Sex and long-term soy diets affect the metabolism and excretion of soy isoflavones in humans

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Abstract

Soybean consumption may be protective against hormone-dependent cancers, possibly in part because of the isoflavones daidzein and genistein, which are weakly estrogenic. This paper reviews our studies of the metabolism and disposition of these phytoestrogens in humans. During 1 mo of daily soy ingestion in a metabolic unit [1,065 L (36 oz) soymilk, providing 80-210 mg of each isoflavone daily], women initially excreted more isoflavone conjugates in urine than did men. Recoveries of conjugates of genistein, daidzein, and equol were 24%, 66%, and 28% of the amounts ingested in women, respectively, and 15%, 47%, and 15%, respectively, of those in men. A progressive decrease in urinary excretion of genistein and daidzein was observed in women but not in men during the study. At least 10% of ingested daidzin was excreted in urine as equol conjugate in one man and one woman after the first soy ingestion. Three more women but no more men developed the ability to produce and excrete large amounts of equol. Absorption rate constants (k(a)) of the isoflavones were estimated to be 0.24-0.50 h-1. The elimination rates (k(e)) for genistein, daidzein, and equol were 0.1, 0.16, and 0.08 h-1, respectively, in women and 0.19, 0.25, and 0.13 h-1, respectively, in men. Thus, the excretion half-life values of genistein were longer in women (7, 4, and 9 h, respectively) than in men (4, 3, and 5 h, respectively) after the first soy ingestion. The excretion half-life shortened progressively in women but lengthened progressively in men over the study period. Thus, isoflavone metabolism and disposition were affected by the duration of soy ingestion and by sex.

Original languageEnglish (US)
JournalAmerican Journal of Clinical Nutrition
Volume68
Issue number6 SUPPL.
StatePublished - Dec 1998

Fingerprint

Isoflavones
isoflavones
excretion
Equol
Genistein
genistein
Diet
metabolism
daidzein
gender
diet
Eating
ingestion
half life
Half-Life
urine
Urine
daidzin
Phytoestrogens
plant estrogens

Keywords

  • Chemopr evention
  • Daidzein
  • Equol
  • Genistein
  • Hormone-dependent cancers
  • Humans
  • Isoflavones
  • Pharmacokinetics
  • Phytoestrogens
  • Soybeans

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Food Science

Cite this

@article{556c3180f1994830a1ae22aa3f07a304,
title = "Sex and long-term soy diets affect the metabolism and excretion of soy isoflavones in humans",
abstract = "Soybean consumption may be protective against hormone-dependent cancers, possibly in part because of the isoflavones daidzein and genistein, which are weakly estrogenic. This paper reviews our studies of the metabolism and disposition of these phytoestrogens in humans. During 1 mo of daily soy ingestion in a metabolic unit [1,065 L (36 oz) soymilk, providing 80-210 mg of each isoflavone daily], women initially excreted more isoflavone conjugates in urine than did men. Recoveries of conjugates of genistein, daidzein, and equol were 24{\%}, 66{\%}, and 28{\%} of the amounts ingested in women, respectively, and 15{\%}, 47{\%}, and 15{\%}, respectively, of those in men. A progressive decrease in urinary excretion of genistein and daidzein was observed in women but not in men during the study. At least 10{\%} of ingested daidzin was excreted in urine as equol conjugate in one man and one woman after the first soy ingestion. Three more women but no more men developed the ability to produce and excrete large amounts of equol. Absorption rate constants (k(a)) of the isoflavones were estimated to be 0.24-0.50 h-1. The elimination rates (k(e)) for genistein, daidzein, and equol were 0.1, 0.16, and 0.08 h-1, respectively, in women and 0.19, 0.25, and 0.13 h-1, respectively, in men. Thus, the excretion half-life values of genistein were longer in women (7, 4, and 9 h, respectively) than in men (4, 3, and 5 h, respectively) after the first soy ingestion. The excretion half-life shortened progressively in women but lengthened progressively in men over the study period. Thus, isoflavone metabolism and disposition were affected by the duration of soy ingestion and by sex.",
keywords = "Chemopr evention, Daidzein, Equol, Genistein, Hormone-dependent cancers, Humans, Isoflavones, Pharmacokinetics, Phytoestrogens, Soybeans",
author = "Leejane Lu and Karl Anderson",
year = "1998",
month = "12",
language = "English (US)",
volume = "68",
journal = "American Journal of Clinical Nutrition",
issn = "0002-9165",
publisher = "American Society for Nutrition",
number = "6 SUPPL.",

