咀嚼

咀嚼是一部分有頜動物在進食過程中反覆開合頜骨並用牙齒重複碾壓研磨吞入的食物的行為，是消化過程的第一部分。咀嚼產生物理粉碎的效果，可以增加食物的比表面積使其更容易被消化液中的酶分解掉，改善整體的消化效率。

在咀嚼過程中，食物會由舌頭和臉頰的肌肉推送到上下頜的牙齒之間，然後由咀嚼肌施力將頜骨緊密咬合並且伴有些許的側向運動來剪切食物。在咀嚼的同時，由唾腺分泌的唾液會混入食物碎塊之中，唾液中所含的澱粉酶和脂酶也會開始初步的消化過程。被咀嚼的食物也會逐步軟化，使其更容易在吞咽時滑過咽喉進入食道並通過蠕動成功進入胃臟開始進一步的消化過程^[1]，從而降低噎阻的風險^[2]。增加咀嚼頻率還會刺激腸道激素的分泌，改善整體的消化質量^[3]。

一些人類的父母還會將食物咀嚼後吐出並餵給尚無咀嚼能力（通常是因為沒長好牙齒）的嬰兒，以便其能夠儘早斷奶並適應固態食物^[4]。這種行為稱作「替嚼」（premastication）。

演化

咀嚼主要是哺乳動物為了適應食植並消化較難水解的纖維素而演化出的功能，而臼齒則是專門用於咀嚼的牙齒。一些偶蹄目動物（比如牛、羊和駱駝）甚至會將之前已經吞咽入胃的食物反向推回口中（反芻）進行再次咀嚼，來進一步瓦解纖維素並改善營養的吸收程度，通常更多在晚間進行^[5]。食肉動物則通常很少咀嚼，而是用門齒和犬齒撕啃下大塊食物後強行咽下^[6]。

一些非哺乳類的動物也會趨同演化出咀嚼能力，比如許多硬骨魚類都長有咽頭齒來幫助咀嚼吞入的食物。鳥腳亞目恐龍（包括著名的鴨嘴龍）就在白堊紀時期發展出了與哺乳動物臼齒和門齒相似的牙齒來消化更加堅韌的植物，使其可以和必須依賴超長的消化道和胃石才能消化纖維素的蜥腳恐龍競爭生態位^[7]，它們在白堊紀-古近紀滅絕事件之前是最為成功的恐龍之一。

營養和健康

咀嚼可以刺激唾液分泌並增強對食物的主觀感受^[8]。有研究表明咀嚼可以減少飢餓感和食物的攝入量^[3]^[9]。經常食用不需要咀嚼就可攝入的食物（比如流食和高度加工的食品）可能會因為來自新鮮蔬菜和水果的纖維攝入量不足而造成營養不平衡^[10]。

咀嚼還可以刺激海馬體並維持其正常功能^[11]。

另見

參考

^ Prehension, Mastication and Swallowing. [2022-06-27]. （原始內容存檔於2015-07-15）.
^ How Many Times Should You Chew Your Food?. Healthline. 2018-10-17 [2022-02-11]. （原始內容存檔於2022-08-09）（英語）.
^ ^3.0 ^3.1 Miquel-Kergoat, Sophie; Azais-Braesco, Veronique; Burton-Freeman, Britt; Hetherington, Marion M. Effects of chewing on appetite, food intake and gut hormones: A systematic review and meta-analysis. Physiology & Behavior. 2015-11-01, 151: 88–96. ISSN 1873-507X. PMID 26188140. doi:10.1016/j.physbeh.2015.07.017  .
^ Holmes, Wendy, Influences on maternal and child nutrition in the highlands of the northern Lao PDR, Asia Pac J Clin Nutr, 2007, 16 (3): 537–545, PMID 17704036
^ Zebeli, Q.; Tafaj, M.; Weber, I.; Dijkstra, J.; Steingass, H.; Drochner, W. Effects of Varying Dietary Forage Particle Size in Two Concentrate Levels on Chewing Activity, Ruminal Mat Characteristics, and Passage in Dairy Cows. Journal of Dairy Science. April 2007, 90 (4): 1929–1942. PMID 17369233. doi:10.3168/jds.2006-354  （英語）.
^ Hiiemae, K.M.; Crompton, A.W. Mastication, Food Transport, and Swallowing. Functional Vertebrate Morphology. 1985. doi:10.4159/harvard.9780674184404.c14.
^ Sanders, P. Martin; Clauss, Marcus. Sauropod Gigantism. Science. 10 October 2008, 322 (5899): 200–201. PMID 18845734. S2CID 206514245. doi:10.1126/science.1160904.
^ Peyron, Marie-Agnès; Gierczynski, Isabelle; Hartmann, Christoph; Loret, Chrystel; Dardevet, Dominique; Martin, Nathalie; Woda, Alain. Role of Physical Bolus Properties as Sensory Inputs in the Trigger of Swallowing. PLOS ONE. 27 June 2011, 6 (6): e21167. Bibcode:2011PLoSO...621167P. ISSN 1932-6203. PMC 3124480  . PMID 21738616. doi:10.1371/journal.pone.0021167  .
^ Cassady, Bridget A; Hollis, James H; Fulford, Angie D; Considine, Robert V; Mattes, Richard D. Mastication of almonds: effects of lipid bioaccessibility, appetite, and hormone response. The American Journal of Clinical Nutrition. 2009-03-01, 89 (3): 794–800. ISSN 0002-9165. PMID 19144727. doi:10.3945/ajcn.2008.26669  （英語）.
^ N'Gom, Papa Ibrahima; Woda, Alain. Influence of impaired mastication on nutrition. The Journal of Prosthetic Dentistry. June 2002, 87 (6): 667–673. PMID 12131890. doi:10.1067/mpr.2002.123229.
^ Chen, Huayue; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-Ya. Chewing Maintains Hippocampus-Dependent Cognitive Function. International Journal of Medical Sciences. 9 June 2015, 12 (6): 502–509. ISSN 1449-1907. PMC 4466515  . PMID 26078711. doi:10.7150/ijms.11911.

