Magnesium Oxide: Cheap, but Poorly Absorbed

Magnesium oxide is everywhere, and it’s cheap. On the label it looks generous too, with more elemental magnesium per gram than any other common form. The catch: your body absorbs relatively little of it. The US National Institutes of Health lists oxide among the lower-bioavailability forms.

What isn’t absorbed doesn’t just leave quietly. It draws water into the gut, which is why oxide turns up in laxatives and some antacids, and why a decent dose can send you to the bathroom in a hurry. Useful, if that’s what you bought it for. If your actual goal is raising your magnesium levels, a better-absorbed form like magnesium glycinate or magnesium citrate will do more with less.

Worth checking: some budget supplements blend oxide into other forms to fatten the label numbers. The ingredients list gives it away.

Sources: NIH Office of Dietary Supplements — Magnesium Fact Sheet (https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/)

This article is general information, not medical advice.