Vitamin D does not decrease pain or headache more than placebo

Reference

Knutsen KV, Madar AA, Brekke M, et al. Effect of vitamin D on musculoskeletal pain and headache: A randomized, double-blind, placebo-controlled trial among adult ethnic minorities in Norway. Pain 2014;155(12):2591-2598.

Synopsis

The investigators enrolled 251 adults assumed to be healthy who were born in, or had parents born in the Middle East, Africa, or South Asia, although 93% reported pain of some type and degree over the previous 2 weeks and 63% reported headache. These populations were targeted because they tend to have lower vitamin D levels; the average 25-hydroxyvitamin D level was 26 nmol/L (10.4 ng/mL), with a range of range 5 to 87 nmol/L (2 to 35 ng/mL) in this cohort. These levels aren't necessarily representative of vitamin D deficiency; the Institute of Medicine sets normal at 20 nmol/L (8 ng/mL) or higher, and researchers point out even this cutoff really isn't a cutoff (Manson JE, et al. N Engl J Med 2016; 375:1817-1820). The patients were randomized, allocation concealment not described, to receive placebo or vitamin D3 supplementation at either 10 mcg/day or 25 mcg/day for 16 weeks. Vitamin D levels increased with supplementation. Pain and headache scores also improved, though similarly in treated and untreated patients. The power of the study to find a difference if one truly existed was not reported. Vitamin D supplementation also does not affect fatigue (POEM 200111).