Effects of Thickening Agents on the Mucociliary Transport Function: Comparison by the Type of Thickening Agents and the Viscosity of Thickened Water.
Erika Matsumura, Kanji Nohara, Hikari Fukatsu and 3 others
PMID 38777870WHAT IT FOUND
Thickened water slows down the body's natural airway clearance mechanism.
Higher viscosity caused significantly longer delays in transporting fluid out of the airways compared to thin water. This suggests that while thickening prevents aspiration, it may make clearing aspirated fluid harder.
Key findings
01Saccharin transport time was significantly longer for all thickened water samples compared to unthickened water.
02Higher viscosity within the same thickening agent type resulted in significantly longer transport times.
03There was no significant difference in transport time between starch-based and xanthan-gum-based agents at the same viscosity levels.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study was conducted on healthy adults, not on the elderly or dysphagic population that typically uses thickened liquids. The test measured nasal mucociliary transport, assuming it reflects tracheal transport, rather than directly measuring airway clearance in the lungs. The sample size was small (23 participants). The study did not measure clinical outcomes like pneumonia incidence, only the physiological transport time.
Declared interests
The paper states it was supported by non-U.S. government research funding. No specific conflicts of interest with the thickening agent manufacturers (Hormel, Nestle) are declared in the provided text, though their products were used.
The easy way to misread this
Do not conclude that thickened liquids cause pneumonia in patients. This study only shows that thickened liquids clear from the airways more slowly in healthy adults. The clinical impact on actual pneumonia rates in dysphagic patients is not established by this paper.