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

Soy Product Consumption and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

The association between soy product consumption and cancer risk varies among studies. Therefore, this comprehensive meta-analysis of observational studies examines the association between soy product consumption and total cancer risk.

METHODS

This study was conducted following the PRISMA guidelines. Up to October 2023, all eligible published studies were searched through PubMed and Web of Science databases.

RESULTS

A total of 52 studies on soy product consumption were included in this meta-analysis (17 cohort studies and 35 case-control studies). High consumption of total soy products (RR: 0.69; 95% CI: 0.60, 0.80), tofu (RR: 0.78; 95% CI: 0.70, 0.86), and soymilk (RR: 0.75; 95% CI: 0.60, 0.93) were associated with reduced total cancer risk. No association was found between high consumption of fermented soy products (RR: 1.18; 95% CI: 0.95, 1.47), non-fermented soy products (RR: 0.95; 95% CI: 0.77, 1.18), soy paste (RR: 1.00; 95% CI: 0.88, 1.14), miso soup (RR: 0.99; 95% CI: 0.87, 1.12), or natto (RR: 0.96; 95% CI: 0.82, 1.11) and cancer risk. A 54 g per day increment of total soy products reduced cancer risk by 11%, a 61 g per day increment of tofu reduced cancer risk by 12%, and a 23 g per day increment of soymilk reduced cancer risk by 28%, while none of the other soy products were associated with cancer risk.

CONCLUSION

Our findings suggest that high total soy product consumption, especially soymilk and tofu, is associated with lower cancer risk. More prospective cohort studies are still needed to confirm the causal relationship between soy product consumption and cancer risk.

Soy-derived isoflavones as chemo-preventive agents targeting multiple signalling pathways for cancer prevention and therapy

The chemopreventive and chemotherapeutic properties of soy and soy-derived compounds, especially isoflavones, have been extensively studied in recent years. However, in contrast to their anticancer effects, such as cell growth inhibition, cell cycle arrest and apoptosis induction, isoflavones have also been found to promote the growth of cancer cells. Therefore, the aim of this comprehensive review article is to present the current state of knowledge regarding the molecular mechanisms by which soy-derived isoflavones target multiple cellular signalling pathways in cancer cells. Our findings indicate that soy-derived isoflavones act as, among other things, potent modulators of HOX transcript antisense RNA (HOTAIR)/SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), vascular endothelial growth factor (VEGF)/C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor type 4 (CXCR4), 17-β-oestradiol (E2)/oestrogen receptor-α (ERα)/neuroglobin (NGB) and sonic hedgehog signalling pathways, epigenetic modulatory agents (i.a. miR-155, miR-34a and miR-10a-5p) and cancer stem cells and epithelial-to-mesenchymal transition inhibitors. The paper also discusses the latest epidemiological studies and clinical trials and provides an insight into recent extensive research on the chemo-preventive and therapeutic potential of soy-derived isoflavones.

Dietary intake and cancer incidence in Korean adults: a systematic review and meta-analysis of observational studies

Cancer is a major health burden in Korea, and dietary factors have been suggested as putative risk factors for cancer development at various sites. This study systematically reviewed the published literature investigating the associations between dietary factors and cancer incidence among Korean adults, following the Preferred Reporting Items for Systematic Reviews and Meta- Analyses guidelines. We focused on the 5 most studied cancer sites (stomach, colorectum, breast, thyroid, and cervix) as outcomes and dietary exposures with evidence levels greater than limited-suggestive according to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) panel's judgment for any of the cancer sites. This resulted in the inclusion of 72 studies. Pooled estimates of the impact of dietary factors on cancer risk suggested protective associations of fruits and vegetables with risks for gastric cancer (GC), colorectal cancer (CRC), and breast cancer (BC) and dietary vitamin C with the risk of GC, as well as a harmful association between fermented soy products and the risk of GC. Despite the limited number of studies, we observed consistent protective associations of dietary fiber with GC and dietary fiber, coffee, and calcium with CRC. These findings are largely consistent with the WCRF/AICR expert report. However, pooled estimates for the associations of other salt-preserved foods with GC, meat with CRC, and dietary carotenoids and dairy products with BC did not reach statistical significance. Further studies with prospective designs, larger sample sizes, and diverse types of dietary factors and cancer sites are necessary.

Microbial consortia and up-to-date technologies in global soy sauce production: A review

Soy sauce is an Oriental fermented condiment, and key ingredient in many Asian cuisines. As consumers around the world are becoming more adventurous with their eating choices and preferences, the demand for and popularity of Asian cuisines are increasing globally. The underlying basis of soy sauce fermentation is intricate microbial interactions which play a vital role in defining the quality, flavour, and smell of the resulting soy sauce. Traditional soy sauce fermentation consists of a two-step process: koji and moromi fermentation. Despite the presence of beneficial microorganisms in soy sauce, various harmful microorganisms can also be found during the koji or moromi step, thus resulting in soy sauce contamination. Therefore, studying the biodiversity and interactions of microorganisms is critical in ensuring soy sauce quality. The present review thus discusses in depth the various bacterial and fungal species that are either beneficial or harmful to soy sauce fermentation. The present review also discusses the advances in soy sauce fermentation such as the enhancement of gamma-aminobutyric acid (GABA) in soy sauce by microorganisms, the enhancement of soy sauce flavour by mixed starter culture, and by genome shuffling starter culture.

