Unlock the Secrets of Texture Modified Diets: Essential Guidelines You Need to Know!

As we age or face health challenges, the ability to chew and swallow regular food can diminish, leading to the need for texture-modified diets. These diets are not merely about sustenance; they are about maintaining dignity, pleasure, and overall well-being. Texture modification involves altering the viscosity of liquids and/or softening, chopping, or pureeing solid foods, often guided by standardized guidelines such as those developed by the International Dysphagia Diet Standardisation Initiative (IDDSI).

The Importance of Texture-Modified Diets

Texture-modified diets play a crucial role in:

Safety: Swallowing difficulties (dysphagia) can lead to choking, aspiration (food or liquid entering the lungs), and malnutrition.
Nutrition: Maintaining proper nutrition is essential for overall health, especially for individuals with dysphagia who may have difficulty consuming adequate nutrients from a regular diet.
Quality of Life: Enjoying meals is a fundamental part of our lives. Texture-modified diets allow individuals with swallowing difficulties to continue to experience the pleasure of eating.

Understanding Dysphagia

Dysphagia refers to difficulty in swallowing, or sometimes the impossibility of swallowing liquid or semisolid/solid food. This condition affects almost 580 million people worldwide, especially infants and the elderly, and it leads to nutritional deficiencies. As populations in many developed countries age, the number of dysphagic patients is likely to rise. Approximately 2 billion people will be aged 60 and over by 2050, in many countries, (e.g., Japan, Germany and Korea); around 15% of their populations will be over 80 years old. The older population is the global population’s fastest growing segment. Average life expectancy at birth is expected to rise from the present 70 years to 77 years by 2045, with more than 400 million individuals older than 80 years by 2050. Hence, urgent attention must be paid to the food and nutrition requirements of the elderly, particularly those who are very old and frail. This creates an excellent opportunity for food scientists to respond by formulating food products that meet this demand.

Conservative estimates suggest that dysphagia (difficulty swallowing) affects approximately 8 % of the world’s population. Dysphagia is associated with malnutrition, dehydration, chest infection and potentially death. While promising treatments are being developed to improve function, the modification of food texture and liquid thickness has become a cornerstone of dysphagia management. Foods are chopped, mashed or puréed to compensate for chewing difficulties or fatigue, improve swallowing safety and avoid asphyxiation. Liquids are typically thickened to slow their speed of transit through the oral and pharyngeal phases of swallowing, to avoid aspiration of material into the airway and improve transit to the esophagus.

At its broadest, dysphagia can be described as difficulty moving food, liquid, saliva or medication from the mouth to the stomach. Over the last 30 years, as the field of dysphagia research has grown, more technical definitions delineating the difference between oropharyngeal and esophageal dysphagia have emerged [1]. Oropharyngeal dysphagia is specifically classified by the World Health Organization in the International Statistical Classification of Diseases and Related Health Problems ICD-9 and ICD-10 (787.2, R13). The consequences of oropharyngeal dysphagia include dehydration, malnutrition, aspiration and asphyxiation and a negative impact on quality of life and social participation in eating and drinking. According to the Population Reference Bureau this amounts to a sobering 99 million individuals from the developed world. Although dysphagia touches individuals across their life span, it is most insidious at either end of life, with infants and the elderly being frequently affected. Although sufferers are sometimes unaware of the disorder, oropharyngeal dysphagia is a highly prevalent clinical condition as it affects more than 30 % of patients with stroke [2], 60-80 % of patients with neurodegenerative diseases [3], 10-30 % of adults aged 65 and older [4] and more than 51 % of institutionalized elderly patients [5]. Treatment to rehabilitate swallowing function and compensation to ‘work around’ swallowing difficulties are common pathways for managing dysphagia.

The Role of Speech-Language Pathologists (SLPs)

While there is no specific policy or guidance from the American Speech-Language-Hearing Association (ASHA) mandating the use of texture-modified diets, SLPs play a critical role in dysphagia management. They are encouraged to explore current evidence and consider patients holistically when developing individualized plans of care that meet their specific needs.

SLPs are responsible for:

Assessing a person’s ability to safely manage food textures and recommending an optimal diet.
Ensuring that diet orders are correct.
Clarifying regulations/protocols for how any nutritional restrictions and other components that fall outside the speech-language pathology scope of practice will be carried over when changing diet textures/liquid consistencies.

