More practical information because I'm following up with GP recommendations after my last visit, but Magnesium glycinate followed by Magnesium citrate are most absorbed by the body. An ED nurse friend said if I were to look to buy vitamins and minerals, do not buy gummies, and get ones that are bioavailable to the body.

She specifically said that if I had gotten Magnesium oxide, she'd have told me to bin it. Strength ("high strength", etc. on the label) doesn't matter if the body can't absorb it.

So life pro tip: Research the vit/min you're looking for first, stay within the maximum recommended daily intake (online), and read the label. If it says "equivalent to (vit/min) ###.# mg", that's the amount your body can actually absorb, not the "Magnesium 1200g" on the front of the bottle.