Skip to main content Accessibility help

Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials

  • Jia-Yi Dong (a1), Xing Tong (a1), Zhi-Wei Wu (a1), Peng-Cheng Xun (a2) (a3), Ka He (a2) and Li-Qiang Qin (a1)...


Observational studies have indicated that soya food consumption is inversely associated with blood pressure (BP). Evidence from randomised controlled trials (RCT) on the BP-lowering effects of soya protein intake is inconclusive. We aimed to evaluate the effectiveness of soya protein intake in lowering BP. The PubMed database was searched for published RCT in the English language through to April 2010, which compared a soya protein diet with a control diet. We conducted a random-effects meta-analysis to examine the effects of soya protein on BP. Subgroup and meta-regression analyses were performed to explore possible explanations for heterogeneity among trials. Meta-analyses of twenty-seven RCT showed a mean decrease of 2·21 mmHg (95 % CI − 4·10, − 0·33; P = 0·021) for systolic BP (SBP) and 1·44 mmHg (95 % CI − 2·56, − 0·31; P = 0·012) for diastolic BP (DBP), comparing the participants in the soya protein group with those in the control group. Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet. Meta-regression analyses further revealed a significantly inverse association between pre-treatment BP and the level of BP reductions. In conclusion, soya protein intake, compared with a control diet, significantly reduces both SBP and DBP, but the BP reductions are related to pre-treatment BP levels of subjects and the type of control diet used as comparison.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials
      Available formats

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials
      Available formats

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials
      Available formats


