Risks of eating pine nuts
A small minority of pine nuts cultivated in China can cause taste disturbances, lasting between few days to maximal a week after consumption. A bitter, metallic taste is described. Though unpleasant, there are no lasting effects. This phenomenon was first described in a scientific paper in 2001[11]. Some publications have made reference to this phenomenon as "pine mouth"[12]. The Nestle Research Centre has hypothesized that a particular species of Chinese pine nuts, Pinus armandii, is the cause of the problem. The suspect species of pine nuts are smaller, duller, and more rounded than typical pine nuts[13]. This finding has recently been confirmed[14]. In 1998 the FAO published a list of edible tree nuts, containing 29 species of pine nuts that are regullarly consumed somewhere in the world[15] and the aforementioned Chinese pine species were not included. Metallic taste disturbance, known as metallogeusia, is typically reported 1–3 days after ingestion, being worse on day 2 and lasting typically up to 2 weeks. Cases are self-limited and resolve without treatment[16] Möller[17] has postulated an hypothesis that could explain why the bitter taste appears several days after ingestion and lasts for as long. A well known physiological process known as enterohepatic recirculation (EHR) could play a key role in the development of PNS.
