Magnesium Absorption and Effects of Other Supplements

Magnesium and fat from pork - what's the deal?The good news is, the fat you eat may be giving you more magnesium – even though it may not be a magnesium rich food itself.

At least sometimes.

This shouldn’t be a surprise, despite the demonization of fat, it has been a staple part of the human diet dating back to dawn of hunting and fire. Indeed, insufficient fat was a much bigger concern throughout most of history. As always, abundance turns the world upside down, and fat got on the wrong side of many dieticians, not to mention dieters.

Well, here’s a reason to make sure you have at least some fat in your diet. But, before you get too exited, evidence has shown that excess fat can actually block the absorption of magnesium.

So here goes – things that help you absorb more magnesium:


A study by the American Journal of Clinical Nutrition (Vol. 80, No. 2, 396-403, August 2004) looked at a small group of people to compare their absorption of carotenoids when eating salads with fat-free dressing as opposed to regular salad dressing with oil. Lo and behold, those who went fat-free absorbed almost no carotenoids, suggesting that the fat was needed for the body to access the nutrients.

I am very much opposed to “fat-free” concoctions for a number of reasons, not least being the manufactured crap they use to trick your body into tasting fat. Here’s another. If you’re worried about too much fat, do the old fashioned thing and reduce your portions. Your portions may be small, but at least they’ll be real, delicious and healthy.


Often cited as assisting magnesium absorption, there is very little evidence either way. But, since vitamin C is generally good for you, I’d rather err on the side of taking my supplements.


A 1972 study in the International Urology and Nephrology Journal in the Netherlands suggested that vitamin D could be helpful in assisting patients who needed greater absorption of magnesium through the intestine. This has been backed up by other studies, including “The Journal of Nutrition” study published in 1991.

However, and this is a big “however,” the 1991 study showed that vitamin D greatly increased the excretion of magnesium through the urine!

Easy come, easy go.

The jury is out on Vitamin D, but at the very least vitamin D supplements would seem to be unnecessary for magnesium absorption.


This is a biggy. Many websites will tell you that calium is a magnesium antagonist, inhibiting its entry into cells. Other sites will tell you that they need each other. Magnesium helps calcium to work, and vice versa. They are in fact friends.

Not to confuse you, but all of the above appears to be true. Maybe it’s best to think of calcium of magnesium as a turbulent married couple (or even Tweedledee and Tweedledum)- not always helpful to each other, yet they both needCalcium and Magnesium are Tweedledum and Tweedledee the other. There’s a fine balance between the blow out fights, the affairs, and the love and support.

In the case of magnesium and calcium, many people have decided that the ration of 2 parts calcium to one part magnesium is this perfect ration.

This 2 to 1 ratio appears to be plucked out of thin air.

In fact, in Japan, which has a very low rate of heart disease, the ration is closer to 1/1.

The only thing I can say here is to take it easy on the calcium supplements.


Long term, and massive doses, of oral vitamin B6 appear to boost magnesium levels. Since massive doses of anything should only be administered by a competent physician, just put this in the back of your mind. B6 shots will temporarily boost magnesium levels, and at the same time crash your calcium levels. So while B6 does encourage magnesium retention, it’s not something you’d want to try lightly.


If you’re getting your magnesium from mineral water, a 2002 study published in the American Journal of Clinical Nutrition showed that, while 50% of the water’s magnesium was absorbed when drunk without food, that amount greatly increased when the water was taken with a meal. To which we say “bon apetit!”

Going back to the fat, since most magnesium rich nuts, such as almonds and cashews, contain oil, you’re probably better off munching on them. So far as other supplements to boost your magnesium absorption, just forget it. Keep your consumption of alcohol, caffeine and carbonated drinks to a minimum, eat fresh foods, and especially green leafy things. Don’t go into mad scientist mode trying to make the perfect supplement concoction. Eat foods high in magnesium and enjoy life!

Magnesium During Pregnancy

Magnesium and Pregnancy - Some ThoughtsIs Magnesium Safe During Pregnancy?

As long as you don’t overdo it, yes. The United States daily requirements for magnesium are actually increased in pregnant women as follows:

Adult Female: 300mg

Pregnant Female: 320mg

Breastfeeding Female: 350mg

That’s too little according to many sources. The Baby Center goes even farther:

Pregnant women, 19 to 30 years of age: 350 milligrams (mg) of magnesium per day
Pregnant, 18 and younger: 400 mg
Pregnant, 31 and older: 360 mg
Breastfeeding women, 19 to 30: 310 mg
Breastfeeding, 18 and younger: 360 mg
Breastfeeding, 31 and older: 320 mg

There is some evidence that magnesium helps prevent the uterus from contracting too soon, though this is still inconclusive. Magnesium certainly helps prevent cramps, though.

Magnesium citrate, on the other hand, is something that the FDA recommends taking only when the benefits outweigh the risks.

In BJOG: An International Journal of Obstetrics and Gynaecology in August 2007, two studies are cited. The first study concluded:

“Additional magnesium appeared to benefit the fetus during labour. Significantly fewer showed fetal heart rate irregularities, meconium-stained liquor and partogram abnormalities. The supplemented group also had fewer late stillbirths either before or during labour.”

“It must be stressed that these secondary findings, although of interest, need to be substantiated by further work. Until then, supplementation cannot be recommended but poorly nourished women should be encouraged to eat a diet that contains adequate magnesium, in particular brown – rather than white – bread.”

The second study had the following comments:

“In our commentary, we recommend further research to find out whether improving calcium intake from before pregnancy might reduce not only blood pressure, but associated problems such as protein in the urine as well. We suggest that fortification of staple foods might make the benefits of adequate calcium intake available to all pregnant women, not only those with access to antenatal care.”

“While these studies show that the consumption of certain minerals during pregnancy results in favourable outcomes for mother or baby, it must be stressed that in these studies, the intake of supplements are carefully measured.”

“Women should attend their antenatal clinics so that tests identifying problems can be carried out. If they are interested to know more about supplementation, they should speak to their GPs and midwives for further advice.”

We should note that women who do not have a deficiency in magnesium or calcium need to be careful about taking extra supplements if they don’t need it.”

So, while magnesium looked like a plus, these were undernourished women in the study. Assuming you have a healthy diet, you may want to think twice about using magnesium supplements.

There are several other studies, and while most suggest that magnesium isĀ  beneficial for the fetus, almost all balance that by saying that the results for well-nourished women may be different.

So What to Do?

In light of the research, try eating better. An extra serving of spinach, nuts or halibut each day may do wonders. If you really feel the need to take supplements, at least try to make sure the dosage is not much over the RDA of 350mg.