Monday, February 22, 2010

Magnesium and Insulin Sensitivity

From a paper based on US NHANES nutrition and health survey data (1):
During 1999–2000, the diet of a large proportion of the U.S. population did not contain adequate magnesium... Furthermore, racial or ethnic differences in magnesium persist and may contribute to some health disparities.... Because magnesium intake is low among many people in the United States and inadequate magnesium status is associated with increased risk of acute and chronic conditions, an urgent need exists to perform a current survey to assess the physiologic status of magnesium in the U.S. population.
Magnesium is an essential mineral that many people apparently don't get enough of. One of the many things it's necessary for in mammals is proper insulin sensitivity and glucose control. A loss of glucose control due to insulin resistance can eventually lead to diabetes and all its complications.

Magnesium status is associated with insulin sensitivity (2, 3), and a low magnesium intake predicts the development of type II diabetes in most studies (4, 5) but not all (6). Magnesium supplements largely prevent diabetes in a rat model* (7). Interestingly, excess blood glucose and insulin themselves seem to reduce magnesium status, possibly creating a vicious cycle.

In a 1993 trial, a low-magnesium diet reduced insulin sensitivity in healthy volunteers by 25% in just four weeks (8). It also increased urinary thromboxane concentration, a potential concern for cardiovascular health**.

At least three trials have shown that magnesium supplementation increases insulin sensitivity in insulin-resistant diabetics and non-diabetics (9, 10, 11). In some cases, the results were remarkable. In type II diabetics, 16 weeks of magnesium supplementation improved fasting glucose, calculated insulin sensitivity and HbA1c*** (12). HbA1c dropped by 22 percent.

In insulin resistant volunteers with low blood magnesium, magnesium supplementation for four months reduced estimated insulin resistance by 43 percent and decreased fasting insulin by 32 percent (13). This suggests to me that magnesium deficiency was probably one of the main reasons they were insulin resistant in the first place. But the study had another very interesting finding: magnesium improved the subjects' blood lipid profile remarkably. Total cholesterol decreased, LDL decreased, HDL increased and triglycerides decreased by a whopping 39 percent. The same thing had been reported in the medical literature decades earlier when doctors used magnesium injections to treat heart disease, and also in animals treated with magnesium. Magnesium supplementation also suppresses atherosclerosis (thickening and hardening of the arteries) in animal models, a fact that I may discuss in more detail at some point (14, 15).

In the previous study, participants were given 2.5 g magnesium chloride (MgCl2) per day. That's a bit more than the USDA recommended daily allowance (MgCl2 is mostly chloride by weight), in addition to what they were already getting from their diet. Most of a person's magnesium is in their bones, so correcting a deficiency by eating a nutritious diet may take a while.

Speaking of nutritious diets, how does one get magnesium? Good sources include halibut, leafy greens, chocolate and nuts. Bone broths may also be a source of magnesium. Whole grains and beans are also fairly good sources, while refined grains lack most of the magnesium in the whole grain. Organic foods, particularly artisanally produced foods from a farmer's market, are richer in magnesium because they grow on better soil and often use older varieties that are more nutritious.

The problem with seeds such as grains, beans and nuts is that they also contain phytic acid which prevents the absorption of magnesium and other minerals (16). Healthy non-industrial societies that relied on grains took great care in their preparation: they soaked them, often fermented them, and also frequently removed a portion of the bran before cooking (17). These steps all served to reduce the level of phytic acid and other anti-nutrients. I've posted a method for effectively reducing the amount of phytic acid in brown rice (18). Beans should ideally be soaked for 24 hours before cooking, preferably in warm water.

Industrial agriculture has systematically depleted our soil of many minerals, due to high-yield crop varieties and the fact that synthetic fertilizers only replace a few minerals. The mineral content of foods in the US, including magnesium, has dropped sharply in the last 50 years. The reason we need to use fertilizers in the first place is that we've broken the natural nutrient cycle in which minerals always return to the soil in the same place they were removed. In 21st century America, minerals are removed from the soil, pass through our toilets, and end up in the landfill or in waste water. This will continue until we find an acceptable way to return human feces and urine to agricultural soil, as many cultures do to this day****.

