en Nutrition Nutrition Original Research Original Research <p> <strong> Background </strong>:Hyperhomocysteinemia is a risk factor for cardiovascular disease particularly in patients with end stage renal disease (ESRD). Vitamin B12 supplementation on its own still remains as a controversial issue for clinicians in decreasing the level of homcysteine in this group of patients. </p><p> <strong> Methods </strong>: Using all randomized controlled trials (RCTs), clinical trials and pre-post-trial studies found during January 1999 to March 2014, we conducted a systematic review which assessed the effects of vitamin B12 in decreasing homocysteine levels in patients with ESRD. </p><p> <strong> Results </strong>: The findings of this study revealed that, overall, the greatest effect of B12 supplementation on decreasing homocysteine levels in patients with ESRDs occurred when it was combined with folate supplementation. It was also demonstrated that injection treatments might be more beneficial than oral intake treatments. </p><p> <strong> Conclusion </strong>: More rigorous studies are needed to draw a firm conclusion about B12 therapy and the level of homocyteine in patients with ESRD. </p> Homocysteine, Kidney Failure, Vitamin B12, Hemodialysis, Kidney, Amino Acids, Renal Failure, Review. 54 61 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-777&slc_lang=en&sid=1 Maryam Amini aminmar67@yahoo.com 200319475328460015425 200319475328460015425 No Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Maryam Khosravi k27666@yahoo.com 200319475328460015426 200319475328460015426 Yes Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Hamid Reza Baradaran baradaran.hr@iums.ac.ir 200319475328460015427 200319475328460015427 No Endocrine Research Center (Firouzgar), Institute of Endocrinology & Metabolism, Iran University of Medical Sciences, Tehran, Iran. Rasha Atlasi rashaatlasi@gmail.com 200319475328460015428 200319475328460015428 No EBM Group, Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.