Vitamin D deficiency is associated with more pain after breast surgery

Researchers report that vitamin D deficiency is associated with more moderate to severe pain after breast cancer surgery.

The findings were published online on May 19, 2026 in the journal Regional Anesthesia & Pain Medicine.

“Vitamin D deficiency is associated with a higher occurrence of moderate to severe postoperative pain and increased opioid consumption in patients undergoing unilateral modified radical mastectomy,” the authors said. “Preoperative vitamin D supplementation in breast cancer patients with vitamin D levels below 30 nmol/L may have a role in modulating postoperative pain.” they added.

Investigators conducted the study at Fayoum University Hospital in Egypt between September 2024 and April 2025. They enrolled 184 breast cancer patients scheduled for surgical removal of one entire breast.

Half of the subjects were vitamin D deficient (below 30 nmol/L) and half were vitamin D sufficient (above 30 nmol/L).

Baseline characteristics were similar between the groups. There was an average age of 44 in the vitamin D deficient group and 42 in the vitamin D sufficient group.

Clinical staff managed the subjects according to the hospital’s routine protocol, both during and after surgery. Staff were unaware of vitamin D levels.

To manage acute pain, subjects received the opioid fentanyl during the operation.

Post-surgery, they received paracetamol through a drip every 8 hours. The subjects could self-administer the opioid tramadol by pressing a button.

They reported pain levels at zero, 6 hours, 12 hours, 18 hours and 24 hours after surgery.

The investigators reported that vitamin D deficient patients received, on average, 8 μg (micrograms) more fentanyl during surgery. According to the authors this was a modest difference.

But the vitamin D deficient group required substantially more tramadol (average 112mg more) post-surgery than the subjects who had sufficient vitamin D levels.

The authors concluded, “Vitamin D deficiency is associated with a higher occurrence of moderate to severe postoperative pain and increased opioid consumption in patients undergoing unilateral modified radical mastectomy.”