Effect of human saliva on the consistency of thickened drinks for individuals with dysphagia

Background Thickening of foods and fluids is commonly used in the management of dysphagia to reduce the risk of aspiration. The use of starch-based thickeners is established. However, the use of gums in thickeners is gaining interest as they are resistant to salivary amylase, which may promote safer swallowing. Aims To compare the effect of human saliva on the consistency of drinks thickened with a gum-containing (GC) thickener with that of drinks thickened with four starch-based (SB) thickeners. Methods & Procedures Three drinks (artificial tap water, hot coffee and full-fat milk) were thickened to custard consistency with the different thickeners. Compression force and amount of thin liquid formed were determined after 10 and 50 min of contact with human saliva with standardized amylase activity and compared with a control inoculated with water. Outcomes & Results Drinks thickened with GC thickener were significantly less sensitive to thinning by human saliva compared with drinks thickened with all four SB thickeners (p < 0.05). Moreover, incubation of SB-thickened drinks with human saliva resulted in the formation of at least 10 g of decantable liquid, while for GC-thickened drinks, almost no liquid was formed. Conclusions & Implications These results show that GC thickeners contain their consistency better in contact with human saliva than SD thickeners. This may enhance the swallowing safety of people with dysphagia. © 2014 Royal College of Speech and Language Therapists