外部連結

MeSH A02.633.567.600

[1] Prehension, Mastication and Swallowing. [2022-06-27]. （原始內容存檔於2015-07-15）.

[2] How Many Times Should You Chew Your Food?. Healthline. 2018-10-17 [2022-02-11]. （原始內容存檔於2022-08-09）（英語）.

[:0-3] 3.0 ^3.1 Miquel-Kergoat, Sophie; Azais-Braesco, Veronique; Burton-Freeman, Britt; Hetherington, Marion M. Effects of chewing on appetite, food intake and gut hormones: A systematic review and meta-analysis. Physiology & Behavior. 2015-11-01, 151: 88–96. ISSN 1873-507X. PMID 26188140. doi:10.1016/j.physbeh.2015.07.017  .

[HolmesEA-4] Holmes, Wendy, Influences on maternal and child nutrition in the highlands of the northern Lao PDR, Asia Pac J Clin Nutr, 2007, 16 (3): 537–545, PMID 17704036

[5] Zebeli, Q.; Tafaj, M.; Weber, I.; Dijkstra, J.; Steingass, H.; Drochner, W. Effects of Varying Dietary Forage Particle Size in Two Concentrate Levels on Chewing Activity, Ruminal Mat Characteristics, and Passage in Dairy Cows. Journal of Dairy Science. April 2007, 90 (4): 1929–1942. PMID 17369233. doi:10.3168/jds.2006-354  （英語）.

[6] Hiiemae, K.M.; Crompton, A.W. Mastication, Food Transport, and Swallowing. Functional Vertebrate Morphology. 1985. doi:10.4159/harvard.9780674184404.c14.

[7] Sanders, P. Martin; Clauss, Marcus. Sauropod Gigantism. Science. 10 October 2008, 322 (5899): 200–201. PMID 18845734. S2CID 206514245. doi:10.1126/science.1160904.

[8] Peyron, Marie-Agnès; Gierczynski, Isabelle; Hartmann, Christoph; Loret, Chrystel; Dardevet, Dominique; Martin, Nathalie; Woda, Alain. Role of Physical Bolus Properties as Sensory Inputs in the Trigger of Swallowing. PLOS ONE. 27 June 2011, 6 (6): e21167. Bibcode:2011PLoSO...621167P. ISSN 1932-6203. PMC 3124480  . PMID 21738616. doi:10.1371/journal.pone.0021167  .

[9] Cassady, Bridget A; Hollis, James H; Fulford, Angie D; Considine, Robert V; Mattes, Richard D. Mastication of almonds: effects of lipid bioaccessibility, appetite, and hormone response. The American Journal of Clinical Nutrition. 2009-03-01, 89 (3): 794–800. ISSN 0002-9165. PMID 19144727. doi:10.3945/ajcn.2008.26669  （英語）.

[10] N'Gom, Papa Ibrahima; Woda, Alain. Influence of impaired mastication on nutrition. The Journal of Prosthetic Dentistry. June 2002, 87 (6): 667–673. PMID 12131890. doi:10.1067/mpr.2002.123229.

[11] Chen, Huayue; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-Ya. Chewing Maintains Hippocampus-Dependent Cognitive Function. International Journal of Medical Sciences. 9 June 2015, 12 (6): 502–509. ISSN 1449-1907. PMC 4466515  . PMID 26078711. doi:10.7150/ijms.11911.

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