Pain is a natural part of being human. It is so ingrained into our biology that we “just know” when we experience pain or when others experience pain. It is not uncommon to cringe or feel some pain ourselves when watching others be harmed. Pain is essentially a subjective perceptual experience that originates in sensory receptors throughout the body but is interpreted as pain by the conscious brain.
One possible way of classifying pain is in two groups: acute and chronic. We have all experienced acute pain – hitting our head, stubbing our toe, or worst of all, stepping barefoot on a Lego piece. These pain sensations vary greatly in strength and serve as a warning sign that continuing with an action may cause bodily harm or that something about the body isn’t as it should be. However, this pain subsides when the insult is removed or when the damaged area heals.
By contrast, chronic pain is defined by the International Association for the Study of Pain as “pain that has persisted beyond normal tissue healing time.” This timeframe is considered to be about three months, although some chronic pain disorders (such as rheumatoid arthritis) are characterized by short, recurrent “flares” of pain. Recent evidence has shown that chronic pain is associated with chemical, functional, and anatomical changes throughout the nervous system. These changes and the pain itself can also be brought about by tissue damage, inflammation, or injury to the nervous system.
Although vitamin D’s principal role in the body is to regulate bone health and calcium status, we now know that vitamin D plays a role in many biological processes. Vitamin D deficiency has been linked to various chronic pain conditions and vitamin D may influence the perception of pain through its effects on nerve conduction and health, inflammatory signaling, and immune activation.
A number of randomized controlled trials (RCTs) have investigated the effect of vitamin D supplementation on various types of pain, and several review articles have addressed these studies using qualitative (narrative) methods. This study performed a quantitative meta-analysis, to show what the full body of trial evidence shows for vitamin D supplementation and pain reduction.
Pain is something we are all familiar with, but some individuals suffer from disorders in which pain is chronic or recurring. Vitamin D has been implicated in many of these chronic pain conditions and numerous RCTs have investigated whether vitamin D supplementation can reduce pain in a variety of conditions. The current study was a meta-analysis of RCTs that sought to determine whether vitamin D supplementation can reduce pain compared to placebo.