• Welcome to Phoenix Rising!

    Created in 2008, Phoenix Rising is the largest and oldest forum dedicated to furthering the understanding of and finding treatments for complex chronic illnesses such as chronic fatigue syndrome (ME/CFS), fibromyalgia (FM), long COVID, postural orthostatic tachycardia syndrome (POTS), mast cell activation syndrome (MCAS), and allied diseases.

    To become a member, simply click the Register button at the top right.

Does Magnesium deplete Calcium?

Tiger Lily 813

Senior Member

I want to take magnesium for various reasons right now, but became concerned that it would lower calcium? Can someone please confirm if this is so? I've heard that calcium can lower magnesium, and that has me wondering if the reverse is also true. Basically, I just want to know if I can take magnesium without consequences (I don't take calcium).

I've had bone health issues and wanted to be sure that taking magnesium (alone, without calcium) would not screw up my calcium levels. I'm waiting on bloodwork results so I can know the specific balance of everything I should be taking, but would generally like to know more about this interaction. I know that magnesium can support calcium utilization (one of the reasons I want to take it)...



Senior Member
My understanding is that this concern is about Magnesium and calcium competing for the same transporters in the gut.

If you take too much magnesium orally you risk malabsorption diarrhoea - where the unabsorbed magnesium exerts an osmotic pressure to holds water in the gut and not allow it to pass into the body.

I would suggest trying MgSO4 (Epsom salts) in a bath or footbath, as this allows a lot to be absorbed without risking malabsorption diarrhoea. Some people prefer MgCl, I have used both. The MgCl seemed more effective, I felt it was doing something pretty much immediately, but it is more expensive and I find that it stings if you have even the slightest abrasion on your skin.

I have not read all of this but I find examine a good source on minerals and other supplements https://examine.com/supplements/magnesium/


Senior Member
Yes, they interact and in both ways, in fact all minerals have interactions, usually in both directions. An example would be copper, zinc, manganese and iron, if one becomes dominant then the others can be suppressed. They refer to this as agonist/antagonist. You can image search for "mineral wheel" which is a diagram showing these relationships.

Bone health is comprised of many minerals including magnesium, copper, boron and many others (including calcium).

Magnesium comes in many forms and not all of them work the same, for instance mag oxide is a poorly absorbed form and you will find this in many formulas. I use mag glycinate combined with mag lysinate (Doctor's Best High Absorption) which has worked well for myself and many others. UltraMag is another good form.


Senior Member
I've heard that calcium can lower magnesium, and that has me wondering if the reverse is also true.

Only my personal experience here. I got a very severe magnesium deficiency 10 years ago. Where only very high doses of all kind of magnesium, titrating up to even 2.6 g/d of oral elemental supplemented magnesium till now, eased very painful muscle-cramps only somewhat. Finally I could get Mg-sulfate IVs since last year, and only theses additional to my very high Mg-intake ceased the cramps completely.

In the first 2 of these 10 years my serum calcium had been deficient. Probably by also increasing vitamin D3 intake to optimal levels, serum calcium has remained optimal since (while supplementing only minimal calcium, about 600 mg/d). Therefore actually I rather suspect having raised vitamin D, by increased magnesium utilization, to have been responsible for this very severe and long lasting Mg-deficiency.

So in my case very high daily oral intake of up to 2.6 elemental Mg had no depleting effect on serum calcium at all. But I can't be sure of the opposite, that through the optimized calcium with vitamin D there might have been a somewhat antagonistic effect on my magnesium status.

Since we are all different, one can only experiment by starting with lowest doses, and increase gradually over weeks, months and years. While monitoring lab-markers and adjust accordingly.

Magnesium comes in many forms and not all of them work the same, for instance mag oxide is a poorly absorbed form and you will find this in many formulas.