I believe that an adequate magnesium intake is critical for proper insulin sensitivity and overall health.

* Zucker rats that lack leptin signaling

** Thromboxane A2 is an omega-6 derived eicosanoid that potently constricts blood vessels and promotes blood clotting. It's interesting that magnesium has such a strong effect on it. It indicates that fatty acid balance is not the only major influence on eicosanoid production.

*** Glycated hemoglobin. A measure of the average blood glucose level over the past few weeks.

**** Anyone interested in further reading on this should look up The Humanure Handbook


Anonymous said...

I know you are not a big supplements guy, but do you have any recommendation as to the form of a magnesium supplement?

Anonymous said...

nice info here

ReBorn Again said...

I've read that in the presence of fluoride the magnesium bonds to it to make magnesium fluoride, so if the animals you make bone soup from have been given fluoridated water (fluoride accumulates in the bones, turning them brown) then they would not be a source of magnesium and may further deplete magnesium levels.

I do wonder, if the magnesium fluoride theory is correct, if water fluoridation could be a larger part of the widespread magnesium deficiency.

Robert Andrew Brown said...
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Robert Andrew Brown said...

Another great post.

How old were the analyses used to compute the magnesium food content. IF they are old then intake levels may well be significantly lower.

I emailed the USDA asking them how they computed the mineral content of foods, and asked had the figures been revised to take account of falling mineral levels in foods after I had read the second paper below. The first USDA paper seems to suggest that mineral intake generally has not fallen in the last 50 years which is hard to comprehend given the results in the second paper.

I have not had a response.

Scary potential implications, which will feed through the food chain.

Thanks for the book recommendation - I bought it.

Moran Bentzur said...

2.5 grams of MgCl2 is not that much magnesium. If my calculations are correct it only comes out 625mg of Mg which is 150% of the RDA.

Adolfo David said...

I remember Dr Eades said years ago that magnesium would be for him the most important supplement to take.

Adolfo David said...

Also, its difficult to obtain magnesium in diet as you said.

Couldnt cocoa be a more or less good source/option of magnesium? Mary Enig asserts that chocholate cravings in some cases are due to magnesium neccesity.

Unknown said...

Great post. It's amazing to me how profound an influence magnesium had in the studies you cited. We're not talking about a piddling little 5% improvement...we're talking practically curing insulin resistance with magnesium alone!

This further buttresses my conviction that carbs (Other than fructose) are NOT causing insulin resistance. There are other underlying nutritional and lifestyle factors making people "carb sensitive" - so it appears the carbs are the problem, but in fact they are not.

Heck, I once read that a few nights of massive sleep deprivation can make you temporarily as insulin resistant as a type-2 diabetic. And we are a sleep deprived society. Not to mention vitamin D deprived and magnesium deprived.

BTW - I found the book The Magnesium Factor to be an excellent layman's introduction to the importance of magnesium.

Mehdi said...

Hi Stephan,
Are you possibly thinking about adding a Recommended Reading list to your side panel? It would be a great resource for us health enthusiasts who want to have read the latest research but also the classics.
Just a suggestion

Greg said...

Does anyone know about the absorption of magnesium pills and magnesium oil?

How about absorbtion from water? There is a magnesium advocacy site with scientific evidence:

I live close to one of the best sources of magnesium water and was going to start drinking it.

zach said...

Even when I am eating lots of salads, I need to take Magnesium Citrate or the constipation cometh.

Aaron Blaisdell said...

Excellent post Stephen! I cook my bone stocks with Britta filtered water to remove the fluoride other resident nasties. I've also switched the family to using toothpaste without fluoride and turn away the fluoride treatments our dentists keep pushing on us.

