Table 11.

Blood Levels of Total Isoflavones (Aglycones+Conjugates) Following Ingestion of Soy Products

	Plasma or serum levels nM [μg/L] (mean±SD)
Population and exposure condition	Genistein	Daidzein	Reference
Women ingesting 0.7 mg/kg bw isoflavone (44% genistein and 56% daidzein) through soy milk powder	740±440 [200±119]	790±40 [201±10]	Xu et al., 1994
Women ingesting 1.3 mg/kg bw isoflavone (44% genistein and 56% daidzein) through soy milk powder	1070±630 [289±170]	1220±670 [310±170]	Xu et al., 1994
Women ingesting 2.0 mg/kg bw isoflavone (44% genistein and 56% daidzein) through soy milk powder	2150±1330 [581±359]	2240±1180 [570±300]	Xu et al., 1994
Women consuming 4.5 mmol/kg bw isoflavones through soy milk (48.9% genistein, 43.3% daidzein, 7.8% glycitein)a	1700±1010 [459±273]	1040±610 [264±155]	Zhang et al., 1999b
Women consuming 4.5 mmol/kg bw isoflavones through soy germ (12.6% genistein, 48.5% daidzein, 38.9% glycitein)a	510±190 [138±51]	1630±1030 [414±262]	Zhang et al., 1999b
Men consuming 4.5 mmol/kg bw isoflavones through soy milk (48.9% genistein, 43.3% daidzein, 7.8% glycitein)a	1780±830 [481±224]	1290±500 [328±83]	Zhang et al., 1999b
Men consuming 4.5 mmol/kg bw isoflavones through soy germ (12.6% genistein, 48.5% daidzein, 38.9% glycitein)a	470±290 [127±78]	1160±440 [295±11]	Zhang et al., 1999b
Males ingesting cereal bar containing 8 g defatted soy grit (~20 mg isoflavones)	468 [126]	392 [100]	Pumford et al., 2002
Males ingesting cake containing 10.95 mg genistein and 8.54 mg daidzein for 3 days. Day 3 values listed.	445 [120]	297 [75.5]	Pumford et al., 2002
Males ingesting 16 mg isoflavone/kg bw	7700 [2081] (total) 70 [19] (free)	Not reported	Busby et al. (2002) as cited in UK Committee on Toxicity, 2003
Males consuming soy protein isolate beverage (60 g/day) for 28 days	907±245 [245±66]	498±102 [127±26]	Gooderham et al. (1996) as cited in ILSI, 1999
Male ingesting soy supplement at dose of 35.6 mg/day daidzein and 5.6 mg/day genistein for 7 days	138±13 [37.3±3.5]	671±46 [171±12]	Doerge et al., 2000
Female ingesting soy supplement at dose of 35.6 mg/day daidzein and 5.6 mg/day genistein for 7 days	383±16 [104±4.3]	558±14 [142±3.6]	Doerge et al., 2000
Females ingesting 5 mg genistin or 5 mg daidzin	1220±470b [330±127]	1550±240b [394±61]	Setchell et al., 2001
Females ingesting 5 mg genistein or 5 mg daidzein	1260±270b [341±73]	760±120b [193±49]	Setchell et al., 2001

Equol was not reported in these studies. Conversions in the table refer to aglycone equivalents.

^aPlasma glycitein values were reported at 200±80 nM [57±23 μg/L] in women consuming soy milk, 730±220 nM [208±63 μg/L] in women consuming soy germ, 220±80 nM [63±23 μg/L] in men consuming soy milk, and 850±250 nM [242±71 μg/L] in men consuming soy germ.

^bVariance not specified.