Isoflavone intake in persons at high risk of cardiovascular events: implications for vascular endothelial function and the carotid atherosclerotic burden.
BACKGROUND
Epidemiologic studies have suggested that a high phytoestrogen intake is inversely associated with cardiovascular disease risk factors and the incidence of cardiovascular events. However, the relation between the intake of isoflavone, a major component of phytoestrogen, and vascular endothelial function and the atherosclerotic burden remains unclear.


OBJECTIVE
We aimed to investigate the effects of various dietary soy isoflavone intakes on brachial artery flow-mediated dilation and mean maximum carotid intima-media thickness.


METHODS
We studied 126 consecutive patients (x +/- SD age: 66.5 +/- 11.1 y; 69% male) at high risk of cardiovascular events (94% had documented coronary artery disease or stroke; 44% had diabetes). A validated food-frequency questionnaire was used to estimate their dietary intake after they achieved stable dietary patterns for 3 mo.


RESULTS
The median intakes of isoflavone and soy protein were 5.5 (range: 2.2-13.3) mg/d and 1.2 (range: 0.4-2.8) g/d, respectively. Persons in the 4th quartile of daily isoflavone intake had significantly (P < 0.05) greater flow-mediated dilation-but not mean maximum carotid intima-media thickness-than did those in the lower quartiles. After adjustment for potential confounders, a higher isoflavone intake in the 4th than in the 1st quartile (>13.3 mg/d), but not a higher intake of soy protein, predicted an absolute 2.71% increase in flow-mediated dilation (relative increase: 103%; P = 0.02) and a 0.17-mm decrease in mean maximum carotid intima-media thickness (relative decrease: 14.5%; P = 0.04).


CONCLUSIONS
In persons at high risk of cardiovascular events, a greater isoflavone intake is associated with better vascular endothelial function and lower carotid atherosclerotic burden.
Chan
Yap-Hang
YH
Cardiology Division, Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
Lau
Kui-Kai
KK
Yiu
Kai-Hang
KH
Li
Sheung-Wai
SW
Chan
Hiu-Ting
HT
Tam
Sidney
S
Shu
Xiao-Ou
XO
Lau
Chu-Pak
CP
Tse
Hung-Fat
HF
D000368:Aged; D000704:Analysis of Variance; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000378:metabolism; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000473:pathology*; D004034:Diet Surveys; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007529:Isoflavones / Q000008:administration & dosage*; D050356:Lipid Metabolism / Q000187:drug effects / Q000502:physiology; D008297:Male; D012307:Risk Factors; D030262:Soybean Proteins / Q000008:administration & dosage*; D013025:Glycine max / Q000737:chemistry; D011795:Surveys and Questionnaires; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography
D007529:Isoflavones; D030262:Soybean Proteins