[jc55]

My first post. I've been using magnesium oxide to prevent constipation. My understanding is that magnesium oxide has a poor absorption rate - and therefore excels as a laxative.

I'm attempting to 'fine tune' my magnesium regimen. My question: Is magnesium oxide a better laxative choice than magnesium chelate - which appears to have a higher absorption rate?

I guess I'm looking for the least absorbable magnesium which should equate as being the best magnesium laxative.

Comments appreciated ~ james

[Peter B]

Originally Posted by jc55

My first post. I've been using magnesium oxide to prevent constipation. My understanding is that magnesium oxide has a poor absorption rate - and therefore excels as a laxative.

I'm attempting to 'fine tune' my magnesium regimen. My question: Is magnesium oxide a better laxative choice than magnesium chelate - which appears to have a higher absorption rate?

I guess I'm looking for the least absorbable magnesium which should equate as being the best magnesium laxative.

Comments appreciated ~ james

I'm wondering if there are better options for what you need.
There is a risk of over dosing on magnesium with heart problems a concern.
I take the chelate version for muscle tightness relief, but it is not cheap. It also has a laxative effect.
Have you considered some of the herbal laxatives, such as Herbalax?
I take this every day to compensate for pain tablets. Easy to vary the dose as required.
I wonder if it would be both cheaper and more reliably effective than fiddling around with an unknown supplement.

[mrsD]

One gets about 8mg of magnesium from 400mg of magnesium oxide. This was done in studies.

Magnes Res. 2001 Dec;14(4):257-62.
Bioavailability of US commercial magnesium preparations.

Firoz M, Graber M.

Department of Veterans Affairs Medical Center, Northport, NY 11768, USA.

Magnesium deficiency is seen with some frequency in the outpatient setting and requires oral repletion or maintenance therapy. The purpose of this study was to measure the bioavailability of four commercially-available preparations of magnesium, and to test the claim that organic salts are more easily absorbed. Bioavailability was measured as the increment of urinary maginesium excretion in normal volunteers given approximately 21 mEq/day of the test preparations. Results indicated relatively poor bioavailability of magnesium oxide (fractional absorption 4 per cent) but significantly higher and equivalent bioavailability of magnesium chloride, magnesium lactate and magnesium aspartate. We conclude that there is relatively poor bioavailability of magnesium oxide, but greater and equivalent bioavailability of magnesium chloride, lactate, and aspartate. Inorganic magnesium salts, depending on the preparation, may have bioavailability equivalent to organic magnesium salts.

PMID: 11794633 [PubMed - indexed for MEDLINE]

from... http://www.ncbi.nlm.nih.gov/pubmed/11794633?ordinalpos=1&itool=EntrezSystem2.PEntrez. Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.P ubmed_Discovery_RA&linkpos=2&log$=relatedarticles& logdbfrom=pubmed

400mg of mag oxide has 200mg of elemental magnesium, so 4% of 200mg is 8mg.

So yes, for a laxative mag oxide will work. There is a product of magnesium designed as a laxative...Phillips Milk of Magnesia. It contains magnesium oxide.
http://phillipsrelief.com/caplets.html

[jc55]

Thanks Peter B and mrsD,

It was after trying MOM that I 'discovered' magnesium. After considerable trial-and-error, I ended up with a daily regimen of 800 mg of magnesium oxide and 750 mg of chelated magnesium {1050 mg total daily}. This combination provides near normal regularity when split morning/eve {as long as I drink copious amounts of liquid}.

My desire to fine-tune {minimize my daily magnesium intake for the long haul}, has led me to consider replacing the 750 mg of chelated magnesium with less regular magnesium oxide - since it appears to be the least absorbed of all the magnesiums - and therefore functions best as a laxative.

I've been taking 1050 mg for over a year - and all seems well. I was just wondering about replacing the chelated magnesium with magnesium. Then, I read about magnesium citrate . . . {so many different kinds of magnesium out there}.

Thoughts? ~ james

[mrsD]

The chelate you have probably is mostly chelate and not much mag. For example 1000mg of magnesium malate has about 150mg of magnesium in it. The chelate portion is an organic molecule and weighs quite a bit.

The RDA for magnesium for an adult is 350mg -400mg.
Most people do not consume the RDA...the average is about 200mg if they are lucky.

