Soy Food Intake Research Articles

Prediagnosis Soy Food Consumption and Lung Cancer Survival in Women

We recently reported an inverse association between soy food intake and lung cancer risk among nonsmoking women. The effect size for aggressive lung cancers was larger than that observed for other types of lung cancer. Therefore, we hypothesized that soy consumption may favorably affect the overall survival of patients with lung cancer. This analysis included 444 women with incident lung cancer identified from the Shanghai Women's Health Study. Prediagnosis soy food intake was assessed at enrollment and reassessed 2 years later. Proportional hazards models were used to evaluate the association between soy food intake and overall survival. Of the 444 patients with lung cancer, 318 died during follow-up. Initial analyses including all patients showed that higher intake of soy food was associated with better overall survival after adjusting for demographic and lifestyle characteristics and other nonclinical factors. Larger effect sizes for the association were found after additional adjustment for tumor stage and treatment in analyses including 301 patients with data available on these clinical factors. Compared with the median intake of soy food, fully adjusted hazard ratios for total mortality associated with the 10th, 30th, 70th, and 90th percentiles of intake were 1.81 (95% CI, 1.26 to 2.59), 1.25 (95% CI, 1.09 to 1.42), 0.88 (95% CI, 0.80 to 0.97), and 0.89 (95% CI, 0.68 to 1.16), respectively. Similar inverse associations were observed for dietary isoflavone intake. This study suggests, to the best of our knowledge for the first time, that, among women with lung cancer, prediagnosis intake of soy food is associated with better overall survival.

Soy food intake and risk of lung cancer: evidence from the Shanghai Women's Health Study and a meta-analysis.

The authors prospectively evaluated the association of soy food intake with lung cancer risk, overall and by tumor aggressiveness, and performed a meta-analysis of published data. Included in the analysis were 71,550 women recruited into the Shanghai Women's Health Study (Shanghai, China) in 1997-2000. Usual soy food intake was assessed at baseline and reassessed during follow-up through in-person interviews. During a mean follow-up period of 9.1 years, 370 incident lung cancer cases were identified; 340 patients were lifetime never smokers. After adjustment for potential confounders, soy food intake was inversely associated with subsequent risk of lung cancer (P(trend) = 0.004); the hazard ratio for the highest quintile of intake compared with the lowest was 0.63 (95% confidence interval: 0.44, 0.90). This inverse association appeared predominately among women with later age at menopause (P(interaction) = 0.01) and for aggressive lung cancer as defined by length of survival (<12 months vs. ≥12 months; P(heterogeneity) = 0.057). Meta-analysis of 7 studies conducted among nonsmokers found a summary relative risk of 0.59 (95% confidence interval: 0.49, 0.71) for the highest categories of soy or isoflavone intake versus the lowest. This study suggests that soy food consumption may reduce lung cancer risk in nonsmoking women, particularly for aggressive tumors, and its effect may be modified by endogenous estrogens.

Soy food intake after diagnosis of breast cancer and survival: an in-depth analysis of combined evidence from cohort studies of US and Chinese women

Soy isoflavones have antiestrogenic and anticancer properties but also possess estrogen-like properties, which has raised concern about soy food consumption among breast cancer survivors. We prospectively evaluated the association between postdiagnosis soy food consumption and breast cancer outcomes among US and Chinese women by using data from the After Breast Cancer Pooling Project. The analysis included 9514 breast cancer survivors with a diagnosis of invasive breast cancer between 1991 and 2006 from 2 US cohorts and 1 Chinese cohort. Soy isoflavone intake (mg/d) was measured with validated food-frequency questionnaires. HRs and 95% CIs were estimated by using delayed-entry Cox regression models, adjusted for sociodemographic, clinical, and lifestyle factors. After a mean follow-up of 7.4 y, we identified 1171 total deaths (881 from breast cancer) and 1348 recurrences. Despite large differences in soy isoflavone intake by country, isoflavone consumption was inversely associated with recurrence among both US and Chinese women, regardless of whether data were analyzed separately by country or combined. No heterogeneity was observed. In the pooled analysis, consumption of ≥10 mg isoflavones/d was associated with a nonsignificant reduced risk of all-cause (HR: 0.87; 95% CI: 0.70, 1.10) and breast cancer-specific (HR: 0.83; 95% CI: 0.64, 1.07) mortality and a statistically significant reduced risk of recurrence (HR: 0.75; 95% CI: 0.61, 0.92). In this large study of combined data on US and Chinese women, postdiagnosis soy food consumption of ≥10 mg isoflavones/d was associated with a nonsignificant reduced risk of breast cancer-specific mortality and a statistically significant reduced risk of recurrence.