International Dysphagia Diet Standardisation Initiative (IDDSI)

The IDDSI is an international collaboration that developed a standardized framework for labeling texture-modified foods and thickened liquids. ASHA supports the IDDSI framework and encourages its members who assess and treat individuals with dysphagia to consider using it. The IDDSI framework consists of a continuum of 8 levels (0 - 7), where drinks are measured from Levels 0 - 4, while foods are measured from Levels 3 - 7. The IDDSI Framework provides a common terminology to describe food textures and drink thickness.

Two primary reasons for pursuing international standardized terminology are: (1) improved patient safety and (2) evolution of the field of dysphagia to deliver better treatment outcomes. With regard to patient safety, texture-modified foods are generally provided to reduce risks associated with choking, while thickened liquids are provided to reduce risks associated with aspiration.

IDDSI Pureed (Level 4) in Detail

IDDSI Pureed (Level 4) is represented by the number 4 and the color green. As with all other IDDSI food levels, it is shown within the downwards pointing triangle, while all IDDSI drink levels are represented with an upwards pointing triangle. The abbreviation for IDDSI Pureed (Level 4) is PU4.

Individuals who are served IDDSI Pureed (Level 4) have a serious swallowing disorder called dysphagia. This means they cannot safely chew or swallow, so the food we serve must be smooth, moist, and prepared ready to swallow to minimize their risk of choking. Individuals with dysphagia who need IDDSI Pureed (Level 4) have the following problems and/or limitations:

Reduced tongue control
Pain or difficulty swallowing
Does not chew well
Cannot form a bolus
Missing teeth, dentures not fitted

For these reasons, individuals with dysphagia on IDDSI Pureed (Level 4) require smooth, moist, pureed foods in which only the tongue is needed to move food back and forth for swallowing.

Characteristics of IDDSI Pureed (Level 4)

Foods on IDDSI Pureed (Level 4) will maintain the same characteristics no matter where in the world you serve pureed foods. The characteristics include:

Smooth, no lumps, or thin separate liquid
Food holds shape as a mound above the fork.
A small amount may flow through and form a short tail below the tines of the fork but it does not flow or drip continuously through the tines.
Food is cohesive enough to hold shape on the spoon.
It can slide off easily when you tilt or gently flick the spoon over a plate with very little food left on the spoon.

Testing Methods for IDDSI Pureed (Level 4)

Foods must pass the following IDDSI tests:

Appearance: Smooth, no lumps, or thin separate liquid
Fork Drip Test: Food holds shape as a mound above the fork. A small amount may flow through and form a short tail below the tines of the fork but it does not flow or drip continuously through the tines.
Spoon Tilt Test: Food is cohesive enough to hold shape on the spoon. It can slide off easily when you tilt or gently flick the spoon over a plate with very little food left on the spoon.

Testing is done during preparation and again at the time of service. It should be done under the same conditions we intend to serve our food -- including consistent temperature. Remember, temperature and holding time will affect the consistency of food.

It is important to note that on the IDDSI.org Audit Tool for Pureed, Level 4 it states: “A puree needs to be able to be put in the mouth and swallowed whole. No chewing and no bolus formation skills should be needed to eat this consistency.” And: “If the sample is gelled or compressed so that it is firm enough to pick it up with your fingers and bite a piece of it at serving temperature, the sample is not a puree and poses a choking risk.” So be careful to not over thicken or over gel foods.

Facility-Established Protocols

Many facilities utilize their own dysphagia diet levels. However, the challenge with these individualized systems is the limited ability to communicate and coordinate across health care facilities/settings and inconsistency with product labeling of commercially available dysphagia products. Research has indicated that there is considerable variation in terminology with 27 different labels being used to refer to ≤5 levels of drink thickness and 54 labels used to refer to ≤5 levels of texture-modified foods (Cichero et al., 2016).

State Laws and Facility Regulations

State laws and facility regulations impact permissions for writing orders and entering orders in documentation systems. Therefore, ASHA does not have a policy that specifically addresses writing or modifying diet orders. Clinicians should adhere to specific state and facility guidance.

Addressing Nutritional Needs

Modifying food texture and liquid thickness, without compromising nutritional quality, will play a key role in dysphagia management to ensure that patients can meet their nutritional requirements. Dysphagic patients need nutritious foods; such foods need to be of the right texture to improve their consumption and deliver the required nutrients.

