When we were down in Louisiana a month or so ago, we made a pesto sauce. Turns out I was the only one who ate it. Afterward, for several days I couldn’t eat anything without it tasting really metallic and unpleasant. It seemed to me that it had to do with the pesto, but I couldn’t really say why. The pesto tasted fine. It lasted for about a week, this effect. Very, very unpleasant. Nothing tasted right.
Well, Julie just handed me a newsletter from a Philly organic market in which the store explained why it switched to more expensive pine nuts: a condition known as “pine mouth,” which makes all foods taste bitter and metallic for people afflicted with it. The store says that lots of their customers complained about the effect, so they switched from Chinese-supplied pine nuts to pine nuts from other countries, and have had no problems.
Turns out this really is a thing. From a USA Today report on pine mouth:

First described by a Belgian poison-control doctor in 2001, the rare syndrome can linger for up to two weeks. A recent article about it in the Journal of Medical Toxicology found dozens of anecdotal reports online.
Marc-David Munk, a professor in the Department of Emergency Medicine at the University of New Mexico in Albuquerque, was struck with the syndrome himself and describes it in the Toxicology paper.
“It’s surprising to me that more people don’t know about it,” he says.
Although almost non-existent in the medical literature, the syndrome is certainly something people who have had it are aware of. In the past year, the Food and Drug Administration received 51 complaints of “taste disturbances” related to pine nuts. The agency hopes information from consumers and tests of pine nuts associated with this syndrome will help it determine what’s causing the problem, says spokesman Michael Herndon. Because it’s related only to taste, it’s not considered a public health problem, he says.

The mystery deepens. From a British newspaper account:

In reply to a group of pine mouth sufferers in Wales, the Food Standards Agency contacted doctors at the Brussels Poisons Centre, who have carried out tests on the pine nuts, but have been unable to identify any chemical differences between those that cause pine mouth and those that don’t.
The good news is that no pesticide or heavy metal contamination has been found in the pine nuts. The puzzling news is that while some people get pine mouth, others don’t, even though they’ve eaten the same batch of nuts.

Do you suppose this could be a Chinese pine nuts thing? I’m prepared to believe Chinese food products are tainted with anything. On the other hand, tests have shown no chemical difference in these nuts, and, as you’ve just read, some people get pine mouth from batches of nuts that affect others not at all.
All I know is that it was a very, very unpleasant thing, and I’m probably never going to eat pine nuts again, to avoid the risk. Bleah.