Meat extenders are non-meat substances with substantial protein content.
[1] Extenders are distinguished from fillers by their high protein content, compared to the high carbohydrate content of fillers.
Extenders were originally used to reduce costs, but they were later used to make meat products more healthy by adding plant protein, dietary fiber, or to improve the texture.
[3] By the 1970s, soy protein was commonly used as a meat extender.
[4] Textured vegetable protein, which was invented in the 1960s,[5] has become a common extender in the 1990s.