Dysphagia Knowledge Hub — 吞嚥困難知識庫
Thickeners for Dysphagia: Starch vs Xanthan Gum, IDDSI Levels and Common Errors
Thickeners are the most widely used intervention for managing liquids in dysphagia. Choosing the wrong type or preparing them incorrectly can increase rather than reduce aspiration risk. This guide explains the two main thickener types, IDDSI level preparation, available products, and the most common clinical and caregiver errors.
Two Main Thickener Types
Starch-Based Thickeners
- Main ingredient: Modified cornstarch or potato starch
- Advantages: Tasteless and colorless; lower cost; widely available
- Critical disadvantage: Salivary amylase — an enzyme naturally present in saliva — breaks down starch over time, causing the liquid to become progressively thinner after preparation. This is a significant safety concern.
- When appropriate: Only for immediate preparation and immediate consumption; not suitable for advance batch preparation
Xanthan Gum-Based Thickeners
- Main ingredient: Xanthan gum (fermented polysaccharide)
- Advantages: Not broken down by salivary amylase — viscosity remains stable over time; unaffected by acidity (e.g., citrus juice)
- Minor disadvantage: Some patients find the texture slightly gummy; slightly higher cost than starch
- Clinical recommendation: IDDSI guidelines and most speech-language pathologists recommend xanthan gum-based thickeners, particularly for patients with prolonged mealtimes
IDDSI Levels and Preparation Reference
| IDDSI Level | Description | Flow Test | Xanthan Gum Amount (per 250mL water) |
|---|---|---|---|
| Level 1 (Slightly Thick) | Slightly thicker than water | Flows quickly off fork | ~1 tsp (see product label) |
| Level 2 (Mildly Thick) | Similar to full-fat milk | Drips slowly off fork | ~1.5-2 tsp |
| Level 3 (Moderately Thick) | Flows off fork in a ribbon | Pours like a thick syrup | ~2.5-3 tsp |
| Level 4 (Extremely Thick / Pudding) | Holds shape; like yogurt or pudding | Does not flow off fork; can be scooped | ~4-5 tsp |
Important notes:
- Amounts above are approximate — thickening power varies significantly across brands. Always follow the specific product instructions.
- Add all powder at once and stir thoroughly. Adding in stages causes lumping.
- Allow 30-60 seconds after mixing for viscosity to stabilize, then perform a fork or spoon test to verify the level.
Product Comparison
| Product | Type | Market | Notes |
|---|---|---|---|
| Resource ThickenUp Clear (Nestlé) | Xanthan gum | US, UK, EU, Asia | Clear/transparent; widely recommended by SLPs |
| Thick-It Original (Medline) | Starch-based | US | Original formula; note amylase degradation risk |
| Thick-It Clear (Medline) | Xanthan gum | US | Clear version; improved stability vs original |
| Nutilis Clear (Nutricia) | Xanthan gum | UK, EU, Australia | Frequently used in NHS settings |
| Simply Thick EasyMix | Xanthan gum | US | Gel-form individual sachets; popular in clinical settings |
| Thick & Easy Clear (Hormel) | Xanthan gum | US, Hong Kong | Transparent type; does not alter drink appearance |
Common Errors and Corrections
Error 1: Preparing Large Batches in Advance with Starch Thickeners
Problem: Starch thickeners can lose a significant portion of their viscosity within hours due to salivary amylase in shared containers or continued enzymatic breakdown — the liquid may no longer meet the prescribed IDDSI level by the time it’s consumed.
Correction: Prepare starch-thickened drinks immediately before consumption. If advance preparation is necessary, use xanthan gum-based thickeners; store in a sealed container for no more than 24 hours.
Error 2: Adding Thickener to Hot Beverages Incorrectly
Problem: Very hot liquids (above ~70°C) can affect starch thickener performance. Xanthan gum is more heat-stable but still shows some variation.
Correction: Allow hot drinks to cool slightly (below ~60°C) before adding thickener. Follow the product’s temperature guidelines.
Error 3: Thickening Acidic or Concentrated Drinks
Problem: High-acidity drinks (orange juice, lemonade) can reduce starch thickener effectiveness; may require more powder than usual.
Correction: Use xanthan gum-based thickeners for acidic beverages. Always test the final viscosity — do not assume the standard amount is sufficient for every liquid type.
Error 4: Relying on Visual Appearance to Judge Viscosity
Problem: Caregivers and family members often estimate viscosity by appearance or how the drink “feels,” which is highly inaccurate.
Correction: Teach caregivers to use the IDDSI Fork Drip Test (hold a fork horizontally over a glass; correct viscosity drips at the expected rate) and the spoon tilt test to objectively verify the IDDSI level matches the prescription.
Error 5: Assuming All Thickeners Are Interchangeable
Problem: Switching brands without re-testing can result in the same volume producing a different viscosity level.
Correction: When changing products, re-establish the dose from scratch using the new product’s guidelines and confirm with testing before serving.
Patients Who Resist Thickened Liquids
Resistance to thickened drinks is common and clinically significant:
- Offer stronger-tasting drinks (fruit juice, malt drinks, flavored milk) where thickened texture is less noticeable
- Try cold or ice-slushy preparations — some patients tolerate these better
- Modified Water Protocol: In carefully selected patients (upright posture, small sips, immediate oral hygiene afterward), plain water may be permitted under specific conditions determined by an SLP. This is a clinical decision, not a general recommendation.
Summary
| Starch-Based | Xanthan Gum-Based | |
|---|---|---|
| Salivary amylase stability | ✕ Degrades over time | ✓ Stable |
| Acidic drink performance | Variable | Stable |
| Heat stability | Lower | Higher |
| Transparency | Opaque | Clear |
| IDDSI recommendation | Not preferred | Preferred |
| Cost | Lower | Slightly higher |
Xanthan gum-based thickeners are the IDDSI-preferred choice for clinical safety. Correct preparation — right amount, immediate mixing, objective viscosity testing — is as important as choosing the right product type. Any changes to a thickening prescription should be made in consultation with a speech-language pathologist.