Why are ‘mixed consistency’ or ‘dual consistency’ or ‘two phase’ foods not recommended for people with dysphagia?
By definition, mixed or dual consistency foods include both solids and liquids. Some mixed or dual consistency foods are easily recognized on the plate or in a bowl (e.g. vegetables in a soup broth). Other items that appear to be a single consistency on a plate may quickly separate into two consistencies in the mouth (e.g., watermelon). As a general rule, ‘mixed’ or ‘dual consistency’ foods are more challenging to swallow, because a person must have adequate abilities to handle both the solid and the liquid component of these items, which requires more advanced oral control and swallowing coordination abilities. The risks associated with swallowing a mixed consistency item are as follows:
- The liquid component of the item may separate and spill into the pharynx during oral preparation of the bolus (Saitoh et al., 2007). This may represent an increased aspiration risk in people with dysphagia.
- Solid particles may be washed into the pharynx with the liquid component, before they have been adequately chewed. If these particles enter the airway, there is an increased risk of choking and airway obstruction.
In order to properly describe the texture or a mixed or dual consistency food, it is necessary to characterise both the liquid and the solid components of the food. The IDDSI testing methods can be used to do this by separating the components. For example, a soup containing soft, 1.2 cm sized cubes of carrot floating in a broth would be classified as 6-0 capturing the Level 6 – soft and bite-sized (food) and the Level 0 – thin (liquid).
Dual consistency foods in which the liquid component is thin (Level 0) and easily separates from the solid component are not appropriate for people who require thickened liquids.
If both the solid and liquid components of a dual consistency item fall within the range of diet textures that have been recommended for a patient, assessment is needed to determine whether the patient may be able to handle that item. For example, if a Level 4 pureed food item is served with a level 3 sauce, such as a creamy mashed potato with moderately thick gravy, then a patient whose diet texture prescription spans a range containing both levels 3 and 4 on the framework may be able to handle both components of this item. Clinical evaluation of a patient’s ability to handle specific mixed or dual consistency items should be performed before recommending that these items be included on a diet.
References: Saitoh E, Shibata S, Matsuo K, Baba M, Fujii W, Palmer JB. Chewing and food consistency: Effects on bolus transport and swallow initiation. Dysphagia. 2007;22: 100–7