Soy Food Intake and Circulating Levels of Inflammatory Markers in Chinese Women

BackgroundSoy and some of its constituents, such as isoflavones, have been shown to affect the inflammatory process in animal studies. The association between soy food intake and inflammatory markers has not been evaluated adequately in humans. ObjectiveOur aim was to evaluate whether higher intake of soy foods was inversely associated with inflammatory markers in 1,005 middle-aged Chinese women. DesignIn this cross-sectional study, dietary intake of soy foods was assessed by a validated food frequency questionnaire and by a 24-hour recall when biospecimens were procured. A general linear model was used to estimate the geometric means of selected inflammatory markers, including interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNFα), soluble IL-6 receptor, soluble GP130, soluble TNF receptors 1 and 2, and C-reactive protein, across categories of soy food intake after adjusting for age, lifestyle and dietary factors, and history of infectious or inflammation-related diseases. ResultsWe found that multivariable-adjusted geometric mean concentrations of IL-6 and TNFα were inversely associated with quintiles of soy food intake, with a difference between the highest and lowest quintiles of 25.5% for IL-6 (P for trend=0.008) and 14% for TNFα (P for trend=0.04). Similar inverse associations were found for TNFα (P for trend=0.003), soluble TNF receptor 1 (P for trend=0.01), soluble TNF receptor 2 (P for trend=0.02), IL-1β (P for trend=0.05), and IL-6 (P for trend=0.04) when soy food consumption was assessed by the frequency of consumption in the preceding 24 hours. No significant associations were found for other markers studied. ConclusionsThis study suggests that soy food consumption is related to lower circulating levels of IL-6, TNFα, and soluble TNF receptors 1 and 2 in Chinese women.

Abstract 646: Soy food intake and risk of lung cancer: Evidence from the Shanghai Women's Health Study and a meta-analysis

Abstract Background: Recent large-scale clinical trials raised concerns regarding increased risk of aggressive lung cancer and lung cancer mortality among users of postmenopausal estrogen therapy. Soy and its phytoestrogens have been shown to act as a natural estrogen antagonist and have cancer-inhibitory activities in experimental studies. Objective: We prospectively evaluated the association of soy food intake with lung cancer risk, overall and by tumor aggressiveness, and perform a meta-analysis of published data. Methods: Included in this analysis were 71,550 women recruited in the Shanghai Women's Health Study, a population-based cohort study. Usual soy food intake was assessed at baseline and re-assessed during follow-up through in-person interviews. Previous studies were identified through a MEDLINE search. Results: During a mean follow-up of 9.1 years, 370 incident lung cancer cases were identified; 340 were lifetime never smokers. After adjustment for potential confounders, soy food intake was inversely associated with subsequent risk of lung cancer; the hazard ratio (HR) for the highest compared with lowest quintile of intake was 0.63 (95% CI: 0.44 - 0.90; P trend = 0.004). This inverse association appeared predominately among women with a later age at menopause (P interaction = 0.01) and varied by tumor aggressiveness as defined by length of survival (&amp;lt;12 versus β12 months), with corresponding HR of 0.49 for more aggressive lung cancer versus 0.76 for less aggressive lung cancer (P heterogeneity = 0.057). Similar inverse associations were observed for isoflavone intake. A meta-analysis of seven studies conducted among never smokers found a summary odds ratio of 0.59 (95% CI: 0.49 - 0.71) for the highest versus lowest categories of soy or isoflavone intake. Conclusion: This study suggests that soy food consumption may reduce lung cancer risk in nonsmoking women, particularly for aggressive lung cancer, and its effect may be modified by endogenous estrogens. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 646. doi:1538-7445.AM2012-646

