Andrew Telzak got a great deal on pine nuts at an Asian market and whipped up a batch of pesto for friends. It tasted great. But for days afterward, nothing else did.
"I started getting this weird taste, kind of a metallic taste, in the back of my tongue," said Telzak, 23, a North Baltimore resident who works for the city health department. "Everything was tasting real bitter."
Some of his guests had the same experience. One of them Googled "everything tastes bitter" and came across "pine mouth," a mysterious taste dysfunction associated with pine nuts that can last for weeks.
On foodie Web sites and blogs, legions of self-diagnosed pine-mouth sufferers have concluded that Asian pine nuts, as opposed to more expensive European varieties, are to blame.
While one nut importer has dismissed the claims as "an Internet sensation," the Food and Drug Administration is investigating. One importer has dropped a particular type of Asian pine nut in response to concerns. And Costco, which sells Asian pine nuts, says it has taken the matter seriously enough to consult the FDA and university researchers.
"The universities we've asked have all kind of gone, 'Humph. We know it's there, and we don't know why, either,' '' said Craig Wilson, assistant vice president of food safety at Costco's Issaquah, Wash., headquarters. "The FDA's bewildered. They're as bewildered as anybody else."
The FDA has received about two dozen complaints about pine nuts in recent months, said Stephanie Kwisnek, an FDA press officer.
"Many of the complainants report an 'aftertaste' associated with the product but no illness," she said via e-mail. "The agency is looking into these complaints. Should the FDA find a public health hazard, then we will advise consumers accordingly."
The "nuts" at the center of this mystery are not technically nuts at all but the seeds of various pine trees. Used since ancient times in Mediterranean and Asian cuisines, pine nuts add creamy texture to classic pestos and crunch to high-end salads.
If pine nuts were a problem, why wouldn't the ancient Romans have yanked them from their honey-and-sheep's-milk tarts before the things caught on?
One possible explanation is that pine nuts aren't what they used to be. A generation ago in the United States, pine nuts were a relatively obscure ethnic-gourmet item imported from Spain and Portugal. Today, they appear on the shelves of ordinary supermarkets and on the menus of restaurants as unexotic as T.G.I. Friday's. The United States imports 25 million pounds of pine nuts a year, 90 percent of them from China.
There is no shortage of people claiming to have been afflicted by what Food and Wine recently described as "The Pine Nut Menace." The phenomenon has been noted in forums ranging from Epicurious and Chowhound to the European Journal of Emergency Medicine. Researchers at a Belgian poison center investigated seven cases but found no explanation, according to that journal article, titled "Taste disturbances after pine nut ingestion."
Accounts on Internet foodie sites tend to be as bitter as the reported aftertaste.
"Costco knows about this ... but they won't admit that to you," writes one Chowhound poster. "I have been in touch with Costco's liability law firm. ... I want them to either pull the product off the shelves or label it with a warning label. And we should be compensated for our suffering."
Wilson, the Costco food-safety official, said the company did not know what to make of the phenomenon but did not think it posed a health risk. Costco stores continue to sell the nuts.
"Everything's pretty benign at this point," Wilson said. "We've talked to a couple, or three, universities about it."
Asked which universities, Wilson then said Costco had, in fact, asked only one university to investigate: The University of California, Davis, Fruit and Nut Research and Information Center.
Officials at the center said they could not recall doing any pine nut research. Wilson said it took place six or seven years ago.
Andrew Rosen, an official with New Jersey-based Food Import Group, said he stopped bringing in one specific variety of Chinese pine nut three months ago because he suspected it was "the culprit." It was the Huashan pine nut, named for an area in Eastern China where the nut was either grown or processed. (In addition to its own nuts, China shells pine nuts grown in Korea, Mongolia and Russia, he said.)
Chinese pine nuts are smaller, shaped like corn kernels and more suitable for savory dishes than for desserts. The European type is sweeter, longer and tapered on both ends like a grain of rice. The prices are different too.
"Chinese you can get $6 or $7 a pound. Portuguese, $24," said Lucia Varella, office manager for Vaccaro's bakery in Baltimore, who was checking with brokers on the price of pine nuts last month. "Holiday season, I've paid all the way up to $28, and we go through between 60 to 100 cases just in November and December."
Even so, she said, Vaccaro's uses only the European nuts.
Some chefs have been forced to switch to the Chinese variety because the European ones have nearly doubled in price in recent months for reasons that are unclear even to importers. (Blame is placed alternately on the strength of the euro and on some sort of blight and deforestation of the wild pines from which the nuts are harvested.)
Asian pine nuts are hard for the home cook to avoid at any price. Many stores have quit stocking those grown in Spain and Portugal because they have become too expensive.