Weston Price discusses in Nutrition and Physical Degeneration the demineralization of our agricultural top soils due to over use and no returns. Top soil is like a huge bank account that we've been withdrawing from time after time with virtually no deposits. Eventually you go bankrupt and the US agricultural belt will become just like today's Iraq and Egypt. I remember learning about the fertile crescent in history class, but look at what centuries of withdrawing the topsoil did to that place. Lierre Kieth discusses this in her book The Vegetarian Myth.

Chris Kresser said...

I like magnesium glycinate from Pure Encapsulations. Mag glycinate doesn't cause diarrhea or loose stools like mag citrate, and tends to be better absorbed and tolerated. It's one of only two supplements I take (the other being high-vitamin CLO).

Stephan Guyenet said...

Hi Todd,

I haven't looked into it. The study I discussed the most used magnesium chloride.

Hi ReBorn Again,

I'm interested to read more about that; do you have references?

Hi Robert,

I think the papers are about a decade old. The USDA acknowledges that minerals are declining in soil and crops, but I don't think their calculations of mineral availability in the US diet reflect that understanding. If you look at the USDA stats, it looks like we're eating the same amount of Mg, Cu etc as we were 100 years ago, but I'm pretty sure that's not the case. I don't think the numbers are adjusted for mineral loss in crops.


You're right, I let that one slip by me! Corrected it.


Yes, chocolate is rich in Mg. I added it to the post. The one problem is it can be rich in phytic acid as well, reducing the Mg availability. Still, it contains so much Mg that it's probably a good source anyway.

Hi Deb,

I agree. I think it may be one of the major reasons why the "paleo" diet trials have been so successful.

Hi Inphidel,

I have so much info on the sidebars right now... I'm concerned I'd be burying the other info at some point. I may post on it someday.

Hi Aaron,

Britas remove chlorine but not fluoride. I do remember Price focusing a lot on soil quality. One of the things that I find surprising is that not only have plant foods become less rich in minerals, but so have the animal foods that eat those plants-- to a larger degree than I thought possible.

John Speno said...

The Drs. Eades have been recommending Mg supplements for year, at least since their 'Protein Power Lifeplan' book. They recommend chelated Mg, and I've been taking Now Foods, Magnesium Citrate, 200 mg tablets, twice a day for many years.

JBG said...

Stephan, two things puzzle me about the study using MgCl2.

"In insulin resistant volunteers with low blood magnesium..." My understanding has been that the Mg level in the blood is almost useless as an indicator of body Mg status. But these folks not only used it, but apparently used it successfully.

"...participants were given 2.5 g magnesium chloride (MgCl) per day..." Here you meant, as you've already indicated in response to another comment, "2.5g Mg as MGCl2". What puzzles me about this is that I would think such a large amount of Mg on a continuing basis would lead to serious cases of the runs.

I apparently can't get to the full text of the article without paying real money to see what the authors say. Can you shed any light on these questions?

RLL said...

Centrum for senior, the Costco, and I suspect other generic brands have 3.5 mg of magnesium.

JBG said...

Re the question about supplements, here are the results of a (non-exhaustive) survey I did only yesterday (so have not yet bought or tried any of them, except the PP Malic acid, which I've been using for a long time). I restricted the survey to chelated forms and the citrate, other common forms, such as MgO, being reputed to be poorly absorbed. A number of sources especially tout magnesium taurate, although it is expensive.

