Carpal tunnel syndrome (CTS) is most often associated with repetitive movements and inflammation that impedes the function of the median nerve as it passes through the wrist, but recent studies have identified vitamin D deficiency as a risk factor for CTS, as well as more severe CTS-associated symptoms.
Vitamin D plays many roles in the body, some of which include facilitating nerve function, speeding the healing process following nerve injury, reducing nerve fiber hypersensitivity, and reducing inflammation and scar tissue formation. As such, when vitamin D levels are low, nerves may be more susceptible to injury and take longer to heal.
In a study published in December 2021, researchers reviewed data from four studies involving vitamin D supplementation in CTS patients with low vitamin D status (less than 20 ng/ml). The data show that administering between 7,100-8,600 IU of vitamin D3 per day for three months was effective for improving vitamin D levels to a more normal range of at least 20 ng/ml. The authors noted that sensory symptoms like numbness and tingling improved sooner than motor functions (like strength), which is logical as sensory symptoms are often the first to manifest in patients with CTS. They also reported that median nerve function—as per neuroconductive velocity testing—only improved in mild-to-moderate CTS cases but not in severe cases.
In their conclusion, the research team noted that for patients with poor vitamin D status, the duration of supplementation may vary from patient to patient but should not be the sole form of treatment. Rather, addressing insufficient vitamin D levels should be just one aspect of a multimodal approach for alleviating pressure on the median nerve and restoring more normal median nerve function.
Doctors of chiropractic have extensive undergraduate, graduate, and even post-graduate training in clinical nutrition, and many jurisdictions require continuing post-graduate education hours to maintain licensure. Vitamin D3 is commonly recommended for MANY reasons, and CTS can be added to that long list.
