Table 1.

Epidemiologic studies on soy consumption in association with colorectal cancer risk

ReferenceDesignDescription of studySoy food assessedIntake comparison*HR/RR/OR (95% CI)Confounding factors adjusted
Studies that assessed colorectal cancer incidence
Yang et al. 2009 (6)Cohort321 incident cases/68,412 cohort size, Chinese, ChinaSoy foods≤12.8 vs >21.0 g/dColorectalAge, education, household income, physical activity, BMI, menopausal status, family history of colorectal cancer, total caloric intake, and average intakes of fruit, vegetables, red meat, nonsoy calcium, nonsoy fiber, and nonsoy folic acid.
0.67 (0.49-0.90) women
Colon
0.76 (0.52-1.13) women
Rectum
0.55 (0.34- 0.90) women
Wang et al. 2009 (16)Cohort301 incident cases/38,408 cohort size, female U.S. health professionals, United StatesTofu<1 time/mo vs ≥1 time/wkColorectalAge, race, total energy intake, randomized treatment assignment, smoking, alcohol use, physical activity, postmenopausal status, hormone replacement therapy use, multivitamin use, BMI, family history of colorectal cancer, ovary cancer or breast cancer, and intake of fruit and vegetables, fiber, folate and saturated fat.
0.54 (0.20- 1.46) women
Akhter et al. 2008 (17)Cohort886 incident cases/83,063 cohort size, Japanese, JapanSoy foods≤35.4 vs >169.9 g/d, menColorectalAge, public health center area, history of diabetes mellitus, BMI, leisure time physical activity, cigarette smoking, alcohol drinking, and intake of vitamin D, dairy products, meats, vegetable, fruit and fish. Also adjusted for menopausal status and current use of female hormones in women.
0.89 (0.68- 1.17) men
≤35.6 vs >170.3 g/d, women1.04 (0.76-1.42) women
Colon
0.77 (0.55- 1.06) men
1.11 (0.77- 1.60) women
Rectum
1.20 (0.74- 1.95) men
0.90 (0.50- 1.62) women
MisoNever vs. dailyColorectal
0.88 (0.64- 1.10) men
1.03 (0.75- 1.43) women
Oba et al. 2007 (7)Cohort213 incident cases/30,221 cohort size, Japanese, JapanSoy products§≤49.22 vs >141.09 g/d, menColonAge, height, alcohol intake, smoking status, BMI, physical exercise, coffee intake, and use of hormone replacement therapy (women only).
1.24 (0.77- 2.00) men
≤46.29 vs >128.03 g/d, women0.56 (0.34- 0.92) women
Huang et al. 2004 (18)C-C1,352 cases/50,706 controls, Japanese, JapanBean curd<3 vs ≥3 times/wkColorectalAge and sex.
1.11 (0.92- 1.33)
Miso soup<1 time/d vs ≥1 time/dColorectal
0.89 (0.79- 1.00)
Le Marchand et al. 1997 (19)C-C1,192 cases/1,192 controls, multi-ethnic, United StatesTofu0 vs ≥25 g/dColorectalAge, family history of colorectal cancer, alcoholic drink per week, pack-years of cigarette smoking, lifetime recreational activity, Quetelet index 5 y earlier, total calories, egg and calcium intake.
1.0 (0.6-1.6) men
0.9 (0.5-1.5) women
Nishi et al. 1997 (20)C-C330 cases/660 controls, Japanese, JapanTofu<3 vs ≥3 times/wkColonAge, sex and registered residence.
0.79 (0.55- 1.13)
Rectum
1.02 (0.67- 1.53)
Miso soup<3 times/d vs 3 times/dColon
0.69 (0.42- 1.16)
Rectum
0.93 (0.54- 1.60)
