Vitamin D is a hormone synthesized in the skin in the presence of sunlight. Like other hormones, vitamin D plays a role in a wide range of processes in the body. Here we review the possible role of vitamin D in nociceptive and inflammatory pain. In observational studies, low vitamin D levels have been associated with increased pain and higher opioid doses. Recent interventional studies have shown promising effects of vitamin D supplementation on cancer pain and muscular pain—but only in patients with insufficient levels of vitamin D when starting intervention. Possible mechanisms for vitamin D in pain management are the anti-inflammatory effects mediated by reduced cytokine and prostaglandin release and effects on T-cell responses. The recent finding of vitamin D-mediated inhibition of Prostaglandin E2 (PGE2) is especially interesting and exhibits a credible mechanistic explanation. Having reviewed current literature, we suggest that patients with deficient levels defined as 25-hydroxyvitamin D (25-OHD) levels 50 nmol/L probably have little benefit from supplementation. Our conclusion is that vitamin D may constitute a safe, simple and potentially beneficial way to reduce pain among patients with vitamin D deficiency, but that more randomized and placebo-controlled studies are needed before any firm conclusions can be drawn.

Fatigue is one of the most distressing symptoms experienced by cancer patients. The suggested biological mechanism for cancer related fatigue (CRF) includes immune activation triggered by tumor tissue or by anticancer treatment but other mechanisms have also been proposed. Previous large meta-analysis of interventions on fatigue focuses mostly on patients early in the disease trajectory, with only one tenth of included studies performed in palliative cohorts. The aim of this narrative review is therefore to present a background on CRF with focus on the palliative setting. A summary of recent randomized, controlled trials on pharmacological interventions on CRF in palliative care is presented, including studies on psychostimulants, corticosteroids, testosterone and melatonin. Interestingly, in several of these studies there was a positive and similar effect on fatigue in both the intervention and the placebo arm—indicating an important placebo effect for any pharmacological treatment. In addition, studies on dietary supplements and on pharmacological complementary medicines are discussed. To conclude, the evidence is still weak for using pharmacological treatments on CRF in palliative care patients—although methylphenidate and corticosteroids might be considered.

The aim of the ‘Palliative-D’ study was to test the hypothesis that correction of vitamin D deficiency reduces opioid use in cancer patients admitted to palliative care. A multicenter randomized, placebo-controlled, double-blind trial in three home-based palliative care facilities in Sweden was performed. Patients with advanced cancer and 25-hydroxyvitamin D < 50 nmol/L were randomized to vitamin D3 4000 IU/day or placebo for 12 weeks. The primary endpoint was the difference of long-acting opioid use (fentanyl ug/h) between the groups during 12 weeks, based on four time points. Secondary outcomes included changes in antibiotic use, fatigue and Quality of Life (QoL). A total of 244 patients were randomized, and 150 patients completed the 12 weeks. The major reason for drop-out was death due to cancer. The vitamin D-group had a significantly smaller increase of opioid doses compared to the placebo-group; beta coefficient −0.56 (p = 0.03), i.e., 0.56 µg less fentanyl/h per week with vitamin D treatment. Vitamin D-reduced fatigue assessed with ESAS was −1.1 points after 12 weeks (p < 0.01). Antibiotic use or QoL did not differ significantly between the groups. The treatment was safe and well-tolerated. In conclusion, correction of vitamin D deficiency may have positive effects on opioid use and fatigue in palliative cancer patients, but only in those with a survival time more than 12 weeks.

Albumin is an important biochemical marker in palliative cancer care, used for assessment of nutritional status, disease severity and prognosis. Our primary aim was to investigate sex differences in the association between appetite and albumin levels in palliative cancer patients. We also aimed to study associations between appetite and C-reactive protein (CRP), Quality of Life (QoL), pain and fatigue. In the Palliative D-cohort, consisting of 266 men and 264 women, we found a correlation between appetite and albumin; low appetite, measured with the Edmonton Symptom Assessment System, correlated significantly with low albumin in men: (r = −0.33, p < 0.001), but not in women (r = −0.03, p = 0.65). In a regression analysis adjusted for confounding factors, results were similar. Lower appetite was correlated with higher CRP in men (r = 0.27, p < 0.001), but not in women (r = 0.12, p = 0.05). Appetite was correlated with QoL, fatigue and pain in both men and women; those with a low appetite had a low QoL and high fatigue- and pain-scores (p < 0.001). In conclusion, our results indicated possible sex differences in the associations between appetite and albumin, and between appetite and CRP, in palliative care patients. Understanding these associations could provide additional value for clinical practice.

Background: Vitamin D₃ supplements are available as tablets or oil drops, but there is no consensus as to whether either of these preparations is more effective than the other. Methods: We compared the effectiveness of tablets versus oil in raising S-25-hydroxyvitamin D (S-25-OHD) in plasma by re-analyzing data from a previously performed observational study in which immunodeficient patients with S-25-OHD concentrations <75 nmol/L were randomly prescribed vitamin D₃ tablets (1600 IU/day) or vitamin D₃ oil-drops (1500 IU/day) for twelve months. Tablets and oil were compared for the effect on S-25-OHD concentrations after 3–5 months and antibiotic use. Results: Data on S-25-OHD after ≥ 3 months was available for 137 patients treated with tablets and 69 with oil drops. Both groups exhibited a significant increase in S-25-OHD—oil-drops from 55 to 86 nmol/L and tablets from 52 to 87 nmol/L—with no difference between groups (p = 0.77). In a subgroup of patients without immunoglobulin replacement, vitamin D₃ supplementation with oil drops (n = 34) but not with tablets (n = 60) resulted in significantly lower antibiotic administration (p < 0.001 and p = 0.58). Conclusion: Vitamin D₃ supplementation with tablets and oil drops were equally efficient in raising S-25-OHD concentrations. Only oil drops caused a reduction in antibiotic consumption in immuno-deficient patients who did not receive immunoglobulin replacement.