Abstract P359: Dietary Patterns and Risk of All-Cause and Cause-Specific Mortality in Chinese Men and Women: The Singapore Chinese Health Study

Over the last half century dietary composition has been shown to have a clear role in the development of cardiovascular disease (CVD) and other conditions. Yet, research is limited on overall dietary patterns in relation to all-cause and cause-specific mortality, especially in non-western populations. We aimed to empirically derive dietary patterns and examine their association with all-cause and cause-specific mortality in men and women aged 45-74 enrolled in the Singapore Chinese Health Study from 1993 - 1998. We excluded those with a history of cancer, CVD and diabetes, as well as extreme caloric intakes, leaving 52,584 participants. Participants were followed through December 31, 2009 and 8,359 deaths were identified. Follow-up for mortality is considered virtually complete due to linkage with the national birth and death registry. Included in the baseline assessment was a 165-item food frequency questionnaire specifically developed for and validated in the study population. Two major dietary patterns were identified using principal components analysis; a vegetable, fruit, and soy rich pattern (VFS) and a dim sum and meat rich pattern (DSM). Pattern scores for each participant were calculated and examined with risk of mortality using Cox regression. The VFS dietary pattern with higher intake of vegetables, fruits, and soy foods was inversely associated with risk of death from CVD, cancer, respiratory diseases, and all-causes. The DSM dietary pattern with higher intake of dim sum, meat and processed meat, sweetened foods and beverages and fried foods was associated with a significantly increased risk of death from all causes as well as cause-specific deaths. There was no evidence these results differed by age, sex, education, smoking status, physical activity or BMI. These findings suggest population level shifts towards a more traditional and prudent dietary pattern would have significant impact on not only CVD mortality rates, but also mortality from cancer, respiratory diseases, and possibly other causes. Hazard ratios and 95% confidence intervals of mortality due to cardiovascular disease, cancer, respiratory, and all causes in Chinese men and women according to quintile of dietary pattern score Vegetable, fruit, and soy rich pattern Q1 Q2 Q3 Q4 Q5 Type of Death HR (95% CI) HR (95% CI) HR (95% CI) HR (95% CI) P Trend All Cause 1.0 0.88 (0.83-0.93) 0.79 (0.74-0.85) 0.79 (0.74-0.85) 0.75 (0.70-0.81) &amp;#60;0.0001 CVD 1.0 0.86 (0.77-0.95) 0.73 (0.64-0.82) 0.78 (0.69-0.88) 0.67 (0.58-0.77) &amp;#60;0.0001 Cancer 1.0 0.96 (0.86-1.06) 0.87 (0.78-0.96) 0.88 (0.79-0.99) 0.84 (0.74-0.95) 0.001 Respiratory 1.0 0.74 (0.63-0.87) 0.75 (0.64-0.89) 0.68 (0.56-0.81) 0.66 (0.54-0.80) &amp;#60;0.0001 Dim sum and meat rich pattern Type of Death Q1 Q2 Q3 Q4 Q5 P Trend All Cause 1.0 0.98 (0.92-1.04) 1.03 (0.96-1.10) 1.06 (0.99-1.14) 1.16 (1.07-1.26) &amp;#60;0.0001 CVD 1.0 0.99 (0.88-1.11) 1.04 (0.92-1.17) 1.10 (0.97-1.25) 1.23 (1.06-1.42) 0.003 Cancer 1.0 0.97 (0.87-1.08) 1.00 (0.90-1.12) 1.09 (0.98-1.23) 1.14 (1.00-1.29) 0.01 Respiratory 1.0 1.04 (0.88-1.22) 1.06 (0.89-1.26) 0.88 (0.72-1.06) 1.21 (0.99-1.49) 0.23 -Models adjusted for age, sex, dialect, education, marital status, smoking, physical activity, sleep, BMI and energy intake. -Definition of outcomes: CVD (ICD-9 =394-459, N=2,626), Cancer (ICD-9=140-239, N=3,279), Respiratory (e.g. Influenza, pneumonia, COPD) (ICD-9=480-488, 490-96, N=1,289)

