Vitamin D is a prohormone obtained through diet, supplementation, or sun exposure. Once absorbed, this nutritional vitamin D undergoes a two-step reaction in the liver and in the kidney to become the active hormone, calcitriol. Besides the kidney, many other body tissues are capable of local vitamin D activation. This local tissue activity is important for maintenance of health and relies on adequate levels of nutritional vitamin D. Not only are dialysis patients deficient in calcitriol due to kidney failure, but they are also deficiency in nutritional vitamin D. Low levels of vitamin D have been associated with higher rates of death, heart and blood vessel disease, osteoporosis, falls, cancer, and autoimmune diseases. Despite this, there is a lack of randomized controlled trials (RCT) examining the effects of nutritional vitamin D in hemodialysis (HD) patients. The investigators hypothesize that long-term supplementation with nutritional vitamin D in HD patients improves survival and cardiovascular outcomes. Before embarking on a large scale RCT, the investigators propose a small pilot RCT with 20 hemodialysis patients to: i) To determine the effects of cholecalciferol (vitamin D3) in raising blood vitamin D levels; ii) To determine the feasibility and barriers to successful randomization and adherence to treatment protocols, which will inform subsequent studies.

Inclusion Criteria:

1. Participant is ≥ 18 years

2. Participant is on hemodialysis ≥ 3 months

   Exclusion Criteria:

3. Serum calcium >2.75 mmol/L

4. On concurrent vitamin D treatment ≥ 800 IU/day. Includes ergocalciferol, cholecalciferol, calcedidiol, over-the-counter vitamin D. Does not include one-alpha calcidol (One Alfa®) or 1, 25 di-hydroxy-D3 (Rocaltrol® or Calcijex®)

5. Known hypersensitivity or allergy to Vitamin D

6. End stage liver disease

7. Severe untreated malabsorption or resection of large segment of small bowel

8. Lack of informed consent or inability to consent

9. Currently enrolled in a RCT