So I doubt you are getting too much magnesium at this time.
The fact that you have laxative action, means not much is getting absorbed.

I have a magnesium thread here:
http://neurotalk.psychcentral.com/showthread.php?t=1138

[jc55]

Since chelated magnesium is mostly chelate and little magnesium, it appears replacing my daily 750 mg of chelated magnesium with magnesium oxide might be the way to go. Based upon your information, my daily 1550 mg dose might be lowered to something far less of straight magnesium oxide - maybe about 1000 mg. {OH!, I errored in my previous post. I stated my daily regimen was 1050 mg magnesium. I really meant: 1550 mg - 1050 mg before breakfast and 500 mg before supper}. I shall begin experimenting with lesser amounts of {only} magnesium oxide.

I do have one remaining question: From reading the magnesium thread you provided, magnesium citrate is touted a 'a laxative.' Also, magnesium citrate is described as possessing a higher absorption rate than magnesium oxide. I've been led to equate a lower absorption rate with a having a better 'laxative effect.'

Since magnesium oxide appears to have a lower absorption rate, my simple reasoning would conclude that magnesium oxide would function better as a laxative than magnesium citrate?

Thanks ~ james

[mrsD]

Magnesium citrate used in large amounts is a laxative.
It is used to prep for some X-rays...but now that we have the PeG type it is less common. It is still sold in drugstores on the shelf in a glass pop bottle -- called Citrate of Magnesia

People vary in response to magnesium products. Really slow movers can tolerate more magnesium citrate than others with fast transit. It is a personal thing. So when used in small amounts some mag will be absorbed into the blood stream.

The whole idea for magnesium supplements is to have the best absorption as possible, since this mineral is so critical for the body, and 7 out of 10 Americans are deficient.

For laxative action, absorption is not the goal.

[jc55]

Originally Posted by mrsD

For laxative action, absorption is not the goal.

The whole idea for magnesium supplements is to have the best absorption as possible, since this mineral is so critical for the body, and 7 out of 10 Americans are deficient.

mrsD, please forgive my density. For maximum laxative action, wouldn't the magnesium with the least absorption rate make the best laxative?

My primary reason for taking magnesium is to establish and maintain regularity. At my current consumption rate of 1000-1500 mg of poorly absorbed magnesium oxide, I would think I'm getting enough absorption of magnesium for my normal daily requirements? My fear was in consuming too much magnesium.

james

[mrsD]

No, magnesium is not appreciably absorbed from mag oxide.
8mg/400mg dose is negligible.

The chelates give better absorption from studies, but DOSE is also a factor. Take enough of a chelate and it will be laxative too.

Based on the study I put up here, 1500mg of mag oxide would yield about 30mg absorbable magnesium (if it weren't somehow lessened by the increased motility it caused). 30mg is about 1/10 of the RDA.

Don't forget you must account for elemental values. 400mg of mag ox is about 50% mag and only 4 % of that is absorbed under ideal conditions.

So magnesium oxide is in the Laxative called Phillips caplets:
http://phillipsrelief.com/caplets.html

Magnesium citrate taken in large amounts is also laxative, and has been used that way for decades. That Citrate of Magnesia bottle is totally consumed for that effect.
http://www.allegromedical.com/otc-me...19e33618e01127
TEN ounces all at once!

While you are looking only for laxative action, what are you doing for your supplement needs? It is this that confuses me about your post.

[jc55]

Originally Posted by mrsD

Based on the study I put up here, 1500mg of mag oxide would yield about 30mg absorbable magnesium.

So magnesium oxide is in the Laxative called Phillips caplets:

While you are looking only for laxative action, what are you doing for your supplement needs? It is this that confuses me about your post.

WOW! mrsD, Most informative! Thanks. Much appreciated information here.

Here I'm thinking I was on the verge of OD'ing, and now it appears my 1550mg {being ½ mag oxide} is actually closer to under-dosing. I appreciated the Phillips caplet URL. Their caplets are essentailly 100% mag oxide. I didn't know that.

I can see why you were wondering about the wisdom of my 'daily dose.' Even at 1550mg {only 750mg being chelated mag}, I may be falling short of meeting my daily magnesium needs. Maybe I should maintain the 1550mg and just add more mag oxide should I feel a need to increase the laxative effect.

Whole new ballgame here.

Thanks mrsD ~ james