Even that isn't true. After having blown up a lot of money after years with allegedly more bio-available forms of magnesium, came across a blog post which pointed out the fallacies in those studies measuring low bio-availability with Mg-oxide, and pointed to more dependable studies which showed equal to other Mg-forms bio-availability. Which in my case I could readily rectify, since I always needed an equal amount of elemental magnesium to alleviate my muscle-cramps equally. And thereby found could save a lot of money by doing without the more expensive forms.

But there is meanwhile so much money to be made by this promotional myth, and therefore wont die easily.

However what still is true, different individuals will have different tolerances to different Mg-forms. Therefore also here only slowly experimenting with different forms will show what anyone individual tolerates the most, without getting loose bowel-movements.
Last edited:


Senior Member
U.S., Earth
I'm not sure that supplemental magnesium "depletes" calcium, but the body does need to maintain a relatively constant ratio of magnesium to calcium, especially for proper nerve function.

To share my N=1 experience:
In my case, I started taking Magnesium and, after some initial start-up effects, I started to feel noticeably better.

Then, after a number of weeks I started to get some bad effects which, after careful analysis, could only be traced to the Magnesium.

I was somewhat stumped. How can something work so well in the short term but slowly develop bad effects over time?

When I remembered that the body needs to maintain a certain ratio of magnesium to calcium, I realized that the bad effects that I had developed happened to be the same as those seen with calcium deficiency.

As a test, I popped a couple of calcium supplements and all the bad effects disappeared in about 12 hours. I then set about slowly increasing my daily calcium intake until I stopped developing the bad effects.

Based on my experience, I would recommend that any supplemental magnesium be complemented with supplemental calcium in the ratio of one part magnesium to roughly 2.4 parts calcium. (Which also happens to be the ratio of the two RDA's.)

Just don't take the magnesium and calcium at the same time, as they compete for absorption. For what it's worth, I have been taking 160mg Magnesium Citrate and 400mg Calcium Citrate per day for a number of years now.

And as always, we must remember that everyone has the potential to react differently.


Senior Member
Based on my experience, I would recommend that any supplemental magnesium be complemented with supplemental calcium in the ratio of one part magnesium to roughly 2.4 parts calcium.

As just said, always be aware that personal experience differ. Just as an example from the clinical experience of the late Dr. Nicholas Gonzales I noted down from an interview, the calcium to magnesium ratios for different individuals in bold:

Dominant sympathetic types: Typ ‘A’ personalities, disciplined; mostly solid cancers; do good on much plant based foods: fruits, vegies, seeds, grains, nuts, plant based oils: hemp, flax; Vitamin B1, B2, B3, 8:1 ratio magnesium to calcium, High vitamin C & D; but not on much meat protein, No b12, no choline, no pantheonic acid, no zinc, no selenium, no fish oil. Yes to beta Carotene, chromium, folic acid, riboflavin, thiamin,& niacin

Parasympathetic types are rather creative with unconventional ‘formal’ education; mostly blood-based cancers; do good on lots of meat and a ketogenic diet, saturated fats, fats from fish oils, Calcium 10-15 ratio to magnesium (High magnesium causes depression), Vitamin B12, B5, Choline; not as good on grains or seed. Need zinc & selenium, not good with other large Vitamin B doses.

Mixed or balanced types: suffer rather from allergies and fatigue.

I seem to be a mixed type, since getting really sick after 30 years being vegan. And improved a lot by adding much healthy fats, eggs, fish and a little beef (once a month) back in.

During the last 10 years got magnesium 0.63 g/d from diet + 2.63 g/d from supplements = 3.26 g/d elemental magnesium.
But 1.11 g/d of calcium from diet + 0.63 g/d from supplements = 1.74 g/d elemental calcium. Therefore about a 2:1 ratio of magnesium to calcium. An opposite to the ratio leading to chronic diseases before from dietary sources alone - and after when I experienced improvement in chronic diseases (PAD, COPD 1). So also in this respect falling somewhere between the extremes.