The presence of D-fagomine in the human diet from buckwheat-based foodstuffs Susana Amézqueta a , Esther Galán a , Ingrid Vila-Fernández a , Sergio Pumarola a , Montserrat Carrascal b , Joaquin Abian b , Lourdes Ribas-Barba c , Lluís Serra-Majem c,d , Josep Lluís Torres e,⇑ a Bioglane SLNE, Tavern 17, 08006 Barcelona, Spain b CSIC/UAB Proteomics Laboratory, IIBB-CSIC/IDIBAPS, Facultat de Medicina, Building M, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain c Fundación para la Investigación Nutricional, Parc Científic de Barcelona, Baldiri Reixac 4-8, Torre D, 08028 Barcelona, Spain d Department of Clinical Sciences, University of Las Palmas de Gran Canaria, P.O. Box 550, 35080 Las Palmas de Gran Canaria, Spain e Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain article info Article history: Received 13 July 2012 Received in revised form 3 September 2012 Accepted 6 September 2012 Available online 18 September 2012 Keywords: D-Fagomine Iminosugar Iminocyclitol Buckwheat Food HPLC/MS Diet abstract Buckwheat (Fagopyrum esculentum Moench) groats contain the iminosugar D-fagomine as a minor com- ponent that might contribute to the alleged health benefits of this pseudo-cereal. This study presents analysis of D-fagomine in buckwheat-based foodstuffs by liquid chromatography coupled to mass spec- trometry and an estimation of its presence in the human diet based on a published population-based cross-sectional nutrition survey. D-Fagomine is present in common buckwheat-based foodstuffs in amounts ranging from 1 to 25 mg/kg or mg/L, it is stable during boiling, baking, frying and fermentation, and it is biosynthesised upon sprouting. The estimated total intake of D-fagomine resulting from a diet that includes such foodstuffs would be between 3 and 17 mg per day (mean for both genders; range from P5 to P95). A diet rich in buckwheat products would provide a daily amount of D-fagomine that may in part explain the beneficial properties traditionally attributed to buckwheat consumption. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Buckwheat is mainly produced in Russia, China, Ukraine, France and the USA, with 1.9 million hectares of the crop harvested and 1.6 million tonnes produced in 2010 (FAO, 2010). The produce is mainly used for food and livestock feed. Common buckwheat was domesticated and first cultivated in inland South East Asia, possibly as long ago as 6000 BC, and from there it spread to Central Asia and Tibet, and then to the Middle East and Europe (Ohnishi, 1998). Different evidence suggests that buckwheat was introduced early on into areas of present-day Germany, France and Portugal by Slavs and Scythians (Jahns, 2007). Buckwheat was later introduced into North America by Europeans. Nowadays, buckwheat flour is used to prepare different foodstuffs including noodles (Japanese soba, Korean makguksu and Italian pizzoccheri), groats (Polish Ka- sha), pancakes (French crêpes de Bretagne, Slavic blinis and North American ployes), boiled flour (Italian polenta, and Slovenian and Croatian z ˇganci), fried dough (Spanish farinetes de fajol from Catalonia), beer, cookies, bread and a myriad of other foodstuffs. Buckwheat is considered a healthy food because it is a source of lysine-rich proteins of the globulin kind, which makes it suitable for both general consumers and coeliacs, and because it contains functional components such as polyphenols (rutin and flavanols) and fagopyritols that may help to regulate blood sugar and prevent insulin resistance (Ortmeyer, Larner, & Hansen, 1995; Steadman et al., 2000; Watanabe, 1998; Wijngaard & Arendt, 2006). One such component is D-fagomine; first isolated from seeds of buckwheat in 1974 (Koyama & Sakamura, 1974). D-Fagomine (Fig. 1) is an iminocyclitol, also referred to as an iminosugar. As D-fagomine and other iminosugars are intestinal glycosidase inhibitors, they have the potential to modulate post- prandial blood glucose concentration (Asano, Oseki, Tomioka, Kizu, & Matsui, 1994). Therefore, they are useful in reducing the risks of developing insulin resistance and of becoming overweight. While most iminosugars are only found in exotic plant sources used for ornamental and/or medicinal purposes, D-fagomine is the only imi- nosugar known to be part of a traditional food source (Asano et al., 2005). Together with other iminosugars, such as 1-deoxinojirimi- cin (DNJ), D-fagomine is also found in edible mulberry extracts (Asano et al., 2001). We recently reported that D-fagomine per- forms a double action during its transit along the intestinal tract. First, it effectively delays sucrose and starch breakdown with the consequence of lowering blood glucose concentration; and second, it selectively agglutinates fimbriated Entero bacteriaceae, such as Escherichia coli, Salmonella enterica serovar Typhimurium, and 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2012.09.038 ⇑ Corresponding author. Tel.: +34 93 400 6112; fax: +34 93 204 5904. E-mail address: joseplluis.torres@iqac.csic.es (J.L. Torres). Food Chemistry 136 (2013) 1316–1321 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem