Is foie gras a health hazard?

Protests aside, there may be another reason to pass on the foie gras. Scientists report that these livers of overstuffed waterfowl contain abnormal proteins that, when fed to laboratory mice, caused them to quickly develop the protein clumps themselves.

Various human diseases - among them Alzheimer's, Parkinson's, and rheumatoid arthritis - are associated with these clumps, known as amyloids.

The new paper, published last week in the Proceedings of the National Academy of Sciences, provides no direct evidence that people are in danger. But the researchers do suggest that some people avoid indulging.

Foie gras is a traditional food in France and throughout Europe - where, interestingly, amyloidosis is more common than here - but arrived on the American culinary scene in the 1990s.

"It used to be just the French restaurants, but now every gastro-pub incorporates foie gras," says Terry McNally, co-owner of Philadelphia's London Grill.

So why is this heavy, fat-rich delicacy also rich in amyloids?

Put simply, force-feeding makes animals sick. To produce the succulent livers, tubes are inserted into the birds' throats and corn mush is pumped in, massively inflating the animals and making them tasty.

"The ducks and geese are certainly getting liver damage," says Alexander Whitehead, an amyloid researcher at the University of Pennsylvania who was not involved with the new study.

When animals are stressed for any number of reasons, their livers go into overdrive, making more of a specific type of protein that is linked to inflammatory rheumatoid arthritis. If the stress is prolonged, the excess protein may build up and bunch together as amyloids - first in the delicious fowl liver, then elsewhere.

Human livers, too, can be overwhelmed by amyloids in conjunction with chronic inflammatory disorders. Between 4 percent and 5 percent of people with rheumatoid arthritis, for example, come down with amyloidosis, a massive and sometimes fatal influx of amyloids into organs.

Each amyloid disease involves the clumping of a different protein. Alzheimer's amyloids don't match arthritis amyloids, for example. Before they form amyloids, however, these proteins are often part of a normal, healthy organism.

It is only when normal proteins encounter contagious abnormal proteins such as those now found in foie gras that things may go south.

"They get into vital tissues and compromise the function of that organ," says Alan Solomon, an internist at the University of Tennessee and the study's lead author.

In a telephone interview last week, Solomon said neither he nor his colleagues have any connection with animal rights groups. (And their research findings came from experiments on mice.)

Nevertheless, for animal rights groups already at odds with foie gras, the scientific evidence may sound too good to be true.

Activists believe force-feeding animals is cruel. In Chicago, restaurants can no longer serve foie gras. California has outlawed it, effective in 2012. Foie gras is banned in all of Israel. Philadelphia, too, is considering taking a stance on the issue. City Councilman Jack Kelly's bill prohibiting the sale of foie gras is currently in committee.

For the University of Tennessee study, 18 mice - all made to be susceptible to amyloidosis - were divided into two groups. Eight were fed foie gras; the other 10 ate a more plebeian diet.

All those given foie gras had developed amyloids within eight weeks. The others took more than twice as long, on average.

The amount of foie gras given to the mice would equal about 31/2 pounds over five days for humans, Solomon estimates. This may seem like a lot, especially considering that even in France the annual consumption is about half a pound.

Yet evidence suggests that it takes very little of the protein clumps to instigate amyloidosis - and that amyloids, rather than being digested, may just lurk about until there are enough to cause disease.

"This material can stay in the body indefinitely," Solomon says.

If the danger to humans turns out to be real, Penn's Whitehead admits thinking about "the delicious irony of those who live well doing themselves in with foie gras."

This story recalls the days when gout was known as the disease of kings. Gout is caused by a diet rich in meat, so only the wealthy and overindulgent were afflicted.

Today, "the new young professionals all eat foie gras," notes restaurateur McNally. "But then there's the wealth of Philadelphia; they eat it because they are used to eating at four-star restaurants."

In any case, the scientists wrote in their paper that "it would seem prudent for children and adults with rheumatoid arthritis or other diseases who are at risk . . . to avoid foods that may be contaminated by [amyloids]."

"It's one of these things where everything you eat or drink in France is either very good for you or very bad for you," said Whitehead. "But they live longer than Americans so they must be doing something right."

Perhaps red wine dissolves amyloids.