Positive Effects of Soy Isoflavone Food on Survival of Breast Cancer Patients in China

Soy foods are the major source of isoflavones, which are believed to play important roles in genesis of breast cancer and its progression. We here conducted a prospective study to evaluate the association of soy isoflavone food consumption with breast cancer prognosis. A prospective study was performed from January 2004 and January 2006 in China. Trained interviewers conducted face-to-face interviews using a structured questionnaire to collect information on dietary habits and potential confounding factors. The relative risk [hazard ratio (HR)] and 95% CI were calculated from the Cox regression model for all significant predictors from cancer diagnosis to the endpoint of the study (event). After a median follow up of 52.1 months (range, 9-60 months), a total of 79 breast cancer related deaths were recorded in our study, risk being inversely associated with a high intake of soy isoflavone. With an average intake of soy isoflavone above 17.3 mg/day, the mortality of breast cancer can be reduced by about 38-36%. We also found the decreased breast cancer death with high soy protein intake, with a HR (95% CI) of 0.71 (0.52-0.98). Stratified analysis with reference to the ER status, further demonstrated a better prognosis of ER positive breast cancer with a high intake of soy isoflavone (HR 0.59, 0.40-0.93). Our study shows the soy food intake is associated with longer survival and low recurrence among breast cancer patients. A cohort study with a larger sample size and long term follow-up is now needed.

Differential Influence of Dietary Soy Intake on the Risk of Breast Cancer Recurrence Related to HER2 Status

The effects of soy products and isoflavone on breast cancer recurrence were compared according to receptor status including epidermal growth factor receptor-2 (HER2) with 339 Korean women. Dietary intake of soy foods was assessed using a validated food frequency questionnaire with 103 food items. Twenty-five patients experienced breast cancer recurrence, 17 patients were HER2 negative, and 8 patients were HER2 positive. Legume intake (mostly from black soybeans) was inversely associated with the risk of breast cancer recurrence in HER2 negative cancer patients (HR: 0.27, 95% CI: 0.13–0.57, P for trend < 0.01), whereas legume intake was positively associated in HER2 positive cancer patients (P for trend = 0.02). In HER2 negative cancer patients, isoflavone was inversely associated with breast cancer recurrence (HR: 0.23, 95% CI: 0.06–0.89; P for trend = 0.01). Total soy intake was not associated with an increased risk of cancer recurrence. In conclusion, overall soy food intake might not affect the risk of cancer recurrence, but high intake of soy isoflavones increased the risk of cancer recurrence in HER2-positive breast cancer patients. However, further research is needed to confirm these results due to the small number of cancer recurrence events.

Isoflavone intake and risk of gastric cancer: a population-based prospective cohort study in Japan

Isoflavones are structurally similar to 17β-estradiol and may be able to prevent gastric cancer. However, there is contradictory evidence concerning the relation between the intake of soy food, which is rich in isoflavones, and gastric cancer. The association with gastric cancer might differ between isoflavones and soy foods, and research on the effects of isoflavone intake alone on gastric cancer is needed. We investigated the association between isoflavone intake and the incidence of gastric cancer. We conducted a large, population-based prospective study of 39,569 men and 45,312 women aged 45-74 y. Dietary soy and isoflavone intakes were measured by using a validated food-frequency questionnaire in 1995 and 1998. During 806,550 person-years of follow-up, we identified 1249 new gastric cancer cases. Isoflavone intake was not associated with gastric cancer in either men or women. Compared with the lowest quartile, the HR and 95% CI for developing gastric cancer in the fourth quartile of isoflavone intake was 1.00 (0.81, 1.24) for men and 1.07 (0.77, 1.50) for women. In a stratified analysis by exogenous female hormones (women only), however, we found an increasing trend in risk of gastric cancer associated with higher isoflavone intakes among exogenous female hormone users (P-trend = 0.03) but not for nonusers (P-interaction = 0.04). The current study does not support the hypothesis that higher intakes of isoflavones prevent gastric cancer in either men or women.

