Plant-Based Dietary Patterns and Culinary–Medicinal Mushrooms in Inflammation and Cardiometabolic Health: A Systematic Review of Human Evidence and Potential Mechanisms

Background/Objectives: Plant-based dietary patterns and culinary–medicinal mushrooms may reduce inflammation and cardiometabolic risk but have not been reviewed together. This systematic review assessed their effects on inflammatory and cardiometabolic outcomes and whether proposed mechanisms were directly measured. Methods: PubMed/MEDLINE, Scopus, Embase, and Web of Science were searched (PROSPERO CRD420261503833). Fifty-five human studies (28 intervention and 27 observational) were included and synthesized narratively owing to heterogeneity. Risk of bias was assessed using RoB 2, ROBINS-I, and the Newcastle–Ottawa Scale. Results: Randomized trials supported modest reductions in body weight and LDL-C with vegan and vegetarian diets, whereas effects on CRP and other inflammatory markers were inconsistent. Observational studies consistently associated higher plant-based diet quality with lower CRP, insulin resistance, and type 2 diabetes risk, whereas less healthful plant-based patterns showed opposite associations. Mushroom studies were small and preparation-specific, with mixed findings; a large cohort found no association with incident cardiovascular disease or diabetes. Direct human evidence for the proposed mechanisms was limited, and none was shown to mediate clinical outcomes. Most randomized trials had some risk-of-bias concerns. Conclusions: Healthful plant-based dietary patterns are of interest for cardiometabolic prevention, with benefits depending on diet quality rather than a plant-based label. Evidence for culinary–medicinal mushrooms is insufficient to support recommendations, and proposed mechanisms remain unproven.