Magnesium – The Stress Mineral, and more

mmm, tasty almondsFollowing on from the article on vegan calcium sources we’re now going to take a look at another macromineral, magnesium.

Firstly, it’s important to mention that calcium and magnesium are antagonistic. They have a love hate relationship, you might say. When you increase your calcium intake, it’s generally wise to up you magnesium intake, and vice versa. Otherwise, long term, one or the other may become deficient as they can compete for absorption. Having said that, they need each other to function correctly in the body. Without magnesium, calcium cannot do what it’s supposed to in the bones, and without calcium, well, magnesium would also be bereft.

So what does magnesium actually do, and how can you tell if you’re getting enough?

Magnesium’s Role in the Body

Magnesium is essential for the transmission of nerve impulses and also has a structural role in the body, with 57% of bodily magnesium found in the bone. Magnesium is also an essential co-factor in the Adenosine triphosphate complex (ATP-Mg) that provides all cellular energy and any deficiency will therefore lead to a shortage of cellular energy in the body, with subsequent deleterious effects on such actions, for example, as detoxification, growth, and healing. So, if you’re low in magnesium, you’ll start feeling tired, cranky, less energetic, easily fatigued, and have muscle cramps, headaches, and most likely more PMT/PMS symptoms (if applicable) than previously. Magnesium and B6 are commonly used to help women with bad premenstrual symptoms, and for those with depression or anxiety.

Magnesium Deficiency Symptoms

If magnesium intake is low expect to start experiencing tremors, hypersensitive nerves, confusion and disorientation (Flink, E.B., 1980); all relating to magnesium’s role in transmitting nerve impulses and controlling muscle contraction (Durlach, et al, 2000). In the longer term problems with calcium excess may occur, such as kidney stones or calcification of arteries, due to magnesium’s role in keeping calcium levels in check (Kubena, et al, 1990). Taking high levels of calcium once you’re over fifty might be useful for some in staving off bone diseases like osteoporosis, but only if your magnesium levels and vitamin D levels are also good. Otherwise, that calcium can cause some serious damage by depositing in places other than the bones, such as the arteries, leading to arterial stenosis, high blood pressure, and heart attacks. Calcium-channel blockers prescribed by your doctor for high blood pressure? Are you taking a bone-building supplement too? Maybe it’s time to see a nutritionist and really find out what’s going on. It could be as simple as a few dietary and lifestyle changes and you could be off the medications altogether (make sure you find a qualified practitioner, this site is not condoning the sudden cessation of medication or that you ignore medical advice! Just promoting gentle questioning as necessary…).

Magnesium and pH Balance

Magnesium plays a part in balancing the body’s pH as well. All those alkalising supplements, green foods etc, are usually very magnesium-rich, and if they’re not, you should question whether they’ll actually work or not. Chlorella, spirulina, barley grass – all rich in magnesium, and alkalising.

Magnesium Absorption from Foods

If magnesium intake were suddenly to drop significantly then the body can reabsorb 80% of the magnesium in the system, although 50-60% is more common (Sigel, 1990). In those with excellent magnesium intake a short-term deficit in the diet will usually not lead to deficiency symptoms. Those who have consistently poor dietary magnesium levels and have lots of counterproductive things occurring, such as high calcium levels, smoking, coffee-drinking etc, are much more liable to experience short and long term deficiency signs.

Other things that can affect magnesium levels include low potassium intake (or high sodium intake), high aldosterone levels, hyperparathyroidism, alcoholism (or excessive alcohol drinking), hyperthyroidism, antibiotics, diuretics, and chemo drugs.

Specific Signs of Magnesium Deficiency

And what could you expect with extreme and acute deficiency of magnesium? Symptoms would include: hyperexcitable nerves, tremors, convulsions, behavioural problems, vertigo, apprehensiveness, confusion and disorientation, overtight bowel/constipation and haemorrhoid development, oedema, leucocytosis, spleen enlargement, thymus changes, antibody levels dropping, kidney problems due to calcium crystallisation, poor bone mineralization, hypokalemia, negative potassium balance, positive sodium balance, with the latter three all contributing to low energy due to poor sodium-pump action in addition to the loss of a specific energy enzyme co-factor.

Still with me?!

Basically, you’ve got problems if your magnesium level is too low. The imbalance of potassium and sodium means high blood pressure is likely, and with the potential for calcification of the arteries, this makes a heart attack a likely prospect. Platelet aggregation also occurs, with blood clots and potential aneurysms as a cause of stroke. All that said, some simple dietary modifications can boost your magnesium levels and stop all of these scary things from becoming realities.