Texture and Rheology Assessment in the Food Industry

Food texture is a major food quality parameter. The physicochemical properties of food changes when processed in households or industries, resulting in modified textures. A better understanding of these properties is important for the sensory and textural characteristics of foods that target consumers of all ages, from children to the elderly, especially when food product development is considered for dysphagia. Dysphagia management should ensure that texture-modified (TM) food is nutritious and easy to swallow.

Food colloids are multi-component, multi-phase systems, involving a complex mixture of water, proteins, polysaccharides, lipids, and many minor constituents that contribute to food textures [1]. While eating and swallowing food, sensory tasks require the tongue’s motor behavior to explore, squeeze, or move a bolus to ascertain its flow properties [2].

Texture is a sensory multiparameter attribute. It includes all the attributes of the rheological and structural properties of a food product, perceptible by mechanical, visual, auditory and tactile preceptors [14,15]. The roots of the multiparameter attributes of texture lies in its molecular, microscopic, or macroscopic structure. Moreover, certain texture aspects can be seen by the naked eye (e.g., coarse or fine cake texture) or heard by ears (e.g., sounds made when biting on a crunchy celery stalk or a crisp piece of toast) [16].

The International Organization of Standardization (ISO) recognizes texture as both a sensory quality attribute and a multiparameter attribute. Texture and rheology are important parameters that need to be assessed when developing food products. One of the physical properties in food technological and sensory analyses that agrees with the ISO definition related to food texture is given by Szczesniak [25] as: “the sensory and functional manifestation of the structural, mechanical and surface properties of foods detected through the senses of vision, hearing, touch and kinesthetics”. Texture is one of the key food attributes that is used to define product quality and acceptability [26], and even shelf life. This characteristic is present in all food, can affect its handling and processing, and can even be decisive for both shelf life and consumer acceptance. It will depend on the analyzed food type. Thus raw material food, handling and processing conditions, such as storage temperature, can have a significant influence on, for example, meat textural properties [27]. To understand this physical food property, we should understand the role of rheology in food. It was defined by Steffe [28] as “a branch of physics that studies the deformation and flow of matter”. This means that it is the condition under which materials respond to an applied force or deformation, despite the fact that many authors relate rheology to liquid or semiliquid food sensory properties rather than to solids. All materials have rheological properties that can be employed to assess raw materials and process characteristics, as well as their behavior and stability, throughout storage time until they are eaten to determine their customer acceptance [30]. Food rheology has been defined as “the science of the deformation and flow of matter” [31].

Hydrocolloids as Texture Modifiers

In cases where swallowing food is difficult, hydrocolloids, which exhibit many functionalities in foods, including thickening, gelling, water-holding, dispersing, stabilizing, film-forming, and foaming agents are useful [29]. They have been used as a texture modifiers in almost all kinds of processed food products [29].

Texture Profile Analysis (TPA)

A widely used imitative test today in the food technology field is the so-called Texture Profile Analysis (TPA). The TPA is not only widespread, but also convenient for rapid food texture evaluations [33], although texture can be measured by expert people with sensorial analyses. This test involves double compression to determine food textural properties. Any food texture identity is rarely a simple matter of understanding a singular characteristic, such as toughness or cohesion. The texture of each food is versatile and related to consumers’ sensory expectations.

Viscosity

Viscosity is a fundamental property that is obtained from rheological measurements, and is used as the most important criterion in developing thickeners for dysphagia patients. The American Dietetic Association reached an agreement, which was published in the National Dysphagia Diet T [36], and categorizes foods according to their viscosity (at 50 s−1) shear rate range values. The categories are: (1) nectar-like (51-350 cP); (2) honey-like (351-1750 cP); (3) spoon thick (>1750 cP)) to ensure safe swallowing and to facilitate palliative care procedures for different types of patient needs, although the categorization does not consider very relevant sensory aspects. Although viscosity values are obtained at 50 s−1, no consensus has been reached by the scientific community about the shear rate value of the swallowing process [36]. ISO 11036:2020 [38] sensory profiling methods can be used for these attributes. This ISO document specifies a method for developing a texture profile of food products (solids, semisolids, liquids). This method is one approach to the sensory texture profile analysis. Chemical composition determines the basic physical structure of foods which, in turn, influences texture.

Ingredients and Processing Methods Impact on Food Texture

Food processing industries are adopting various treatments-including thermal and non-thermal treatments-to modify texture. Future trends will likely include a combination of three-dimensional (3D) printing and drying to design foods, and to enhance textural and sensory characteristics for dysphagic patients [24]. A good starting point to develop these new food products is to gain a better understanding on sensory and rheological characteristics (see Table 1), which will be useful for modifying food texture.