The associations of soya intakes with non-communicable diseases: a scoping review of meta-analyses

This scoping review aimed to identify published meta-analyses of the associations of dietary soya intakes with cardiovascular, cancer and diabetes II diseases and the best relative risk estimates. A published novel assessment process combining the well-validated Cochrane Review measures, the AMSTAR 2 checklist and a published algorithm specifically designed for conducting a scoping review of similar meta-analyses was employed. This scoping review identified and evaluated twenty-eight meta-analysis reports, published between 2000 and 2021, on the associations of soya intakes with cardiovascular, cancer and diabetes II diseases. It identified eighteen significantly negatively associated risk–disease pairs for total soya intakes, four significantly negatively associated risk–disease pairs for unfermented soya intakes and four significantly negatively associated risk–disease pairs for fermented soya intakes when compared high against low intakes. The largest significant risk decrease found was gastric cancer mortalities with relative risk (RR) 0·49 (95 % CI: 0·35, 0·68); followed by colorectal cancer mortalities RR 0·59 (95 % CI: 0·41, 0·84); ovarian cancer RR 0·52 (95 % CI: 0·42, 0·66) and endocrine-related gynaecological cancer RR 0·61 (95 % CI: 0·53, 0·72). The fermented soya intake and gastric cancer risk–disease pair were identified to be significantly positively associated, RR 1·22 (95 % CI: 1·02, 1·44) when compared high against low intakes. Four significantly negatively associated risk–disease dose–responses were also identified. Being the products with lower greenhouse gas emission intensities, soya products could be the better dietary alternatives to animal products for reducing cardiovascular, cancer and diabetes II diseases and helping combat climate change.

The health effects of soy: A reference guide for health professionals

Soy is a hotly debated and widely discussed topic in the field of nutrition. However, health practitioners may be ill-equipped to counsel clients and patients about the use of soyfoods because of the enormous, and often contradictory, amount of research that has been published over the past 30 years. As interest in plant-based diets increases, there will be increased pressure for practitioners to gain a working knowledge of this area. The purpose of this review is to provide concise literature summaries (400-500 words) along with a short perspective on the current state of knowledge of a wide range of topics related to soy, from the cholesterol-lowering effects of soy protein to the impact of isoflavones on breast cancer risk. In addition to the literature summaries, general background information on soyfoods, soy protein, and isoflavones is provided. This analysis can serve as a tool for health professionals to be used when discussing soyfoods with their clients and patients.

Digestion Resistance of Soybean 7S Protein and Its Implications for Reinforcing the Gastric Mucus Barrier

Previous studies have found that soybean protein, especially soybean 7S protein (β-conglycinin), exhibits digestion resistance, but the mechanism of digestion resistance and its implications for human health are still unclear. Here, we show that the extracted soybean 7S protein contains both oligomer globulins and amyloid aggregates, while the gastric digested soybean 7S protein only contains amyloid aggregates and thus exhibits digestion resistance. An animal experiment shows that un-digestible soybean 7S protein effectively prevents aspirin-induced acute gastric mucosa damage. The impacts of un-digestible soybean 7S protein on gastric mucus barrier properties are investigated using quartz crystal microbalance with dissipation (QCM-D), Langmuir monolayer, and multiple particle tracking (MPT). Results show that these un-digestible protein aggregates can penetrate into gastric mucus, increase the viscosity and compactness of the mucin layer, and reinforce the gastric mucus barrier properties. The findings are helpful to understand that high consumption of non-fermented soybean foods is associated with a decreased risk of gastric cancer.

Gastro-Protective Effect of Fermented Soybean (Glycine max (L.) Merr.) in a Rat Model of Ethanol/HCl-Induced Gastric Injury

The present research purposed to examine the gastro-protective effect of Glycine max (L.) Merr. fermented using Lactobacillus delbrueckii ssp. delbrueckii Rosell-187 (Gastro-AD®) on ethanol/HCl-induced gastric damage, specifically on gastric acid secretion. After oral supplementation of Gastro-AD® to Sprague-Dawley (SD) rats with ethanol/HCl-induced gastric damage, we determined that Gastro-AD® attenuated the gastric mucosal lesion, hemorrhage and gastric acid secretion induced by ethanol/HCl. In addition, we observed that the Gastro-AD® treatment increased the serum prostaglandin E2 level and decreased the levels of gastric acid secretion-related receptors in both gastric tissues and primary gastric parietal cells. Furthermore, it decreased the levels of inflammatory factors, including serum histamine and expression of p-IκB, p-p65, iNOS and COX-2 and the activity of apoptotic signaling pathways, including those involving p-JNK, Bcl2/Bax, Fas, FADD, caspase-8 and caspase-3, in the stomach of the ethanol/HCl-treated rats. Thus, we suggest that Gastro-AD® supplementation may reduce ethanol/HCl-induced gastric acid secretion and prevent gastric injury.

Comparison between the impact of fermented and unfermented soy intake on the risk of liver cancer: the JPHC Study

PURPOSE

The aim of this study was to compare the impact of fermented and unfermented soy intake, based on the following soy-derived products: tofu, soymilk, natto, and miso, on the risk of liver cancer among Japanese adults.

METHODS

75,089 Participants of the Japan Public Health Center-based Prospective Study (JPHC Study) were followed from the time of the 5-year follow-up questionnaire until the end of 2012-2013. Subjects with available data on hepatitis B virus (HBV) and hepatitis C virus (HCV) infection status from blood samples (n = 14,016) and those who were anti-HCV antibody (anti-HCV) or hepatitis B virus antigen (HBsAg) positive (n = 1033) were also analyzed separately. Cox proportional hazard models were employed to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

During 1,145,453 person-years, 534 newly diagnosed cases of liver cancer were identified in the JPHC Study. For miso intake among men, the multivariate-adjusted highest versus lowest quartile HR was 0.65 (95% CI, 0.48-0.89); p for trend = 0.006. Results were similar in those who were anti-HCV or HBsAg positive, 0.24 (0.08-0.70); p for trend = 0.004 highest versus lowest tertile. For the sub-analysis among only participants with known hepatitis infection status and HCV and HBsAg adjustment, a similar association was observed. In the multivariate complete cohort analysis, among women, the highest intake of fried tofu was inversely associated with the risk of liver cancer, HR = 0.45 (0.26-0.80); p for trend = 0.014.

