IJCS | Volume 31, Nº4, July / August 2018

429 Jorge et al. Vitamin D and cardiovascular disease Int J Cardiovasc Sci. 2018;31(4)422-432 Review Article in healthy patients and individuals with vitamin D deficiency, obesity, prediabetes, and diabetes. Compared with placebo, vitamin D had no effect on insulin resistance, insulin secretion, or glycated hemoglobin. 72 In regards to obesity, several studies have evaluated the effect of vitaminD supplementationwith andwithout the addition of calciumonweight and body composition. Most of these studies showed no significant effect of vitamin D on BMI or body composition. 73 Additionally, CAD does not seem to be significantly influenced by vitamin D supplementation. An important study named RECORD 74 involving 5,292 individuals compared the effects of vitamin D, calcium, vitamin D plus calcium, or placebo on cardiovascular events. The results showed that although vitamin D can exert a protective role on HF, it does not seem to protect against AMI and stroke. Ameta-analysis of 51 controlled studies found that supplementation of vitamin D has no significant impact on AMI. 75 Vitamin D supplementation seems to have some benefits on HF, although the mechanisms of action have not been well established. Recent studies have reported that in individuals with established HF and vitamin D deficiency, vitamin supplementation is associated with improved survival. 76 Conclusions CVDs remain the main cause of mortality in several countries worldwide. An understanding of the pathophysiological mechanisms involved, as well as their risk factors, is essential for planning of prevention and treatment strategies. In recent years,many studies have shown a relationship between vitamin D deficiency and CVDs, with a direct influence on prognosis. Based on the understanding of this association, the focus of researchers has been in the correction of vitamin deficiency with the aim of preventing diseases and improving the prognosis of established diseases. However, there are still no consistent data to recommend vitamin D replacement in the context of cardiac diseases. One point that deserves attention is the broad worldwide variation in the prevalence of vitamin D deficiency. Since endogenous vitamin D synthesis is dependent on solar exposure, which in turn varies according to latitude, perhaps the reference level for serumvitamin D also differs among countries depending on sunlight exposure. It is unclear whether the disappointment of the results of studies with vitamin D supplementation is due to an inability of the vitamin in exerting effects on established disease, or use of inappropriate supplementation doses. It is important to understand the doses required tomaintain the serum levels of vitamin D above the desired level, as well as serial measurements of 25-hydroxyvitaminDwith the aim of maintaining adequate levels of this vitamin during the entire follow-up duration. Author contributions Conception and design of the research: Jorge AJL, Cordeiro JR. Acquisition of data: Cordeiro JR. Writing of the manuscript: Jorge AJL, Cordeiro JR, Bianchi DBC. Critical revision of the manuscript for intellectual content: Jorge AJL, Rosa MLG.Supervision / as the major investigador: Jorge AJL. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This article is part of the thesis of master submitted by Jamerson Reis Cordeiro, from Universidade Federal Fluminense. Ethics approval and consent to participate This article does not contain any studies with human participants or animals performed by any of the authors. 1. Holick MF. McCollum Award Lecture, 1994: vitamin D – new horizonts for the 21st century. Am J Clin Nutr. 1994;60(4):619-30. PMID:8092101 2. Castro LCG. O sistema endocrinológico vitamina D. Arq Bras Endocrinol Metab. 2011;55(8):566-75. PMID:22218438 References