Super-Strength Magnesium Citrate
Swanson $5.49 Item #: SWU339 225 mg 120 Tabs 20.3 cents/gram

NOW Foods Magnesium Citrate
Swanson $4.40 Item #: NWF065 200 mg 100 Tabs 22.0 cents/gram

Swanson Ultra Albion Chelated Magnesium Glycinate
Swanson $6.99 Item #: SWU074 100 mg 180 Caps 38.8 cents/gram

Puritan's Pride Malic Acid 825 mg
PP $7.20 Item #008655 152 mg 180 Tabs 26.3 cents/gram

Puritan's Pride Magnesium Citrate
PP $8.40 Item #015219 100 mg 200 Caps 42.0 cents/gram

Puritan's Pride Magnesium Gluconate
PP $3.20 Item #001100 30 mg 100 Tabs 106.7 cents/gram

Douglas Labs Magnesium Taurate (via Amazon)
DL $20.40 ASIN: B0010ZX1H8 100 mg 120 Tabs 170.0 cents/gram
Four Tablets Contain: Magnesium400 mg.(From 5,000 mg. of Magnesium TaurateComplex, fully reacted)
Cheaper – 135.8 cents/gram – at

Cardiovascular Research - Magnesium Taurate (via Amazon)
CR $25.98 ASIN: B000OP5N12 125 mg 180 caps 115.5 cents/gram
From an Amazon review (not by me): "This brand has smaller capsules than the two other brands I have tried (one had very large tablets, the other had larger gelcaps with 1/3 less magnesium in each capsule). With one of the less expensive brands that I tried, I had to up my dosage by 50% when some of my symptoms began to return."

Supplement Warehouse claims to sell the 125 mg 60 caps version for <$5!

Harold said...

The big problem with Mg is that the serum levels are relatively meaningless as Mg is primarily an intracellular mineral and very difficult and expensive to measure. According to "The Magnesium Factor" (which I think is an excellent book) most older people in our society are deficient in Mg and K and should be getting extra Mg.

JBG said...

For hopefully my last post for the day... Recently I bought some magnesium "oil" (actually a supersaturated water solution of MgCl2) from Swanson:

It comes in an 8-oz spray bottle. You spritz some on your skin and rub it in (takes a while). Have just used it three times so far. No evident problem (some people report stinging) but also too soon to have any results to report.

TedHutchinson said...

Magnesium Chloride (dead sea salts) can be used transdermally as can epsom salts. Usually quite cheap in 25kg bags from Equine/farm animal suppliers.

Krispin has a useful calculator to work out your magnesium requirement from ideal body weight

Wyn said...

Years ago, like in the late 70's, I had uncontrolled PMS which wasn't really even recognized in those days. I saw a tv program out of California that stated that PMS was showing that it could be contolled somewhat with a Mg/Cal supplement. I started taking it right away and had good results. I also noticed that my cravings for chocolate went away as long as I stayed on the Mg. I entered menopause several years ago and haven't taken any more Mg but I have developed Type 2 diabetes. Wonder if their is any relation. I shall certainly start my supplements again. Thanks for the article.

JBG said...

Yet one more post, to answer my own questions from earlier.

Another, related article in Stephan's original post provides the needed information:

There it is made clear that the authors understand the limitations on using serum Mg level, but feel they were on solid ground because ALL their subjects started with diminished levels (and the orderly results suggest that perhaps their assumption was correct).

Secondly, the article makes clear that I had misunderstood Stephan's correction about the Mg dose the subjects received. It was indeed 2.5 of the chloride, not of elemental magnesium. And that disposes of the issue of the dose causing diarrhea.

John said...
This comment has been removed by the author.
John said...

"Interestingly, excess blood glucose and insulin themselves seem to reduce magnesium status..."

This brings up a chicken/egg-type situation, no? Good magnesium sources are uncommon compared to other minerals, so aren't we simply back to choosing foods to avoid excess insulin and blood glucose?

Robert Andrew Brown said...

Stimulated by Stephan's post I came across this paper, which was for me a useful source of information.

Magnesium Metabolism and its Disorders
R Swaminathan

Holly said...

I take Epsom Salt baths 2-3x week to get my magnesium as recommended by my Doc. Supposedly, good absorption rate.

B322 said...

Does anyone know if magnesium oxide is absorbed as well as other Mg compounds? MgO is what I take as a supplement - 500 mg per tablet (125% of the US RDA).

Gabriella Kadar said...

Amazing. I was just going to email you about magnesium.