CONCLUSIONS

We observed no association between total soy intake, fermented and unfermented, and risk of liver cancer, and only an inverse association between miso intake and liver cancer among men.

Associations of Japanese food intake with survival of stomach and colorectal cancer: A prospective patient cohort study

Dietary factors may affect the prognosis of digestive tract cancer, but evidence has been sparse. We investigated the association between pretreatment intake of 6 Japanese foods (including soy food, miso [soybean paste] soup and seaweed) and the risk of death among patients with histologically confirmed major digestive tract cancers (stomach, 1931; colon, 793; rectum, 510) diagnosed during 1997‐2013 at a single institution in Japan. Pretreatment dietary intake was assessed using a food frequency questionnaire, and the patients were followed until December 2016. The Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Among the patients with stomach cancer, frequent intake of soy food was inversely associated with the risk of all‐cause (P_trend for four frequency groups = 0.01; HR = 0.72, 95% CI: 0.50‐1.04 for highest vs lowest group) and stomach cancer (P_trend = 0.03; HR = 0.63, 95% CI: 0.40‐0.99) death. A similar inverse association was also found for intake of miso soup. In contrast, frequent seaweed intake was inversely associated with the risk of all‐cause death among the patients with colon cancer (P_trend = 0.03). Rectal cancer patients who had frequently consumed seaweed tended to have a lower risk of rectal cancer death (P_trend = 0.02). These findings indicate that pretreatment intake of Japanese foods such as soybean products and seaweed may have favorable effects on patient survival of stomach and colorectal cancer, although this needs to be confirmed by further research.

Higher dietary soy intake appears inversely related to breast cancer risk independent of estrogen receptor breast cancer phenotypes

The relationship between soy intake (SI) and breast cancer (BC) has been widely investigated with limited information on the significance of hormone receptor status of BC on the association. This study assessed the relationship between SI and BC risk in the context of oestrogen receptor (ER) status of BC. We meta-analyzed data from published studies on SI and BC after a methodical search of EMBASE, PubMed and Cochrane Library through December 2019. Summary estimates with 95% confidence intervals (CI) were presented using a random-effects model. Eighteen (5 cohorts and 13 case-control) studies, were included in this meta-analysis and SI was inversely associated with BC risk [OR (95%) for highest vs. lowest soy food intake = 0.88 (0.84-0.92), P < 0.001, I ² = 76.1%, Egger's p-value = 0.425] among all women. The inverse relationship was stronger among premenopausal women [OR (95%) = 0.79 (0.71-0.87), P < 0.001, I ² = 77.3%, Egger's p-value = 0.644]. In addition, SI was inversely associated with BC risk among ER-negative (-) BC women [OR (95%) = 0.71 (0.57-0.90), P = 0.013, I ² = 72.0%, Egger's p-value = 0.355] and among ER-positive (+) BC women [OR (95%) = 0.87 (0.79-0.96), P = 0.008 I ² = 74.6%, Egger's p-value = 0.061]. SI appears inversely associated with BC risk, with a stronger inverse association among pre-menopausal and ER-negative BC women.

Nineteen-year trends in fermented food consumption and sodium intake from fermented foods for Korean adults from 1998 to 2016

Objective:

Fermented foods such as kimchi are traditional foods in Korea and could provide beneficial health effects. However, fermented foods also contribute to increased Na intake since salt is added during the fermentation process. The present research aimed to examine trends in the consumption of fermented foods and Na intake over time by Korean adults, using data from the Korea National Health and Nutrition Examination Survey (KNHANES).

Design:

KNHANES is a cross-sectional survey; data from 1998 to 2016 were divided into seven groups from KNHANES I to VII.

Setting:

Demographic information on sex, age, education and income were collected. Assessment of fermented food and Na consumption was conducted via analysis of 24 h dietary recall data. Multivariate linear regressions and logistic regressions were performed to calculate the P for trends by applying strata, cluster and sampling weights by SAS PROC SURVEY.

Participants:

The target population was Korean adults, aged ≥19 years, who participated in a 24 h dietary recall. The total number was 76 199, with 32 324 men and 43 875 women.

Results:

A significant decline in fermented food consumption was observed from 1998 to 2016 in both men and women (P < 0·0001). Among fermented foods, kimchi consumption was greatly reduced while pickled vegetables consumption showed a marked increase. Similarly, Na intake from fermented foods declined significantly over time in both men and women (P < 0·0001).

Conclusions:

The consumption of fermented foods and Na intake from fermented foods by Korean adults decreased significantly over time from 1998 to 2016.

Associations between intake of dietary fermented soy food and concentrations of inflammatory markers: a cross-sectional study in Japanese workers

Epidemiological investigations have shown that consumption of soybeans or soy foods reduces the risk of the development of cardiovascular disease, cancer and osteoporosis. The aim of this study was to determine the associations between different soy foods and inflammatory markers, including high-sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, and IL-18, in Japanese workers. The cross-sectional study included 1,426 Japanese workers (1,053 men and 373 women) aged 20 to 64 years. Intake of 12 soy foods was estimated by a validated food frequency questionnaire. Associations of total soy foods, fermented soy food, non-fermented soy food, soy isoflavone with hs-CRP, IL-6, and IL-18 levels were examined by general linear model regression analysis. We found that total fermented soy food intake was inversely associated with multivariable-adjusted geometric concentration of IL-6 in men (Q1:1.03 pg/mL, Q5:0.94 pg /mL;P for trend = 0.031). Furthermore, it was shown that IL-6 concentrations were inversely associated with miso intake (β = -0.068;p = 0.034) and soy sauce intake in men (β = -0.074;p = 0.018). This study suggests that intake of total fermented soy food, miso and soy sauce be associated with IL-6 concentrations in Japanese men. J. Med. Invest. 65:74-80, February, 2018.

