Association of dietary phytochemical index with cardiometabolic risk factors A systematic review and meta-analysis on observational studies

Objective(s): Cardio-metabolic risk factors are becoming a global health concern. To address this problem, one of the proposed ways is to focus on phytochemical-rich foods consumption. Therefore, we aimed to summarize the results of observational studies (cohorts, case-control, and cross-sectional) that investigated the association between dietary phytochemical index (PI) as a new index for evaluating phytochemical-rich food intake and various risk factors of cardio-metabolic disorders. Methods: We conducted a comprehensive systematic review through PubMed, Scopus, and Web of Science databases. The literature search was performed up to August 2021 with no publication year restriction on observational studies investigating the association between PI and cardiometabolic risk factors on adults and children. A random-effect meta-analysis was used. Results: Overall, 16 articles (cross-sectional, case-control, cohort) were eligible for this systematic review and 8 studies with 99771 participants were included in the meta-analysis. Random effect meta-analysis showed that adherence to higher dietary PI decrease the odds of abdominal obesity (OR: 0.73, 95% CI: 0.58, 0.88, I-2: 84.90), generalized obesity (OR: 0.84, 95% CI: 0.69, 0.98, I-2: 68.10), hypertriglyceridemia (OR: 0.81, 95% CI: 0.73, 0.89, I-2: 0.00), hypertension (OR: 0.86, 95% CI: 0.73, 0.99, I-2: 7.02), and MetS (OR: 0.79, 95% CI: 0.69, 0.88, I-2: 84.90). However, results considering the associations between dietary PI with glycemic indices, and low high-density lipoprotein (HDL) were not significant (p<0.05). Conclusion: Evidence showed adverse associations between dietary PI and some cardio metabolicrisk factors such as obesity, hypertriglyceridemia, hypertension and metabolic syndrome.