Witte et al. 1996 (21)C-C488 cases/488 controls, multi-ethnic, United StatesTofu or soybeansNone vs ≥1 serving/wkColorectalRace, BMI, physical activity, smoking, calories, saturated fat, dietary fiber, folate, β-carotene and vitamin C.
0.55 (0.27- 1.11)
Inoue et al. (1995) (ref. 22)C-C432 cases/31,782 controls, Japanese, JapanBean curd≤3 vs >3 times/wkProximal colonAge.
0.9 (0.5-1.6) men
1.3 (0.7-2.4) women
Distal colon
1.7 (1.0-2.6) men
0.6 (0.4-1.0) women
Rectum
1.2 (0.8-1.7) men
0.9 (0.6-1.5) women
Soybean paste soup≤3 times/wk vs >3 times/wkProximal colon
1.2 (0.6-2.2) men
0.8 (0.4-1.4) women
Distal colon
0.7 (0.4-1.1) men
0.8 (0.5-1.3) women
Rectum
0.8 (0.6-1.2) men
1.1 (0.7-1.8) women
Hoshiyama et al. 1993 (23)C-C181 cases/653 controls, Japanese, JapanSoybean products≤4 vs ≥8 times/wkColonSex and age for colon cancer and selected food items, sex and age for rectal cancer.
0.6 (0.3-1.3)
Rectum
0.4 (0.2-1.0)
Miso soup<1 cup/d vs ≥2 cups/dColon
1.9 (0.8-4.4)
Rectum
0.8 (0.4-1.6)
Kono et al. 1993 (24)C-C187 cases/1,557 controls, Japanese, JapanSoy paste soup<1 vs ≥2 bowls/dColonSmoking, alcohol use, rank and BMI.
0.87 (0.55-1.37)
Studies that assessed colorectal cancer mortality
Iso and Kubota 2007 (25)Cohort648 incident cases/104,742 cohort size, Japanese, JapanTofu<3 vs ≥5 times/wkColonAge and area of study.
1.12 (0.78-1.62) men
0.87 (0.60-1.26) women
Rectum
1.21 (0.81-1.83) men
1.00 (0.60-1.68) women
Miso1 bowl/d vs ≥2 bowls/dColon
0.81 (0.56-1.17) men
0.82 (0.57-1.18) women
Rectum
0.81 (0.54-1.23) men
0.93 (0.52-1.66) women
Khan et al. 2004 (26)Cohort3,158 cohort size Japanese, JapanSoybean curd≤several times/m vs ≥several times/wkColorectalAge and smoking status for men; age, health status, health education, health screening and smoking status for women.
1.5 (0.2-11.2) men
0.9 (0.1-6.9) women
Hirayama 1990 (27)Cohort265,118 cohort size, Japanese, JapanSoybean paste soupNondaily vs dailyColonAge and sex.
1.13 (0.97-1.32)
Rectum
1.04 (0.89-1.21)
Ho et al. 2006 (28)C-C870 cases/10,178 controls, Chinese, Hong KongSoy products**<1 time/m vs ≥4 times/wkColorectalAge, educational attainment, leisure exercise, job type, alcohol consumption, smoking habits and consumption frequency of fruits, dairy products and Chinese tea.
0.66 (0.40-1.08) men
0.47 (0.28-0.81) women

NOTE: If not specified, data are from both genders.

Abbreviations: HR, hazard ratio; RR, relative risk; C-C, case-control; BMI, body mass index.

  • *The highest reported category of intake compared with the lowest category of intake.

  • Soy foods: soy milk, tofu, fried tofu, dried or pressed tofu, fresh green soy beans, dry soy beans, soy sprouts, and other soy products.

  • Tofu, pre-drained tofu, freeze-dried tofu, deep-fried tofu, fermented soybean and soymilk.

  • §Tofu, miso, soybeans, natto, soymilk, okara, dried tofu, fried tofu, deep-fried tofu, and fried tofu with minced vegetables/seaweed.

  • Not specified.

  • Incident cases not reported.

  • **Not specified.