A new study suggests that breast cancer patients with low vitamin D levels may experience more pain after surgery and may need larger amounts of opioid pain medication during recovery.
The research was published in the journal Regional Anesthesia & Pain Medicine and adds to growing evidence that vitamin D may play an important role in how the body processes pain.
Vitamin D is best known for helping the body absorb calcium and keep bones strong. The body naturally produces vitamin D when skin is exposed to sunlight, and it can also be obtained from foods such as oily fish, egg yolks, fortified dairy products, and supplements. However, vitamin D may do much more than support bone health.
In recent years, scientists have discovered that vitamin D also affects the immune system, inflammation, muscles, and even the nervous system.
Some studies suggest it may influence the way pain signals are processed in the body. Because of this, researchers have become interested in whether low vitamin D levels could make people more sensitive to pain after surgery.
Vitamin D deficiency is common worldwide, including among people with breast cancer. Some patients may have low vitamin D because of poor nutrition, limited sun exposure, chronic illness, or the effects of cancer treatment itself.
To better understand the possible connection, researchers at Fayoum University Hospital in Egypt carried out a prospective observational study between September 2024 and April 2025.
The study involved 184 women with breast cancer who were preparing to undergo unilateral modified radical mastectomy, a surgery where one entire breast is removed.
Before surgery, the researchers measured vitamin D levels in all participants. Half of the patients were classified as vitamin D deficient, meaning their vitamin D levels were below 30 nanomoles per liter. The other half had vitamin D levels above that level and were considered vitamin D sufficient.
The two groups were otherwise similar in important ways, including age. Women in the vitamin D deficient group had an average age of 44 years, while those in the vitamin D sufficient group had an average age of 42 years.
Importantly, the doctors and healthcare workers caring for the patients did not know which patients had low vitamin D levels. This helped reduce the chance of bias during treatment and pain management.
All patients received the same standard medical care during and after surgery. During the operation, doctors used fentanyl, a strong opioid drug, to control pain.
After surgery, all patients were given paracetamol through an intravenous drip every eight hours. Patients could also control additional pain relief themselves by pressing a button that delivered tramadol, another opioid medication.
The researchers monitored pain levels at several time points during the first 24 hours after surgery, including immediately after surgery and then six, 12, 18, and 24 hours later. They also recorded side effects such as nausea, vomiting, drowsiness, and how long patients stayed in the hospital.
The results showed a clear difference between the two groups.
Patients with vitamin D deficiency were around three times more likely to report moderate to severe postoperative pain compared with patients who had healthy vitamin D levels.
The researchers noted that none of the patients in either group reported extremely severe pain. Instead, the main difference involved moderate pain levels.
Women with low vitamin D also needed more opioid medication after surgery. During surgery, patients with vitamin D deficiency required slightly more fentanyl than patients with normal vitamin D levels. However, the difference became much larger after surgery.
On average, patients with low vitamin D used an additional 112 milligrams of tramadol during recovery.
This is important because opioid drugs can cause side effects such as nausea, vomiting, confusion, drowsiness, constipation, and breathing problems. Long-term opioid use may also increase the risk of dependence and addiction.
The study also found that nausea after surgery was more common among patients with vitamin D deficiency. Vomiting occurred only in the vitamin D deficient group, although the number of cases was small and not large enough for scientists to say the difference was statistically certain.
The researchers believe vitamin D’s anti-inflammatory effects may partly explain the findings. Inflammation after surgery can increase pain signals in the body. Since vitamin D appears to help regulate inflammation and immune responses, low levels might make patients more sensitive to pain after surgery.
Still, the researchers stressed that the study has several important limitations. Because it was observational, it cannot prove that low vitamin D directly caused the increase in pain. The research was also carried out at a single hospital, so the findings may not apply to every population or healthcare setting.
In addition, the scientists did not measure inflammatory markers or collect information about factors such as anxiety, depression, sleep problems, cancer stage, or previous treatments, all of which could affect pain levels after surgery.
Even with these limitations, the findings are considered important because they point to a possible low-cost way to improve recovery for breast cancer patients.
The researchers suggest that women with low vitamin D levels may benefit from taking vitamin D supplements before surgery, although larger clinical trials are still needed to confirm whether supplementation directly reduces pain.
The study also highlights how nutrition and overall health may affect surgical recovery more than many people realize. Vitamin deficiencies may influence not only physical healing but also how patients experience pain and respond to medications.
If you care about nutrition, please read studies about berry that can prevent cancer, diabetes, and obesity, and the harm of vitamin D deficiency you need to know.
For more health information, please see recent studies about the connection between potatoes and high blood pressure, and results showing why turmeric is a health game-changer.
Source: Fayoum University Hospital.
