Citation: Muszy ´ nski, T.; Polak, K.; Fr ˛ atczak, A.; Miziolek, B.; Bergler- Czop, B.; Szczepanik, A. Vitamin D—The Nutritional Status of Post-Gastrectomy Gastric Cancer Patients—Systematic Review. Nutrients 2022, 14, 2712. https:// doi.org/10.3390/nu14132712 Academic Editor: Tyler Barker Received: 30 May 2022 Accepted: 28 June 2022 Published: 29 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). nutrients Systematic Review Vitamin D—The Nutritional Status of Post-Gastrectomy Gastric Cancer Patients—Systematic Review Tomasz Muszy´ nski 1,2, *, Karina Polak 3 , Aleksandra Fr ˛ atczak 4 , Bartosz Miziolek 4 , Beata Bergler-Czop 4 and Antoni Szczepanik 2 1 Doctoral School of Medical and Health Sciences, Jagiellonian University Medical College, 31-530 Kraków, Poland 2 Department of General, Oncological and Gastroenterological Surgery, Jagiellonian University Medical College, 31-501 Kraków, Poland; antoni.szczepanik@uj.edu.pl 3 Doctoral School, Medical University of Silesia, 40-055 Katowice, Poland; m.carrine@gmail.com 4 Chair and Department of Dermatology, Medical University of Silesia, 40-027 Katowice, Poland; ola.fratczak89@gmail.com (A.F.); bmiziolek@gmail.com (B.M.); bettina2@tlen.pl (B.B.-C.) * Correspondence: thomasmuszynski@gmail.com Abstract: Gastric cancer is a malignant neoplasm of the gastrointestinal tract, with one of the standard treatment methods remaining gastrectomy. The authors conducted a systemic review of the Medline and Embase databases concerning the serum vitamin D level in post-gastrectomy gastric cancer patients, regarding all articles published until 22 May 2022 according to the PRISMA guidelines. 18 studies with a total number of 908 gastric cancer survivors were included in the analysis. The initial rate of vitamin D deficiency in gastric cancer patients undergoing gastrectomy appears to be similar to the global population deficiency. In post-gastrectomy survivors, the level of 25(OH)D may remain stable or decrease, while the level of 1, 25(OH) 2 D remains normal. Supplementation with vitamin D results in an improvement in its serum concentration and positively affects bone mineral density, which is gradually reduced in post-gastrectomy survivors. Combining vitamin D supplementation with calcium and bisphosphonates enables us to obtain better results than vitamin D and calcium only. The type of surgery influences the level of serum vitamin D and its metabolites, with total or partial gastrectomy and maintenance of the duodenal food passage remaining the most important factors. There is a strong need for randomized, controlled trials that would investigate this matter in the future. Keywords: gastric cancer; stomach cancer; vitamin D; gastrectomy 1. Introduction Gastric cancer. Gastric cancer is a malignant neoplasm of the gastrointestinal tract that continues to be a significant global clinical and epidemiological problem. It is estimated to be the fifth most common and third highest mortality cancer in the world, with the most dominant type of adenocarcinoma. According to gender, men are 2.2 times more likely to suffer from it. A relationship is also observed between the incidence and the region of the world with the highest prevalence and mortality in eastern and central Asia, as well as Latin America [1–3]. Gastrectomy. Gastric cancer is often diagnosed at a late stage, leading to unfavorable treatment results. In the case of early gastric cancer, 5-year survival can exceed 80%, while survival in more advanced stages decreases significantly. However, in recent decades, the incidence of gastric cancer has been declining due to the treatment of Helicobacter pylori infection and treatment results being better due to earlier detection and new treatment options. However, gastric resection remains a method necessary for the treatment of gastric cancer. The standard is a partial or total gastric resection with D2 lymphadenectomy (D2- LND). There are several techniques, such as endoscopic removal in the very early stages Nutrients 2022, 14, 2712. https://doi.org/10.3390/nu14132712 https://www.mdpi.com/journal/nutrients