Corresponding author

*Corresponding author: L.-Q. Qin, fax +86 512 65880050, email


Hide All
1 Kearney, PM, Whelton, M, Reynolds, K, et al. (2005) Global burden of hypertension: analysis of worldwide data. Lancet 365, 217223.
2 Wolf-Maier, K, Cooper, RS, Banegas, JR, et al. (2003) Hypertension prevalence and blood pressure levels in 6 European countries, Canada, and the United States. JAMA 289, 23632369.
3 Rivas, M, Garay, RP, Escanero, JF, et al. (2002) Soy milk lowers blood pressure in men and women with mild to moderate essential hypertension. J Nutr 132, 19001902.
4 Teede, HJ, Giannopoulos, D, Dalais, FS, et al. (2006) Randomised, controlled, cross-over trial of soy protein with isoflavones on blood pressure and arterial function in hypertensive subjects. J Am Coll Nutr 25, 533540.
5 Welty, FK, Lee, KS, Lew, NS, et al. (2007) Effect of soy nuts on blood pressure and lipid levels in hypertensive, prehypertensive, and normotensive postmenopausal women. Arch Intern Med 167, 10601067.
6 Hooper, L, Kroon, PA, Rimm, EB, et al. (2008) Flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials. Am J Clin Nutr 88, 3850.
7 Llaneza, P, Gonzalez, C, Fernandez-Inarrea, J, et al. (2010) Soy isoflavones, Mediterranean diet, and physical exercise in postmenopausal women with insulin resistance. Menopause 17, 372378.
8 Chan, YH, Lau, KK, Yiu, KH, et al. (2008) Reduction of C-reactive protein with isoflavone supplement reverses endothelial dysfunction in patients with ischaemic stroke. Eur Heart J 29, 28002807.
9 Khaodhiar, L, Ricciotti, H, Li, L, et al. (2008) Daidzein-rich isoflavone aglycones are potentially effective in reducing hot flashes in menopausal women. Menopause 15, 125132.
10 Nagata, C, Shimizu, H, Takami, R, et al. (2003) Association of blood pressure with intake of soy products and other food groups in Japanese men and women. Prev Med 36, 692697.
11 Yang, G, Shu, XO, Jin, F, et al. (2005) Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women. Am J Clin Nutr 81, 10121017.
12 Pan, A, Franco, OH, Ye, J, et al. (2008) Soy protein intake has sex-specific effects on the risk of metabolic syndrome in middle-aged and elderly Chinese. J Nutr 138, 24132421.
13 Teede, HJ, Dalais, FS, Kotsopoulos, D, et al. (2001) Dietary soy has both beneficial and potentially adverse cardiovascular effects: a placebo-controlled study in men and postmenopausal women. J Clin Endocrinol Metab 86, 30533060.
14 He, J, Gu, D, Wu, X, et al. (2005) Effect of soybean protein on blood pressure: a randomized, controlled trial. Ann Intern Med 143, 19.
15 Jadad, AR, Moore, RA, Carroll, D, et al. (1996) Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 17, 112.
16 Follmann, D, Elliott, P, Suh, I, et al. (1992) Variance imputation for overviews of clinical trials with continuous response. J Clin Epidemiol 45, 769773.
17 Higgins, JP, Thompson, SG, Deeks, JJ, et al. (2003) Measuring inconsistency in meta-analyses. BMJ 327, 557560.
18 Begg, CB & Mazumdar, M (1994) Operating characteristics of a rank correlation test for publication bias. Biometrics 50, 10881101.
19 Egger, M, Davey Smith, G, Schneider, M, et al. (1997) Bias in meta-analysis detected by a simple, graphical test. BMJ 315, 629634.
20 Kurowska, EM, Jordan, J, Spence, JD, et al. (1997) Effects of substituting dietary soybean protein and oil for milk protein and fat in subjects with hypercholesterolemia. Clin Invest Med 20, 162170.
21 Washburn, S, Burke, GL, Morgan, T, et al. (1999) Effect of soy protein supplementation on serum lipoproteins, blood pressure, and menopausal symptoms in perimenopausal women. Menopause 6, 713.
22 Burke, V, Hodgson, JM, Beilin, LJ, et al. (2001) Dietary protein and soluble fiber reduce ambulatory blood pressure in treated hypertensives. Hypertension 38, 821826.
23 Hermansen, K, Sondergaard, M, Hoie, L, et al. (2001) Beneficial effects of a soy-based dietary supplement on lipid levels and cardiovascular risk markers in type 2 diabetic subjects. Diabetes Care 24, 228233.
24 Jayagopal, V, Albertazzi, P, Kilpatrick, ES, et al. (2002) Beneficial effects of soy phytoestrogen intake in postmenopausal women with type 2 diabetes. Diabetes Care 25, 17091714.
25 Jenkins, DJ, Kendall, CW, Jackson, CJ, et al. (2002) Effects of high- and low-isoflavone soyfoods on blood lipids, oxidized LDL, homocysteine, and blood pressure in hyperlipidemic men and women. Am J Clin Nutr 76, 365372.
26 Allison, DB, Gadbury, G, Schwartz, LG, et al. (2003) A novel soy-based meal replacement formula for weight loss among obese individuals: a randomized controlled clinical trial. Eur J Clin Nutr 57, 514522.
