Dietary supplements are extensively consumed, but irrational use is a health hazard. Pharmacy students, being future healthcare providers, can facilitate rational use. The present study evaluated the knowledge, attitudes, and practices of pharmacy students at Srinivas College of Pharmacy, Mangalore, about dietary supplements and their role as an advocate, in addition to mental health correlations. 250 students selected through stratified random sampling took part in a cross-sectional mixed-methods study. A 30-question instrument (Cronbach's alpha=0.85) measured demographics, dietary supplement usage, knowledge, attitude, practices, and mental health was evaluated with the depression, anxiety, and stress Scale-21 (DASS-21). The data were collected during January-March 2025 and were analyzed with the chi-square test, logistic regression, and Pearson correlation tests. 35.0% (n=88) used dietary supplements regularly, with a preference for multivitamins (50%) and protein supplements (30%). Knowledge was moderate (60% risk aware), attitudes favorable (70% in favor of counseling), but practice restricted (25% informed peers). Everyday use of dietary supplements escalated stress probability (OR=2.5, 95% CI: 1.8-3.4, p<0.001), with correlation (r=0.38, p<0.01). In conclusion, students have promise as dietary supplement champions but require additional training to close knowledge-practice gaps and mitigate mental health risks. Curriculum and policy interventions are needed to enhance students' abilities in encouraging rational dietary supplement use and identifying potential mental health effects.