Isoflavone intake in persons at high risk of cardiovascular events: implications for vascular endothelial function and the carotid atherosclerotic burden

Am J Clin Nutr. 2007 Oct;86(4):938-45. doi: 10.1093/ajcn/86.4.938.


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.

Design: 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).

Conclusion: In persons at high risk of cardiovascular events, a greater isoflavone intake is associated with better vascular endothelial function and lower carotid atherosclerotic burden.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Analysis of Variance
  • Blood Flow Velocity
  • Blood Pressure / drug effects
  • Blood Pressure / physiology
  • Cardiovascular Diseases / epidemiology*
  • Cardiovascular Diseases / metabolism
  • Carotid Arteries / diagnostic imaging
  • Carotid Arteries / pathology*
  • Diet Surveys
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / physiology*
  • Female
  • Humans
  • Incidence
  • Isoflavones / administration & dosage*
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / physiology
  • Male
  • Risk Factors
  • Soybean Proteins / administration & dosage*
  • Soybeans / chemistry
  • Surveys and Questionnaires
  • Tunica Intima / diagnostic imaging
  • Tunica Intima / pathology
  • Tunica Media / diagnostic imaging
  • Tunica Media / pathology
  • Ultrasonography


  • Isoflavones
  • Soybean Proteins