Table 14.

Benefits of using the healthful and unhealthful plant-based dietary index in nutrition research.

Benefit of classifying PDI in terms of hPDI and uPDI	Implications for researchers	Implication for policy makers	Implication for public/consumers
Can calculate healthful and unhealthful indices from preexisting dietary intake data	Facilitates research because no new data required to calculate PDI, hPDI, and uPDI	Using existing studies is efficient and is cost-effective by limiting need for new data	No need to complete new food surveys beyond those already included
Does not require a priori or self-reported dietary groupings (vegan, vegetarian, omnivore)	Reduces concerns over degree of adherence to a specific diet or dietary category	Obviates need to deal with vague and heterogeneous diet categories	Avoids categorizing diet patterns and related value judgments (e.g., ethical vegan)
Provides a continuous dietary index, not just a binary measure of adherence to a specific diet type	Allows comparisons by index extremes (quartiles, quintiles, deciles) and dose–response analysis	Guidance is facilitated by low versus high index level comparisons and by dose–response information	Comparisons of high versus low index outcomes are easy to grasp for healthy versus unhealthy plant-based foods
Shows benefits of healthy plant foods that might be missed by a PDI or diet category that does not consider plant-food quality	hPDI may better detect positive associations with outcomes than an overall PDI in a given sample (Tables 2–13)	Emphasizes healthy foods, not just foods in a specific diet or food group, allowing more nuanced dietary recommendations	Raises awareness about the benefits of eating healthy foods and why being “plant-based” does not ensure a high diet quality
Shows detriments of unhealthy plant foods that might be missed by a PDI or diet category that does not consider plant-food quality	uPDI may better detect negative associations with outcomes than an overall PDI in a given sample (Tables 2–13)	Highlights unhealthy refined and highly processed plant foods and beverages to avoid in nutrition guidelines	Raises awareness about the detriments of refined grains, fruit juices, sweets, sugar-sweetened beverages, and processed foods
Conceptualizes healthy eating as a continuum of food choices, not as strict adherence to a specific diet type, or as plant- versus animal-foods	Generalizability of findings is increased by seeing impact of quality changes and by aligning better with real-world diets	Guidance may promote better adherence if promoting healthy plant foods, rather than shunning animal or unhealthy foods	Empowers consumers to make incremental additions of healthy plant foods that may ultimately displace unhealthy foods

PDI, plant-based dietary index; hPDI, healthful PDI; uPDI, unhealthful PDI.