A Diverse Plate, A Healthier Future: Exploring the Link Between Nutritional Biodiversity and Disease Prevention

Background: Global diets are increasingly dominated by a narrow range of plant and animal species, despite the availability of thousands of edible options. This dietary homogenization has coincided with rising rates of noncommunicable diseases (NCDs). Nutritional biodiversity, measured through Dietary Species Richness (DSR)—the number of unique edible species consumed—offers a novel approach to assessing and improving diet quality, with potential implications for human and planetary health. Objective: To systematically review and synthesize evidence linking DSR and related species-level diversity metrics to public health outcomes, including nutrient adequacy, gut microbiome composition, inflammation, and all-cause mortality. Methods: We searched multiple databases (PubMed, Scopus, Embase, Web of Science) and grey literature sources up to May 2025. Studies were eligible if they reported on species-level dietary diversity (e.g., DSR, Hill numbers) and at least one health-related outcome. Risk of bias was assessed using ROBINS-I and RoB 2.0; certainty of evidence was evaluated using GRADE. Results: Fifteen studies met inclusion criteria (11 observational; 4 RCTs), encompassing >450,000 participants across diverse settings. Micronutrient adequacy: Eight observational studies in LMICs and high-income countries found a consistent positive association between DSR and nutrient adequacy (+0.03 NAR per species; p < 0.001). Mortality: Meta-analysis of five European cohorts (n ≈ 450,000) showed a 37% reduced risk of all-cause mortality among those in the highest DSR quintile (pooled HR = 0.68; 95% CI: 0.60–0.77; I² = 46%). Microbiome and inflammation: RCTs using fermented food as a proxy for DSR showed increased α-diversity (~10–15%) and reductions in inflammatory proteins (e.g., IL-6), though no trials directly manipulated DSR as an intervention. Conclusions: Species-level dietary diversity, particularly as measured by DSR, is a consistent and underutilized predictor of improved nutritional adequacy, microbiome resilience, and reduced mortality risk. Despite promising associations, RCTs explicitly manipulating DSR remain absent. Integrating DSR into dietary guidelines, clinical screening tools, and sustainability policies offers a novel and actionable pathway toward aligning nutrition and biodiversity goals.