Thickening of liquid increases swallowing safety dysphagia patients

This latest research in Journal of Neurogastroenterology & Motility shows that a specific xanthan/guar gum-based thickener increased the safety of swallow over a wide range of viscosities in patients with post-stroke oropharyngeal dysphagia (PSOD), without increasing pharyngeal residue. Interestingly, the thickener also improved the physiology of swallowing.

Post stroke dysphagia increases mortality

Stroke is the second leading cause of death and the third leading cause of disability worldwide.1,2 An independent risk factor for increased mortality after stroke is oropharyngeal dysphagia (OD)3. OD is defined as a swallowing difficulty affecting the transport of foods and liquids from the mouth to the oesophagus. OD is characterized by impaired swallowing mechanisms including safety, efficacy and physiology of swallowing and is associated with malnutrition and respiratory infections.4
PSOD is a common complication following stroke, with an incidence up to 78% in acute stroke patients5 PSOD was recently also found to be a risk factor for prolonged hospital stay and a decreased functional capacity.3

Thickening agents

A review by the European Society for Swallowing Disorders (ESSD) concludes that there is evidence for increasing viscosity to reduce the risk of airway invasion and it is a valid strategy for the management of OD.6 Thickening agents can be used to increase the viscosity of thin liquids and modify the texture of food. Most studies on thickening agents only tested a few viscosity levels per study, and the optimal viscosity levels for patients suffering PSOD have not been determined yet.

TripleS study

The Journal of Neurogastroenterology & Motility published results of the TripleS (Safety of Swallowing in Stroke) study, titled “Effect of a gum-based thickener on the safety of swallowing in patients with post-stroke oropharyngeal dysphagia”. The publication reported the effect of a specific amylase resistant xanthan/guar gum-based thickener in 120 patients with PSOD.
The effect of the thickener was tested on safety, efficacy (e.g. presence of pharyngeal residue) and physiology of swallowing (e.g. time to laryngeal vestibule closure (LVC)). Safe swallowing occurs when the food bolus does not enter the airways. Pharyngeal residue occurs when part of the food remains in the throat (pharynx), which may increase post-swallow airway invasion. The LVC is a protective mechanism which guarantees that the airways are not accessible by the food bolus during the swallowing process.
The study was conducted by evaluating 10 mL boluses of 150, 250, 450, 800, 1400, and 2000 mPa.s in comparison to unthickened (thin) liquid. Swallowing mechanisms were evaluated with videofluoroscopy (VFSS) and Penetration Aspiration Scale (PAS).

Why is the TripleS study unique?

TripleS is the first study designed to evaluate the effect of 7 different viscosities in PSOD patients.


Study results demonstrated:
• Safety of swallowing: an increase in the percentage of patients swallowing safely at each tested viscosity compared to thin liquid (p< 0.001). The study also found that almost 60% of
• Efficacy of swallowing: no increase in pharyngeal residue at each tested viscosity compared to thin liquid (p> 0.05).
• Physiology of swallowing: a decrease in the time to LVC and total duration of the swallowing response at each tested viscosity compared to thin liquid (p< 0.01) (time to LVC and total duration of the swallowing response have been shown to be increased in patients with dysphagia).
The study highlights the therapeutic effect of this specific xanthan/guar gum-based thickener on the safety and physiology of swallowing.


Thickening of liquids is a valid compensatory strategy to manage patients with dysphagia. Interestingly, the observed effect on swallowing physiology, i.e. a reduction in time to LVC in the TripleS study, suggests a mode of action of this thickener beyond a simple ‘compensatory’ effect. Furthermore, the specific gum-based thickener did not increase pharyngeal residue with increasing viscosity. This differentiates gum-based thickeners from purely starch-based thickeners, where increased pharyngeal residue with increased viscosity has been observed.7


These results confirm the effectiveness of this specific xanthan/guar gum-based thickener and support the recommendation of use in the management of oropharyngeal dysphagia.

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Rofes, L, Muriana, D, Palomeras, E, et al. Prevalence, risk factors and complications of oropharyngeal dysphagia in stroke patients: A cohort study. Neurogastroenterol Motil. 2018; 30:e13338. 10.1111/nmo.13338″ target=”_blank” rel=”noopener noreferrer”>
Clave & Shaker. (2015). Dysphagia: current reality and scope of the problem. Nature Reviews Gastroenterology & Hepatology 12, 259-270.
Martino R , Foley N , Bhogal S , et al . Dysphagia after stroke: incidence, diagnosis, and pulmonary complications. Stroke 2005;36:2756–63.doi:10.1161/01.STR.0000190056.76543.eb.
Newman R., Vilardell N., Clave P., Speyer R. Effect of Bolus Viscosity on the Safety and Efficacy of Swallowing and the Kinematics of the Swallow Response in Patients with Oropharyngeal Dysphagia: White Paper by the European Society for Swallowing Disorders (ESSD). Dysphagia. 2016; 31:232-249.
Vilardell N., Rofes L., Arreola V., et al. A Comparative Study Between Modified Starch and Xanthan Gum Thickeners in Post-Stroke Oropharyngeal Dysphagia. Dysphagia 2016; 31: 169-179.