One of us needs to add 'Mindreader' to their resumé. :)

Nanonymous said...

What is the mechanism behind increasing magnesium deficiency? Mg2+ is a major metal ion in every cell, involved in a good quarter of all biochemical reactions. All foods should contain plenty of it. I just don't get what it is that we can do to food to reduce Mg2+ content of it. Soaking/pressing?

Julie Bird said...

Magneisum Oxide only has a 4% absorption rate per the book Magnesium Miracle. On the other hand, it is one of the best ones to relieve constipation. :-)

Nanonymous said...

Let's correct one error here:

In the previous study, participants were given 2.5 g magnesium chloride (MgCl) per day. That's scarcely more than the USDA recommended daily allowance. (MgCl2, right?)

It may be very debatable how much Mg2+ we should ingest daily but the USDA recommended daily allowance is 420 mg (today it is called Dietary Reference Intake; former RDA was 400 mg). That is a whopping 6-fold less than 2.5 g - hardly "scarcely more".

Stephan Guyenet said...

Hi John,

It's partially a chicken and egg situation, but Mg deficiency can cause glucose intolerance. Then the glucose intolerance can further worsen Mg status.

Hi Nanonymous,

MgCl is mostly Cl by weight. So 2.5 g MgCl is not the same as 2.5 g Mg, and it's not 6 times the RDA.

When Mg in the diet/soil is low, both plants and animals have reduced tissue concentrations of Mg. Your statement that "all foods should contain plenty of it" isn't consistent with what the data show.

Unknown said...

Magnesium is the fourth most abundant mineral in the body and is essential to good health. Approximately 50% of total body magnesium is found in bone. The other half is found predominantly inside cells of body tissues and organs. But the body works very hard to keep blood levels of magnesium constant. Phentramin-d

barefootmommy said...

I just came across your blog from 180 degree health blog. It couldn't have come at a better time. I'm a 27 year old exhausted mom of 2 with symptoms of insulin-resistance and adrenal fatigue. I've been reading Dr. Schwarzbeins books which have been a great help, but putting emphasis on Magnesium makes great sense to me. I do feel so much better when I cut out coffee and grains, and include bone broths in my day. I'll also be looking into further supplementation. Thanks so much for sharing this.

TedHutchinson said...

Evidence of decreasing mineral density in wheat grain over the last 160 years.

The concentrations of zinc, iron, copper and magnesium remained stable between 1845 and the mid 1960s, but since then have decreased significantly, which coincided with the introduction of semi-dwarf, high-yielding cultivars. In comparison, the concentrations in soil have either increased or remained stable. Similarly decreasing trends were observed in different treatments receiving no fertilizers, inorganic fertilizers or organic manure. Multiple regression analysis showed that both increasing yield and harvest index were highly significant factors that explained the downward trend in grain mineral concentration.
The same process of selective breeding for faster growth and higher yields is prevalent in the all commercial farming.

dextery said...

<a href=""

Not only does Mg influence influence sensitivity, it also is critical to memory. But don't look to Mg supplements currently available to assist in memory as Mg does not cross the blood brain barrier...except in the form of magnesium-L-theronate...which is not available currently. So get your Mg from green leaves, broccoli, almonds, cashews and fruit.

Carl said...
This comment has been removed by the author.
Carl said...

The Study.....Enhancement of Learning and Memory
by Elevating Brain Magnesium

Nanonymous said...

MgCl is mostly Cl by weight. So 2.5 g MgCl is not the same as 2.5 g Mg, and it's not 6 times the RDA

Oh, my bad! Yes, MgCl2 is only about a quarter Mg so the 2.5 g is only a little over 1.5 times the RDA.

Barkeater said...

Magnesium hydroxide is readily available (Milk of Magnesia) but poorly absorbed. Dr. William Davis, a solid and trustworthy guy (he runs the Trackyourplaque website and authors the heart scan blog), says that mag water is a great way to supplement, and the mag is well absorbed in this way. I have seen a medical study saying the same thing. I find mag water to be an easy and cheap way to supplement magnesium.

