Evaluation of the composition and concentration of isoflavones in soy based supplements, health products and infant formulas Molamma P. Prabhakaran, Lim Soo Hui, Conrad O. Perera * Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, Singapore 117 543, Singapore Received 10 November 2005; accepted 22 January 2006 Abstract Isoflavones are weak estrogenic compounds found in soybeans and soy foods. The objective of the present study was to determine the content and composition of isoflavones in different soy isoflavone supplements, soy based health products and infant formulas. Com- mercially available samples of 13 different soy supplements and 11 soy based health products obtained from South East Asia were analyzed for their isoflavone concentrations by using high-performance liquid chromatography and their peak identities confirmed by LC–MS. The extent of daily intake of isoflavones from different products based on the directions for their consumption was further eval- uated. The amount of isoflavones in dietary supplements, soy based health products and infant formulas ranged from 405 to 57,570, 46.32–1333.80 and 59.54–226.84 lg/g of the sample, respectively, expressed as aglycone equivalents. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Soy; Isoflavone; HPLC; Supplement; Infant formulas 1. Introduction Soybeans and soy foods are a particularly abundant source of isoflavones. Several experimental studies have shown soy or isoflavones as having anti-carcinogenic effects on hormone-related diseases including cancer, menopausal symptoms, osteoporosis, etc. These effects may be related to the estrogenic or anti-estrogenic activities of isoflavones (Adlercreutz & Mazur, 1997; Bingham, Atkinson, Liggins, Bluck, & Coward, 1998; Messina, Persky, Setchell, & Barnes, 1994). The approval by the United States FDA (1999) relating the consumption of soy protein with the alleviation of cardiovascular disease has further gained increased attention in recent years. The active components of soy proteins responsible for this effect is not clearly understood, but a large number of studies have suggested isoflavones as the most beneficial group of soy components (Crouse et al., 1999). Daidzein, glycitein and genistein are the three major soy isoflavones existing in its aglycone form, while the respective 7-O-glucosides are called daid- zin, glycitin and genistin (Fig. 1). The glucosides esterified at the 6 00 -O-position of the glucose ring with acetyl or mal- onyl groups form their respective acetyl and malonyl gluco- sides. Thus, there are a total of 12 soy isoflavones. Due to the purported beneficial effects of isoflavones, the use of soy isoflavone supplements and soy-based health products have become popular. These products are widely commercialized in many countries as alternative therapy for alleviating menopausal discomforts and for the preven- tion of diseases such as osteoporosis or for possible preven- tion of breast cancer (Penalvo et al., 2004). A large number of soy isoflavone supplements and soy based health prod- ucts are available in the market place. While the isoflavone exposure assessment data are essential when studying the health effects of soy-based products, there are currently a number of drawbacks in some of these studies. One of them is the lack of exposure assessment data when studying health effects of isoflavone-contained foods and supplements. 0963-9969/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2006.01.011 * Corresponding author. Present address: P.O. Box 462, Palmerston North, 5301 New Zealand. Tel.: +64 6 3554622. E-mail address: pereraco@hotmail.com (C.O. Perera). www.elsevier.com/locate/foodres Food Research International 39 (2006) 730–738