Relationship of intake of plant-based foods with 6-n-propylthiouracil sensitivity and food neophobia in Japanese preschool children

Diets rich in plant-based foods such as vegetables, fruits and soy foods have been suggested to have beneficial effects on health. However, phytochemicals contained in plant-based foods are generally bitter and acrid. We investigated whether intake of vegetables, fruits and soy foods is associated with sensitivity to bitterness and reluctance to eat new foods (food neophobia) in Japanese preschool children. Subjects of this cross-sectional study were healthy Japanese, 167 boys and 156 girls, aged 4-6 years. Intake of vegetables, fruits and soy foods was estimated from 3-day dietary records. Subjects were classified as either tasters or non-tasters of 6-n-propylthiouracil (PROP) based on their ability to taste 0.56 mmol/l PROP. Information on each child's age, height, weight, food neophobia status and food variety, as well as maternal diet and parental control over the child's eating, was obtained by a parent-administered questionnaire. Food neophobia was assessed using the Child Food Neophobia Scale (CFNS). A high intake of vegetables was significantly associated with a low CFNS score in boys after controlling for covariates (P=0.0008). Among the boys, soy food intake was significantly higher in PROP non-tasters than in tasters, except those with low CFNS scores (P=0.0019). High intake of soy foods was significantly associated with a low neophobia score in PROP tasters but not in non-tasters (P=0.0024). These data suggest that sensitivity to bitter taste and food neophobia may influence the consumption of vegetables and soy foods among Japanese preschool boys.

Abstract 4665: Postdiagnosis soy food intake and breast cancer survival: Report from the After Breast Cancer Pooling Project

Abstract Background: Soy constituents possess anti-estrogenic and other anti-cancer properties. Soy food consumption has been associated with lower risk of development of breast cancer. However, the ability of soy isoflavones to bind to estrogen receptors, stimulate cell proliferation, and potentially interact with tamoxifen therapy, has raised concern about soy food consumption among breast cancer survivors. Two recent reports from China and one report from the US have suggested that postdiagnosis soy intake may improve prognosis among breast cancer survivors. Methods: We evaluated postdiagnosis soy food intake and breast cancer outcomes using data from the After Breast Cancer Pooling Project, which includes 18,312 women diagnosed with invasive primary breast cancer between ages 20 and 83 years and who participated in four prospective cohorts, three from the US and one from Shanghai, China. In two cohorts, information on soy food intake was assessed using food frequency questionnaires designed to capture soy food intake; two cohorts only collected information on two soy foods (tofu and soy milk), and multiple imputation was applied to derive total isoflavone intake based on information gathered by the US study with comprehensive assessment of soy intake. Delayed entry Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of isoflavones with total mortality and breast cancer recurrence, adjusted for age at diagnosis, estrogen receptor/progesterone receptor status, stage, chemotherapy, radiotherapy, hormonal therapy, smoking, body mass index, exercise, race/ethnicity, and education and stratified by study. Analyses included 16,048 women with information on soy food intake. Results: After an average follow-up of 9.2 years, a total of 2,592 deaths and 2,622 recurrences were documented. Mean soy isoflavone intake (mg), as assessed at an average of 13 months postdiagnosis (range: 1-48 months), was 3.2 (standard deviation (SD)=5.8) for US women and 45.9 (SD=38.3) for Chinese women. Pooled analyses based on study-specific deciles showed that, compared with the lowest deciles, higher isoflavone intakes were associated with HRs in the range of 0.85-0.89 for mortality and 0.85-0.83 for recurrence (not all HRs were significant). Corresponding HRs restricted to only US cohorts ranged from 0.84-1.04 for mortality and 0.87-0.88 for recurrence, although none were significant. Using common cut-points for the pooled data including all cohorts, HRs (95% CIs) for the highest intake category (&amp;gt;23 mg/day) vs. the lowest (≤0.48 mg/day) were 0.91 (0.70-1.19) for mortality and 0.85 (0.66-1.11) for recurrence. Additional analyses conducted among non-Asian US women showed a similar pattern. Conclusions: Soy food consumption was not associated with an increased risk of mortality or cancer recurrence among breast cancer survivors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4665. doi:10.1158/1538-7445.AM2011-4665

