Background/Objectives: The increasing use of dietary supplements in Türkiye underscores the need for validated instruments to assess dietitians' knowledge, attitudes and self‐efficacy regarding supplements. However, no validated Turkish tool is currently available. This study aimed to culturally adapt the Dietitians' Survey of Comfort, Opinions and Preparedness in Education in Supplements (‐SCOPE) Questionnaire into Turkish (Diyetisyenlerin Eğitim, Supleman Tercihleri ve Konforu Anketi; DESTEK) and evaluate its psychometric properties. Methods: This methodological study included 223 dietitians. Exploratory factor analysis (Principal Axis Factoring with Direct Oblimin rotation) was conducted to identify the underlying structure, followed by confirmatory factor analysis to test model fit. Internal consistency was assessed using Cronbach's alpha. Convergent validity was examined through composite reliability and average variance extracted, and discriminant validity was evaluated using the Fornell–Larcker criterion. Results: A four‐factor structure explaining 38.3% of total variance was identified. Sampling adequacy was acceptable (KMO = 0.78; Bartlett's test: χ ² (153) = 1023.27, p < 0.001). Confirmatory factor analysis demonstrated acceptable model fit (CFI = 0.915; TLI = 0.893; RMSEA = 0.062; SRMR = 0.057). The total scale showed acceptable internal consistency (α = 0.795), with subscale α values ranging from 0.531 to 0.824. Composite reliability values ranged from 0.60 to 0.83. Test–retest analysis demonstrated acceptable temporal stability (overall ICC = 0.772). Discriminant validity was supported. Conclusions: The findings provide preliminary evidence supporting the validity and reliability of the DESTEK scale for assessing Turkish dietitians' knowledge, attitudes and perceived preparedness regarding dietary supplements. Given its multidimensional structure, DESTEK may be useful for evaluating specific domains of supplement‐related competence; however, further validation in larger and more diverse samples is recommended.

Background/Objectives: This study evaluated the nutrient calculation accuracy, reproducibility, and expert-rated clinical appropriateness and safety indicators of three-day diet plans generated for women with polycystic ovary syndrome (PCOS), recently proposed to be termed polyendocrine metabolic ovarian syndrome (PMOS). Methods: Anonymized data from six women with heterogeneous PMOS profiles, purposively selected from a single clinic, were converted into standardized Turkish prompts and submitted to ChatGPT-4, Claude Sonnet 4.6, Gemini 2.5 Flash, and Mistral 2.0 through free web interfaces. Three independent generations per case–model combination yielded 216 daily menus. LLM-reported nutrient values were compared with BeBiS 9.0 calculations. Reproducibility was assessed using intraclass correlation coefficients (ICCs). Two experts independently evaluated the first generated plan for each case–model combination using a study-specific clinical appropriateness rubric and red-flag checklist. Results: No model achieved consistently low error across nutrients. Claude Sonnet 4.6 showed the lowest percentage errors for energy, carbohydrate, and fiber; ChatGPT-4 for protein; and Mistral 2.0 for fat. Gemini 2.5 Flash showed the largest percentage errors across all nutrients and a mean energy bias of +531.1 kcal. ChatGPT-4 showed comparatively higher plan-level reproducibility, while the remaining models generally showed poor reproducibility. Claude Sonnet 4.6 had the highest descriptive clinical appropriateness scores and Gemini 2.5 Flash the lowest, but no pairwise differences remained significant after Holm correction. Gemini 2.5 Flash generated the most confirmed study-specific red flags (n = 28), with all six cases meeting the criterion for the “masked low-energy” indicator. Conclusions: LLM-generated diet plans showed model-dependent calculation errors and limited reproducibility, and the present findings do not support their independent or unsupervised use as individualized clinical nutrition recommendations.