Getting Magnesium from Vegan Foods

Just for transparency’s sake, I had a look at my own diet and analysed the magnesium content and my likelihood of deficiency. Ah, the fun I have.

So, over ten days, apparently I ate a lot of food… ahem. Still, this was largely unprocessed, fresh fruit, vegetables, grains, and cereals. Vegetables and fruits were generally baked, eaten raw, slightly steamed or stir-fried. My average daily magnesium intake for the period was 784.25mg. This is far above the UK RNI of 270mg and even the US figure of 350mg. Some nutritionists recommend higher levels still, such as Cheraskin (400mg), and Seelig (6mg/kg body weight). Even by these standards I’m still doing alright though! Hurrah! However…

…magnesium absorption is thought to be around 30-50% so my actual likely magnesium level is 235.275-392.125mg/day, which is still close to the UK RNI even accounting for possible low absorption (their figure is for dietary intake and doesn’t account for absorption, which is a big issue in the use of these figures that plagues nutritionists everywhere).

Boosting Magnesium Absorption

Magnesium absorption is inhibited by free fatty acids, oxalates, fibre, phytates, and phosphates (Kivisto, 1986). I don’t drink fizzy drinks or eat lots of wheat bran, so the phosphates are not really an issue. I do, however eat quite a lot of beans and pulses (particularly soy), which contain phytates but, as I cook these, the phytates should be mostly destroyed making them pretty much a non-issue in my magnesium absorption.

Another potential problem is the amount of fibre I eat. This comes from vegetable sources in the main which, luckily, also provide magnesium! So the fibre’s inhibiting effect should be counteracted for the most part (Coudray, C., 1997). The vegetable matter also contains chlorophyll which is a good source of magnesium.

So, which foods do I eat that are really high in magnesium? That would be the pumpkin seeds, sunflower seeds, tofu, rice and quinoa; all vegan of course. If these foods were removed from my diet though, there would still be sufficient magnesium from other sources to meet Cheraskin’s suggested intake. So, it’s not necessarily going to make you magnesium deficient if you turn vegan, you just have to eat a balanced diet, as is the general advice.

If you feel you might be missing out on magnesium though, other than changing your diet to include more pumpkin seeds, sesame seeds, tofu, quinoa etc… what else can you do? Take a look at some advice on choosing a magnesium supplement.

References, for all you academic types:

Coudray C. Bellanger J. Castiglia-Delavaud C. Remesy C. Vermorel M. Rayssignuier Y. Effect of soluble or partly soluble dietary fibres supplementation on absorption and balance of calcium, magnesium, iron and zinc in healthy young men. [Clinical Trial. Controlled Clinical Trial. Journal Article. Research Support, Non-U.S. Gov’t] European Journal of Clinical Nutrition. 51(6):375-80, 1997 Jun.

Durlach J. Bac P. Bara M. Guiet-Bara A. Physiopathology of symptomatic and latent forms of central nervous hyperexcitability due to magnesium deficiency: a current general scheme. [Review] [64 refs] [Journal Article. Review] Magnesium Research. 13(4):293-302, 2000 Dec.

Flink EB. Magnesium deficiency. Etiology and clinical spectrum. [Review] [70 refs] [Journal Article. Review] Acta Medica Scandinavica – Supplementum. 647:125-37, 1981.

Kivisto B. Andersson H. Cederblad G. Sandberg AS. Sandstrom B. Extrusion cooking of a high-fibre cereal product. 2. Effects on apparent absorption of zinc, iron, calcium, magnesium and phosphorus in humans. [Clinical Trial. Journal Article. Randomized Controlled Trial. Research Support, Non-U.S. Gov’t] British Journal of Nutrition. 55(2):255-60, 1986 Mar.

Kubena KS. Durlach J. Historical review of the effects of marginal intake of magnesium in chronic experimental magnesium deficiency. [Review] [73 refs] [Historical Article. Journal Article. Review] Magnesium Research. 3(3):219-26, 1990 Sep.

Nielsen FH. Milne DB. A moderately high intake compared to a low intake of zinc depresses magnesium balance and alters indices of bone turnover in postmenopausal women. [Clinical Trial. Journal Article. Randomized Controlled Trial. Research Support, Non-U.S. Gov’t] European Journal of Clinical Nutrition. 58(5):703-10, 2004 May.

Sigel, H., Sigel, A., (1990), Compendium on Magnesium and Its Role in Biology, Nutrition, and Physiology, CRC Press.

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