The Effect of Soy Food Intake on Mineral Status in Premenopausal Women

Soy foods have been substituted for meat in recent years because of proposed health benefits. Research indicates, however, that soy protein and phytate in soy products inhibit the absorption of divalent cations. Our study was primarily designed to determine the effect of consuming two to three servings per day of soy foods, providing ∼19 g protein and ∼36 mg isoflavones, on iron and zinc status in premenopausal women during a 10-weeks period. As secondary outcomes, we also tested the effect of soy foods on biochemical markers of bone and thyroid hormones. Nonsmoking women (18-28 years) without chronic disease, anemia, pregnancy, or irregular menstrual cycles were randomly assigned to either the soy food (SF, n=31) or animal food (AF, n=32) group. Blood and urine samples and 3-day dietary records were collected at baseline and postintervention. At baseline, iron and zinc status, bone markers, and thyroid hormones were not different between groups. After intervention, no significant changes were observed in hemoglobin, transferrin saturation, serum iron, ferritin, or transferrin receptor (TFR) concentrations. Plasma zinc, but not serum alkaline phosphatase, significantly decreased in both groups (-0.8 μmol/L). The change in bone-specific alkaline phosphatase was significant between SF (1.5 U/L) and AF (-0.7 U/L) groups. No significant changes were observed in bone resorption, thyroid-stimulating hormone (TSH), or free thyroxine after soy food intake. Incorporating ∼19 g soy protein from soy foods for 10 weeks had no significant effect on iron or zinc status, bone resorption or formation, or thyroid hormone status in premenopausal women.

Dietary Patterns and Incident Type 2 Diabetes in Chinese Men and Women

OBJECTIVETo empirically derive dietary patterns and examine their association with incident type 2 diabetes.RESEARCH DESIGN AND METHODSWe used data from the Singapore Chinese Health Study, including 43,176 Chinese men and women (aged 45–74 years), free of diabetes, cardiovascular disease, and cancer at baseline (1993–1998) and followed up through 2004. Two major dietary patterns were identified using principal components analysis: a vegetable, fruit, and soy-rich pattern (VFS) and a dim sum and meat-rich pattern (DSM). Pattern scores for each participant were calculated and examined with type 2 diabetes risk using Cox regression.RESULTSThe associations of the two dietary patterns with diabetes risk were modified by smoking status. Neither pattern was associated with risk of diabetes in ever smokers. In never smokers, the VFS dietary pattern was inversely associated with risk of type 2 diabetes. Compared with the lowest quintile of the VFS dietary pattern score, the hazard ratios (HRs) for quintiles 2–5 were 0.91, 0.82, 0.73, and 0.75 (P = 0.0005 for trend). The DSM dietary pattern was positively associated with risk of type 2 diabetes in never smokers, with HRs for quintiles 2–5 of 1.07, 1.25, 1.18, and 1.47 (P < 0.0001 for trend).CONCLUSIONSA dietary pattern with higher intake of vegetables, fruits, and soy foods was inversely associated with risk of incident type 2 diabetes, and a pattern with higher intake of dim sum, meat and processed meat, sweetened foods and beverages, and fried foods was associated with a significantly increased risk of type 2 diabetes in Chinese men and women in Singapore.

Fermented and non‐fermented soy food consumption and gastric cancer in Japanese and Korean populations: A meta‐analysis of observational studies

Soy food is known to contribute greatly to a reduction in the risk of gastric cancer (GC). However, both Japanese and Korean populations have high incidence rates of GC despite the consumption of a wide variety of soy foods. One primary reason is that they consume fermented rather than non-fermented soy foods. In order to assess the varying effects of fermented and non-fermented soy intake on GC risk in these populations, we conducted a meta-analysis of published reports. Twenty studies assessing the effect of the consumption of fermented soy food on GC risk were included, and 17 studies assessing the effect of the consumption of non-fermented soy food on GC risk were included. We found that a high intake of fermented soy foods was significantly associated with an increased risk of GC (odds ratio [OR] = 1.22, 95% confidence interval [CI] = 1.02-1.44, I(2) = 71.48), whereas an increased intake of non-fermented soy foods was significantly associated with a decreased risk of GC (overall summary OR = 0.64, 95% CI = 0.54-0.77, I(2) = 64.27). These findings show that a high level of consumption of non-fermented soy foods, rather than fermented soy foods, is important in reducing GC risk.

