A potential trigger for pine mouth: a case of a homozygous phenylthiocarbamide taster

Abstract

Pine mouth, also known as Pine Nut Syndrome (PNS), is an uncommon dysgeusia that generally begins 12–48 hours after consuming pine nuts. It is characterized by a bitter metallic taste, usually amplified by the consumption of other foods, which lasts 2–4 weeks. Recent findings have correlated this disorder with the consumption of nuts of the species Pinus armandii, but no potential triggers or common underlying medical causes have been identified in individuals affected by this syndrome. We report a 23-year-old patient affected by pine mouth that also underwent a PTC taste test and was found to be a taster for this compound. TAS2R38 genotyping demonstrated this subject was a homozygous carrier of the PAV taster haplotype. We therefore hypothesize that homozygous PTC taster status may be a potential contributor for pine mouth events. Although based on a single observation, this research suggests a connection between genetically determined bitter taste perception and the occurrence of pine nut dysgeusia events.

Is the Profile of Fatty Acids, Tocopherols, and Amino Acids Suitable to Differentiate Pinus armandii Suspicious to Be Responsible for the Pine Nut Syndrome from Other Pinus Species?

“…[26] The predominant fatty acids in the seed oils are linoleic acid (35.2 g/100 g (P. torreyana)) -58.2 g/ 100 g (P. eldarica)), oleic acid (14.6 g/100 g (P. sylvestris 1) -48.5 g/100 g (P. torreyana)) and pinolenic acid (0.2 g/100 g (P. pinea 5,7) -22.4 g/100 g (P. roxburghii) ( Table 2). Additionally to pinolenic acid (C18:3D 5,9,12 ), also taxoleic acid (18:2D 5,9 ) and sciadonic acid (20:3D 5,11,14 ) can be found as D 5 -UPIFA in the seed oil of Pinus species, but in distinctly lower amounts. These results are in agreement with other investigations which also found oleic, linoleic, and pinolenic acid as predominant in the seed oil of Pinus species.…”

“…A higher loading factor for lysine was found for PC6 (+0.65). The contribution of PC2 to the total variance amounts to 18.5% with the highest influence found for fatty acids 16:0 (À0.83), 18:1D 9 (À0.81), 18:2D 5,9 (0.71), 18:3D 5,9,12 (0.71), 20:2D 5,11 (0.74), and 20:3D 5,11,14 (0.71), as well as oil content (À0.70) and DI (0.83). This indicates that the predominant usual fatty acids (negative correlation) and D 5fatty acids (positive correlation) have an opposite effect on principle component 2.…”

“…The influence of 20:2D 11,14 , c-tocopherol, and lysine was remarkably smaller. Square II is À0.12756 0.60775 18:2D 5,9 À0.42222 0.71477 18:2D 9,12 0.42290 À0.11651 18:3D 5,9,12 À0.57780 0.71373 20:1D 11 À0.09159 0.20838 20:2D 5,11 0.30428 0.74080 20:2D 11,14 0.32156 0.19656 20:3D 5,11,14 0.14541 0. dominated by 18:3D 5,9,12 , 18:2D 5,9 , and DI, while the contribution of 18:1D 11 , a-tocopherol, 20:1D 11 , and dtocopherol is much smaller. Although d-tocopherol is predestined to support the differentiation of Pinus species due to the absence in some members of the genus, Figure 1 only shows a very small importance of this variable.…”

“…Up to now, only little is known about the mechanism behind this disturbance. Risso et al [9] hypothesized that homozygous phenylthiocarbamide taster status may be a potential contributor for pine mouth events. They suggested a connection between genetically determined bitter taste perception and the occurrence of pine nut dysgeusia events.…”

“…Wolff et al showed that members of the genus Pinus contained unique fatty acid compositions useful for taxonomy and phylogeny. [12] The seeds contain, in addition to the common fatty acids 18:1D 9 (oleic acid) and linoleic acid (18:2D 9,12 ), also a group of D 5 -fatty acids with 18:2D 5,9 (taxoleic acid), 18:3D 5,9,12 (pinolenic acid), and 20:3D 5,11,14 (sciadonic acid) as main representatives. A diagnostic index (DI) calculated from the content of D 5 -unsaturated fatty acids relative to that of their fatty acid precursors has been proposed for the differentiation of pine nuts from different species, but especially the DI values for P. armandii and P. sibirica were very close together, resulting in some uncertainty for reliable distinction.…”