Thick water, or thickened liquid, is a specialized dietary modification used to make drinking safer for individuals with certain medical conditions. This fluid is created by adding a thickening agent to regular liquids like water, juice, or coffee to increase their viscosity. The goal is to alter the physical properties of the fluid so it can be swallowed with greater control and safety. This modification is commonly recommended by speech-language pathologists and other healthcare providers to manage swallowing difficulties.
The Purpose of Thickened Liquids
The need for thickened liquids arises from dysphagia, the medical term for difficulty swallowing. This impairment can result from various neurological disorders, such as stroke or Parkinson’s disease, or from head and neck cancer treatment. For people with dysphagia, thin liquids move quickly, making them difficult to control in the mouth and throat.
This lack of control increases the risk of aspiration, where fluid passes into the trachea and enters the lungs instead of the esophagus. Aspiration can lead to serious respiratory complications, most notably aspiration pneumonia. Increasing the viscosity of the liquid slows its flow, allowing the throat muscles more time to coordinate the swallow reflex and protect the airway.
Thickened liquids provide a cohesive mass of fluid that is easier for the individual to manage during swallowing. This modification enhances control and sensation, reducing the chance of fluid prematurely entering the airway. It is a widely used and effective method for improving swallow safety and promoting hydration.
Key Ingredients: The Thickening Agents
Commercial thickening products are typically powdered formulas that use food-grade polymers to increase the viscosity of liquids. These agents fall into two main categories: starch-based thickeners and gum-based thickeners.
Starch-Based Thickeners
Starch-based thickeners are commonly derived from modified cornstarch. When mixed into a liquid, the starch granules swell and absorb water, creating the desired thickness. A significant drawback is their susceptibility to salivary amylase, an enzyme in saliva that breaks down starch. This breakdown can cause the liquid to thin out in the mouth, potentially compromising swallow safety and increasing aspiration risk. Starch-based liquids may also continue to thicken over time after preparation, often giving the fluid a cloudy appearance and a slightly starchy taste.
Gum-Based Thickeners
Gum-based thickeners, particularly those made with xanthan gum, offer advantages over their starch counterparts. Xanthan gum is amylase-resistant, meaning it maintains a stable viscosity even when mixed with saliva. This stability ensures the liquid remains at the prescribed thickness throughout the entire swallowing process. Xanthan gum creates thickness by forming a mesh-like structure that traps water molecules, often resulting in a clearer liquid that is less noticeable to the drinker and has a minimal impact on taste. Due to their stability, xanthan gum products have become the preferred choice in many clinical settings, leading to better patient acceptance and higher fluid intake.
Standardized Levels of Thickness
The consistency of thickened liquids is prescribed using a standardized, objective framework. The International Dysphagia Diet Standardization Initiative (IDDSI) provides a global terminology for describing drink thickness and food textures. The IDDSI framework uses an eight-level continuum, with drinks spanning from Level 0 (Thin) to Level 4 (Extremely Thick).
Healthcare professionals use this system to match the precise fluid viscosity to an individual’s specific swallowing abilities. The drink levels are defined by a flow test, which measures how quickly a liquid passes through the nozzle of a syringe within a set amount of time.
The modified levels include:
- Level 1 (Slightly Thick) is the thinnest modified level.
- Level 2 (Mildly Thick) often corresponds to the consistency of a fruit nectar.
- Level 3 (Moderately Thick) has a consistency similar to honey and flows more slowly.
- Level 4 (Extremely Thick) is non-pourable and holds its shape, often eaten like pudding.
Using these standardized levels ensures that an individual receives the exact thickness required for a safe and consistent swallow.