Vitamin D reduces menstrual pain and medication use: Review
Writing in the journal Nutrients, researchers from Taiwan evaluated the effect of vitamin D supplementation in 687 menstruating females across 11 studies by measuring pain score reduction. They then conducted trial sequential analysis (TSA) to assess the statistical power and precision of the meta-analysis and identify the ‘true’ intervention effect.
“In the pooled analyses, we found that vitamin D supplementation significantly decreased the pain intensity of dysmenorrhoea, and the cumulative power supports a ‘true’ treatment response,” they wrote, concluding that vitamin D reduced prostaglandin levels (lipids with a role in menstruation) and inflammation.
A common condition, significant burden
Dysmenorrhoea, characterized by painful menstrual periods, is a common condition that affects 45% to 95% of females.
It can be classified into ‘primary’ dysmenorrhoea, defined as painful menstruation in the absence of pelvic pathology, or ‘secondary’ dysmenorrhoea, which is characterized by painful menses due to pelvic pathology or a recognized medical condition.
"Dysmenorrhoea represents a significant global health burden that requires attention," the researchers wrote. "Healthcare costs for patients with dysmenorrhoea are 2.2 times those for the general population. Additionally, in some countries, the annual cost associated with dysmenorrhoea treatment is 25 million USD."
Previous research has suggested that vitamin D supplementation can alleviate dysmenorrhoea symptoms by inhibiting pain signals and reducing inflammation.
The Taiwanese researchers, however, noted that some studies have reported limited effects, with variations in supplementation levels and dosages.
Vitamin D for menstrual pain
The review collected studies through a systematic search of the Cochrane Library, Embase, Google Scholar, Medline and Scopus databases, from inception up until Dec. 30, 2023.
Studies were included if they were randomized controlled trials, involved women who had regular menstruation, compared vitamin D supplementation with placebo or other active treatments before and after their use, and assessed pain severity using a validated tool.
Primary and secondary outcomes were measured by the changes in pain intensity and rescue analgesic use, respectively.
The assessment showed that vitamin D supplementation significantly decreased pain intensity in patients with dysmenorrhoea compared with controls, and subgroup analysis revealed that vitamin D supplementation reduced primary dysmenorrhoea pain but not secondary dysmenorrhoea pain.
The authors noted that while one study suggested an association between underlying vitamin D concentration and various pain-related conditions, the specific mechanism of vitamin D on dysmenorrhoea remains unclear.
They hypothesized that as vitamin D receptors are found in the ovaries, uterus, placenta and pituitary gland, vitamin D could suppress the expression of inflammation-induced markers and contractile-associated factors in uterine myometrial smooth-muscle cells by interacting with these receptors.
Additionally, in the studies included, a decrease in serum vitamin D (25(OH)D) levels was observed in the luteal phase of the menstrual cycle, which the authors suggested could stimulate an increase in inflammatory cytokines and prostaglandins, exacerbating the pain intensity of dysmenorrhoea.
They noted that due to the inter-study heterogeneity, the results should be interpreted with caution, and further large-scale high-quality studies are necessary to confirm the findings.
Journal: Nutrients
doi: 10.3390/nu16071089
“Vitamin D Supplementation for Patients with Dysmenorrhoea: A Meta-Analysis with Trial Sequential Analysis of Randomised Controlled Trials”
Authors: Kan-Chu Lin et al.
