Although an inadequacy of vitamin D may not be the main cause of chronic pain, it can exacerbate it. It's long been known that a vitamin D deficiency can cause pain and muscle weakness. Now a study at the Mayo Comprehensive Pain Rehabilitation Center in Rochester, Minnesota, has revealed that approximately one-fourth of the patients who suffer with chronic pain also have inadequate blood levels of vitamin D. In addition, the study showed that those with inadequate vitamin D levels required higher doses of morphine for a longer period of time.

Researchers studied 267 adults who were receiving outpatient treatment for chronic pain. They recorded patients' serum vitamin D levels, morphine dosage and duration of use, as well as physical and general health functioning. Results showed:

• Twenty-six percent of those tested had a vitamin D inadequacy.
• The morphine dose for patients deficient in vitamin D was nearly twice that of the rest of the group.
• Those with inadequate vitamin D used morphine for an average of 71.1 months, as opposed to the others, who averaged 43.8 months.
• The vitamin D deficient patients reported lower levels of physical functioning and had a poorer view of their overall health.

If you've never had your vitamin D levels checked, you might want to ask your doctor about it when it's time to have your next blood work done. A vitamin D inadequacy can be treated fairly easily and inexpensively with supplements. While vitamin D is a relatively safe supplement, it is possible to take too much. Excess vitamin D can cause nausea, vomiting, weakness, confusion, and heart rhythm abnormalities. So be sure to discuss the dosage with your doctor first.