The association between dietary isoflavones intake and gastric cancer risk: a meta-analysis of epidemiological studies

Background

Isoflavones, a class of phytoestrogenic compounds, are abundant in soybeans. A number of epidemiological studies have investigated the association between dietary isoflavones intake and the risk of gastric cancer. However, the results are inconclusive. Therefore, the meta-analysis was conducted to evaluate the effect of dietary isoflavones intake on the risk of gastric cancer.

Methods

Relevant studies from May 1992 to May 2017 were identified through searching PubMed and Web of Science. Additional articles were identified from the reference lists of relevant review articles. Pooled risk ratios (RRs) or odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a fixed-effects model. Funnel plot and Egger’s test were used to evaluate publication bias.

Results

Seven articles reporting 12 studies were included in the current meta-analysis. We found no significant association between dietary isoflavones intake and gastric cancer risk with the highest versus the lowest categories of dietary isoflavones intake (OR = 0.97, 95% CI = 0.87–1.09, I² = 27.5%). Subgroup analyses generally yield similar results.

Conclusions

Higher dietary isoflavones intake is not associated with a decline in the risk of gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5424-7) contains supplementary material, which is available to authorized users.

Local Acetaldehyde-An Essential Role in Alcohol-Related Upper Gastrointestinal Tract Carcinogenesis

The resident microbiome plays a key role in exposure of the upper gastrointestinal (GI) tract mucosa to acetaldehyde (ACH), a carcinogenic metabolite of ethanol. Poor oral health is a significant risk factor for oral and esophageal carcinogenesis and is characterized by a dysbiotic microbiome. Dysbiosis leads to increased growth of opportunistic pathogens (such as Candida yeasts) and may cause an up to 100% increase in the local ACH production, which is further modified by organ-specific expression and gene polymorphisms of ethanol-metabolizing and ACH-metabolizing enzymes. A point mutation in the aldehyde dehydrogenase 2 gene has randomized millions of alcohol consumers to markedly increased local ACH exposure via saliva and gastric juice, which is associated with a manifold risk for upper GI tract cancers. This human cancer model proves conclusively the causal relationship between ACH and upper GI tract carcinogenesis and provides novel possibilities for the quantitative assessment of ACH carcinogenicity in the human oropharynx. ACH formed from ethanol present in "non-alcoholic" beverages, fermented food, or added during food preparation forms a significant epidemiologic bias in cancer epidemiology. The same also concerns "free" ACH present in mutagenic concentrations in multiple beverages and foodstuffs. Local exposure to ACH is cumulative and can be reduced markedly both at the population and individual level. At best, a person would never consume tobacco, alcohol, or both. However, even smoking cessation and moderation of alcohol consumption are associated with a marked decrease in local ACH exposure and cancer risk, especially among established risk groups.

Environmental contributions to gastrointestinal and liver cancer in the Asia-Pacific region

In the Asia-Pacific region, gastric, colorectal, and hepatocellular (liver) cancer show substantial regional variation in incidence consistent with the presence of important environmental factors. For gastric cancer, global incidence is concentrated in Asia with substantially higher rates in East Asia than in South-East Asia and Australia. The differences in incidence rates for gastric cancer in the Asia-Pacific region may be due, in part, to differences in the prevalence of Helicobacter pylori infection and the prevalence of H. pylori virulence factors. Smoking is also correlated with gastric cancer risk and is responsible for the highest population attributable fraction among men in East Asia. Colorectal cancer has increased rapidly in incidence to become the third most common digestive cancer in Asia. According to cohort studies in Asia, smoking, alcohol use, obesity, and physical inactivity increase the risk of colorectal cancer. Unlike West Asia, East Asia and Australia have high incidence rates for colorectal cancer that correlates to a high Human Development Index and a high prevalence of alcohol consumption and obesity. Liver cancer is the second most common digestive cancer in Asia. The high incidence of liver cancer in East Asia and South-East Asia is concordant with the high prevalence of hepatitis B virus and hepatitis C virus infection. Other important risk factors include alcohol use, smoking, and diabetes. The identification of the earlier and other environmental factors (currently under investigation) is central to the development and implementation of effective cancer control programs for the region.

Prevalence, risk factors, and virulence genes of Helicobacter pylori among dyspeptic patients in two different gastric cancer risk regions of Thailand

Gastric cancer risk is varied among different regions of Thailand. We examined the characteristics of Helicobacter pylori infection in two regions of Thailand. The H. pylori status of 273 dyspeptic patients (136 from the South and 137 from the North; a low and high incidence of gastric cancer region, respectively) was evaluated, and virulence genotypes (cagA, vacA, hrgA and jhp0562-positive/β-(1,3)galT) were determined. The overall H. pylori infection rate was 34.1% (93/273). The prevalence was higher in the North than in the South (50.4% vs. 17.6%, P <0.001) and was significantly higher among individuals with the following characteristics: low income, birthplace in the Northeast or North regions, agricultural employment, or consumption of alcohol or unboiling water. Among these socio-demographic determinants, region was an independent risk factor for H. pylori infection (odds ratio = 6.37). Patients including both H. pylori infected and uninfected cases who lived in the North had significantly more severe histological scores than those in the South. In contrast, among H. pylori-positive cases, patients in the South had significantly more severe histological scores than those in the North. Of the 74 strains cultured, 56.8% carried Western-type cagA, with a higher proportion in the South than in the North (76.2% vs. 49.1%, P = 0.05). In disagreement with the current consensus, patients infected with the Western-type cagA strains had more severe inflammation scores in the antrum than those infected with the East Asian-type cagA strains (P = 0.027). Moreover, Western-type cagA strains induced more severe histological scores in patients from the South than those of either genotype from the North. Other virulence genes had no influence on histological scores. The incidence of gastric cancer in Thailand was different among regions and corresponded to differences in the prevalence of H. pylori infection. More careful follow-up for patients in the South will be required, even if they are infected with H. pylori carrying Western-type cagA.

