Plant-Based Diets and Cardiometabolic Diseases in a Cohort of Iranian Adults: A Systematic Review of Evidence from the Tehran Lipid and Glucose Study

Abstract

Background: Although numerous studies have demonstrated that plant-based diets can reduce the risk of cardiometabolic diseases, their applicability and health benefits within Iran remain unconfirmed. Objectives: This systematic review aimed to clarify the findings from the Tehran Lipid and Glucose Study (TLGS) regarding the benefits of these recommended diets against cardiometabolic diseases in the Iranian population. Methods: A systematic literature search was conducted in PubMed/Medline, Web of Science, and Scopus until September 2025. Studies that assessed the association between plant-based diets, including the Mediterranean diet (MeDi), dietary approaches to stop hypertension (DASH), Mediterranean-DASH intervention for neurodegenerative delay (MIND), Nordic, and Portfolio diets, and cardiometabolic diseases [i.e., cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM)] or their risk factors [i.e., overweight/obesity, hyperglycemia or insulin resistance (IR), dyslipidemia, and hypertension (HTN)] within the TLGS framework were included. Results: From the 1,293 articles, 13 studies were included. Nine studies were identified on the MeDi score and cardiometabolic diseases; most found no significant associations. Five studies were conducted on the DASH score, which revealed an inverse association with risk of IR but no other outcomes. Two studies assessed the link between the MIND and Nordic diets and CVD with protective associations. There was one study on the Portfolio diet that showed no association with T2DM risk. Conclusions: Within the TLGS, the MeDi and DASH diet scores have been studied more than other plant-based diets, yet most findings show no beneficial association with cardiometabolic diseases. Conversely, recent findings regarding the MIND and Nordic diets indicate a significant inverse association with CVD incidence. Given the scarcity of research in this area, further investigation into plant-based diets and cardiometabolic health within the TLGS is warranted.