This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.
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Introduction: Some case-control studies have suggested soy products may lower the risk of breast cancer. However, findings from large prospective cohort studies have been mixed. As a result, the potential benefit of a high soy diet on breast cancer risk remains unclear. The topic is under active study.
Read our perspective on soy and the risk breast cancer.
Learn more about soy and breast cancer risk.
Learn about the strengths and weaknesses of different types of studies.
See how this risk factor compares with other risk factors for breast cancer.
Study selection criteria: Prospective cohort studies and case-control studies with at least 400 breast cancer cases, meta-analyses and pooled analyses.
Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
Study
|
Study Population
(number of participants)
|
Dietary Soy Intake
(categories compared)
|
Relative Risk of Breast Cancer in Women with High versus Low Dietary Intake of Soy Products,
RR (95% CI)
|
Prospective cohort studies
|
Butler et al. [1]
|
34,028
(629 cases)
|
Soy food intake:
High vs. Low
|
0.83
(0.62-1.11)
|
Lee et al. [2]
|
73,223
(592 cases)
|
Soy protein intake in adulthood:
12.8 or more vs.
4.9 or fewer g/day
|
All women:
0.89
(0.66-1.15)
Premenopausal:
0.41
(0.25-0.70)
Postmenopausal:
1.22
(0.87-1.71)
|
| |
|
Soy protein intake in adolescence:
11.3 or more vs.
2.8 or fewer g/day
|
All women:
0.97
(0.75-1.27)
Premenopausal:
0.57
(0.34-0.97)
Postmenopausal:
1.20
(0.87-1.65)
|
Travis et al. [3]
|
37,643
(585 cases)
|
Soy food plus soy milk intake:
More than 20 mg/day vs.
Less than 10 mg/day
|
1.17
(0.79-1.71)
|
Key et al. [4]
|
34,759
(427 cases)
|
Tofu intake:
5 or more vs.
1 or fewer times/week
|
1.07
(0.78-1.47)
|
| |
|
Miso soup intake:
5 or more times/week vs. Never
|
0.87
(0.68-1.120)
|
| |
|
Total intake of miso soup and tofu:
High vs. Low
|
0.94
(0.73-1.20)
|
Case-control studies
|
| |
Cases
|
Controls
|
|
|
Zaineddin et al. [5]
|
2,884
|
5,509
|
Tofu intake:
High vs. None
|
0.89
(0.73-1.07)
|
| |
|
|
Soy milk intake:
High vs. None
|
0.94
(0.75-1.18)
|
Sanderson et al. [6]
|
1,459
|
1,556
|
Soy food intake:
More than12.22 vs.
Less than 6.96 grams/day
|
1.0
(0.7-1.5)
|
Horn-Ross et al. [7]
|
1,326
|
1,657
|
Soy milk intake:
Any vs. None
|
0.57
(0.38-0.85)
|
| |
|
|
Miso soup intake:
1 or more serving/month vs.
None
|
1.1
(0.81-1.50)
|
Hirose et al. [8]
|
1,186
|
21,295
|
Miso soup intake:
Daily vs.
Less than daily
|
1.2
(1.0-1.4)*
|
| |
|
|
Tofu intake:
3 or more times/week vs.
3 or fewer times/month
|
0.78
(0.60-1.00)*
|
Yuan et al. [9]
|
834
|
834
|
Soy protein intake:
High vs. Low
|
1.0
(0.7-1.4)
|
Suzuki et al. [10]
|
678
|
3,390
|
Soy food intake:
High vs. Low
|
0.80
(0.64-0.99)
|
| |
|
|
Tofu intake:
3 or more times/month vs.
3 or fewer times/week
|
0.89
(0.72-1.12)
|
Korde et al. [11]
|
597
|
966
|
Soy food intake during adulthood:
1.5 or more vs.
0 to <1 times/week
|
0.76
(0.56-1.02)
|
| |
|
|
Soy food intake during adolescence:
1.5 or more vs.
0 to <1 times/week
|
0.80
(0.59-1.08)
|
Wu et al. [12]
|
501
|
594
|
Soy food intake during adulthood:
High vs. Low
|
0.61
(0.39-0.97)
|
| |
|
|
Tofu intake during adolescence:
4 or more times/week vs.
Less than monthly
|
0.65
(0.38-1.10)
|
Zhang et al. [13]
|
438
|
438
|
Soy protein intake:
High vs. Low
|
0.62
(0.40-0.96)
|
Pooled and meta-analyses
|
Trock et al. [14]
|
981,379
|
Multiple measures of dietary soy intake:
High vs. Low
|
0.86
(0.75-0.99)†
|
| |
|
Per one gram increase of soy protein intake
|
0.97
(0.94-1.00)‡
|
Qin et al. [15]
|
21 studies
|
Total soy food intake:
High vs. Low
|
0.75
(0.59-0.95)
|
| |
|
Total tofu intake:
High vs. Low |
0.78
(0.69-0.88)
|
| |
|
Total miso intake:
High vs. Low |
0.88
(0.78-1.00)
|
Wu et al. [16]
|
8 studies
(Asian and Asian American women only)
|
Total soyfood intake:
20 or more vs.
5 or fewer mg/day
|
0.71
(0.60-0.85) |
| |
|
Total soyfood intake:
10-20 vs.