Nature, Nurture, and Cancer Risks: Genetic and Nutritional Contributions to Cancer

It is speculated that genetic variants are associated with differential responses to nutrients (known as gene-diet interactions) and that these variations may be linked to different cancer risks. In this review, we critically evaluate the evidence across 314 meta-analyses of observational studies and randomized controlled trials of dietary risk factors and the five most common cancers (breast, lung, prostate, colorectal, and stomach). We also critically evaluate the evidence across 13 meta-analyses of observational studies of gene-diet interactions for the same cancers. Convincing evidence for association was found only for the intake of alcohol and whole grains in relation to colorectal cancer risk. Three nutrient associations had highly suggestive evidence and another 15 associations had suggestive evidence. Among the examined gene-diet interactions, only one had moderately strong evidence.

Key role of local acetaldehyde in upper GI tract carcinogenesis

Ethanol is neither genotoxic nor mutagenic. Its first metabolite acetaldehyde, however, is a powerful local carcinogen. Point mutation in ALDH2 gene proves the causal relationship between acetaldehyde and upper digestive tract cancer in humans. Salivary acetaldehyde concentration and exposure time are the two major and quantifiable factors regulating the degree of local acetaldehyde exposure in the ideal target organ, oropharynx. Instant microbial acetaldehyde formation from alcohol represents >70% of total ethanol associated acetaldehyde exposure in the mouth. In the oropharynx and achlorhydric stomach acetaldehyde is not metabolized to safe products, instead in the presence of alcohol it accumulates in saliva and gastric juice in mutagenic concentrations. A common denominator in alcohol, tobacco and food associated upper digestive tract carcinogenesis is acetaldehyde. Epidemiological studies on upper GI tract cancer are biased, since they miss information on acetaldehyde exposure derived from alcohol and acetaldehyde present in 'non-alcoholic' beverages and food.

Soy food intake and risk of gastric cancer: A dose-response meta-analysis of prospective studies

Epidemiological studies were inconsistent on the association between soy food intake and risk of gastric cancer (GC). This study aimed to determine the role of soy food intake in the development of GC.A systematic search was conducted in PubMed and Web of Science to identify all relevant studies. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were pooled using a random-effects model, and the dose-response relationship between soy food intake and GC risk was also assessed.Thirteen prospective studies were identified with a total of 517,106 participants and 5800 cases. Among 11 types of soy food, high intake of total soy food (the highest vs the lowest category: RR: 0.78, 95% CI: 0.62-0.98) and nonfermented soy food (RR: 0.63, 95% CI: 0.50-0.79) were inversely associated with GC risk, while high intake of miso soup was associated with the risk in male (RR: 1.17, 95% CI: 1.02-1.36). In dose-response meta-analysis, total soy food intake (0-150 g/day) showed no significant association with GC risk, while high intake of nonfermented soy food was inversely related, especially an intake of more than 100 g/day. In male, miso soup intake (1-5 cups/day) was significantly associated with GC risk.High intake of nonfermented soy food might reduce the risk of GC, while miso soup intake might increase the risk in male.

Meta-analysis of Soy Consumption and Gastrointestinal Cancer Risk

Soy consumption has received considerable attention for its potential role in reducing cancer incidence and mortality. However, its effects on gastrointestinal (GI) cancer are controversial. Therefore, we performed a meta-analysis to evaluate the association between soy consumption and gastrointestinal cancer risk by searching for prospective studies in PubMed, Web of Science, EMBASE and the reference lists of the included articles. The study-specific odds ratio (OR), relative risk (RR) or hazard ratio (HR) estimates and 95% confidence intervals (CIs) were pooled using either a fixed-effect or random-effect model. Twenty-two independent prospective studies were eligible for our meta-analysis, including 21 cohort studies and one nested case-control study. Soy product consumption was inversely associated with the incidence of overall GI cancer (0.857; 95% CI: 0.766, 0.959) and the gastric cancer subgroup (0.847; 95% CI: 0.722, 0.994) but not the colorectal cancer subgroup. After stratifying the results according to gender, an inverse association was observed between soy product intake and the incidence of GI cancer for females (0.711; 95% CI: 0.506, 0.999) but not for males.

Fruit and vegetable consumption, Helicobacter pylori antibodies, and gastric cancer risk: A pooled analysis of prospective studies in China, Japan, and Korea

Epidemiological findings on the association between fruit and vegetable consumption and gastric cancer risk remain inconsistent. The present analysis included 810 prospectively ascertained non-cardia gastric cancer cases and 1,160 matched controls from the Helicobacter pylori Biomarker Cohort Consortium, which collected blood samples, demographic, lifestyle, and dietary data at baseline. Conditional logistic regression adjusting for total energy intake, smoking, and H. pylori status, was applied to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for gastric cancer risk across cohort- and sex-specific quartiles of fruit and vegetable intake. Increasing fruit intake was associated with decreasing risk of non-cardia gastric cancer (OR = 0.71, 95% CI: 0.52-0.95, p trend = 0.02). Compared to low-fruit consumers infected with CagA-positive H. pylori, high-fruit consumers without evidence of H. pylori antibodies had the lowest odds for gastric cancer incidence (OR = 0.12, 95% CI: 0.06-0.25), whereby the inverse association with high-fruit consumption was attenuated among individuals infected with CagA-positive H. pylori (OR = 0.82, 95% CI: 0.66-1.03). To note, the small number of H. pylori negative individuals does influence this finding. We observed a weaker, nondose-response suggestion of an inverse association of vegetable intake with non-cardia gastric cancer risk. High fruit intake may play a role in decreasing risk of non-cardia gastric cancer in Asia.

