Introduction : Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death, and its prevalence is increasing. Nutritional depletion is a common problem among chronic obstructive pulmonary disease (COPD) patients. It is caused, to a large extent, by an imbalance between low- energy intake and high- energy requirements. This problem adversely affects morbidity and mortality. The present study aimed to assess the effects of nutritional guideline education on spirometric tests (FEV1, FVC, FEV1/FVC) among patients with COPD.

  Methods: A quasi-experimental study was conducted through a before and after design. Thirty hospitalized COPD patients drawn from Alborz hospital in Karaj were recruited to the study by random sampling. After filling the demographic questionnaire out, spirometric assessment was undertaken. Individual face to face education concerning proper nutrition was carried out during four sessions. Each session last 15 minutes and was given in four consequent days. Spirometric tests were measured again one and three months after education. They were followed up after discharge through home visits and telephone calls. Then, the indexes were compared.

  Results: Significant differences were found among mean FEV1 before intervention, one month (P=0.004) and three months after intervention (P=0.001). There were significant differences between mean FVC after one month (0.015) and three months after the intervention (P=0.000). Increased FEV1/FVC Indexes were reversely correlated with samples’ weight (P=0.034, r=0.426). FEV1/FVC Indexes three months after intervention were correlated with age (P=0.029, r=0.399). That meant older patients had higher FEV1/FVC values and Pearson coefficient test demonstrated the difference significant.

  Conclusion: The study suggests that patients with COPD should be aware of effectual factors on respiratory conditions. They need to be instructed regarding the foods have negative or positive impacts on their respiratory function.