This phase III trial studies how well vitamin D3 given with standard chemotherapy and bevacizumab works in treating patients with colorectal cancer that has spread to other parts of the body. Vitamin D3 helps the body use calcium and phosphorus to make strong bones and teeth. Drugs used in chemotherapy, such as leucovorin calcium, fluorouracil, oxaliplatin, and irinotecan hydrochloride, work in different ways to stop the growth of tumor cells by killing the cells, by stopping them from dividing, or by stopping them from spreading. Immunotherapy with monoclonal antibodies, such as bevacizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving vitamin D3 with chemotherapy and bevacizumab may work better in shrinking or stabilizing colorectal cancer. It is not yet known whether giving high-dose vitamin D3 in addition to chemotherapy and bevacizumab would extend patients' time without disease compared to the usual approach (chemotherapy and bevacizumab).