“Pine nut mouth” — a mildly allergic reaction to Asian pine nuts which, until recently, had not been widely available in the U.S. — appears to be a growing phenomenon, reports the Oakland Tribune. The main symptom: a strongly bitter and metallic taste on the tongue after eating food that lasts for several days. The cause: imported pine nuts from China sold at Trader Joe’s, Costco, and elsewhere. Trader’s hasn’t issued any warnings, but a European journal first reported the reaction back in 2001. [Oakland Tribune]