The Influence of Liquid Consistency and Food Texture on Swallowing: A Systematic Review Update

Diet texture modification is a common intervention for oropharyngeal dysphagia. In 2015, the International Dysphagia Diet Standardisation Initiative (IDDSI) published a systematic review summarizing evidence on how liquid consistency and food texture influence swallowing behavior. This updated review synthesizes new evidence published between 2012 and 2024 addressing how differences in liquid consistency or food texture affect swallowing in humans. A PROSPERO‑registered, PRISMA‑guided review was conducted using the Covidence platform. A multi‑engine search identified English, peer‑reviewed studies reporting comparable quantitative measures across two or more consistencies defined using IDDSI terminology. Screening and full‑text review were performed in duplicate. Articles were appraised using the FRONTIERS framework, and data synthesis focused on swallowing safety, efficiency, and other physiologic metrics. From 63,247 initial records, 24,196 abstracts were screened and 2,310 full texts reviewed, yielding 465 eligible studies. Of these, 70 studies (from 2017 onward) provided non‑overlapping data mapped to the IDDSI Framework. Sixty‑eight articles reported findings for drink levels 0-4 and 25 for food levels 5-7. Videofluoroscopy was the most common instrumental method used, followed by endoscopy and high‑resolution manometry; other physiologic measures were used less frequently. Across all 25 studies reporting safety outcomes, thicker liquids improved swallowing safety compared with thinner liquids. Among studies reporting efficiency, smaller bolus volumes helped limit residue with thickened liquids. Food textures seldom elicited penetration-aspiration but were associated with increased residue in patient populations. Overall, findings reinforce the need for individualized clinical decision‑making regarding texture modification, informed by careful assessment.