Soy Intake Is Associated With Lower Endometrial Cancer Risk: A Systematic Review and Meta-Analysis of Observational Studies

Epidemiologic studies reporting the effect of soy intake on endometrial cancer risk conveyed conflicting results. We systematically reviewed the literature to investigate whether there was an inverse relation between dietary soy intake and endometrial cancer risk. PubMed, EMBASE, the Cochrane Library, and 4 main Chinese literature databases were searched from their inception to August 25, 2015 for both case-control studies and cohort studies that assessed the effect of soy intake on endometrial cancer risk. Study-specific most-adjusted odds ratios (ORs) or relative risks (RRs) were combined by using fixed-effects or random-effects model to calculate pooled risk estimates (REs). A total of 10 epidemiologic studies were included in this meta-analysis, including 8 case-control studies and 2 prospective cohort studies. Dietary soy intake was inversely associated with endometrial cancer risk with an overall RE of 0.81 (95% CI: 0.72, 0.91). In subgroup analyses, a statistically significant protective effect of soy intake was found for unfermented soy food (RE: 0.81, 95% CI: 0.67, 0.97), postmenopausal women (RE: 0.76, 95% CI: 0.61, 0.95), and Asian (RE: 0.79, 95% CI: 0.66, 0.95) and non-Asian population (RE: 0.83, 95% CI: 0.71, 0.96). Current evidence indicates that soy food intake is associated with lower endometrial cancer risk. Further larger cohort studies are warranted to fully clarify such an association.

Complementary and Alternative Approaches to Menopause

Given the persistent confusion about the risks and benefits of hormone therapy since 2002 and the first publication from the Women's Health Initiative's primary findings, women and health care providers are increasingly motivated to find effective, nonhormonal approaches to treat menopause-related symptoms. Complementary and alternative medicine has grown increasingly popular in the last decade. A wide array of botanic medicines is offered as an alternative approach to hormone therapy for menopause, but data documenting efficacy and safety are limited. None of the available botanicals is as effective as hormone therapy in the management of vasomotor symptoms.

Isoflavones: chemistry, analysis, functions and effects on health and cancer

Isoflavones are phytoestrogens and natural plant compounds which are similar to 17-β-estradiol in chemical structure. It is known that they can act as estrogen agonists or antagonists, depending on endocrine estrogenic levels, but actions of isoflavones are rather complex due to large number of variables such as chemical structures and mechanisms. Some hypotheses on biological mechanisms have not satisfactorily been confirmed to date and human epidemiological and experimental studies have been relatively limited. Nevertheless, isoflavones and isoflavone rich foods have become a focus on interest due to positive health benefits on many diseases, especially prevention of hormone-related cancers, cardiovascular disease, osteoporosis, and adverse postmenopausal symptoms, and improvement of physiological condition such as maintaining cognitive function. This review provides an overview of chemistry, analytical techniques (focused on human biospecimens), functions including biological mechanisms, and effects of isoflavones, on the basis of the available meta-analysis and review articles and some original articles, on health and cancer.

The relationship between fermented food intake and mortality risk in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort

The objective of the present study was to investigate the relationship between total and subtypes of bacterial fermented food intake (dairy products, cheese, vegetables and meat) and mortality due to all causes, total cancer and CVD. From the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort, 34 409 Dutch men and women, aged 20–70 years who were free from CVD or cancer at baseline, were included. Baseline intakes of total and subtypes of fermented foods were measured with a validated FFQ. Data on the incidence and causes of death were obtained from the national mortality register. Cox proportional hazards models were used to analyse mortality in relation to the quartiles of fermented food intake. After a mean follow-up of 15 (sd2·5) years, 2436 deaths occurred (1216 from cancer and 727 from CVD). After adjustment for age, sex, total energy intake, physical activity, education level, hypertension, smoking habit, BMI, and intakes of fruit, vegetables and alcohol, total fermented food intake was not found to be associated with mortality due to all causes (hazard ratio upperv. lowest quartile (HRQ4 v. Q1) 1·00, 95 % CI 0·88, 1·13), cancer (HRQ4 v. Q11·02, 95 % CI 0·86, 1·21) or CVD (HRQ4 v. Q11·04, 95 % CI 0·83, 1·30). Bacterial fermented foods mainly consisted of fermented dairy foods (78 %) and cheese (16 %). None of the subtypes of fermented foods was consistently related to mortality, except for cheese which was moderately inversely associated with CVD mortality, and particularly stroke mortality (HRQ4 v. Q10·59, 95 % CI 0·38, 0·92,Ptrend= 0·046). In conclusion, the present study provides no strong evidence that intake of fermented foods, particularly fermented dairy foods, is associated with mortality.

In vitro assessment of the gastrointestinal tolerance and immunomodulatory function of Bacillus methylotrophicus isolated from a traditional Korean fermented soybean food

AIMS

This study aimed to investigate the potential of Bacillus methylotrophicus as a probiotic.

METHODS AND RESULTS

A Bacillus isolate designated strain C14 was isolated from Korean traditional fermented soybean paste (doenjang). The strain was identified, and its physiological and biochemical properties were characterized. The gastrointestinal tolerance and immunomodulatory function of strain C14 were also investigated. Strain C14 was identified as B. methylotrophicus by analysis of its biochemical properties using the API 50CHB system and by phylogenetic analysis of the 16S rDNA sequence. Strain C14 showed >80% and >75% of survival for artificial gastric juices (pH 2.5 and 1% pepsin) and 0.5% (w/v) bile salt, respectively. Heat-killed B. methylotrophicus C14 inhibited the adhesion of various pathogens and enhanced the adhesion of probiotic bacteria to Caco-2 cells. The heat-killed cells also induced high levels of immune cell proliferation compared with the control and stimulated interleukin-6 and tumour necrosis factor-α production in mouse macrophages.

CONCLUSIONS

Bacillus methylotrophicus C14 could be used as a probiotic.

