Most bakers, even those who would never go near an industrial mixing machine, include an additive called vital wheat gluten to strengthen the dough and to help the loaf rise. (In general, the higher the protein content of wheat, the more gluten it contains.)

Vital wheat gluten is a powdered, concentrated form of the gluten that is found naturally in all bread. It is made by washing wheat flour with water until the starches dissolve. Bakers add extra gluten to their dough to provide the strength and elasticity necessary for it to endure the often brutal process of commercial mixing. Vital wheat gluten increases shelf life and acts as a binder; because it’s so versatile, food companies have added it not only to bread but to pastas, snacks, cereals, and crackers, and as a thickener in hundreds of foods and even in some cosmetics. Chemically, vital wheat gluten is identical to regular gluten, and no more likely to cause harm. But the fact that it is added to the protein already in the flour worries Jones.

http://www.newyorker.com/magazine/2014/11/03/grain