A study of 184 women undergoing mastectomy at Fayoum University Hospital in Egypt has found that those with low vitamin D supplements levels before surgery were about three times more likely to report moderate to severe pain in the first 24 hours afterwards than those with sufficient levels. The prospective observational study, led by Mahdy Ahmed Abdelhady and colleagues, was registered on ClinicalTrials.gov, conducted between September 2024 and April 2025, and published online in the journal Regional Anesthesia & Pain Medicine in September 2026. Patients were split into two groups of 92 based on whether their vitamin D level was below or above 30 nanomoles per litre. The deficient group used roughly 112mg more of the opioid tramadol in the days after surgery and received modestly more fentanyl during the operation itself. The researchers said the findings warrant discussion with a surgical team before an operation rather than independent supplementation.
What the study can and cannot show
This was a single-hospital, non-randomised study, so it cannot prove that low vitamin D caused the extra pain, only that the two were linked in this group. The researchers did not measure inflammatory markers, anxiety, depression, cancer stage or prior treatment, all of which can independently affect how much pain someone reports after surgery. No funding source was disclosed. The 30 nmol/L cutoff used to define deficiency is lower than the level some UK guidance uses to flag insufficiency, and the authors noted findings in an Egyptian population may not generalise to other settings, including the UK.
What this means for your supplement routine
This study does not show that taking a vitamin D supplement before surgery changes pain outcomes; it measured vitamin D status as it already existed in patients, not the effect of giving anyone a supplement. Vitamin D status is something a GP can check with a blood test, which is the only reliable way to know whether levels are low rather than assumed. Anyone reviewing what is already in their supplement cupboard can compare current prices in the vitamins and minerals collection.
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This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.