Abstract
BACKGROUND: The association between plant and animal protein and the risk of cardiovascular disease has been established. However, the association between the plant-to-animal protein ratio and the risk of premature coronary artery disease (PCAD) remains unknown. OBJECTIVE: To explore the association between the plant-to-animal protein ratio and the risk of PCAD and severity of PCAD. METHODS: This multi-center case-control study was conducted in the framework of the Iran Premature Coronary Artery Disease (IPAD) study in 14 cities in Iran. The data were collected from hospitals with catheterization laboratories. Cases were 1435 patients with a stenosis ≥ 75% in at least one vessel or ≥ 50% in the left main artery. Control group were 711 individuals with normal angiography test. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. We calculated the proportion of daily energy intake contributed by plant and animal protein separately, and then derived a unitless plant-to-animal protein ratio by dividing these 2%. The association between the plant-to-animal protein ratio and the risk of PCAD and its severity was investigated using logistics regression. RESULTS: The mean (SD) of plant-to-animal protein ratio was 1.06 (0.44). In the fully adjusted model, the highest tertile of the plant-to-animal protein ratio was significantly associated with a decreased risk of PCAD compared with the lowest tertile (OR = 0.31, 95%CI: 0.22-0.43, P trend < 0.001). There was an inverse relationship between the plant-to-animal protein ratio and the severity of PCAD (OR = 0.60, 95% CI: 0.47-0.77, P trend < 0.001). CONCLUSIONS: Our results revealed an inverse association between the plant-to-animal protein ratio and the risk of PCAD and its severity. More future studies are needed to confirm this association.