27 Cuevas, AM, Irribarra, VL, Castillo, OA, et al. (2003) Isolated soy protein improves endothelial function in postmenopausal hypercholesterolemic women. Eur J Clin Nutr 57, 889894.
28 Meyer, BJ, Larkin, TA, Owen, AJ, et al. (2004) Limited lipid-lowering effects of regular consumption of whole soybean foods. Ann Nutr Metab 48, 6778.
29 Puska, P, Korpelainen, V, Hoie, LH, et al. (2004) Isolated soya protein with standardised levels of isoflavones, cotyledon soya fibres and soya phospholipids improves plasma lipids in hypercholesterolaemia: a double-blind, placebo-controlled trial of a yoghurt formulation. Br J Nutr 91, 393401.
30 Sagara, M, Kanda, T, Njelekera, M, et al. (2004) 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 23, 8591.
31 Anderson, JW & Hoie, LH (2005) Weight loss and lipid changes with low-energy diets: comparator study of milk-based versus soy-based liquid meal replacement interventions. J Am Coll Nutr 24, 210216.
32 Hermansen, K, Hansen, B, Jacobsen, R, et al. (2005) Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects. Eur J Clin Nutr 59, 843850.
33 Kreijkamp-Kaspers, S, Kok, L, Bots, ML, et al. (2005) Randomized controlled trial of the effects of soy protein containing isoflavones on vascular function in postmenopausal women. Am J Clin Nutr 81, 189195.
34 Lukaczer, D, Liska, DJ, Lerman, RH, et al. (2006) Effect of a low glycemic index diet with soy protein and phytosterols on CVD risk factors in postmenopausal women. Nutrition 22, 104113.
35 Anderson, JW, Fuller, J, Patterson, K, et al. (2007) Soy compared to casein meal replacement shakes with energy-restricted diets for obese women: randomized controlled trial. Metabolism 56, 280288.
36 Azadbakht, L, Kimiagar, M, Mehrabi, Y, et al. (2007) Soy inclusion in the diet improves features of the metabolic syndrome: a randomized crossover study in postmenopausal women. Am J Clin Nutr 85, 735741.
37 Matthan, NR, Jalbert, SM, Ausman, LM, et al. (2007) Effect of soy protein from differently processed products on cardiovascular disease risk factors and vascular endothelial function in hypercholesterolemic subjects. Am J Clin Nutr 85, 960966.
38 Santo, AS, Cunningham, AM, Alhassan, S, et al. (2008) NMR analysis of lipoprotein particle size does not increase sensitivity to the effect of soy protein on CVD risk when compared with the traditional lipid profile. Appl Physiol Nutr Metab 33, 489500.
39 Wong, JM, Kendall, CW, de Souza, R, et al. (2010) The effect on the blood lipid profile of soy foods combined with a prebiotic: a randomized controlled trial. Metabolism 59, 13311340.
40 McInnes, GT (2005) Lowering blood pressure for cardiovascular risk reduction. J Hypertens Suppl 23, S3S8.
41 Anderson, JW, Johnstone, BM & Cook-Newell, ME (1995) Meta-analysis of the effects of soy protein intake on serum lipids. N Engl J Med 333, 276282.
42 Zhan, S & Ho, SC (2005) Meta-analysis of the effects of soy protein containing isoflavones on the lipid profile. Am J Clin Nutr 81, 397408.
43 Kris-Etherton, PM, Grieger, JA, Hilpert, KF, et al. (2009) Milk products, dietary patterns and blood pressure management. J Am Coll Nutr 28, Suppl. 1, 103S119S.
44 Appel, LJ, Sacks, FM, Carey, VJ, et al. (2005) Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial. JAMA 294, 24552464.
45 Hodgson, JM, Burke, V, Beilin, LJ, et al. (2006) Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons. Am J Clin Nutr 83, 780787.
46 Thompson, SG (1994) Why sources of heterogeneity in meta-analysis should be investigated. BMJ 309, 13511355.
47 Squadrito, F, Altavilla, D, Squadrito, G, et al. (2000) Genistein supplementation and estrogen replacement therapy improve endothelial dysfunction induced by ovariectomy in rats. Cardiovasc Res 45, 454462.
48 Dudasova, S & Grancicova, E (1992) Influence of casein and soy flour proteins on aminoacid content in the liver of experimental animals. Physiol Res 41, 411416.
49 Kim, JI, Kim, JC, Kang, MJ, et al. (2005) Effects of pinitol isolated from soybeans on glycaemic control and cardiovascular risk factors in Korean patients with type II diabetes mellitus: a randomized controlled study. Eur J Clin Nutr 59, 456458.
50 Setchell, KD, Brown, NM & Lydeking-Olsen, E (2002) The clinical importance of the metabolite equol – a clue to the effectiveness of soy and its isoflavones. J Nutr 132, 35773584.
51 Tormala, RM, Appt, S, Clarkson, TB, et al. (2007) Individual differences in equol production capability modulate blood pressure in tibolone-treated postmenopausal women: lack of effect of soy supplementation. Climacteric 10, 471479.



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed