you are here:
Home  Health benefits  Cardiovascular  Soya and other cardiovascular effects

There are many mechanisms by which soya protein, isoflavones or both might have beneficial cardiovascular effects.

There are the well-recognised improvements in plama lipid and lipoprotein concentrations (i.e. lower LDL cholesterol, lower triglycerides and higher HDL cholesterol).
There is also evidence that soya protein, isoflavones or both could have beneficial effects on the following: blood pressure, vascular and endothelial cell function, platelet activation, aggregation and serotonin storage, LDL oxidation, smooth muscle cell proliferation and migration, possibly ER beta- mediated direct effects on inhibition of atherogenesis and reducing inflammation.

The notion that soyfoods exert multiple coronary benefits is supported by results from a large prospective epidemiologic investigation involving ~65,000 postmenopausal women from Shanghai, China (1). After controlling for a host of dietary and lifestyle factors soy protein intake was associated with marked protection against nonfatal myocardial infarction (relative risk = 0.14; 95% confidence interval, 0.04-0.48); when comparing women in the highest vs. the lowest quartile of intake (P for trend = 0.001).  Especially worthy of note is that in this study the soy protein intake cutoff for the fourth quartile was only about 11 g/d, less than half the amount (25g) established by the FDA as the threshold intake necessary for cholesterol reduction.

Other soya constituents in addition to the soya protein may have a modifying effect on cardiovascular disease independent of the effect on plasma lipoprotein concentrations. Genistein (the most important isoflavone in soya) is known to bind rather weakly to the classical estrogen receptor (ER alpha), but with much higher affinity to ER beta (2). This would suggest that genistein might have more potent effects in tissues expressing ER beta.
Available data suggest that in the process of atherosclerosis, ER beta could play a role in mediating some direct effects of genistein on the artery wall (3).

Different mechanisms by which soyafood can exert beneficial cardiovascular effects

Area Mechanisms References  
Serum Lipids Total cholesterol; LDL and small dense LDL; Apolipoprotein B; Triglycerides, HDL 4-7  
Serum homocysteine Decreases levels 8  
Oxidative stress Decrease LDL-oxidation 9, 10  
Inflammation Decreased inflammation of vascular wall (decreased serum C-reactive protein levels) 6  
Platelat aggregation Decrease platelet aggregation and vascular thrombosis 11  
Vascular reactivity Improve vascular responsiveness and post-ischemic reperfusion 10, 12  
Plaque rupture May be reduced by soya 6, 13  
Blood pressure Decreases blood pressure 14, 15  

References

  1. Zhang X, Shu XO, Gao YT, et al. Soy food consumption is associated with lower risk of coronary heart disease in Chinese women. J Nutr 2003;133(9):2874-8.
  2. Kuiper GG. Interaction of estrogenic chemicals and phytoestrogens with estrogen receptor Beta. Endocrinology 1998 Oct(10); 139: 4252-4263.
  3. Mäkelä S. Differentiation between vasculoprotective and uterotrophic effects of ligands with different binding affinities to estrogen receptors alpha and beta. Proc Natl Acad Sci USA 1999 Jun(8); 96(12): 7077-7082
  4. Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of effects of soya protein intake on serum lipids in humans. New Engl J Med 1995; 333: 276-82.
  5. Hermansen K, Soondergaard M, Hoie L, Carstensen M, Brock B. Beneficial effects of a soya-based dietary supplement on lipid levels and cardiovascular risk markers in type 2 diabetic subjects. Diabetes Care 2001; 24: 228-33.
  6. Jenkins DJA, Kendall CWC, Marchie A et al. Effects of a dietary portfolio of cholesterol-lowering foods versus lovastatin on serum lipids and C-reactive protein. J Amer Med Assoc 2003; 290: 502-10.
  7. Weggemans RM, Trautwein EA. Relation between soya-associated isoflavones and LDL and HDL cholesterol concentrations in humans: a meta-analysis. Eur J Clin Nutr 2003; 57: 940-6.
  8. Jenkins DJA, Kendall CWC, Jackson CJ et al. Effects of high- and low-isoflavone soyafoods on blood lipids, oxidized LDL, homocysteine, and blood pressure in hyperlipidemic men and women. Am J Clin Nutr 2002; 76: 365-72.
  9. Anderson JW, Diwadkar VA, Bridges SR. Selective effects of different antioxidants on oxidation of lipoproteins from rats. PSEBM 1998; 218: 376-81.
  10. Wiseman H, O’Reilly J, Adlercreutz H et al. Isoflavone phytoestrogens consumed in soya decrease F2- isoprostane concentrations and increase resistance of low density lipoprotein to oxidation in humans. Am J Clin Nutr 2000; 72: 395-72.
  11. Gooderham JM, Adlercreutz H, Ojala S, Wahala K, Holub BJ. A soya 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. J Nutr 1996; 126: 2000-6.
  12. Chin-Dusting JPF, Fisher LJ, Lewis TV, Pickarska A, Nestel PJ, Husband A. The vascular activity of some isoflavone metabolites: implications for a cardioprotective effect. Brit J Pharmacol 2001; 133: 595-605.
  13. Anderson JW. Diet first, then medication for hypercholesterolmia. J Amer Med Assoc 2003; 290: 531-3.
  14. West SG. Blood pressure and vascular effects of soya: how strong is the evidence. Current Topics in Nutraceutical Research 2003; 1: 17-30.
  15. He J. et al. Effect of soyabean protein on blood pressure: a randomized, controlled trial. Ann. Int. Med 2005, 143 (1):1-9.