The following was a reader’s submission found on (I have lightly edited it) It closely matches what Dr. Davis recommends and what I have now done for a year:
Date: Sat, 7 Sep 2002 19:32:56 EDT
For some time I've been drinking a Mg-bicarbonate water that I make very inexpensively from Milk of Magnesia (magnesium hydroxide) and seltzer water (CO2 water). . . . Here's the recipe:

The equation Mg(OH)2 + (CO2)2 = Mg(HCO3)2 is interesting, because Mg(OH)2 is magnesium hydroxide, as in milk of magnesia (MoM), and CO2 is the fizz in carbonated (seltzer) water. Combining them produces Mg(HCO3)2 (magnesium-bicarbonate), as in ... and Adobe Springs ("Noah's") water. Be sure to get the MoM in which the "active ingredient" is Magnesium-hydroxide and nothing else [no flavorings], and the "inactive ingredient" is purified water and nothing else. You'll see on the label that one teaspoon of MoM = 400 mg of Mg-hydroxide. 42 % of Mg-hydroxide is Mg, which equals 168 mg of Mg per teaspoon. Chill for an hour or two in the refrigerator a 1 liter bottle of seltzer water (not soda water), which consists of water and CO2 only. Open it, and when the fizzing settles down, spoon in 2 tablespoons (6 teaspoons) of milk of magnesia, put the cap back on, shake gently every few minutes and watch the cloudiness disappear as the Mg-hydroxide reacts with the CO2 and becomes Mg-bicarbonate. This 1 liter (approximately 1 quart) will have ~1,008 mg of magnesium + ~5,061 mg of bicarbonate.

Summary: 1 liter seltzer water + 2 tablespoons (6 teaspoons) milk of magnesia = ~1,008 mg of magnesium + ~5,061 mg of bicarbonate per liter (~ 1 quart). [The original author dilutes this for taste – I mix it with a little orange juice and drink it down as is. Straight has a slightly salty taste, but is not too bad.]

[My cost works out to less than $1 per liter, or 33 cents a day.]

Anonymous said...

Very timely, I've been planning to post on Mg for some time. I am adding it to the arsenal as replacement in my dietary scheme. I take Mg citrate daily.

Anonymous said...

@Ted Hutchinson

If that reference is accurate, then perhaps there is hope for better Mg content in meat and bones from pastured ruminants and wild game. It makes more sense to me than soil depletion, and is less depressing to think about. I still supplement as I can't see a downside to it.


That's a fascinating home brew recipe - I may have to try that. Thanks!

JBG said...

Carl's article can be accessed in web (ie, not pdf) form at:

Notice that successive sections are available via the tabs with labels like Introduction, Results, Discussion, etc.

Unknown said...

Hi - Can Stephan or anyone else here in the know comment on Barkeater's recipe for Magnesium-Bicarbonate Water? Is the math/chemistry correct? Will it have a good absorption rate? How would it compare to Magnesium-Chloride and/or Magnesium Citrate?

While I'm at it, I've had a hard time getting straight on Mg-Chloride vs. -Citrate. An thoughts?

trix said...

To make your own magnesium chloride 'oil':
Magnesium chloride crystals ( I ordered it through a Scientific Co. but will check into the equine type). The ratio of magnesium chloride to water is 50/50. Mix half magnesium chloride to half boiled water. Allow the magnesium chloride to dissolve. Once the mixture of magnesium chloride and water has cooled, pour into the container of your choice for use.
To use transdermally:
Magnesium oil should be applied to the skin using a fine mist spray bottle. To limit overspray, dispense 1-3 sprays into a cupped hand and rub into the skin thoroughly.
• For best results, apply liberally to arms and legs to ensure a large enough surface area for absorption
• If you experience some slight skin irritation, dilute Ancient Minerals magnesium oil with 1 part water to make a 50% strength solution
• 8 sprays of magnesium oil delivers approximately 100mg of elemental magnesium on the skin.
*avoid contact with eyes
(it takes about 20 or 30 mins to absorb after which you may shower if you want.)

