I take the old u.s. RDA of magnesium 400 mg a day either split up into doses once in the morning once at night or just once all at once. I do it for everything depression hearing loss tinnitus heart problems arrhythmias the whole pinata. I'm also on a strict vegan diet for life and luckily the a lot of what I eat has a ton of magnesium including beans which I make from scratch how do I highly advise a vegan diet if you got heart issues plus I lost 20 lb 58 years old I look fuking hot in a speedo not a bad gig when you're single and an actorI'm also taking the glycinate - but it's tricky because the dose is so low compared to the other forms. IF it's more absorbable than the others, perhaps the doses in the bottle are plenty.
Doctors have to do CYA, so they tell you to use the form that's been researched. Perhaps they're right. But in my case, I had to avoid pure oxide, and used Trader Joe's magnesium, which includes Oxide, Citrate, and another form.
When I went into the hospital in late December, my magnesium numbers were up - demonstrating that these supplements ARE increasing the magnesium levels. Sure, I was still taking magnesium oxide, but I'm pretty sure that the other forms also helped.
It would be interesting to see if your blood magnesium changes after taking it -- but of course this would require prescriptions from your doctor before and after taking it for a week or two.