Pine Nuts: the Good and Bad

May 17, 2011

You may have heard of pine nut syndrome, or maybe you have even experienced it. Find out what it is and more here

Imagine enjoying a delicious pesto sauce with your favorite pasta, or adding a sprinkling of pine nuts on a salad only to find that a few days later everything you eat or drink tastes bitter or metallic. Pine nuts, which are actually seeds, are the culprit; except it’s not just any pine nut… researchers are increasingly pointing fingers at a Chinese variety, Pinus aramandii as the cause of the problem. The good news is that if you read the country of origin labeling you can almost guarantee a great pine nut eating experience!

Pine nuts come from pine cones on pine trees and are a very good source of nutrition, including high amounts of protein, fiber, vitamins, minerals, and the “heart friendly” mono-unsaturated fatty acids that are known to reduce blood cholesterol. Typically harvested in cooler climates around the world, but also found in warmer areas, there are 29 species, according to the FAO, of pine nuts regularly consumed around the world. 

So what’s with “pine nut syndrome”? Pine nut syndrome, also known as metallogeusia typically appears about two days after ingestion, and can last for up to nine weeks. Though unpleasant, there are no lasting effects. The phenomenon was first described in a scientific paper in Belgium in 2001, but people have been eating pine nuts for thousands of years, so are people experiencing pine nut syndrome now? 

Many as mentioned above point their finger towards China, as the country recently entered into the global billion dollar pine nut market. In fact, the Nestle Research Centre in a January 2011 report in the Journal of Toxicology has hypothesized that a particular species of Chinese white pine, pine nuts, are the cause of the problem; until recently, the tree was harvested only for lumber, resin, or turpentine. The suspect species of pine nuts are smaller, duller, and more round than typical pine nuts. 

Responding to the research linking the China White Pine to pine nut syndrome, the Chinese Tree Nut Association recently (December 2010) affirmed that a variety of pine nut called the Pinus armandii, from the growing areas of Shaanxi and Shanxi may be the variety responsible for the complaints. The variety has even been deemed “unfit for human consumption” by the EU food standard authorities. 

Experts have determined that the Pinus armandii has a slightly different fatty acid profile but they are baffled as to what actually causes pine nut syndrome. The Food and Drug Administration is actively working with several universities to further investigate the problem.

Do you love pine nuts? SupermarketGuru’s best advice it to read country of origin labeling. Check the packaging or labels on bulk bins as to where the seeds were produced. Also pay attention to the best by or expiration date as this ensures freshness and a greater nutrient density. Pine nuts are a great source of nutrition so don't let the fear of pine nut syndrome stop you from enjoying your favorite pine nut treats!

Do note, there are up to five official varieties of P. armandii but it seems that only one thick-shelled variety originating from the region of Shaanxi and Shanxi of China are causing the bitterness.