Or, pour 6 or more ounces into a warm bath and soak 30 mins. or more.


trix said...

I also take Natural Calm magnesium citrate, taken in warm water, usually before bed.

Barkeater said...

Here is a link to a web site for afib sufferers, with a nice discussion of mag water.

They say "Magnesium dissolved in water (ionized) is considerably more bioavailable than is magnesium in solid tablets or capsules. About 50% of the magnesium contained in magnesium/bicarbonate water is absorbed[4,5]. This is 12 times better than the absorption rate for magnesium oxide."

The citations are to:

4. Sabatier, M., et al. Meal effect on magnesium bioavailability from mineral water in healthy women. American Journal of Clinical Nutrition, Vol. 75, January 2002, pp. 65-71
5. Verhas, M., et al. Magnesium bioavailability from mineral water: a study in adult men. European Journal of Clinical Nutrition, Vol. 56, May 2002, pp. 442-47

Unknown said...

I bought some Milk of Magnesia today. Word to the wise - the local pharmacy chain only had brands that had other ingredients listed as non-medicinal and the pharmacist couldn't say what they were. I finally found a pharmacy that had a more 'natural' bent and they had what the above post requested at 1/2 the cost to boot! Now to find Seltzer water.

Anna said...

The bottle of Kroger/Ralph's brand Milk of Magnesia I had on hand (exp 10/09!) listed Magnesium hydroxide 1200mg per 15 mL Tbsp. Only purified water was listed with inactive ingredients. But under Other Information, it says: each tablespoon (15 mL) contains: calcium 20 mg, magnesium 520 mg, and sodium 2 mg.

Anonymous said...

Re: Barkeater's recipe

The original author suggests substantial dilution to ~84 mg Mg and ~422 bicarbonate per liter, not only for taste but also for pH. I wonder how magnesium absorption is affected by pH.

Come to think of it, wouldn't this Mg(HCO3)2 just turn into MgCl2, CO2 and H2O when it hits the stomach acid? If so perhaps one might simply take MgCl2 and have done with it. Anybody know more about the chemistry here?

Unknown said...

Organic foods, particularly artisanally produced foods from a farmer's market, are richer in magnesium because they grow on better soil and often use older varieties that are more nutritious.

I have been reading your blog for a while and found it well written and cited. But this has me scratching me head. No citation. And the most recent studies on nutritional analysis of organic and conventional have found no statistically significant difference. Do you have a source for this data? I would be interested to read it.

Stephan Guyenet said...

Hi Greg,

Due to this being a blog, I don't feel the need to reference everything. I have to strike a balance between effort expended and content. If you poke around the internet, you'll find a number of references showing that minerals have declined in foods in several countries over the last 50-70 years.

It appears to be partially due to soil quality, and partially due to high-yield varieties. Both of those factors are going to be improved if you buy artisanal food at a farmer's market. I'm not talking about supermarket organic produced on giant farms in California.

I'm making the assumption that artisanal foods will more like the foods we were growing 70 years ago in their nutrient content. I think it's a fair assumption, but I don't have direct evidence to support it in the case of magnesium in plant foods. Although pastured animal foods are clearly more nutritious than conventional animal foods, particularly eggs and dairy.

Unknown said...

Stephen, thanks for responding. I'll work some Google magic. But your answer provides more specifics that were missing. My understand about the experiments that show no difference is that they indeed used "supermarket" organics, not heirloom varieties. The soil richness gambit should, in theory, be applicable to the supermarket organics as well. I can imagine that a varietal would show a substantial difference in nutritive content, though. Again, thanks.

Robert Andrew Brown said...


I too have seen several papers including that cited above which suggest falling mineral density in food crops.

