Vitamin D for Fibromyalgia and Chronic Fatigue Syndrome

The Benefits

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Vitamin D: What it Does

Vitamin D performs a lot of important jobs in your body. It's essential for bone strength, cell growth and reproduction,  immune function, and neuromuscular health. It's also an anti-inflammatory. Without vitamin D, your body is unable to absorb calcium properly.

Low vitamin D levels are linked to rickets (in children), osteoporosis in adults. Symptoms of a deficiency can include:

  • problems thinking
  • bone pain, softness, or brittleness
  • muscle pain and weakness
  • unexplained fatigue

However, many people who are vitamin D deficient have no identifiable symptoms.

Things that contribute to vitamin D deficiency include:

  • inadequate sunlight, from too little time outside or use of sunscreen
  • obesity
  • darkly pigmented skin
  • medical conditions that prevent proper digestion or absorption

Those medical conditions may include fibromyalgia (FMS) and chronic fatigue syndrome (CFS or ME/CFS). We don't yet know why, but research suggests that as many as 25 percent of people with these conditions have low vitamin D levels. Additionally, vitamin D supplements may be an effective treatment for some of their many symptoms.

FMS and ME/CFS are believed to be linked to abnormalities in the central nervous system (CNS), which is made up of the brain and spinal column. Vitamin D is important to several areas of the CNS, including:

  • numerous regions of the brain, including many that deal with pain regulation
  • the function of neurons (brain cells)
  • the function of glial cells (the brain's support system for neurons)

Vitamin D is believed to play an important role in brain development, to act as a regulator for neurons, to promote nerve growth, and to have neuroprotective effects.

Vitamin D deficiency and supplementation may play special roles in each of these conditions.

Vitamin D & Fibromyalgia

A growing body of research suggests that low vitamin D levels may be linked to multiple symptoms of FMS and that raising levels may ease these symptoms.

FMS is linked to high levels of molecules that stimulate the brain to help with learning and focus. However, studies suggest that we don't have enough of the molecules that calm things down later.

That can leave us in a hyper-aware state in which noises are too loud, lights are too bright, and we're primed for sensory overload.

Vitamin D is believed to help calm the brain, so a deficiency could contribute to a hyper-stimulated brain and supplementation may help combat the symptom.

Vitamin D is also believed to fight inflammation. So far, we don't know the exact role of inflammation in FMS, but many of us have mildly elevated inflammatory markers, and some researchers believe inflammation is central to the condition.

At least one study suggests that vitamin D-deficient people need twice as much narcotic pain reliever as non-deficient people.

If this deficiency is common in FMS, it could help explain why narcotics tend to have a smaller effect on our pain.

Vitamin D & Chronic Fatigue Syndrome

Low vitamin D levels are linked to fatigue in general, but we don't yet understand what role it may play in the unique types of fatigue that we see in ME/CFS. However, we're learning about specific effects that may help alleviate symptoms.

In this disease, vitamin D deficiency is hypothesized to increase your susceptibility to infections and also raise your risk of severe infection. The abnormal immune system of ME/CFS already leaves you at risk.

Inflammation likely plays an important role in ME/CFS, and vitamin D deficiency is suspected of driving inflammation.

Some research indicates that this deficiency may be involved with oxidative stress (OS) and mitochondrial dysfunction (MD), which some researchers think are important mechanisms of ME/CFS.

Vitamin D Dosage

Some FMS and ME/CFS experts recommend between 1,000 to 2,000 IU of vitamin D daily.

That far exceeds the National Institutes of Health's recommendation of 600 IU/day for most adults. However, recent discoveries about the importance of vitamin D for overall health are changing opinions about how much is enough.

Before determining how much vitamin D you should be taking, your doctor may want you to have a blood test to check your levels. If you have a serious deficiency, he/she may prescribe an ultra-high prescription dose aimed at normalizing your levels, followed by a smaller maintenance dosage once you're within normal parameters.

Vitamin D in Your Diet

If you prefer to get vitamin D through foods instead of or in addition to supplements, it's fairly easy to do.

Vitamin D is naturally available in:

  • eggs
  • swiss cheese
  • some types of fish, including salmon, mackerel, tuna and sardines

You also get it from sunshine, so just increasing your time outside can help. In addition, food makers add it cereal and milk, which was originally done to help prevent rickets in children.

Vitamin D Side Effects

As with just about any supplement, vitamin D can cause unwanted side effects. In fact, too much vitamin D is potentially toxic.

Potential side effects include:

  • nausea
  • vomiting
  • poor appetite
  • constipation
  • weakness
  • weight loss

Again, be sure to include your doctor in the conversation about how much vitamin D is right for you.


Karras S, Rapti E, Matsoukas S, Kotsa K. Vitamin D in Fibromyalgia: A Causative or Confounding Biological Interplay? Nutrients. 2016 Jun 4;8(6). pii: E343.

Morris G, Anderson G, Galecki P, et al. A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior. BMC medicine. 2013 Mar 8;11:64.

Morris G, Berk M. The many roads to mitochondrial dysfunction in neuroimmune and neuropsychiatric disorders. BMC medicine. 2015; 13: 68.

National Institutes of Health Office of Dietary Supplements. "Vitamin D: Fact Sheet for Health Professionals" Accessed September 2016.

Turner MK, Hooten WM, Schmidt JE, et al. Prevalence and Clinical Correlates of Vitamin D Inadequacy among Patients with Chronic Pain. Pain Journal. 2008 Nov;9(8):979-84.

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