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Recommendations Summary

HTN: Soy Foods 2008

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.

• Recommendation(s)

  Soy Foods

  Advise that the consumption of soy foods may or may not be beneficial for the reduction of blood pressure, since the effect of increased soy food intake on blood pressure is unclear.

  Rating: Weak
  Imperative

  • Risks/Harms of Implementing This Recommendation

    None.

  • Conditions of Application

    No conditions specified.

  • Potential Costs Associated with Application

    None.

  • Recommendation Narrative

    • In nine randomized trials, supplemented daily soy protein intake ranged from 18g to 40g per day or 70mg to 143mg per day of isoflavones for one month to one year; two of these studies included soy milk and yogurt.  While four of the nine trials reported no effect of soy or isoflavone intake on blood pressure (Jayagopal et al, 2002; Meyer et al, 2004; Hermansen et al, 2005; Kreijkamp-Kaspers et al, 2005) and one reported an increase in systolic blood pressure in women (Harrison et al, 2004), four trials reported that soy or isoflavone intake decreased systolic blood pressure by 4.3 to 18.4mm Hg and diastolic blood pressure by 2.8 to 15.9 mmHg (Teede et al, 2001; Rivas et al, 2002; Sagara et al, 2004; He et al, 2005). 
    • Cohort and cross-sectional studies reported conflicting findings between increased soy and isoflavone intake and reductions in blood pressure (Goodman-Gruen et al, 2001; Nagata et al, 2003; Yang et al, 2005).

  • Recommendation Strength Rationale

    • Conclusion Statement is Grade III

  • Minority Opinions

    Consensus reached.

• Supporting Evidence

  The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).

  What is the relationship between soy food intake and blood pressure in healthy and hypertensive adults?

  • References

    Goodman-Gruen D, Kritz-Silverstein D. Usual dietary isoflavone intake is associated with cardiovascular disease risk factors in postmenopausal women. J Nutr. 2001; 131: 1,202-1,206.
    
    Harrison RA, Sagara M, Rajura A, Armitage L, Birt N, Birt CA, Yaori Y, Can foods with added soy-protein or fish-oil reduce risk factors for coronary disease? A factorial randomised controlled trial, Nutr Metab Cardiovasc Dis. 2004, 14: 344-350.
    
    He J, Gu D, Wu X, Chen J, Duan X, Chen J, Whelton PK. Effect of soybean protein on blood pressure: A randomized, controlled trial. Ann Int Med. 2005; 143: 1-9. 
    
    Hermansen K, Hansen B, Jacobsen R, Clausen P, Dalgaard M, Dinesen B, Holst JJ, Pedersen E, Astrup A. Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects. Eur J Clin Nutr. 2005; 59: 843-850.
    
    Jayagopal V, Albertazzi P, Kilpatrick ES, Howarth EM, Jennings PE, Hepburn DA, Atkin SL. Beneficial effects of soy phytoestrogen intake in postmenopausal women with type 2 diabetes. Diabetes Care, 2002; 25: 1,709-1,714.
    
    Kreijkamp-Kaspers S, Kok L, Bots ML, Grobbee DE, Lampe JW, van der Schouw Y. Randomized controlled trial of the effects of soy protein containing isoflavones on vascular function in postmenopausal women. Am J Clin Nutr. 2005; 81: 189-195.
    
    Meyer BJ, Larkin TA, Owen AJ, Astheimer LB, Tapsell LC, Howe PRC. Limited lipid-lowering efects of regular consumption of whole soybean foods. Ann Nutr Metab. 2004; 49: 67-78.
    
    Nagata C, Shimizu H, Takami R, Hayashi M, Takeda N, Yasuda K. Association of blood pressure with intake of soy products and other food groups in Japanese men and women. Prev Med. 2003: 36: 692-697.  
    
    Rivas M, Garay RP, Escanero JF, Cia P, Cia P, Alda JO. Soy milk lowers blood pressure in men and women with mild to moderate essential hypertension. J Nutr. 2002; 132: 1,900-1,902.
    
    Sacks FM, Lichtenstein A, Van Horn L, Harris W, Kris-Etherton P, Winston M. Soy protein, isoflavones, and cardiovascular health: An American Heart Association science advisory for professionals from the Nutrition Committee. Circulation. 2006; 113: 1,034-1,044.
    
    Sagara M, Kanda T, Jelekera MN, Teramoto T, Armitage L, Birt N, Birt C, Yamori Y. Effects of dietary intake of soy protein and isoflavones on cardiovascular disease risk factors in high risk, middle-aged men in Scotland. J Am Coll Nutr. 2003; 23 (1): 85-91.
    
    Teede HJ, Dalais FS, Kotsopoulos D, Liang Y, Davis S, McGrath BP. Dietary soy has both beneficial and potentially adverse cardiovascular effects: A placebo-controlled study in men and postmenopausal women. The Journal of Clinical Endocrinology and Metabolism, 2001; 86: 3,053-3,060. 
    
    Yang G, Shu X-O, Jin F, Zhang X, Li H-L, Li Q, Gao Y-T, Zheng W. Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women. Am J Clin Nutr. 2005: 81: 1,012-1,017. 

  • References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process

    None.