Dietary Phytoestrogens, Including Isoflavones, Lignans, and Coumestrol, in Nonvitamin, Nonmineral Supplements Commonly Consumed by Women in Canada

Abstract

Twenty-one nonvitamin, nonmineral dietary supplements commonly consumed by women in Canada were analyzed for isoflavones (formononetin, daidzein, genistein, glycitein), lignans (pinoresinol, lariciresinol, secoisolariciresinol, matairesinol), and coumestrol to complement our previously published food phytoestrogen database. Supplements containing soy or red clover had the highest concentrations of total isoflavones (728.2–35,417.0 ug/g) and total phytoestrogens (1030.1–35,517.7 ug/g) followed by licorice and licorice-containing supplements (41.3–363.3 ug/g isoflavones; 56.5–370.0 ug/g total phytoestrogens). Other supplements had considerably less isoflavones (≤ 19.0 ug/g) and total phytoestrogens (≤ 44.2 ug/g). Lignans were present in all (≤ 298.9 ug/g), whereas coumestrol was either not present or present in only small amounts (≤ 3.0 ug/g). Supplements differed in phytoestrogen profiles. The daily intake of isoflavones and lignans from some supplements may greatly exceed those from several servings of soy or vegetables. Hence, the intake of supplements should be taken into consideration in clinical or epidemiological studies for more accurate estimation of phytoestrogen intakes.

Acknowledgments and Notes

We thank Luda Solovetskia and Sheng Min Guo for technical assistance. The study was supported by the Canadian Breast Cancer Research Alliance with special funding support of the Canadian Breast Cancer Foundation Ontario Chapter [CBCRA Grant 13572; MC, principal investigator (PI)] and Natural Sciences and Engineering Research Council of Canada (LUT, PI).

LUT is the principal investigator of this substudy, which is a component of a larger study (MC, PI). LUT and BAB co-drafted the manuscript. MC, BAB, NK, and LUT identified the need for this database and obtained the funding. MC, NK, and ZL helped in the writing of the manuscript. BAB, MC, and NK designed and analyzed the survey to determine the supplements to be analyzed. ZL standardized the analytical methods. None of the authors had conflict of interest.

Notes

a: All details are from label except missing manufacturer location, which was obtained from distributor (Purity Life, Acton, Ontario, Canada).

b: Ingredients exclude capsule shell unless indicated.

c: Analysis of oily supplements included capsule contents and shell.

a: Abbreviations are as follows: FOR, formononetin; DAI, daidzein; GEN, genistein; GLY, glycitein; MAT, matairesinol; LAR, lariciresinol; PINO, pinoresinol; SECO, secoisolariciresinol; COU, coumestrol; GC-MS, gas chromatography-mass spectrometry.

b: Amount that can be detected by the GC-MS.

c: Estimated lowest concentration in sample that can be quantified using the GC-MS method.

a: Abbreviations are as follows: FOR, formononetin; DAI, daidzein; GEN, genistein; GLY, glycitein; MAT, matairesinol; LAR, lariciresinol; PINO, pinoresinol; SECO, secoisolariciresinol; COU, coumestrol; ISO, isoflavones; LIG, lignans; PE, phytoestrogens; nd, below quantitation limit (0.001 ug/g, GEN; 0.010 ug/g, FOR, DAI, COU; 0.050 ug/g GLY, MAT, PINO, SECO; 0.100 ug/g LAR); 0.0, > 0.01 but < 0.05 ug/g. Differences between reported individual and calculated PE totals, and between per g and calculated per unit or per serving values are due to rounding to one decimal point.

b: Daily dose was based on recommended usual dose on label; midpoint rounded up to next unit is reported when usual dose given as range.

c: Natural Factors, Burnaby, British Columbia, Canada.

d: Swiss Herbal Remedies Ltd., Richmond Hill, Ontario, Canada.

e: Shawla Herbs, Roseneath, Ontario, Canada.

f: Sundown Herbals, Boca Raton, FL.

g: Nature's Way Products Inc., Springville, UT.

h: Jamieson Laboratories, Toronto, Ontario, Canada.

i: Analysis of oily supplements included capsule contents and shell.

j: Nature's Way Products of Canada Ltd., Newmarket, Ontario, Canada.

k: Novogen, Ancaster, Ontario, Canada.

l: Life Brand, Shoppers Drug Mart, Toronto, Ontario, Canada.