Nutrients in chronic pain: magnesium

Part 1: Magnesium

Chronic pain is complex; no one can deny that. Anyone who is experiencing chronic pain can think of their pain as a giant puzzle. There are many pieces that make up the picture, and an often-overlooked piece is the nutrition piece. Nutrients, which trigger certain (normal) physiological functions, are one part of this nutrition piece, and magnesium is a single one of these numerous nutrients that play a role in the process of persistent pain.

What is the role of magnesium in the body? Magnesium is a cation that plays numerous roles in various body compartments.

It helps maintain the internal “balance” (homeostasis) within the cell, so is imperative in cellular function. Magnesium has a “calcium channel blocking” action.

It is present in high amounts in the extracellular compartments, influencing excitability of nerves and nerve conduction. It has a role in skeletal, smooth and cardiac muscle function.

It is a cofactor for many enzymes, including those involved in the production of brain and gut neurotransmitters, thus influencing both gut and brain function.

Magnesium seems to be linked to various pain disorders and has some potential to help them:

One study showed a statistically significant link between low serum magnesium levels and myofascial pain syndrome. A 2012 study showed that magnesium supplementation helped to prevent migraine. Magnesium reduced pain in primary dysmenorrhea in a 1992 study. Furthermore, a 2007 systematic review of randomised trials found evidence for decreased postoperative analgesic requirements when magnesium was given.

Is there any evidence for the efficacy of magnesium administration in chronic or persistent pain?

One study showed that giving magnesium before surgery could help reduce both muscle fasciculations (twitching or spasms) and myalgia (muscle pain) experienced post-operatively.

Central sensitisation is a key process underlying chronic or persistent pain. An experiment was done with rats, whereby a drug called fentanyl was administered to produce delayed hyperalgesia (a sort of “exaggerated pain”). This was to try to create an animal model of central sensitisation.  Administering magnesium to the rats partially offset this process, resulting in less pain.

In chronic pain, we know there is abnormal processing of sensation. This is part of the “syndrome”, if you like, that is chronic pain (regardless of where in the body you feel it). Certain receptors called the NMDA (N-methyl-D-aspartate) are involved as “gates” that help process this sensation. Activation of the NMDA receptor leads to abnormal processing of sensation – therefore increased pain. This effect – part of what is known as central sensitisation – has effects in the spinal cord, in an area called the dorsal horn, as well as in the brain itself. Magnesium is involved in blocking the NMDA receptor, so that process cannot take place.  This was shown in an experiment with rats with in whom neuropathic pain was induced. The rats developed something called “allodynia” (where a stimulus that is not usually painful becomes painful) and mechanical hypersensitivity (where touch or pressure feels oversensitive). Giving magnesium to the rats “fixed” the allodynia (i.e. made them not feel this abnormal pain to normal stimulus) and delayed the onset of mechanical hypersensitivity, and stopped the change that takes place at the dorsal horn of the spinal cord. Hyperalgesia and allodynia are two aspects of the pain experience that we test in women who have vulvodynia and similar pelvic pain conditions. This makes these findings especially interesting to anyone experiencing these conditions.

Another group of rats was subjected to treatment that creates hyperalgesia. In this experiment, opioid agonists were used to try to resolve the pain (drugs like morphine). The morphine didn’t work – except when the group of rats were given magnesium first, which enhanced the analgesic effect of the morphine. Morphine works in the brain – so it seems that magnesium helps the “brain side” of chronic pain.

Finally, a 2013 study gives us some nice findings on magnesium in neuropathic pain. A 2-week intravenous magnesium infusion followed by 4 weeks of oral magnesium supplementation can reduce pain intensity and improve lumbar spine mobility during a 6-month period in patients with refractory chronic low back pain with a neuropathic component.

Ultimately, magnesium is cheap and fairly harmless as long as you don’t have a kidney disorder.  It’s certainly worth using if you experience persistent pain – and judge for yourself whether it helps. Clinicians working with people with pain should also consider giving magnesium early – before the pain becomes chronic. This might save a whole lot of grief. Not all magnesium supplements are the same, however; absorption (and therefore effectiveness) varies markedly across the different forms. For help in choosing an appropriate magnesium supplement, contact us at Equilibria.