Understanding the Link Between Thickeners and Dehydration
For individuals with dysphagia, or difficulty swallowing, thickened fluids are a crucial safety measure to prevent aspiration, where liquids enter the lungs. While thickeners are designed to slow the flow of liquid to allow for a safer swallow, a significant concern has been the seemingly increased rate of dehydration among those who use them. The critical question is whether the thickener itself is to blame or if other factors are at play.
The Role of Water Bioavailability
Initial concerns focused on whether thickeners could bind water in a way that prevents it from being absorbed by the body. This fear has largely been debunked by scientific studies. Research on both animal and human subjects has demonstrated that water absorption rates are not significantly different when consuming thickened fluids versus un-thickened water. The body effectively absorbs the water from the thickened solution, regardless of whether it was thickened with starches or gums. Therefore, the thickener itself does not inherently cause a state of dehydration by trapping water.
The Core Reasons for Low Fluid Intake
If thickeners don't prevent water absorption, why are so many people using them still at risk for dehydration? The answer lies in a combination of reduced fluid consumption and impaired thirst mechanisms.
Factors that Reduce Fluid Consumption
- Unpleasant Taste and Texture: Many users report that thickened liquids have an unpleasant taste and texture, with some thickeners leaving a grainy or slick mouthfeel. This can lead to a general dislike of the beverages, causing individuals to drink less than they should. Adding a stronger flavor, such as fruit cordial or certain soups, may help.
- Reduced Thirst Quenching: Thick liquids, particularly those made with gum-based thickeners, are less effective at satisfying thirst. When the mouth is coated by a thick liquid, the oral sensors that signal thirst relief are not as effectively triggered as they are with thin liquids. This leaves individuals feeling persistently thirsty, yet less motivated to continue drinking the unappealing beverage.
- Early Satiety: Increased viscosity can cause a feeling of fullness faster, even if the person has not consumed enough fluid. This can be particularly problematic for patients on higher-viscosity liquids, as their feelings of satiety may prevent them from reaching their hydration goals.
- Inconvenience and Access: The process of preparing thickened liquids, especially in care facilities, can be time-consuming and inconsistent. Furthermore, studies have found that thickened fluids are less likely to be placed within reach of patients compared to thin liquids, creating an accessibility barrier.
The Role of Satiety and Oral Perception
Beyond taste, the very mechanism of drinking thick liquids contributes to the problem. Increased viscosity slows down the oral transit time, meaning the liquid stays in the mouth longer. This provides more time for oral receptors to register the texture, which is associated with increased feelings of fullness and satiety. For someone with dysphagia, who may already be taking smaller, more controlled sips, this process is amplified, leading them to feel full more quickly and to stop drinking before they are adequately hydrated.
Comparison Table: Starch-Based vs. Gum-Based Thickeners
| Feature | Starch-Based Thickeners | Gum-Based Thickeners | Impact on Dehydration Risk |
|---|---|---|---|
| Composition | Modified maize starch, maltodextrin. | Xanthan gum, guar gum, locust bean gum. | Dehydration risk is influenced by patient intake, not thickener type, though sensory properties differ. |
| Effect with Saliva | Can be broken down by amylase in saliva, causing them to thin out over time. | Resists amylase breakdown, maintaining a stable, consistent viscosity. | Starch-based thickeners can become unsafe if they thin out, while gum-based ones may coat the mouth, reducing thirst satisfaction. |
| Appearance | Often appears cloudy and can be grainy in texture. | Can be clear and tasteless, improving palatability for some users. | Palatability influences intake; improved taste/appearance of gum-based products may increase consumption. |
| Mixing and Stability | Some types can be unstable and may continue to thicken upon standing. | Generally more stable, mixing quickly and staying at the desired consistency. | Inconsistent thickness can lead to poor adherence and reduced fluid consumption. |
Managing Hydration with Thickened Liquids
To combat the risk of dehydration, several strategies can be implemented, focusing on increasing patient compliance and addressing the underlying reasons for low intake.
- Prioritize Palatability: Work with dietitians and speech-language pathologists (SLPs) to identify preferred beverage flavors and consistencies. Offering a variety of options, like thickened juices or milkshakes, can increase intake.
- Use Ready-to-Drink Products: Pre-thickened beverages are a convenient option that ensures consistent thickness and may have a better taste profile, improving adherence.
- Implement a Free Water Protocol: For carefully selected patients, a 'free water protocol' allows supervised intake of thin water between meals after thorough oral care. This can help quench thirst and increase overall fluid volume without significantly raising the risk of pneumonia in appropriate candidates.
- Offer Frequent Fluids: Schedule frequent, smaller fluid passes throughout the day and with medication administration to help meet hydration goals. Make sure drinks are always within the patient's reach.
- Serve Hydrating Foods: Increase intake of foods with high water content, such as pureed soups, yogurts, and puddings, to supplement fluid intake.
- Review Medication: Some medications, like diuretics or laxatives, can exacerbate dehydration. Pharmacists should be consulted to ensure medications are compatible with a thickened liquid diet.
Conclusion
While thickener does not cause dehydration by preventing water absorption, it is undeniably linked to an increased risk of dehydration in individuals with dysphagia due to factors that reduce overall fluid intake. The low palatability, poor thirst-quenching ability, and feeling of early fullness associated with thickened liquids all contribute to this problem. By implementing strategies that focus on improving the sensory experience, increasing fluid availability, and exploring alternative protocols, caregivers can effectively mitigate this risk and ensure adequate hydration for those who need thickened liquids for safety. Regular reassessment by a healthcare team is crucial to tailor the best hydration plan for each individual.
