even if you know you want 200mg of elemental magnesium, you’ve got to do some math to figure out how much of this some supplements deliver.
- Or, providing the mg of elemental magnesium but mislabeling it as that of the compound.
- Mixing compounds of magnesium — for example, some kind of blend of magnesium glycinate and magnesium oxide — and only providing the mg of this mix. That makes it even harder to figure out how much elemental magnesium is in it (perhaps impossible, because they usually don’t state the ratio of the mix).
- Sneaky “serving size” bullshit. When the front label says “500mg magnesium glycinate” in big print and “per serving” in small print and the back label says “4 capsules per serving,” that’s some sneaky bullshit. In addition to increasing the risk of taking the wrong dose, it’s another way it makes it very hard to shop, not just on price but also with an eye toward simplifying your pill burden. Nobody wants to take 4 capsules when they could take 2, say (all else equal).
There are undoubtedly other tricks and sources of confusion, but these are the ones I easily noticed. The best labels indicate the mg of elemental magnesium and the mg of the full compound of which it is a constituent, per serving. The very best labels consider one capsule a serving.
If all labels were written according to these two “Frakt best practices” magnesium shopping would be far less burdensome. And if all advice-givers were clear about what amount of elemental vs compound-bound magnesium they are talking about, that would reduce confusion.
