I've been trying to research how much magnesium I should be taking, as I I was starting to think I might have been overdoing it. So far, I've come up with a couple of interesting facts I thought I should share:
1. The amount of "elemental magnesium" in different types of magnesium supplements REALLY varies. So, 100mg of say, magnesium oxide is not equivalent to 100mg of magnesium citrate. The amounts of elemental magnesium for different magnesium preparations are the following:
Magnesium oxide 60%
Magnesium citrate 16%
Magnesium chloride 12%
Magnesium lactate 12%
Magnesium sulfate 10%
So this is something to consider when you are calculating how much to take each day. I found one site that recommends not taking more than 490mg of elemental magnesium a day (~40 mEq)
One (1) gram of the various magnesium salts contain the following amounts of elemental magnesium:
magnesium chloride: 120 mg (9.8 mEq) elemental magnesium.
magnesium gluconate: 54 mg (4.4 mEq) elemental magnesium.
magnesium lactate: 120 mg (9.8 mEq) elemental magnesium.
magnesium oxide: 603 mg (49.6 mEq) elemental magnesium.
magnesium sulfate: 99 mg (8.1 mEq) elemental magnesium.
2. Even if you are taking more elemental magnesium per milligram of magnesium supplement, it doesn't mean you're getting more magnesium, as the bioavailability really varies. This study
showed that magnesium oxide is poorly absorbed (4% fractional absorption) compared to magnesium chloride, lactate and aspartate (summary doesn't have % for these, and I can't find the full text to get more details).
If anyone finds more info that would be great... I'm currently dissolving 50mg of magnesium chloride in 1.5 liters of water and taking 40mL of this a day (10mL in the AM and 30mL in the PM), as recommended by the instructions from the pharmacy (they recommend 80mL total for older adults).
I figure that means each mL gives me 33.33mg of magnesium chloride, meaning I get 1,333.2mg a day. I was worried that was too much, but it's really just 160mg of elemental magnesium
. So I could definitely even go up to taking 80 mL of the solution a day. (If someone sees me making some glaring error in my logic here, please do correct me!)
When I was thinking I was taking too much was when I was taking 400mg of magnesium oxide (I messed up and bought that instead of citrate pills) in the morning and the 30mL of m. chloride in the evening. That meant I was getting 240mg elemental mag from the oxide + 120mg from the chloride = 360mg total elemental. So probably not too much either. I might try it again and see if I get the same reaction.
I'm not sure how the bioavailability factors into all of this... the 490mg total recommendation doesn't seem to take it into account... or maybe the differences aren't so great as to affect the general recommendation?
Finally, it appears you absorb magnesium a lot better if you take it in small doses throughout the day: http://www.ncbi.nlm....ubmed/21473800.
'94-'08 On/off ADs. Mostly Zoloft & Wellbutrin, but also Prozac, Celexa, Effexor, etc.
6/08 quit Z & W after tapering, awful anxiety 3 mos. later, reinstated.
11/10 CTed to get pregnant. At first emotional & irritable, but anxiety 3 mos. later & @ 8 mos. much worse (set off by metronidazole). Anxiety, depression, anhedonia, DP, DR, dizziness, severe insomnia, high serum AM cortisol.
12/11 Relapse, work stress. Anx., dep. & insom.
1/12 Gradual improv. in anx. & insom.
4/12 Much better, esp. dep. Insom/anx lower.
7/12 Two weeks of feeling completely healed.
10/12 Awful relapse, DP/DR. Hydrocortisone?
11/12 Improved fairly quickly.
1/13 Best I've ever felt.
3/13 A bit of a relapse.
8/13 Still have probs off and on w/ anxiety & insomnia but much better overall.