Magnesium: the best forms for relieving pain, preventing hypertension and improving memory

There are indeed many forms of magnesium on the market, some of which are cheaper but which can cause troublesome side-effects (mild diarrhoea) or are less well-absorbed by the body. Others are more expensive but offer greater bioavailability, while others still are specifically formulated for cognitive health. Before we look more closely at these different forms, let’s first examine the potential reasons for taking magnesium supplements.

The body needs magnesium in order to function properly. It is involved in hundreds of different activities such as muscle relaxation, blood coagulation, energy conversion, and blood pressure … Unfortunately, however, in developed countries such as the US, France and the UK, magnesium intake is below the daily amount recommended for more than half the population. What’s more, regular drinkers (1), diabetics (2), women who take oral contraceptives, the over-60s, and people with hypertension have greater requirements for magnesium (3). Some people choose to supplement with magnesium for its therapeutic effects: it reduces the risk of osteoporosis and fractures, lowers blood pressure, may be helpful in relieving migraine and period pain, may improve memory, and helps achieve better glucose control in prediabetics!

In short, magnesium supplementation is worth considering if your diet provides less than 300-420mg a day (4) (which is the case for 1 in 2 of us), or if you suffer from migraines, diabetes, pain, memory problems, osteoporosis or hypertension.

Preferred forms of magnesium

Surprisingly perhaps, few studies have looked at how the various forms of magnesium compare in terms of efficacy. The reason is that absorption of magnesium depends on a great many factors which are not easily reproducible in a scientific setting. But it’s important to know this information as the less absorbable the magnesium is, the less the body will be able to use it and the greater will be its laxative effect! Two factors are significant here: its bioavailability (the ease with which the magnesium enters the bloodstream for use by the body) and its solubility.

Magnesium malate, magnesium chloride, magnesium citrate and magnesium gluconate are the most soluble and bioavailable forms (5). Magnesium orotate, which is usually more expensive, has the additional benefit of carrying some of the magnesium into cells, close to the nucleus and mitochondria, for better mineralisation. More expensive still, L-threonate offers benefits for memory and cognitive function: studies show it produces greater increases in magnesium levels in the brain compared with other forms.

In contrast, magnesium sulfate, magnesium carbonate, magnesium oxide and magnesium hydroxide are best avoided as they are much less bioavailable and have a stronger laxative effect. Inorganic magnesium salts are generally less available than organic salts (6-10) (which also include magnesium glycerophosphate, magnesium pidolate, magnesium taurinate and magnesium arginate).

Note: in the case of deficiency, supplementing with any form of magnesium will have the effect of increasing levels of this mineral in the body. But a supplement that does this more effectively, without triggering attacks of diarrhoea, is obviously preferable. To fully capitalise on magnesium’s therapeutic effects, it’s also advisable to choose the most bioavailable supplements as the higher the level of magnesium ingested, the less effectively it is absorbed.

Other factors to consider when taking magnesium

The form of magnesium, while important, is just one of many factors that influence its absorption. If you take it on a daily basis, it’s important to follow the recommendations below. Essentially, magnesium is absorbed in the small intestine by the passive paracellular pathway (11). Only a minor part is absorbed in the large intestine and colon across cell membranes (12). Absorption begins around an hour after the supplement is ingested and ends after six hours (13). This process is influenced by several limiting or enhancing factors, which may or may not produce unwelcome side effects.

Limiting factors