Does Vitamin D Supplementation Defeat Chronic Pain?

The New England Journal of Medicine terms Vitamin D deficiency (which affects an estimated 6% of the population) a pandemic. Some clinicians estimate that nearly 100% of their patients with chronic pain are also vitamin D deficient.

Studies suggest vitamin D deficiency is associated with higher risk of pain, so shouldn’t vitamin D supplementation decrease pain?

The journal Pain has published a study proving that high dose Vitamin D3 supplementation given monthly to the general population does not improve baseline pain or reduce the number of analgesic prescriptions. It may, however, help patients who have significant vitamin D deficiency.

In this double-blinded study, the researchers randomized participants, individuals aged 50 to 84 years old from the general population, to 100,000 international units of vitamin D3 capsules monthly or placebo. They administered the pain impact questionnaire (PIQ-6) at baseline, year 1, and final follow-up at 3.3 years. The New Zealand Ministry of Health provided the number of analgesic prescriptions.

The researchers found no significant difference between mean PIQ-6 scores or number of analgesics between the arms, with 1 exception. Participants defined at baseline as Vitamin D deficient (<50 nmol/L) were more likely to have received fewer NSAID prescriptions.

Previous studies have found anti-inflammatory effects in vitamin D deficient individuals, Specifically, in rheumatoid arthritis patients, pain and vitamin D levels seem to be inversely related. In this study, the reduction of NSAID use in vitamin D deficient patients may have been due to chance alone, so additional research must determine vitamin D supplementation's clinical benefit on pain and NSAID use in deficient patients. In the general population, vitamin D supplementation is not effective for pain reduction.

Because of vitamin D's half-life, patients may have different results when supplemented daily or weekly, so those dosing schedules must be studied further. Also, only patients with mild pain were studied, so the effects of vitamin D supplementation cannot be extrapolated to patients with severe pain.

Reference

Wu Z, Camargo CA Jr, Malihi Z, et al. Monthly vitamin D supplementation, pain, and pattern of analgesic prescription: secondary analysis from the randomized, double-blind, placebo-controlled Vitamin D Assessment study. Pain. 2018;159(6):1074-1082.