GCN2 and FGF21 are Likely Mediators of the Protection from Cancer, Autoimmunity, Obesity, and Diabetes Afforded by Vegan Diets

Vegan diets of moderate protein content, when practiced throughout life, have been linked to a markedly decreased risk for many cancers, as well as for autoimmune disorders, obesity, and diabetes. Such diets also typically lower blood levels of the hormone IGF-I, elevated levels of which may increase cancer risk. This essay proposes that the relatively low essential amino acid content of moderate-protein vegan diets activates the enzyme GCN2, which in turn promotes increased production of the protective hormone FGF21 by the liver. This increase in FGF21 may be responsible for the reduction in IGF-I production observed in vegans, and may work in other ways to lessen risk for obesity and diabetes. Activation of GCN2 within the immune cells of vegans may play a role in their lesser risk for autoimmunity.

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