Effects of soy isoflavones and phytate on homocysteine, C-reactive protein, and iron status in postmenopausal women.
BACKGROUND
Soy protein or its components may protect against the atherosclerotic cardiovascular disease (CVD) risk factors total homocysteine (tHcy), C-reactive protein (CRP), and excess body iron, which generally increase with menopause.


OBJECTIVE
The primary objective of this study was to determine the independent effect of the soy protein components isoflavones and phytate on CVD risk factors in postmenopausal women. The secondary objective was to identify factors [blood lipids, oxidative stress indexes, serum ferritin, plasma folate, plasma vitamin B-12, and body mass index (BMI)] contributing to tHcy and CRP concentrations.


METHODS
In a double-blind, 6-wk study, 55 postmenopausal women aged 47-72 y were randomly assigned to 1 of 4 soy protein (40 g/d) isolate treatments: native phytate and native isoflavone (n = 14), native phytate and low isoflavone (n = 13), low phytate and native isoflavone (n = 14), or low phytate and low isoflavone (n = 14). We measured iron indexes, tHcy, CRP, and BMI.


RESULTS
Soy protein with native phytate significantly reduced tHcy (P = 0.017), transferrin saturation (P = 0.027), and ferritin (P = 0.029), whereas soy protein with native isoflavones had no effect on any variables. At baseline, BMI was highly correlated with tHcy (r = 0.39, P = 0.003) and CRP (r = 0.55, P < 0.0001), whereas HDL cholesterol was correlated with CRP (r = -0.30, P = 0.02). Multiple regression analysis showed that LDL cholesterol and BMI contributed significantly (R2= 19.9%, P = 0.003) to the overall variance in tHcy.


CONCLUSIONS
Consuming phytate-rich foods and maintaining a healthy weight may reduce atherosclerotic CVD risk factors in postmenopausal women.
Hanson
Laura N
LN
Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, USA.
Engelman
Heather M
HM
Alekel
D Lee
DL
Schalinske
Kevin L
KL
Kohut
Marian L
ML
Reddy
Manju B
MB
D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism*; D003324:Coronary Artery Disease / Q000097:blood* / Q000209:etiology / Q000517:prevention & control; D004311:Double-Blind Method; D005260:Female; D005293:Ferritins / Q000097:blood; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D007529:Isoflavones / Q000494:pharmacology*; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D018384:Oxidative Stress; D010833:Phytic Acid / Q000494:pharmacology*; D014674:Plant Proteins, Dietary / Q000494:pharmacology; D017698:Postmenopause / Q000097:blood*; D012044:Regression Analysis; D012307:Risk Factors; D030262:Soybean Proteins / Q000494:pharmacology*; D014168:Transferrin / Q000378:metabolism; D014805:Vitamin B 12 / Q000097:blood
D015415:Biomarkers; D007529:Isoflavones; D008055:Lipids; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins; D014168:Transferrin; D006710:Homocysteine; D010833:Phytic Acid; D002097:C-Reactive Protein; D005293:Ferritins; D005492:Folic Acid; D007501:Iron; D014805:Vitamin B 12