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Are you getting enough magnesium

By David Coory

Magnesium is the most seriously deficient bulk mineral in the New Zealand diet and symptoms of too little include many common health problems. Our New Zealand soils tend to be low in magnesium and the mineral is not replenished by most commercial fertilisers.

Magnesium is also lost during the processing of food. About 80% of magnesium is discarded when wheat is milled into white flour and all magnesium is lost during the refining of white sugar.

Calcium competes for the limited supplies in our body, as it requires magnesium to enter the bones. This can leave insufficient magnesium for the many other needs of the body.

Water-expelling diuretic drugs such as frusemide and excessive perspiration also deplete the body’s supply of magnesium.

Magnesium is an electrolyte. An electrolyte is a scientific term for the macro minerals, potassium, sodium, chloride, calcium and magnesium which are required to operate our body cells. They are called electrolytes as they are able to hold an electrical charge and can be controlled accordingly.


There are many types of magnesium used in supplements (over ten) and there have been a lot of studies over the years about which ones absorb the best. The problem with these studies is the way the tests are run. Often the tests look at magnesium in the blood or the urine or stool, but it is the magnesium retained in the cells that is important.

Unfortunately to do cell tests on humans is not very feasible (requiring surgery) and we were always a bit skeptical about the studies as the results tended to contradict each other.

Luckily an extremely detailed study was undertaken that looked at ten sorts of magnesium and not only looked at blood and urine but also measured the magnesium in the cells (using rats not humans). It also tested the magnesium levels in the stomach, and various parts of the digestive track. It is preferable that the magnesium gets to the small intestine to be absorbed.

The key results were that the organic magnesium salts (like Magnesium Citrate/Gluconate/Lactate and Aspartate) absorbed much better than the inorganic magnesium salts (like Magnesium Oxide/Sulphate and Carbonate).

Amount of Magnesium

The next important factor regarding magnesium is the amount of magnesium. While it is important to be absorbed you also need to get a certain amount. The recommended daily intake of magnesium is in the chart below.

The magnesium with the highest amount of magnesium is Magnesium Oxide (60%) magnesium, but this requires good stomach acid to absorb. In some cases the amount absorbed could be as low as only 4%.

Magnesium Citrate is around 12% magnesium but is very well absorbed.

Magnesium Gluconate is probably the best absorbed, but at only 5% magnesium you get very low levels in a capsule.

What we have done, is purchase a Magnesium Complex, which is mainly Magnesium Citrate along with some Magnesium Oxide. So you get a well absorbed magnesium with around 16% magnesium.

Magnesium from Food

Although a supplement will help keep your levels of magnesium up, you still need to get magnesium from your foods. The following foods are good sources - almonds, wheat bran, pipis, shrimps, taro, sweet corn and pumpkin/sunflower seeds.