Fibromyalgia syndrome (FMS) is a complex disease characterized by widespread musculoskeletal pain, point tenderness and fatigue. Individuals of all ages, genders and races may develop FMS; however, women are 10 times more likely to develop the disease than men.
Researchers have discovered that a key mechanism behind the development of FMS is centralized sensitization. This is a condition in which the central nervous system (CNS) becomes overly sensitive to global stimuli, including touch, sound, sight and smell. FMS patients commonly experience a decreased quality of life due to the anxiety, depression, impaired sleep quality and isolation that frequently occurs as a result of centralized sensitization.
Researchers theorize that vitamin D may play a role in FMS due to its ability to upregulate serotonin expression in the CNS. Low serotonin in the CNS is a key factor that contributes to centralized sensitization, impaired sleep and increased pain severity among FMS patients. Vitamin D also has anti-inflammatory properties. Research shows that low vitamin D status is associated with chronic headaches, carpal tunnel syndrome and chronic low back pain.
In a new study, researchers investigated the role of vitamin D supplementation on FMS outcome. A total of 70 premenopausal women diagnosed with FMS, according to the 2010 FMS classification criteria, and 65 age and sex matched controls were included in the study. Patients were defined as vitamin D deficient at levels less than 20 ng/ml, inadequate at levels between 20 and 30 ng/ml and sufficient at levels greater than 30 ng/ml.
All patients with insufficient vitamin D levels were supplemented with 50,000 IU vitamin D3 on a weekly basis for 12 weeks. At baseline and completion of the study, patients had their vitamin D levels measured and filled out the following assessment tools:
- Fibromyalgia impact questionnaire (FIQ): A form used to assess the current health status of patients with fibromyalgia.
- Arizona sexual experience scale (ASEX): Measures sexual function, with an increased scored indicating a greater level of sexual dysfunction.
- Beck depression inventory (BDI): A questionnaire used to measure the severity of depressive symptoms..
- Visual analog scale (VAS): A subjective form used to measure the severity of pain.
- Short form-36 (SF-36): A tool developed to evaluate an individual’s quality of life.
Here is what the researchers discovered:
- A total of 60% of FMS patients and 50% of controls had 25(OH)D levels below 30 ng/ml.
- Vitamin D supplementation significantly improved FIQ, BDI and pain scale (VAS) outcome (p = 0.001).
- Vitamin D supplementation did not significantly improve ASEX or sleep scores (VAS) (p = 0.176 and p = 0.317, respectively).
- Vitamin D supplementation was associated with significant improvements in physical function, physical and emotional role limitations, social function, mental health and vitality from the SF-36 form (p < 0.01); however, bodily pain severity did not significantly improve from supplementation (p > 0.05).
The researchers concluded,
“Vitamin D deficiency seems to be linked to the pathogenesis of fibromyalgia. Vitamin D supplementation may improve the quality of life in patients with fibromyalgia.”
This study adds validity to the current research that suggests vitamin D may improve pain and quality of quality of life among fibromyalgia patients. However, as always, it is important to note the study’s limitations. The relatively small sample size and short duration decreases the strength of these findings. Additionally, since the patients who received the intervention were not blinded, it is possible these improvements may be a result of placebo effect, not vitamin D.
The researchers stated,
“Long-term randomized, placebo-controlled prospective studies with larger populations are required for the clarification of the relationship between FMS and vitamin D.”
Sturges, M. Vitamin D linked with quality of life in fibromyalgia patients. The Vitamin D Council Blog & Newsletter. July, 2017.