17/08/2026
Part 2: Why we still include magnesium oxide (and why “bioavailable = better” isn’t the full story)
So let’s actually talk about bioavailability, because it’s more nuanced than glycinate good, oxide bad.
Why include oxide at all? It has the highest elemental magnesium content of any common form. Gram for gram, you’re getting more actual magnesium into the mix than almost any other compound.
So what’s the “bioavailability” argument against it?
Magnesium oxide is absorbed more slowly by the body. That’s usually framed as a weakness, but slower absorption isn’t automatically worse. If your goal is restoring whole-body magnesium levels over time, a slower release can mean your body has a better chance to actually retain that magnesium and push it into the cells, rather than it moving through too fast to be used.
And bisglycinate?
It’s broken down and absorbed much faster, that’s genuinely what makes it “more bioavailable.” But it starts with significantly less elemental magnesium to begin with. And because it’s absorbed so quickly, if you go past what your body can actually use at once, there’s a greater chance that excess gets eliminated before it’s retained, meaning fast absorption doesn’t always equal more magnesium staying with you.
The actual point we’re making: neither one is “better.” It depends entirely on your goal.
💜 Want fast, gentle, easily tolerated magnesium in smaller doses? Bisglycinate.
💜 Want to slowly and steadily rebuild total body magnesium levels? Oxide has a role too.
The “glycinate good, oxide bad” narrative sells supplements. It doesn’t tell the whole story.