Soy food and isoflavone intake and colorectal cancer risk: The Fukuoka Colorectal Cancer Study

Objective. It has been suggested that soy food and isoflavone intake may be protective against the risk of colorectal cancer. However, epidemiologic evidence remains sparse and inconsistent. We addressed this issue in the Fukuoka Colorectal Cancer Study. Material and methods. The study subjects were the 816 incident cases of histologically confirmed colorectal cancer and 815 community controls. Intakes of soy foods and isoflavones were assessed by in-person interview using a computer-assisted dietary method. Logistic regression analysis was applied to estimate odds ratio (OR) and 95% confidence interval (CI) of colorectal cancer with adjustment for dietary intakes of calcium and n-3 polyunsaturated fatty acids as well as for body mass index, physical activity, alcohol use, and other lifestyle factors. Results. Energy-adjusted intakes of soy foods (dry weight) and isoflavones were inversely associated with colorectal cancer risk in men and postmenopausal women, but not in premenopausal women. The multivariate-adjusted OR for the highest versus lowest quintile was 0.65 (95% CI 0.41–1.03, p for trend = 0.03) for soy foods and 0.68 (95% CI 0.42–1.10, p for trend = 0.051) for isoflavones in men. The corresponding values for postmenopausal women were 0.60 (95% CI 0.29–1.25, p for trend = 0.053) and 0.68 (95% CI 0.33–1.40, p for trend = 0.049). The site-specific analysis showed inverse associations of soy foods (p for trend = 0.007) and isoflavones (p for trend = 0.02) with rectal cancer in men. Conclusion. The findings add to epidemiologic evidence for protective effects of soy foods and isoflavones in colorectal carcinogenesis.

Soy consumption is not protective against diabetes in Hawaii: the Multiethnic Cohort

Based on the hypothesis that soy consumption may improve glucose tolerance, we examined the association of soy intake with diabetes risk in the Hawaii component of the Multiethnic Cohort. Among 29 719 Caucasian, 35 141 Japanese American and 10 484 Native Hawaiian men and women, 8564 incident diabetes cases were identified during 14 years of follow-up. Cox regression was used to calculate hazard ratios while adjusting for known confounders with stratifications by sex, ethnicity and weight status. We observed no protective effect of soy food consumption on diabetes risk in this population, which has a wide range of soy intakes though lower than in Asian populations. Indeed, higher soy food intake was associated with a weakly elevated diabetes risk across ethnic groups; the higher risk was limited to overweight and obese individuals. The current findings do not support a protective effect of modest levels of soy food consumption against diabetes.

Soy intake in association with menopausal symptoms during the first 6 and 36 months after breast cancer diagnosis

It has been suggested that soy food and its components may relieve menopausal symptoms (MPS) including hot flashes, night sweats, and vaginal dryness in healthy women. However, little is known about the effect of soy food intake on MPS in women with breast cancer. We examined associations of occurrence of MPS with soy food intake in 4,842 Chinese women aged 20-75 years who had non-metastatic breast cancer and had not used hormone replacement therapy. MPS were assessed at 6 and 36 months after cancer diagnosis using a standardized questionnaire, and associations with soy food intake were evaluated in multivariate regression analyses. Daily soy food intake was assessed at 6 months postdiagnosis and over the first 36 months postdiagnosis using a validated food frequency questionnaire. The prevalence of MPS was 56% at 6 months and 63% at 36 months postdiagnosis with the hotflash being the most common MPS (~44-55%). Hot flashes occurred mainly in premenopausal breast cancer patients who were in the highest quartile of isoflavone intake at 6 months postdiagnosis (OR = 1.20, 95% CI: 0.98-1.59) compared with the lowest quartile. This association was stronger at 36 months postdiagnosis (OR = 1.59, 95% CI: 1.02-2.48). We found no significant associations for any MPS, night sweats, or vaginal dryness. Neither tamoxifen use nor BMI modified the association between MPS and isoflavone intake. There was no evidence that soy food consumption reduced MPS among breast cancer patients. High soy intake may increase the prevalence of hotflashes among premenopausal patients. Our study suggests that soy acts as an estrogen antagonist in breast cancer patients.