5 or fewer mg/day
|
0.88
(0.78-0.98) |
| |
11 studies
(Western women only)
|
Total soyfood intake:
0.8 or more mg/day vs.
0.2 or fewer mg/day
|
1.04
(0.97-1.11) |
Dong et al. [17]
|
14 studies
|
Total soy food intake:
High vs. Low
|
0.89
(0.79-0.99)
|
Study
|
Study Population
(number of participants)
|
Soy Supplement Intake
(categories compared)
|
Relative Risk of Breast Cancer in Women with High versus Low Intake of Soy Supplements,
RR (95% CI)
|
Propsective cohort studies
|
VITAL [18]
|
35,016
(880 cases)
|
Users vs. Non-users
|
1.04
(0.74-1.48)
|
* Relative risks for postmenopausal women. Relative risk among premenopausal women was also not statistically significant, 0.76 (0.45-1.67).
† Relative risks are for pre- and postmenopausal women combined. For premenopausal women relative risk was 0.70 (0.58-0.85). For postmenopausal women, relative risk was 0.77 (0.60-0.98). Authors caution interpreting a protective effect due to potential problems with measures of soy intake and lack of a dose-response relationship between soy and breast cancer risk.
‡ Relative risks are for all women. For premenopausal women relative risk was 0.94 (0.92-0.96), and for postmenopausal women, relative risk was 0.95 (0.89-1.00). Authors caution interpreting a protective effect due to potential problems with measures of soy intake and lack of a dose-response relationship between soy and breast cancer risk.
References
- Butler LM, Wu AH, Wang R, Koh WP, Yuan JM, Yu MC. A vegetable-fruit-soy dietary pattern protects against breast cancer among postmenopausal Singapore Chinese women. Am J Clin Nutr. 91(4):1013-9, 2010.
- Lee SA, Shu XO, Li H, et al. Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women's Health Study. Am J Clin Nutr. 89(6):1920-6, 2009.
- Travis RC, Allen NE, Appleby PN, Spencer EA, Roddam AW, Key TJ. A prospective study of vegetarianism and isoflavone intake in relation to breast cancer risk in British women. Int J Cancer.122(3):705-10, 2008.
- Key TJ, Appleby PN, Beral V, et al. Soya foods and breast cancer risk: a prospective study in Hiroshima and Nagasaki, Japan. Br J Cancer. 81(7):1248-1256, 1999.
- Zaineddin AK, Buck K, Vrieling A, et al. The association between dietary lignans, phytoestrogen-rich foods, and fiber intake and postmenopausal breast cancer risk: a German case-control study. Nutr Cancer. 64(5):652-65, 2012.
- Sanderson M, Shu XO, Yu H, et al. Insulin-like growth factor-I, soy protein intake, and breast cancer risk. Nutr Cancer. 50(1):8-15, 2004.
- Horn-Ross PL, John EM, Lee M, et al. Phytoestrogen consumption and breast cancer risk in a multiethnic population: the Bay Area Breast Cancer Study. Am J Epidemiol. 154(5):434-41, 2001.
- Hirose K, Tajima K, Hamajima N, et al. A large-scale, hospital-based case-control study of risk factors of breast cancer according to menopausal status. Jpn J Cancer Res. 86(2):146-54, 1995.
- Yuan JM, Wang QS, Ross RK, et al. Diet and breast cancer in Shanghai and Tianjin, China. Br J Cancer. 71(6):1353-8, 1995.
- Suzuki T, Matsuo K, Tsunoda N, et al. Effect of soybean on breast cancer according to receptor status: a case-control study in Japan. Int J Cancer. 123(7):1674-80, 2008.
- Korde LA, Wu AH, Fears T, et al. Childhood soy intake and breast cancer risk in Asian American women. Cancer Epidemiol Biomarkers Prev. 18(4):1050-9, 2009.
- Wu AH, Wan P, Hankin J, Tseng CC, Yu MC, Pike MC. Adolescent and adult soy intake and risk of breast cancer in Asian-Americans. Carcinogenesis. 23(9):1491-6, 2002.
- Zhang C, Ho SC, Lin F, Cheng S, Fu J, Chen Y. Soy product and isoflavone intake and breast cancer risk defined by hormone receptor status. Cancer Sci. 101(2):501-7, 2010.
- Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-analysis of soy intake and breast cancer risk. J Natl Cancer Inst. 98(7):459-71, 2006.
- Qin LQ, Xu JY, Wany PY, Hoshi K. Soyfood intake in the prevention of breast cancer risk in women: a meta-analysis of observational epidemiological studies. J Nutr Sci Vitaminol (Tokyo). 52(6):428-36, 2006.
- Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 98(1):9-14, 2008.
- Dong JY, Qin LQ. Soy isoflavones consumption and risk of breast cancer incidence or recurrence: a meta-analysis of prospective studies. Breast Cancer Res Treat. 125(2):315-23, 2011.
- Brasky TM, Lampe JW, Potter JD, Patterson RE, White E. Specialty supplements and breast cancer risk in the VITamins And Lifestyle (VITAL) Cohort. Cancer Epidemiol Biomarkers Prev. 19(7):1696-708, 2010.
Updated 08/13/12
