The popular delicacy foie gras (which is French for “fat liver”) is produced in a way that animal rights activists insist is barbaric. Ducks and geese are force-fed corn mash twice a day, through a tube that is inserted into the oesophagus. The birds are slaughtered 2-3 weeks later, and their engorged livers are then removed, to be sold whole or for use in making pâté, mousse or parfait.
But it seems that the birds may be the ones who have the last laugh – researchers from the University of Tennessee Graduate School of Medicine, in collaboration with a group from Uppsala University in Sweden, have found a potential link between foie gras consumption and the development of a number of amyloidogenic diseases. The findings are published online this week, in the Proceedings of the National Academy of Sciences.
The amyloidogenic diseases include Alzheimer’s Disease, variant Creutzfeldt-Jakob Disease (vCJD), tuberculosis, diabetes and rheumatoid arthritis. They are termed “amyloidogenic” because they all involve a process called amyloidosis, whereby genetic mutations lead to the synthesis of abnormally folded and insoluble proteins which accumulate within or around cells and interfere with their function. In all the amyloidogenic diseases, the mutated proteins are believed to accumulate by a process called nucleation (or “seeding”).
The researchers purchased fresh duck- and goose-derived foie gras from three different commercial retail outlets in the United States and France. Histochemical analyses involving staining the liver tissue with amyloid protein-specific antibodies indicated that amyloid proteins were present in all the samples. And electron microscopy revealed that the fibrils which are characteristic of amyloidogenic diseases were indeed present in all the foie gras samples tested.
Then, mice carrying a mutated version of a gene that made them predisposed to amyloidosis were injected with amyloid protein extracts from the foie gras, or were fed with the foie gras for 8 weeks. Afterwards, the animals were dissected and examined, and it was found that 62% of the mice had amyloid deposits in the heart, kidneys, liver, and intestines. The amyloid proteins in the fois gras had significantly hastened the process of amyloidosis in those animals injected with or fed the food. The amyloidogenic effect of the foie gras was reduced, but not competely abolished, by cooking the livers in the way recommended by the suppliers. By contrast, no amyloid deposits were found in control animals that were not fed the foie gras.
Thus, the consumption of foie gras is potentially hazardous to those who are genetically predisposed to (i.e. have a family history of) amyloidogenic disorders. Discounting the consumption of infected brain tissue (during, for example, the ritual of mortuary cannibalism), this is the first time that a dietary component has been implicated in the amyloidogenic diseases.
Solomon, A., et al. (2007). Amyloidogenic potential of foie gras. PNAS doi: 10.1073/pnas.0700848104. [Full text]