Q: When I eat pine nuts, I get a terrible bitter taste in my mouth that lasts for days. Why does this happen?
A: You’re not alone—there’s even a support group for sufferers of “pine mouth” on Facebook. But the cause and specifics of this odd condition (a type of dysgeusia, medically speaking) remain somewhat of a mystery.
First reported in Belgium in 2000 and in more than 20 countries since then, the reaction occurs in some people 12 to 48 hours after they eat pine nuts, and it can last anywhere from a few days to a week or two, or longer. Worse yet, the metallic taste intensifies when you eat other foods during that time, taking a toll on appetite. Pine nuts are often eaten raw (as in salads or hummus, for example), ground (as in pesto), or roasted.
The good news, the FDA assures, is that pine mouth is not a food allergy and, though very unpleasant, has no health consequences.
It’s unclear what causes the reaction—whether it’s from a specific species of pine nut (in the U.S., pine nuts are mostly sold as mixtures of different types, so this has been hard to tease out), the oils in them going rancid, or some contaminant. Some people may have a genetic susceptibility that makes them more sensitive to such bitter tastes. A particular type of pine nut from China (or the chemicals used during the shelling process) has been suspected, but this has not been confirmed.
For the past several years, the FDA has been gathering information to better understand why pine mouth happens and who is affected. Anyone who experiences it is encouraged to contact the FDA. Click here for a listing of state FDA offices.
Also see Take the Taste Test.