Designing and Developing a Population/Literature-Based Westernized Diet Index (WDI) and Its Relevance for Cardiometabolic Health

<b>Background/Objectives</b>: Recent research indicates a global transition from healthy and balanced diets to unhealthy Westernized dietary patterns (WDPs). This transition is linked to increased rates of non-communicable diseases (NCDs), e.g., obesity, type 2 diabetes, and cardiovascular diseases, often preceded by metabolic syndrome (MetS). Therefore, the objective of this study was to develop a diet quality index, termed Westernized Diet Index (WDI), to assess adherence to WDPs and its association with main cardiometabolic health issues, for which MetS and its components were chosen as representatives of NCDs. <b>Methods</b>: The development of the WDI was driven by a semi-systematic and comprehensive examination of the literature (<i>n</i> = 491 articles) that evaluated the influence of WDP components on health outcomes. The scoring algorithm involved multiple steps, assigning scores based on study design, sample size, and the direction of food effects on health outcomes. <b>Results</b>: The final developed index encompassed 30 food groups/items. It was revealed that soft drinks, processed foods, red meat, sodium, and hydrogenated fats had the most detrimental effects on health, significantly influencing the index's coefficients. In contrast, dietary fiber, plant-based metabolites, vitamins, minerals, nuts/seeds, and fish had the most substantial beneficial impacts. <b>Conclusions</b>: The WDI aligns with the existing literature on the importance of specific food items and with other validated diet quality indices, e.g., the Dietary Inflammatory Index (DII) and Alternate Healthy Eating Index (AHEI). Thus, the WDI can provide evidence for clinicians and researchers in formulating evidence-based dietary guidelines as well as strategies for the prevention and treatment of diet-related health issues. However, further validation is proposed to verify the WDI's capability across different contexts.