Dec 12, 2017
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Dysphagia Diets

The National Dysphagia Diet (NDD), was published in 2002 by the Academy of Nutrition and Dietetics, to establish standard terminology for dietary texture modification in dysphagia management.  It proposes the classification of foods according to eight textural properties, and anchor foods to represent points along continuum for each property (1). A hierarchy of diet levels is then proposed, with inclusion and exclusion of items at each level based on subjective comparison with these anchor foods. There are four levels of semisolid/solid foods were proposed in the NDD (1):

  • NDD Level 1: Dysphagia-Pureed (homogenous, very cohesive, pudding-like, requiring very little chewing ability).
  • NDD Level 2: Dysphagia-Mechanical Altered (cohesive, moist, semisolid foods, requiring some chewing).
  • NDD Level 3: Dysphagia-Advanced (soft foods that require more chewing ability).
  • Regular(all foods allowed). (1)

Four frequently used terms were chosen to label levels of liquid viscosity (i.e., thickness or resistance-to-flow) in the NDD; however, the NDD Task Force acknowledges that these ranges are “a commonsense approach” and “a catalyst for more research.”  The American Speech-Language-Hearing Association (ASHA) article suggests that customization of diet recommendations to meet patients’ individual needs will always be preferable to a formulaic approach using classification schemes such as those recommended in the NDD (1).

In 2013, the International Dysphagia Diet Standardization Initiative (IDDSI) was started with the goal of developing new global standardized terminology and definitions to describe texture modified foods and thickened liquids used for individuals with dysphagia of all ages, in all care settings, and all cultures (2).

The International Dysphagia Diet Standardization Committee has created a dysphagia diet framework consisting of a continuum of 8 levels (0-7). Levels are identified by numbers, text labels and color codes (2).

Accurate measurement of fluid flow properties is a complex task. To date, both research and existing national terminologies, have studied the classification of liquids based on viscosity.  However, viscosity measurement is not accessible to most clinicians or caregivers.  For these reasons, a measurement of viscosity has not been included in the IDDSI descriptors. Instead, a gravity flow test using a 10ml slip tip syringe has been chosen by IDDSI as a practical objective measure to classify drinks based on their rate of flow. The controlled conditions are broadly representative of drinking through a straw. (2)


0 – Thin– color: White

1 – Slightly Thick- color: Gray

2 – Mildly Thick- color: Purple

3- Liquefied/ Moderately thick- color: Yellow

4 – Pureed/ Extremely thick- color: Green

5 – Minced & Moist – color: Orange

6 – Soft – color: Blue

7 – Regular – color: Black


A category for transitional foods is provided, numbers 5-7.  It is not expected that all levels will be offered in every setting. For example, level 1 (slightly thick liquids) will have particular utility in pediatric settings (2, 3). Although this level may also prove suitable for other client groups, it may not be offered in all health-care facilities. The IDDSI framework and detailed description of the eight different levels can be viewed at (2, 3)




  1. McCullough, G. et al. National Dysphagia Diet: What to Swallow? The ASHA Leader, November 2003, Vol. 8, 16-27.
  2. International Dysphagia Diet Standardization Initiative. Accessed August 8, 2017.
  3. Marcason, W. What is the International Dysphagia Diet Standardization Initiative?  Journ Acad Nutr Diet. 2017; 117(4): 652.

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