Chewing and its influence on swallowing, gastrointestinal and nutrition-related factors: a systematic review

Abstract

The study aimed to evaluate the hypothesis that chewing is a mechanical and physiological contributor to swallowing, physiologic/pathologic processes of the gastrointestinal tract (GIT), and nutrition-related factors. A search strategy was applied to three different databases to investigate if chewing function in adults affects the swallowing, physiologic/pathologic processes of the GIT, and nutrition-related factors compared to controls with no exposure. The included studies were evaluated for methodological quality and risk of bias and certainty of evidence. The results showed 71 eligible studies. Overall, the results showed that 46 studies supported the hypothesis while 25 refuted it. However, the GRADE analysis showed low to very low certainty of the evidence to support the hypothesis that chewing is an important contributor in the swallowing process, and physiologic/pathologic processes in the GIT. The GRADE analysis also showed a moderate to very low certainty of the evidence to suggest that chewing function contributes to nutrition-related parameters. The overall results of the current study showed that a majority (64.7%) of the studies (46 out of 71) supported the hypothesis. However, robust studies with proper design, adequate sample size, and well-defined outcome parameters are needed to establish conclusive evidence.

Keywords:

• Chewing efficiency
• chewing performance
• gastrointestinal disorders
• oral rehabilitation
• sensorimotor
• videofluorography
• narrative synthesis

Acknowledgements

We would like to thank Emma-Lotta Säätelä, Susanne Gustafsson & Sabina Gillsund, from the Karolinska Institutet library for their effortless support in constructing the search strategies and implementing the literature search.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Data can be obtained from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by the research grant from VINNOVA Utmaningsdriven innovation, grants from Stockholm County Council and Karolinska Institutet (SOF: Styrgruppen för Odontologisk Forskning) and grant from the Swedish research council (Vetenskapsrådet, Klinisk behandlingsforskning 2020).