How Thickener Type, Concentration, and Non-Standard Syringes Affect IDDSI Flow Test Evaluation of Thickened Plant-Based and Dairy Beverages

Adapting low-viscosity liquids for individuals with dysphagia presents persistent challenges in both texture modification and patient compliance. This exploratory study assessed the flow characteristics and nutritional contributions of 30 beverages (22 plant-based and 8 dairy-based) across different thickener concentrations and syringe models, following the International Dysphagia Diet Standardization Initiative (IDDSI) flow test. Flow measurements were obtained using four available 10 mL syringes that differed from the IDDSI-specified model, intending to evaluate their potential impact on results and inform strategies for situations where standard syringes are unavailable. Findings show that flow performance and IDDSI classification are strongly influenced by syringe design, thickener type, and beverage composition. The use of alternative syringes introduced variability in consistency measurements, highlighting the importance of equipment standardization. Interpretation of flow levels was further complicated by transitional IDDSI thresholds and subjective assessments. Nutritionally, the study reinforces the role of hydration in dysphagia management and explores the potential of plant-based beverages to enhance both fluid intake and fiber contribution. Several samples provided meaningful contributions to daily fiber and micronutrient requirements. Importantly, the study found that half the manufacturer’s recommended thickener dose was often sufficient to achieve IDDSI compliance. These findings support the practical use of non-standard syringes in IDDSI testing, inform more efficient thickening strategies, and highlight plant-based beverages as promising alternatives to dairy in dysphagia diets. Together, they offer actionable insights for improving consistency control and nutritional quality in dysphagia care.