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TY - JOUR

T1 - Sex and long-term soy diets affect the metabolism and excretion of soy isoflavones in humans

AU - Lu, Leejane

AU - Anderson, Karl

PY - 1998/12

Y1 - 1998/12

N2 - Soybean consumption may be protective against hormone-dependent cancers, possibly in part because of the isoflavones daidzein and genistein, which are weakly estrogenic. This paper reviews our studies of the metabolism and disposition of these phytoestrogens in humans. During 1 mo of daily soy ingestion in a metabolic unit [1,065 L (36 oz) soymilk, providing 80-210 mg of each isoflavone daily], women initially excreted more isoflavone conjugates in urine than did men. Recoveries of conjugates of genistein, daidzein, and equol were 24%, 66%, and 28% of the amounts ingested in women, respectively, and 15%, 47%, and 15%, respectively, of those in men. A progressive decrease in urinary excretion of genistein and daidzein was observed in women but not in men during the study. At least 10% of ingested daidzin was excreted in urine as equol conjugate in one man and one woman after the first soy ingestion. Three more women but no more men developed the ability to produce and excrete large amounts of equol. Absorption rate constants (k(a)) of the isoflavones were estimated to be 0.24-0.50 h-1. The elimination rates (k(e)) for genistein, daidzein, and equol were 0.1, 0.16, and 0.08 h-1, respectively, in women and 0.19, 0.25, and 0.13 h-1, respectively, in men. Thus, the excretion half-life values of genistein were longer in women (7, 4, and 9 h, respectively) than in men (4, 3, and 5 h, respectively) after the first soy ingestion. The excretion half-life shortened progressively in women but lengthened progressively in men over the study period. Thus, isoflavone metabolism and disposition were affected by the duration of soy ingestion and by sex.

AB - Soybean consumption may be protective against hormone-dependent cancers, possibly in part because of the isoflavones daidzein and genistein, which are weakly estrogenic. This paper reviews our studies of the metabolism and disposition of these phytoestrogens in humans. During 1 mo of daily soy ingestion in a metabolic unit [1,065 L (36 oz) soymilk, providing 80-210 mg of each isoflavone daily], women initially excreted more isoflavone conjugates in urine than did men. Recoveries of conjugates of genistein, daidzein, and equol were 24%, 66%, and 28% of the amounts ingested in women, respectively, and 15%, 47%, and 15%, respectively, of those in men. A progressive decrease in urinary excretion of genistein and daidzein was observed in women but not in men during the study. At least 10% of ingested daidzin was excreted in urine as equol conjugate in one man and one woman after the first soy ingestion. Three more women but no more men developed the ability to produce and excrete large amounts of equol. Absorption rate constants (k(a)) of the isoflavones were estimated to be 0.24-0.50 h-1. The elimination rates (k(e)) for genistein, daidzein, and equol were 0.1, 0.16, and 0.08 h-1, respectively, in women and 0.19, 0.25, and 0.13 h-1, respectively, in men. Thus, the excretion half-life values of genistein were longer in women (7, 4, and 9 h, respectively) than in men (4, 3, and 5 h, respectively) after the first soy ingestion. The excretion half-life shortened progressively in women but lengthened progressively in men over the study period. Thus, isoflavone metabolism and disposition were affected by the duration of soy ingestion and by sex.

KW - Chemopr evention

KW - Daidzein

KW - Equol

KW - Genistein

KW - Hormone-dependent cancers

KW - Humans

KW - Isoflavones

KW - Pharmacokinetics

KW - Phytoestrogens

KW - Soybeans

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M3 - Article

VL - 68

JO - American Journal of Clinical Nutrition

JF - American Journal of Clinical Nutrition

SN - 0002-9165

IS - 6 SUPPL.

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