SIGNIFICANCE AND IMPACT OF THE STUDY

Recently identified B. methylotrophicus is a new potential probiotic with high gastrointestinal tolerance.

Dietary flavonoids and gastric cancer risk in a Korean population

Gastric cancer is the most common cancer among men in Korea, and dietary factors are closely associated with gastric cancer risk. We performed a case-control study using 334 cases and 334 matched controls aged 35–75 years. Significant associations were observed in total dietary flavonoids and their subclasses, with the exception of anthocyanidins and isoflavones (OR (95% CI): 0.49 (0.31–0.76), p trend = 0.007 for total flavonoids). However, these associations were not significant after further adjustment for fruits and vegetable consumption (OR (95% CI): 0.62 (0.36–1.09), p trend = 0.458 for total flavonoids). Total flavonoids and their subclasses, except for isoflavones, were significantly associated with a reduced risk gastric cancer in women (OR (95% CI): 0.33 (0.15–0.73), p trend = 0.001 for total flavonoids) but not in men (OR (95% CI): 0.70 (0.39–1.24), p trend = 0.393 for total flavonoids). A significant inverse association with gastric cancer risk was observed in flavones, even after additional adjustment for fruits and vegetable consumption in women. No significantly different effects of flavonoids were observed between H. pylori-positive and negative subjects. In conclusion, dietary flavonoids were inversely associated with gastric cancer risk, and these protective effects of dietary flavonoids were prominent in women. No clear differences were observed in the subgroup analysis of H. pylori and smoking status.

Intake of specific nonfermented soy foods may be inversely associated with risk of distal gastric cancer in a Chinese population

Because the association between soy consumption and gastric cancer is inconsistent, we evaluated the putative preventive effect of soy food on gastric cancer risk in the Shanghai Women's and Men's Health Studies, comprising a total of 128,687 participants. Intake of nonfermented soy foods was estimated using 2 validated food-frequency questionnaires. HRs were calculated with 95% CIs for intake amounts of total nonfermented soy food intake, soy protein, and isoflavones as well as individual soy food groups using Cox proportional hazards regression. A total of 493 distal gastric cancer cases were identified by 2010. Although all risk estimates for summary measures of soy food intake above the lowest quartile (quartile 1) were suggestive of a protective effect, no statistically significant associations with risk of distal gastric cancer were found. Among the separate soy food groups, significant reductions in risk of distal gastric cancer by increasing intake of tofu were found in men in quartile 2 (HR: 0.59; 95% CI: 0.40, 0.86), quartile 3 (HR: 0.62; 95% CI: 0.44, 0.88), and quartile 4 (HR: 0.64; 95% CI: 0.42, 0.99), resulting in a significant trend (P-trend = 0.02). Dry bean intake was also inversely associated with decreased risk of gastric cancer, but in postmenopausal women only [quartile 2 (HR: 0.54; 95% CI: 0.30, 0.96); quartile 3 (HR: 0.90; 95% CI: 0.64, 1.27); and quartile 4 (HR: 0.63; 95% CI: 0.43, 0.91)], resulting in a significant trend (P-trend = 0.03). Overall, our study found no statistically significant association between nonfermented soy food intake and distal gastric cancer risk, though the data supported the hypothesis that tofu may protect against distal gastric cancer in men and dry bean consumption may decrease the risk of gastric cancer in postmenopausal women.

Habitual consumption of soy products and risk of nasopharyngeal carcinoma in Chinese adults: a case-control study

BACKGROUND AND OBJECTIVES

Many studies have shown a negative association between the consumption of soy products and the risk of some cancers, but little is known about the effect of soy consumption on nasopharyngeal carcinoma. We assessed the association between the consumption of soy products on nasopharyngeal carcinoma risk in Chinese individuals.

METHODS

This case-control study included 600 (448 males and 152 females) incident cases of nasopharyngeal carcinoma, and an equal number of controls, matched according to gender, age (± 3 y) and household type to the nasopharyngeal carcinoma cases. All subjects were recruited from hospitals in Guangzhou, China. A face-to-face interview was conducted with each study individual to collect general information and habitual dietary intake using a 78-item quantitative food-frequency questionnaire. Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression analyses.

RESULTS

The median intakes of soy foods (in protein) were 0.5/0.5, 1.4/1.7, 2.7/3.3 and 6.1/7.7 (male/female) g/d in the quartiles 1 to 4. Both univariate and multivariate analyses showed no significant association between the consumption of soy proteins or soy isoflavones and the risk of nasopharyngeal carcinoma. The adjusted odds ratios (95% confidence intervals) between extreme quartiles were 0.97 (0.66-1.45) for soy proteins and 0.97 (0.66-1.42) for total isoflavones. Null associations were also observed between intake of the individual isoflavones daidzein, genistein and glycitein and NPC risk, with adjusted odds ratios for the extreme quartiles ranging between 0.73 and 1.23.

CONCLUSION

Habitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake.

Intake of soy products and other foods and gastric cancer risk: a prospective study

Background

Gastric cancer, the most common cancer in the world, is affected by some foods or food groups. We examined the relationship between dietary intake and stomach cancer risk in the Korean Multi-Center Cancer Cohort (KMCC).

Methods

The KMCC included 19 688 Korean men and women who were enrolled from 1993 to 2004. Of those subjects, 9724 completed a brief 14-food frequency questionnaire at baseline. Through record linkage with the Korean Central Cancer Registry and National Death Certificate databases, we documented 166 gastric cancer cases as of December 31, 2008. Cox proportional hazard models were used to estimate relative risks (RRs) and 95% CIs.

Results

Frequent intake of soybean/tofu was significantly associated with reduced risk of gastric cancer, after adjustment for age, sex, cigarette smoking, body mass index, alcohol consumption, and area of residence (P for trend = 0.036). We found a significant inverse association between soybean/tofu intake and gastric cancer risk among women (RR = 0.41, 95% CI: 0.22–0.78). Men with a high soybean/tofu intake had a lower risk of gastric cancer, but the reduction was not statistically significant (RR = 0.77, 95% CI: 0.52–1.13). There was no interaction between soybean/tofu intake and cigarette smoking in relation to gastric cancer risk (P for interaction = 0.268).