Considerations for Infants and Children

Texture modification for infants is a normal response to the gradual development of their chewing skills. In western cultures, infants typically progress from foods requiring no chewing (purée), through foods with soft lumps, to mashed, chopped and soft food textures. There is limited literature available regarding the pediatric dysphagia diet, and any literature-based guidance for this population is drawn from information on normal feeding development. Carruth and Skinner [17] published milestones for infant feeding development. For example: eats food with tiny lumps (mean 8.7 months); chews soft foods (9.4 months); chews firm foods (10.5 months); chews and swallows firm foods without choking (mean 12.1 months); and chews foods that produce juice (15.2 months). The ability to tolerate unmodified foods depends on the infant’s oral experiences and the ability of the lips, tongue and jaw to work as independent and co-dependent units. The ability to chew foods with firmness, hardness and different textures is also affected by the pattern of normal dental eruption in the first 2 years of life [17]. Children do not gain their second molars until they are 20-24 months of age, and they are thus not well equipped for grinding of food particles until that time [18]. Children typically achieve an adult pattern of muscle activation for the oral and pharyngeal stages of swallowing after 4 years of age [19, 20]. Factors associated with risk of asphyxiation of food items in infants and children include: (1) inadequate dentition, (2) difficult food textures, (3) concurrent neuromuscular disease (e.g.

The Choking Risk

Choking refers to an inability to breathe because the airway is blocked, constricted or swollen shut. Asphyxiation refers to inadequate delivery, uptake or utilization of oxygen by the body’s cells, and it is often accompanied by carbon dioxide retention. When a bolus becomes lodged in the larynx or pharynx such that the airway is compromised, choking or asphyxiation may occur. Both terms are used in the literature to capture this phenomenon. The risk of death from asphyxiation in the general population has been reported as 0.66 fatalities per 100,000 people [7]. The risk of asphyxiation increases with cognitive impairment, oral stage swallowing impairment and intellectual disability [7]. Information pertaining to choking hazards for adult and pediatric populations has been gathered from research relating to autopsy results and asphyxiation studies [7]. Mature individuals with partial or missing dentition are reported to be more prone to asphyxiation from food [8]. In one sample of 120 adults, autopsy reports of asphyxiated foods included: meat, pastries, bread, fruit, vegetables, egg and cheese. Hard-textured and fibrous foods require sufficient chewing strength and stamina to ensure the food is broken down sufficiently to avoid being a choking risk. Individuals with swallowing difficulties have been shown to have significantly reduced bite force when compared with those without dysphagia [9]. Reduced bite strength may be a function of aging associated with weakened musculature or the result of deterioration in health. Bite force is also associated with the number of remaining teeth, with a correlation between increasing prevalence of dysphagia apparent in those with fewer than 13 remaining teeth. It is also important to appreciate that bite strength varies as a function of gender and ethnicity. For example, males generally have a higher bite force that females, and ethnic Eskimos have a higher bite force than white Americans [10]. In addition, there is evidence of wide inter-individual variation (110-370 N force), helping to explain why consumers may perceive the same food differently [10]. In a retrospective study of 44 autopsy files for food asphyxia, 61 % of the deceased were described as edentulous or having a significant number of missing teeth [11]. Individuals who wear dentures have a different oral experience than those with teeth. Intact teeth are sensitive to vibration, in addition to force and pressure [10]. This tactile sensation allows us to appreciate crisp and crunchy food. However, a loss in this specific tactile sensation impacts on the perception of the force, and pressure required for chewing. Such is the case for individuals who wear dentures. In a small study (n = 15) that looked at the impact of dentures on chewing, swallowing and choking, Berretin-Felix et al. [12•] found that more than 80 % had chewing difficulties and 40 % reported swallowing difficulties. Of interest, 33 % reported difficulty with ingesting liquids, 13 % reported coughing and 46 % reported choking. The participants were then fitted with five dental implants in the mandibular arch, with their dentures converted to an implant-supported prosthesis. The dental implants integrate with the bone in the lower jaw to provide permanent fixation and stability. The participants were tracked at 3, 6 and 18 months post-implant surgery. From 3 months post-surgery statistically significant declines in reported rates of masticatory difficulties, swallowing difficulties, difficulty ingesting liquids, choking and coughing were recorded.

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