Benefits of Increased Dietary Diversity Depend on Food Group and Diversity Dimension: A Microsimulation Modeling...

Dietary diversity is essential for nutrient adequacy, but its effects may vary depending on which food groups are diversified and the dimension of diversity considered (i.e., the number of food subgroups consumed, their consumption evenness, or their nutritional dissimilarity).

This study aimed to identify which food groups and diversity dimensions contribute to positive or negative effects of dietary diversity on the nutrient quality of diets, and to assess the magnitude of these effects and their underlying mechanisms.

Using data from the French National Food Consumption Survey, we developed an individual-level microsimulation model to maximize diversity within 12 food groups-one at a time-either in a single dimension or across the 3 dimensions simultaneously, while keeping the total quantity consumed constant. Nutrient quality was evaluated using probabilistic scores for nutrient adequacy, nutrient security (i.e., risk of deficiency), and moderation (i.e., avoidance of excessive intakes of sugar, sodium, and saturated fat). The effects of increasing diversity were analyzed using factorial repeated-measures analysis of variance.

Five food groups categories emerged based on how increased within-group diversity impacted nutrient quality: "favorable," "no effect, "mixed effects," "highly contrasting effects," and "unfavorable." "Vegetables," "Fish and Seafood," and "Bread" food groups fell into the first category, where greater diversity enhanced nutrient adequacy (with effect sizes ranging from +0.04 to +0.16 SD) without compromising moderation. In these cases, increasing the number of subgroups consumed was the most effective strategy. In contrast, increasing diversity within "Meat, Poultry, Eggs" and "Dairy," classified under the contrasting or unfavorable categories, tended to undermine moderation (from -0.05 to -0.20 SD). These negative effects were primarily driven by increasing consumption evenness and nutrient dissimilarity.

Promoting dietary diversity should not be generic. It should be targeted to the food group and diversification strategies that enhance nutrient adequacy without compromising moderation.