The invention relates to chewable gum base compositions, to chewing gums containing them, and to processes for preparing them. The gum base compositions comprise (a) a polyvinyl acetate matrix, in which the polyvinyl acetate is in the form of a continuous phase, and (b) casein, a modified casein, or both casein and a modified casein, wherein particles of casein and/or modified casein are dispersed throughout the polyvinyl acetate matrix.In preferred embodiments the gum base compositions also contain polyglycerol polyricinoleate, mono- and di-glycerides esterified with mono-acetyl and di-acetyl tartaric acid, acetylated monoglycerides, lecithin and sodium or calcium stearoyl-2-lactylate. Chewing gums of the present invention contain a chewable gum base as described above, in combination with one or more sweeteners and/or flavouring agents, and preferably also glycerol triacetate and stearic acid.