Whilst Stephan's excellent blog has chosen magnesium deficiency issues exist for several other minerals.

As Stephan said reasons given are multifactoral, including soil mineral depletion, high yield varieties, and fertiliser use leading to mineral dilution in crops.

Whilst the popular impressions, presumably based on historic mineral plant yields, suggest that we are meeting RDAs, scientific papers in contrast often suggest that significant numbers are not meeting recommended intakes of a number of minerals.

Looked from the hospital perspective a number of trials looking at the nutritional status of patients suggest they are generally mineral deficient.

Increased numbers of people with compromised digestion, leading to reduced absorption, is logically also a factor in falling mineral levels in patients.

The book free on the web "THE WHEEL OF HEALTH" by G T WRENCH

which was referenced by another in an earlier blog, has some trenchant observations on the values placed by older civilisations on the importance placed on composting everything organic and putting back on the land.

Time and quiet observation had obviously taught previous generations simple truths we have chosen to ignore.

I am not a farmer so cannot evaluate this paper, but it does suggest that in terms of the mineral content of crops in the short term the argument for organic v conventional is not going to be clear cut.

Clearly in the long term our failure to compost everything and return it to the soil is unsustainable.

Comparison of Long-Term Organic and Conventional Crop–Livestock Systems on a Previously Nutrient-Depleted Soil in Sweden

Nigel Kinbrum said...

It looks like Magnesium Citrate is about 4 times more bio-available than Magnesium Oxide.

Unknown said...

I found a study which measured 366 foods and reported their magnesium content (along with the Korean national food agency's statement of the magnesium content for that food): . Your recommendation of mackerel doesn't look so good, at least in Korea.

By the way, this is my first post to your blog, and thank you very much for your work! I greatly appreciate that you combine direct, public, exploration and advice with the traditional routine of scientific experiment and publication.


Zooko Wilcox-O'Hearn

Stephan Guyenet said...

Hi Zooko,

Hmm, well I got my information on mackerel from Nutrition Data:

But now that I look at it again, there are discrepancies between the different types of mackerel they list. There may just have been an error in the Atlantic mackerel page. I'll remove mackerel from the post.

Robert Andrew Brown said...

HI Zooko

Good Find (-: .

Thanks for sharing

Jonty said...

Resnick measured intracellular magnesium and calcium ions directly with NMR, found that the more elements of MetS, the lower the Mgi and the higher the Cai

I found this convincing when
I plotted the ratios he came up with, see, search for "Resnick 1991"

Resnick concluded "Thus, hypertension, peripheral insulin resistance, and hyperinsulinemia may be different clinical manifestations of a common underlying cellular defect in divalent ion metabolism"

But no one's pursued this since Resnick died of pancreatic cancer in 2005

cat42 said...

I have been taking supplemental magnesium since about 1996 because of persistent constipation. I was diagnosed with insulin resistance in 2000, but I had been having symptoms of this problem, namely hypoglycemia, since the 1970s.

I take Mg as an 80% (by weight) solution of anhydrous MgCl2 (that's MgCl2x6H2O). I keep this solution in a dropper bottle; using an eye dropper allows me to adjust my dosage easily. Each dropper-full (about 1 ml) provides about 100 mg elemental magnesium. I use my bowel regularity as a gauge for adjusting my dosage. I started out taking about 1200 mg Mg/day (6 droppersful, twice a day), but now take between 600 and 900 mg per day, and I am consistently regular.

I highly recommend this method. I let my neighborhood compounding pharmacy mix the 80% solution for me, a half-liter at a time, which lasts about 2 months and costs me $20.

However, my fasting insulin is still elevated, which frustrates me no end. Any ideas? I also have mild fatty liver (NAFLD).

Nyx said...

I hate to be gross, but what about dead bodies? You mention that humans are not returning their mineral intake to the soil, but you also point out that most magnesium is in the bones. Doesn't that suggest that most of the magnesium is winding up in cemetaries??