The importance of vitamin D for pain after breast cancer surgery

Vitamin D deficiency in itself increases the risk of breast cancer. Evidence also suggests that low blood levels of vitamin D make the healing process following breast cancer surgery more painful. As a result, the use of opioid painkillers is also significantly higher, according to a study published in Regional Anesthesia & Pain Medicine. The researchers also describe the pain-relieving effects of vitamin D. Overall, there are several reasons why women with breast cancer should optimize their vitamin D status—both before surgery and throughout the rest of their lives.

Vitamin D functions as a steroid hormone that regulates a wide range of gene activities and metabolic processes. As a result, vitamin D plays a crucial role in overall health, even though few people associate it with pain regulation. Nevertheless, it is already well established in scientific research that low blood levels of vitamin D are associated with various musculoskeletal pain conditions as well as post-traumatic and postoperative pain. Many studies have also found a relationship between low vitamin D levels and increased opioid use after surgery. This is associated with more side effects and a greater risk of dependence.
It is likewise well known that low blood levels of vitamin D increase the risk of a number of chronic diseases, including breast cancer and other forms of cancer. Several cancer studies have also shown that vitamin D deficiency is associated with longer hospital stays and a poorer prognosis. However, despite growing interest in the many functions of vitamin D, relatively little has been known about the relationship between blood vitamin D levels and pain intensity following breast cancer surgery. This was the focus of the new study.

Vitamin D deficiency results in more pain and greater opioid use

The study was conducted at Fayoum University Hospital in Egypt and included 184 women with breast cancer who were scheduled to undergo a mastectomy, a procedure in which the entire cancer-affected breast is removed.
The women were divided into two comparable groups. According to the researchers, one group had adequate blood levels of vitamin D (above 30 nmol/L), while the other group had a clear deficiency (below 30 nmol/L). The researchers also recorded the women's pain levels immediately after surgery and again at 6, 12, 18, and 24 hours postoperatively. In addition, the patients' general condition and their use of opioids during surgery (fentanyl) and after surgery (tramadol) were documented.
The study showed that the women with insufficient blood levels of vitamin D experienced the following:

• Treatment with significantly higher amounts of opioids (fentanyl) during surgery
• A significantly higher incidence of moderate to severe pain during the first 12–24 hours after surgery, approximately three times higher than in women with adequate vitamin D levels
• Treatment with significantly higher amounts of opioids (tramadol) after surgery
• A higher incidence of nausea and vomiting

The researchers therefore conclude that vitamin D deficiency is associated with a greater occurrence of moderate to severe postoperative pain and increased opioid use in breast cancer patients who have undergone radical mastectomy.
According to the researchers, it would therefore be relevant for women with breast cancer who are scheduled for mastectomy to receive vitamin D supplementation beforehand in order to optimize their blood levels.

The pain-relieving effects of vitamin D

In the introduction to the study, the authors discuss the pain-relieving effects of vitamin D in greater detail. These effects are attributed primarily to the vitamin’s ability to regulate inflammation, which is the body's response to all forms of cellular damage. Broadly speaking, vitamin D helps regulate the immune system by suppressing a number of pro-inflammatory cytokines.
In addition, vitamin D plays an important role in calcium metabolism and nervous system function, helping to prevent excessive calcium stimulation of nerve cells and other tissues, which can lead to cellular stress and muscle spasms. Evidence also suggests that vitamin D may influence the expression of cellular opioid receptors and thereby affect the efficacy of opioid medications.

More information about vitamin D and the actual requirements for cancer prevention

In the following article, you can learn more about why vitamin D deficiency is so widespread, what it means for health, and why many people may need larger supplements and higher blood levels (100–160 nmol/L) in order to achieve better protection against cancer and a range of other chronic diseases.

• More vitamin D reduces the risk of many serious diseases

References:

Mahdy Ahmed Abdelhady et al. Association between preoperative vitamin D level and postoperative pain in patients undergoing breast cancer surgery: a prospective observational study. Regional Anesthesia & Pain Medicine. 2026

BMJ Group. Scientists discover strange link between vitamin D and pain. ScienceDaily 2026