Dietary intake and major sources of plant lignans in Latvian men and women LAILA MEIJA 1 , PAIVI SO ¨ DERHOLM 2 , ADILE SAMALETDIN 3 , GITA IGNACE 4 , INESE SIKSNA 5 , RAFAELS JOFFE 5 , AIVARS LEJNIEKS 6 , VILNIS LIETUVIETIS 7 , INDRIKIS KRAMS 8 , & HERMAN ADLERCREUTZ 3 1 Department of Doctoral Studies, Riga Stradins University and Department of Food and Nutrition, Pauls Stradins Clinical University Hospital, Riga, Latvia, 2 Institute for Preventive Medicine, Nutrition, and Cancer, Folkha ¨lsan Research Center and Department of Cardiology, Institute of Clinical Medicine, University of Helsinki, Helsinki, Finland, 3 Institute for Preventive Medicine, Nutrition, and Cancer, Folkha ¨lsan Research Center and Division of Clinical Chemistry, University of Helsinki, Helsinki, Finland, 4 Faculty of Rehabilitation, Riga Stradins University, Riga, Latvia, 5 Institute of Food Safety, Animal Health and Environment “BIOR”, Riga, Latvia, 6 Department of Internal Medicine, Riga Stradins University and Department of Internal Medicine, Riga Eastern Clinical University Hospital, Riga, Latvia, 7 Department of Surgery, Riga Stradins University and Department of Urology, Riga Eastern Clinical University Hospital, Riga, Latvia, and 8 Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia Abstract Higher intake of lignans, diphenolic plant compounds, may reduce the risk of certain types of cancer and cardiovascular diseases. We assessed the dietary intake of four lignans: matairesinol, secoisolariciresinol, lariciresinol and pinoresinol. Furthermore, for the breads we supplemented the data with two more lignans: syringaresinol and medioresinol. Study subjects were 172 men and 97 women aged 40 – 75 years, residing in Riga, the capital of Latvia, all living at home, eating habitual food. Median total lignan intake was 2259 (range 1169 – 5759) mg/day. Secoisolariciresinol contributed 58% and syringaresinol 22% of lignan intake. Bread was the major food source of lignans in men (86%), whereas in women it was bread (57%) and flaxseed (35%). Keywords: lignans, intake, bread, flaxseed, diet Introduction Phytoestrogens are natural plant substances or meta- bolites of plant precursor that are structurally and functionally comparable to endogenous estrogens and can have both estrogenic and antiestrogenic effects (Adlercreutz 2007), and they can be considered as natural selective estrogen receptor modulators (Setchell 2001). Moreover, phytoestrogens can also have antioxidative and antiproliferative properties (Adlercreutz 2002). Beneficial effects of phytoestrogens in diets have been studied concerning hormone- dependent cancers (Adlercreutz 2002; Lof and Weiderpass 2006), cardiovascular disease, osteoporosis, menopausal symptoms (Moutsatsou 2007), obesity and Type 2 diabetes (Bhathena and Velasquez 2002). Phytoestrogens are subdivided into three major classes: isoflavones, lignans and coumestans (Cornwell et al. 2004). Predominantly, lignans are the most important sources of phytoestrogens in western diet (Carmichael et al. 2011; Zamora-Ros et al. 2012). Diphenolic plant compounds, lignans are included among the phytoestrogens because some of them are converted in the gut to weakly estrogenic compounds. After consumption, plant lignans can be partially absorbed or further metabolized by the intestinal microbiota into the ‘enterolignans’ enterolactone (ENL) and enterodiol (END) (Borriello et al. 1985). Plant lignan metabolism has been studied in vitro, and it has been discovered that not all lignans have ISSN 0963-7486 print/ISSN 1465-3478 online q 2013 Informa UK, Ltd. DOI: 10.3109/09637486.2013.765835 Correspondence: Laila Meija, Pauls Stradins Clinical University Hospital, Pilsonu street 13, Riga LV 1002, Latvia. Tel: þ 00371 29408199. Fax: þ 00371 67069661. E-mail: laila@meija.lv International Journal of Food Sciences and Nutrition, August 2013; 64(5): 622–630 Int J Food Sci Nutr Downloaded from informahealthcare.com by Turku University on 06/14/13 For personal use only.