Effect of High-Dose vs Standard-Dose Vitamin D3 Supplementation on Body Composition among Patients with Advanced or Metastatic Colorectal Cancer: A Randomized Trial.

Skeletal muscle and adipose tissue express the vitamin D receptor and may be a mechanism through which vitamin D supplementation slows cancer progression and reduces cancer death. In this exploratory analysis of a double-blind, multicenter, randomized phase II clinical trial, 105 patients with advanced or metastatic colorectal cancer who were receiving chemotherapy were randomized to either high-dose vitamin D3 (4000 IU) or standard-dose (400 IU) vitamin D3. Body composition was measured with abdominal computed tomography at enrollment (baseline) and after cycle 8 of chemotherapy (16 weeks). As compared with standard-dose vitamin D3, high-dose vitamin D3 did not significantly change body weight [-0.7 kg; (95% CI: -3.5, 2.0)], body mass index [-0.2 kg/m2; (95% CI: -1.2, 0.7)], muscle area [-1.7 cm2; (95% CI: -9.6, 6.3)], muscle attenuation [-0.4 HU; (95% CI: -4.2, 3.2)], visceral adipose tissue area [-7.5 cm2; (95% CI: -24.5, 9.6)], or subcutaneous adipose tissue area [-8.3 cm2; (95% CI: -35.5, 18.9)] over the first 8 cycles of chemotherapy. Among patients with advanced or metastatic colorectal cancer, the addition of high-dose vitamin D3, vs standard-dose vitamin D3, to standard chemotherapy did not result in any changes in body composition.