What is the National Dysphagia Diet (NDD)?
Created by the Academy of Nutrition and Dietetics, the National Dysphagia Diet (NDD) was a framework used to standardize food textures for individuals with swallowing problems, also known as dysphagia. The goal was to provide a common terminology for clinicians, patients, and caregivers to discuss dietary needs safely. The NDD was historically divided into three primary food texture levels, plus levels for thickened liquids, before the International Dysphagia Diet Standardisation Initiative (IDDSI) gained global adoption.
Why was the NDD replaced by IDDSI?
While the NDD was a foundational step towards standardization, it lacked the rigorous testing methods and consistent, evidence-based definitions provided by the IDDSI framework. For example, the NDD’s “bite-sized” guidance was not based on the actual size of a person’s airway, increasing choking risks for some patients. The IDDSI framework, developed by a range of international experts, includes comprehensive testing methods to ensure patient safety across all age groups and care settings. In 2019, IDDSI was officially recognized as the new standard of practice by the Academy of Nutrition and Dietetics, though many continue to reference the older NDD levels.
The NDD Food Levels
Level 1: Dysphagia Pureed This is the most restrictive level, designed for individuals with moderate to severe dysphagia, poor oral control, and a reduced ability to protect their airway. Foods at this level are completely smooth, homogenous, and cohesive, with a texture similar to pudding or a thick yogurt. No chewing is required.
- Allowed Foods: Pureed meats, smooth puddings, pureed fruits, well-moistened mashed potatoes, and smooth cereals like Cream of Wheat.
- Foods to Avoid: Any lumpy, coarse, or solid food, including whole fruits, breads, and mixed-texture items.
Level 2: Dysphagia Mechanically Altered This level serves as a transition from pureed foods and is for patients with mild to moderate oral and/or pharyngeal dysphagia. It requires some chewing ability. Foods should be moist, cohesive, and soft-textured, with minced or ground meats no larger than one-quarter inch.
- Allowed Foods: Soft pancakes, moistened ground meats with gravy, moist casseroles without rice, and well-cooked, soft vegetables mashed with a fork.
- Foods to Avoid: Tough or dry meats, raw vegetables, hard cheese, rice, and fibrous vegetables like broccoli.
Level 3: Dysphagia Advanced This is the final transitional level before a regular diet, intended for individuals with mild oral and pharyngeal dysphagia. Patients at this level have adequate chewing ability but still require moist, bite-sized foods. They should be able to tolerate some mixed textures.
- Allowed Foods: Tender, bite-sized meats and poultry, soft-peeled fruits like peaches and melons, and soft breads moistened with sauce or butter.
- Foods to Avoid: Hard, crunchy, or very sticky foods such as tough meats, popcorn, nuts, and chewy candies.
The NDD Liquid Levels
Liquids are categorized separately from solid foods and are modified by thickness. The NDD used these classifications:
- Thin: Unrestricted liquids like water, juice, and coffee.
- Nectar-Thick: Slightly thicker than water, similar to tomato juice or nectar. Can be sipped from a cup but with some effort.
- Honey-Thick: Drips slowly from a spoon, significantly slower than nectar-thick.
- Pudding-Thick (Spoon-Thick): Eaten with a spoon, holds its shape, and does not flow freely.
Comparison of NDD and IDDSI Levels
Below is a simplified comparison demonstrating the transition from NDD to the current global standard, IDDSI. For precise texture definitions, always refer to the official IDDSI guidelines at iddsi.org.
| Feature | National Dysphagia Diet (NDD) | International Dysphagia Diet Standardisation Initiative (IDDSI) |
|---|---|---|
| Food Levels | Level 1: Pureed Level 2: Mechanically Altered Level 3: Advanced Level 4: Regular |
Level 4: Pureed Level 5: Minced & Moist Level 6: Soft & Bite-Sized Level 7: Regular |
| Liquid Levels | Thin Nectar-Thick Honey-Thick Pudding-Thick |
Level 0: Thin Level 1: Slightly Thick Level 2: Mildly Thick (Nectar) Level 3: Moderately Thick (Honey) Level 4: Extremely Thick (Pudding) |
| Terminology | Often inconsistent among facilities, leading to confusion and errors. | Standardized terminology and color coding to improve communication globally. |
| Safety Focus | Less prescriptive, especially regarding specific bite sizes for choking risk. | Evidence-based testing methods using tools like a fork or syringe to confirm food and liquid consistency. |
| Global Adoption | Outdated and inconsistent with modern practice standards. | Globally recognized as the best practice for dysphagia management. |
How to Transition to IDDSI from NDD
For healthcare facilities and individuals who have previously used the NDD, transitioning to IDDSI involves re-evaluating existing recipes and diets. The IDDSI framework provides clear testing methods to confirm the correct level for a specific food or drink. A healthcare provider, such as a dietitian or speech-language pathologist, can guide this process. For example, a food previously classified as NDD Level 2 (Mechanically Altered) might need recipe adjustments to meet the IDDSI Level 5 (Minced & Moist) requirements for lump size and moisture. The key is to test and confirm textures rather than simply renaming them.
Conclusion
While the National Dysphagia Diet was a significant step forward in managing swallowing disorders, its limitations regarding standardization and safety have led to its replacement by the IDDSI framework. Understanding the historical NDD levels is valuable for context, but relying on the modern, globally-adopted IDDSI guidelines is crucial for ensuring the safest and most effective care for individuals with dysphagia. By adhering to the standardized IDDSI levels and testing methods, clinicians and caregivers can greatly minimize the risk of choking and aspiration, ultimately improving a patient's quality of life.
References
- International Dysphagia Diet Standardisation Initiative (IDDSI). The IDDSI Framework. Available at: https://www.iddsi.org/standards/framework
- Drugs.com. Level 1 National Dysphagia Diet - What You Need to Know. Available at: https://www.drugs.com/cg/level-1-national-dysphagia-diet.html
- Drugs.com. Level 3 National Dysphagia Diet - What You Need to Know. Available at: https://www.drugs.com/cg/level-3-national-dysphagia-diet.html