Polymorphic catechol-O-methyltransferase gene, soy isoflavone intake and breast cancer in postmenopausal women: a case-control study

Genetic polymorphism Val158Met of catechol-O-methyltransferase (COMT) may contribute to estrogen-induced carcinogenesis of breast cancer. Soy isoflavones possesses chemical structure similar to endogenous estrogen and may promote the carcinogenesis of breast cancer. This study was to investigate the relationship between the polymorphism of COMT, soy isoflavones, and breast cancer in postmenopausal women. In total, 176 patients newly diagnosed histopathologically with breast cancer were recruited from May 2007 to July 2009, and 176 age-matched cancer-free women as controls were selected from a community-based physical check-up population at the same period. The food-frequency questionnaire was used to collect information on soy food intake. Allele-specific polymerase chain reaction (AS-PCR) was employed to analyze genetic polymorphism Val158Met of COMT. Adjusted odd ratios (aORs) and 95% confidence intervals (95% CI) were estimated by multivariable nonconditional logistic regression. The proportion of susceptible genotype (COMT-LL) in breast cancer patients was significantly higher than that in the controls. After adjusting selected risk factors, the aOR and 95% CI of COMT-LL were 3.14 (1.48-6.66) as compared with those of COMT-HH genotype. The intake of soy isoflavones had a negative correlation with breast cancer in a dose-dependent manner (Chi2 = 28.26, P < 0.001). The women with high intake of soy isoflavones (> or = 16.26 mg/d) and carrying susceptible genotype (COMT-LL), as compared with the women carrying the COMT-HH + COMT-HL genotypes and consuming low level of soy isoflavones (< 16.26 mg/d), had no significantly increased risk for breast cancer [ aOR (95% CI) = 1.66 (0.52-5.24)]. In postmenopausal women, carrying COMT-LL genotype may increase the risk for breast cancer, and soy isoflavones intake may protect them from breast cancer. But there may be no interaction between intake of soy isoflavones and COMT-LL genotype.

Biomarkers of Dietary Exposure Are Associated with Lower Risk of Breast Fibroadenomas in Chinese Women ,

Fibroadenomas are the most common benign breast condition among women and account for up to 50% of all breast biopsies being performed. Although considered a benign condition, fibroadenomas utilize substantial resources for management and treatment to rule out potential malignancies. Dietary factors may influence benign fibrocystic breast conditions, but little is known of their association with fibroadenomas. We examined possible associations between a broad spectrum of circulating biomarkers of dietary intake and risk of fibroadenomas. Participants were women in a breast self-examination trial in Shanghai, China who were diagnosed with fibroadenomas (n = 258) and 1035 controls. Conditional logistic regression was used to estimate adjusted odds ratios (OR) and 95% CI. Isoflavone concentrations were inversely associated with risk of fibroadenomas. Adjusted OR (95% CI) for the highest versus the lowest quartile of plasma concentration were 0.36 (0.16–0.79; P-trend < 0.001) for daidzein and 0.39 (0.19–0.84; P-trend = 0.010) for genistein. We also observed inverse associations between higher percentages of the RBC (n-3) fatty acids, eicosapentaenoic acid (EPA) ([0.38 (0.19–0.77); P-trend = 0.007] and docosapentaenoic acid (DPA) [0.32 (0.15–0.70); P-trend = 0.024], and fibroadenoma risk. Circulating concentrations of carotenoids, vitamin C, retinol, and ferritin were not associated with fibroadenoma risk. The inverse associations between plasma isoflavone concentrations and RBC EPA and DPA and fibroadenoma risk suggest that higher intakes of soy foods and fatty fish may lower the risk of fibroadenomas. J. Nutr. 140: 1302–1310, 2010.

Soy food intake and breast cancer

Soy food intake and breast cancer