Introduction: The present study aimed to evaluate the effects of hospitalization on the nutritional status and prooxidant-antioxidant balance (PAB) of the patients with myocardial infarction (MI).Methods: This study was conducted on 57 patients diagnosed with MI with the mean age of 58.44±12.80 years. The patients were admitted to the cardiac care unit (CCU) of Ghaem Hospital in Mashhad, Iran. Nutritional status of the patients was assessed using the nutritional risk screening (NRS-2002) questionnaire. In addition, anthropometric and biochemical parameters and their changes were evaluated. PAB was also assessed as an oxidative stress marker. In total, 15 patients stayed in the hospital for more than one week. The measurements were performed upon admission and discharge.Results: Upon admission, 49.1% of the patients were well-nourished, and 50.9% were at nutritional risk. As expected, the patients were overweight (36.8%) or obese (19.2%), and all the measures of adiposity were high. Well-nourished patients had lower serum PAB comparatively, while the difference was not statistically significant. The prevalence of the suboptimal nutrition index increased from 46.7% upon admission to 53.3% upon discharge. However, the increase was not considered significant due to the small sample size. Serum PAB increased within one week after admission, while the change was not significant (P=0.249).Conclusion: According to the results, the prevalence of suboptimal nutrition was high in the MI patients in Iran and increases during hospitalization
