Beyond Dietary Identity: Habitual Food Consumption, Lifestyle Characteristics, and Mental Health in Adults Following...

Evidence linking plant-based diets with mental health is mixed. One reason may be that dietary labels do not always reflect habitual food intake and often coincide with other lifestyle characteristics.

We conducted a cross-sectional secondary analysis of 158 Polish adults: 105 omnivores and 53 participants who identified as following plant-based diets (34 vegetarians and 19 vegans). Habitual intake frequencies for 33 food groups and diet-quality indices were derived from KomPAN. Anxiety and depressive symptoms were assessed with HADS-M, empathy with the EQ-Short/SSIE, and physical activity with IPAQ. Self-identified dietary pattern was the primary exposure; meat/fish-abstention definitions were examined in sensitivity analyses.

Compared with omnivores, plant-based participants had lower BMI and nHDI scores, higher DQI values, and, among those with valid IPAQ data, higher physical activity. Nineteen of 33 food groups differed after false-discovery-rate correction. We found no statistically significant association between dietary identity and HADS-A or HADS-D in crude, minimally adjusted, or broader sensitivity models; the confidence intervals, however, were too wide to establish equivalence or rule out an association. Of the 53 self-identified plant-based participants, 36 (67.9%) met the meat/fish-abstention criterion and 17 (32.1%) did not. IPAQ analyses included 120 participants, and inverse-probability-weighted sensitivity analyses produced similar HADS estimates. No individual food-frequency variable was associated with HADS-A or HADS-D after multiplicity correction. In exploratory analyses, more frequent vegetable consumption was positively associated with empathy.

Dietary identity corresponded to clear differences in habitual food consumption, diet quality, and selected lifestyle characteristics, but we did not detect a statistically significant association with anxiety or depressive symptoms. The observed mismatch between dietary identity and reported behavior highlights the value of measuring both in studies of plant-based diets and psychological outcomes.