Genistein plasma concentrations

VERKASALO P K, APPLEBY P N, ALLEN N E, DAVEY G, ADLERCREUTZ H AND KEY T J (2001) Soya intake and plasma concentrations of daidzein and genistein validity of dietary assessment among eighty British women (Oxford arm of the European Prospective Investigation into Cancer and Nutrition). 7 86 (3) 415-21. 

Similar plasma concentrations were detected for daidzein, genistein and equol in adults consuming modest quantities of soy foods containing about 50 mg/d of total isoflavones [91]. 

A summary of studies where some isoflavones and their metabolites have been analyzed from blood samples of sheep and cattle fed red clover is presented in Table 9.1. The concentrations of isoflavonoids seem to be at the same level in both sheep and cattle. Conjugated or total equol concentration varied between 33 and 770 xg per 100 mL, and free or unconjugated equol concentration was between 2 and 10 xg per 100 mL. Lundh (1995) has estimated that of the total equol concentration about 5% in cows and 1% in sheep exist as free. The plasma concentrations measured for conjugated formononetin, daidzein, genistein, or biochanin A were 1-55 jig per 100 mL. Concentrations for unconjugated forms were usually very small, less than 1 jig per 100 mL. 

Morabito et al., 2002 European postmenopause placebo, n = 30 genistein, n = 30 HRT, n = 30 First randomized, double-blind placebo-controlled study. Compared to placebo control, genistein (54 mg/day) consumed for 1 year significantly reduced urinary excretion of bone resorption markers and increased bone formation markers at 6 and 12 months BMD was significantly increased at the femoral neck and lumbar spine plasma genistein concentration was around 1.5 pM. HRT showed similar effects to genistein for BMD. 

Mean plasma isoflavone concentrations (after deconjugation) some 5 to 6h after consumption of soya-based foods have been reported as follows daidzein 0.5 to 3.1 p.M genistein 0.3 to 4.1 pM glycitein 0.20 to 0.85 Some data for the individual conjugates of... 

Knowledge of the pharmacokinetics of isoflavones in soy foods is essential for making recommendations regarding efficacy in clinical studies. Die plasma half-life of daidzein and genistein, measured from their plasma appearance and disappearance curves, is 7.9 h in adults peak concentrations occur 6-8 h after administration of the pure compounds [93] with peak concentrations ranging from 80 to 800 ng/ml (after a single oral dose of 50 mg of pure isoflavones). 

Squadrito F, Altavilla D, Morabito N, Crisafulli A, D Anna R, Corrado F, Ruggeri P, Campo GM, Calapai G, Caputi AP, Squadrito G. 2002. The effect of the phytoestrogen genistein on plasma nitric oxide concentrations, endothelin-1 levels and endothelium dependent vasodilation in postmenopausal women. Atherosclerosis 163 339-347. 

Figure 2.4 Plasma and liver genistein concentration in adult (1 year) and senescent (2 years) Sprague-Dawley rats fed 154 and 308 ppm genistein for 5 wk. Values are means SEM, n = 6 in the adult group (white bar) and = 4 in the senescent group (black bar). Values in the same diet differ, P < 0.05.

Chen, C.Y. and Bakhiet, R.M., Age decreased steady-state concentrations of genistein in plasma, liver, and skeletal muscle in Sprague-Dawley rats, Mech. Ageing Dev., 127, 344, 2006. 

Gooderham, M.H., Adlercreutz, H., Ojala, S.T., Wahala, K., and Holub, B.J. 1996. A soy protein isolate rich in genistein and daidzein and its effects on plasma isoflavone concentrations, platelet aggregation, blood lipids and fatty acid composition of plasma phospholipid in normal men. JNutr 126, 2000-2006. 

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