Rethinking the “Dysphagia Diet”

Traditionally, speech language pathologists and other healthcare providers have utilized “dysphagia diets” to compensate for impairments in swallow function. We reduce the texture of the food to compensate for difficulty with oral management and mastication, and we thicken liquids to compensate for delays in swallow response and airway closure.

Unfortunately, these modifications are often unpalatable, affecting our patients’ appetites and reducing their caloric and nutritional intake.^{1, 2}

Perhaps it’s time to rethink the idea of “dysphagia diets.”

Sensory Input Impacts Motor Output

We know that as the food and liquid pass from the oral cavity to the pharynx, all of the sensory information contained within that bolus is transmitted to the brainstem. That sensory input impacts the motor output of the swallow response.

The size, shape, viscosity, and temperature of the bolus have the potential to change the swallow response in any number of ways,^{3, 4} including:

• Onset of swallow response
• Duration and onset of laryngeal valve closure
• Duration of opening of the upper esophageal sphincter
• Pharyngeal transit times

Perhaps then, a true “dysphagia diet” is not one that compensates for impairments, but one that stimulates improvements in swallow function.

Impacts of Sensory Stimulation

Cold

Those among you who have been doing therapy for as long as I have may remember doing thermal stimulation with our clients! Cold was one of the first sensory interventions studied.

In the 1980s, Dr. Jeri Logemann suggested the use of thermal stimulation in the form of a cold laryngeal mirror to the faucal arches as a therapeutic strategy to improve swallow response.⁵ Research results were equivocal, and the focus turned to cold foods and liquids instead. As it turned out, cold does have the potential to improve swallow response, airway protection, and pharyngeal constriction.^{6, 7, 8}

Taste

So if cold can impact swallow function, what about other types of sensory input? Does flavor manipulation, for example, have an impact on swallow response?

Maybe.

Sour, in particular, does seem to have an impact on timing of swallow response.⁹ The problem is that in order to have a measurable impact on swallow function, the bolus has to be very sour—sour enough to be unpalatable. Dr. Cathy Pelletier and Dr. Harry Lawless looked at boluses that were a sweet/sour mix and found that while they were much more palatable to the test subjects, they did not have the same kind of impact on swallow response.¹⁰

Carbonation

And what about fizz? Does carbonation have any kind of effect on swallowing?

A number of studies—including a pediatric study¹¹—demonstrated an impact on various aspects of swallow function in response to carbonated boluses.^{12, 13, 8} In one interesting study, researchers found that the carbonated boluses had an impact on swallow function not only for those swallows, but also for the non-carbonated boluses that followed the carbonation trials.¹⁴ In another study, researchers demonstrated a cumulative benefit to sensory input.¹⁵ When the carbonation was combined with high flavor, the impact on the swallow response was greater than either the carbonation or the flavor stimulation alone.

What Does It All Mean?

So what does this mean for our patients with swallowing impairments?

1. It’s clear that sensory input does have the potential to impact the swallow response in positive ways; cold and carbonation appear to be particularly effective.
2. It’s possible that intermittent stimulation may be an effective tool. This could mitigate the impact of unpleasant stimuli like sour if your client didn’t have to drink the sour boluses for every swallow.
3. Mixed input may be an effective tool—what happens if we combine cold with carbonated? Or sour with cold? There seems to be a cumulative effect with sensory input, and we may need to experiment a bit to find the right combination of stimulants.

Perhaps it’s time to think about dysphagia diets as more than just compensatory, and explore ways in which we can use diet to enhance feeding and swallowing skills.

You can learn more about these interesting studies and how the information they provide is applicable to our practice in the MedBridge course, “Dysphagia and the Older Adult: The Aging Swallow.”