Comments on "A comparison of different physical stomach models and an analysis of shear stresses and strains in these system" by Zhong and Langrish (2020).

Understanding of the fate of foods or specific nutrient(s) during digestion within the different compartments of the gastrointestinal (GI) tract is important for making healthier food products and formulate appropriate dietary advice. In vitro GI models have been extensively employed for digestion-related studies in recent years because they can overcome many of the difficulties associated with human or animal studies as the latter are not always technically, financially and ethically feasible. The origins, mechanisms, advantages/disadvantages and applications of typical in vitro physical stomach models have been summarized and compared in many review papers. These will contribute to the design and construction of more advanced and physiologically-relevant in vitro GI models. The letter to the editor comments on a recently published review paper aiming to clarify some inaccurate descriptions of the rat and human stomach systems in terms of the mechanisms of gastric peristalsis and the materials of construction for the stomach models.