The Pine Mouth (Pine Nut Syndrome) Project:

[Pine_Nut]

In March 2011, the FDA published an advisory titled “Pine Mouth” and Consumption of Pine Nuts.  The report states:

In the past year FDA has received a number of consumer complaints regarding a bitter metallic taste associated with pine nuts. This taste, known as "pine mouth," typically begins 12 to 48 hours after consuming pine nuts, and lasts on average between a few days and two weeks. It is exacerbated by consumption of any other food during this period and significantly decreases appetite and enjoyment of food. The symptoms decrease over time with no apparent adverse clinical side effects.
    
Currently, there are no definitive studies which identify a root cause for this adverse food reaction.
I can attest to the unpleasant nature of Pine Mouth as I experienced it several years ago.  Whether or not I (or others) have a genetic predisposition (i.e. allergy) to pine nuts which results in Pine Mouth remains to be determined.  Additionally, whether or not contaminants (i.e. mold, chemicals, etc.) or a pine nut species plays a role in Pine Mouth continues to remain unresolved.
          
For the sake of public health and science, I have decided to act as a guinea pig in order to shed some light on these questions.  I propose the following scientific study:

Phase I:  Identify retail samples which result in Pine Mouth.
  
Specifically, I plan on buying several retail containers of pine nuts from various brands.  I will eat a measurable amount and document their effects.  All data will be tracked in a spreadsheet.  My experience with Pine Mouth is consistent with all reports in that the effects begin within 12-48 hours.  Given, that I do not observe any of the adverse effects of Pine Mouth after consuming a sample, I will repeat with a different sample after 7 days.  Ideally, I would identify at least 2 retail samples which are positive for Pine Mouth and at least 2 which are negative.    

Phase II:  Extensive testing on the positive and negative samples.  

Using sophisticated technology, I aim to first determine the pine nut species associated with the samples.  Next, I aim to identify candidate chemicals/molecules which may be either natural (oils, etc.) or foreign (processing chemicals) by conducting a comparative analysis of the samples.

This phase is of course dependent on successful completion of Phase I and identifying a collaborator to test the samples.  

Phase III:  Product testing, body fluid testing, and beyond.

This will be discussed at a later day depending on the progression of Phase I and II.  However it is interesting to speculate that testing body fluids (urine, blood, saliva, etc.) for abnormalities while one is experiencing the adverse effects of Pine Mouth may be enlightening and shed some light on the public health significance of this issue.  
Additionally, assuming a root cause can be identified for this issue, developing tests to prevent impacted pine nuts from hitting the market is also an interesting potential.  

I will post again in a month or two with any updates.            

[Paxiled]

First, let me admit I've never heard of this.  But what I do know about pine nuts, having sold them for 18 years when I managed health food stores, is that they go bad very quickly, so it could just be you're buying them from the wrong place and you're very sensitive to rancid pine nuts.  We always kept them refrigerated to prevent rancidity, and told our customers to do likewise when they got them home.  I don't know anything about what Gym is saying, but I do know we sold organically grown pine nuts, which obviously means that minus fraud they were only growing legitimate ones since the growers were small and wouldn't take the time to grow organically inedible pine nuts -- too much effort.  They just have a very short shelf life if not kept under strict temperature control -- like some wines, they just don't travel well.

[gymdandee]

Two theories. One is the fact that pine nut oil goes rancid very quickly and may somehow be the culprit. The other comes from chemical analysis run in Switzerland on imported pine nuts. The researchers found two varieties in commercial products that haven't traditionally been eaten: Chinese White Pine and Chinese Red Pine. (There are more than 100 types of pine nuts, but only 29 are classified as edible by the Food and Agriculture Organization of the United Nations.) I've read that the two varieties identified by the Swiss researchers have different fatty acid profiles from edible pine nuts, which may be a factor in pine mouth syndrome. All pine nuts look alike, so you can't tell one from the other.