If you continue to read that section of the paper you linked, they cite several human studies that all showed how poorly magnesium oxide was absorbed relative t

If you continue to read that section of the paper you linked, they cite several human studies that all showed how poorly magnesium oxide was absorbed relative to all the other magnesium supplementation options, especially in the Table 4 link in section 4.2.5 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5652077/table/T4/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5652077/table/T...). > Siener et al. administered 404 mg/day of magnesium oxide to healthy volunteers and analyzed the magnesium concentration in blood and urine. There was no significant change in blood concentration of magnesium, but urinary magnesium excretion increased by 40% after administration of magnesium oxide. Yoshimura et al. performed a pharmacokinetic study of orally administered magnesium oxide in rats. They showed that 85% of magnesium is excreted in feces, while 15% of magnesium is absorbed from the intestinal tract and excreted in urine. [2] > A 2017 rat study demonstrated its low absorption rate, concluding that only 15% of orally administered magnesium oxide was absorbed, while 85% was excreted in the feces. Older research suggests the absorption rate is even lower in humans [1,2] This study puts the absorption at 4%. [5] It's normally used as an antacid or laxative. > Magnesium oxide is an inorganic salt of magnesium. Even though it contains high amounts of magnesium, it has low absorbability in the body. Still, it has been shown to offer health benefits like constipation relief. [3] Oxide is among the least bioavailable form of magnesium, right down at the none-to-almost-none tier with magnesium stearate. Which is what this study comparing various supplements shows, too. [4] What I meant was that it's a waste of time due to its ultra-low bioavailability. If you're trying to supplement, pick one of the many options that your body can actually use. Unless you're constipated I guess. Yes, I know it's sold as a supplement, and included in many multivitamins. You should know that doesn't mean much, vitamins and supplements in the US are not FDA regulated and there's no real guarantee they (a) do anything or (b) are in a form that does anything. Never hurts to be polite ;) [1] https://pubmed.ncbi.nlm.nih.gov/28123145/ https://pubmed.ncbi.nlm.nih.gov/28123145/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911806/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911806/ [3] https://www.healthline.com/nutrition/magnesium-oxide https://www.healthline.com/nutrition/magnesium-oxide [4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683096/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683096/ [5] https://pubmed.ncbi.nlm.nih.gov/11794633/ https://pubmed.ncbi.nlm.nih.gov/11794633/