Conclusions

Frequent soybean/tofu intake was associated with lower risk of gastric cancer.

Lipid-lowering effect of maize-based traditional Mexican food on a metabolic syndrome model in rats

BACKGROUND

Maize-based food is typical in Mexico and other Mesoamerican countries. Used for millennia, they have recently been replaced by modern food that is associated with an increase in the prevalence of non-communicable chronic diseases. This study was carried out in order to evaluate the effects of traditional food on lipid profiles.

METHODS

Metabolic syndrome was induced in animals given a 30% sucrose solution. The animals were given maize tortillas (n=5) and maize pozol (n=5), traditional Mexican food items. A control group was given a 30% sucrose solution in the laboratory diet (n=5) and a witness group was given plain water and pellets. Triglycerides, cholesterol and glucose in tail blood were recorded each month between weeks 12 to 24. Blood was obtained from the cardiac cavity on week 28 and triglycerides, total cholesterol, LDL, HDL, C-reactive protein, alanine amino transferase, glucose and glycated hemoglobin were recorded.

RESULTS

The animals provided with supplementary traditional food presented a lower increase in triglycerides up to week 24 (p<0.001). Data recorded on week 28 showed lower values of LDL (p<0.05), a lower percentage of glycated hemoglobin when maize tortillas were provided (p<0.01) and lower values of alanine amino transferase when both food items were provided (p<0.01).

CONCLUSIONS

Providing traditional Mexican food generated a protective effect against the intake of a 30% sucrose solution over a long period.

Overview of methodological quality of systematic reviews about gastric cancer risk and protective factors

BACKGROUND AND OBJECTIVE

A comprehensive overall review of gastric cancer (GC) risk and protective factors is a high priority, so we conducted the present study.

METHODS

Systematic searches in common medical electronic databases along with reference tracking were conducted to include all kinds of systematic reviews (SRs) about GC risk and protective factors. Two authors independently selected studies, extracted data, and evaluated the methodological qualities and the quality of evidence using R-AMSTAR and GRADE approaches.

RESULTS

Beta- carotene below 20 mg/day, fruit, vegetables, non-fermented soy-foods, whole-grain, and dairy product were GC protective factors, while beta-carotene 20 mg/day or above, pickled vegetables, fermented soy-foods, processed meat 30 g/d or above, or salty foods, exposure to alcohol or smoking, occupational exposure to Pb, overweight and obesity, helicobacter pylori infection were GC risk factors. So we suggested screening and treating H. pylori infection, limiting the amount of food containing risk factors (processed meat consumption, beta-carotene, pickled vegetables, fermented soy-foods, salty foods, alcohol), stopping smoking, avoiding excessive weight gain, avoidance of Pb, and increasing the quantity of food containing protective components (fresh fruit and vegetables, non-fermented soy-foods, whole-grain, dairy products).

CONCLUSIONS

The conclusions and recommendations of our study were limited by including SRs with poor methodological bases and low quality of evidence, so that more research applying checklists about assessing the methodological qualities and reporting are needed for the future.

Evaluation of nutrient intake and diet quality of gastric cancer patients in Korea

This study was conducted to identify dietary factors that may affect the occurrence of gastric cancer in Koreans. Preoperative daily nutrition intake and diet quality of patients diagnosed with gastric cancer were evaluated. Collected data were comparatively analyzed by gender. The results were then used to prepare basic materials to aid in the creation of a desirable postoperative nutrition management program. The subjects of this study were 812 patients (562 men and 250 women) who were diagnosed with gastric cancer and admitted for surgery at Soonchunhyang University Hospital between January 2003 and December 2010. Nutrition intake and diet quality were evaluated by the 24-hr recall method, the nutrient adequacy ratio, mean adequacy ratio (MAR), nutrient density (ND), index of nutritional quality (INQ), dietary variety score (DVS), and dietary diversity score (DDS). The rate of skipping meals and eating fast, alcohol consumption, and smoking were significantly higher in males than those in females. The levels of energy, protein, fat, carbohydrate, phosphorous, sodium, potassium, vitamin B₁, vitamin B₂, niacin, and cholesterol consumption were significantly higher in males than those in females. Intake of fiber, zinc, vitamin A, retinol, carotene, folic acid were significantly higher in females than those in males. MAR in males was significantly higher (0.83) than that in females (0.79). INQ values were higher in females for zinc, vitamin A, vitamin B₂, vitamin B₆, and folic acid than those in males. The average DVS was 17.63 for females and 13.19 for males. The average DDS was 3.68 and the male's average score was 3.44, whereas the female's average score was 3.92. In conclusion, males had more dietary habit problems and poor nutritional balance than those of females. Our findings suggest that proper nutritional management and adequate dietary education for the primary prevention of gastric cancer should be emphasized in men.

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

BACKGROUND

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.

OBJECTIVE

We investigated the association between isoflavone intake and the incidence of gastric cancer.

DESIGN

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.

RESULTS

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).

CONCLUSION

The current study does not support the hypothesis that higher intakes of isoflavones prevent gastric cancer in either men or women.

Gastric cancer epidemiology in Korea

Gastric cancer has been the most commonly diagnosed cancer in Korea although the age-standardized mortality and incidence has decreased gradually during last two decades. Helicobacter pylori infection and cigarette smoking are well-established risk factors, and the role of dietary factors, such as salted foods, fresh vegetables and fruits, soy foods, and processed or grilled meats on gastric carcinogenesis has been suggested. In this review, we review national and international gastric cancer statistics, studies on environmental risk factors conducted in the Korean population, and gastric cancer screening activities.