Combination of dietary factors in relation to breast-cancer occurrence

The relationship between dairy products intake and breast cancer incidence: a meta-analysis of observational studies

BACKGROUND

The effect of dairy products intake on breast cancer (BC) is highly controversial. This study aims to investigate the relationship between dairy intake and BC incidence.

METHODS

A search was carried out in PubMed, EBSCO, Web of Science, and Cochrane Library databases before January 2021. The primary objective was the risk of BC and intake of dairy products were exposure variables.

RESULTS

The meta-analysis comprised 36 articles with 1,019,232 participants. Total dairy products have a protective effect on female population (hazard ratio (HR) =0.95, 95% confidence interval (CI) =0.91-0.99, p = 0.019), especially for estrogen receptor-positive (ER+) (HR = 0.79, p = 0.002) and progesterone receptor-positive (PR+) BC (HR = 0.75, p = 0.027). For ER+/PR+ BC, there is a trend of protection, but it has not reached statistical significance (HR = 0.92, p = 0.075). Fermented dairy products can reduce BC risk in postmenopausal population (HR = 0.96, 95%CI = 0.93-0.99, p = 0.021), but have no protective effect on premenopausal population (HR = 0.98, 95%CI = 0.94-1.03, p = 0.52). Non-fermented dairy products have no significant effect on BC occurrence (p > 0.05). High-fat dairy products are harmful to women, without statistical difference (HR = 1.06, 95%CI = 1.00-1.13, p = 0.066). On the contrary, low-fat dairy products can protect the premenopausal population (HR = 0.94, 95%CI = 0.89-1.00, p = 0.048).

CONCLUSION

The intake of dairy products can overall reduce BC risk in the female population, but different dairy products have varying effects on different BC subtypes and menopausal status.

Yogurt, cultured fermented milk, and health: a systematic review

Consumption of yogurt and other fermented products is associated with improved health outcomes. Although dairy consumption is included in most dietary guidelines, there have been few specific recommendations for yogurt and cultured dairy products. A qualitative systematic review was conducted to determine the effect of consumption of fermented milk products on gastrointestinal and cardiovascular health, cancer risk, weight management, diabetes and metabolic health, and bone density using PRISMA guidelines. English language papers in PubMed were searched, with no date restrictions. In total, 1057 abstracts were screened, of which 602 were excluded owing to lack of appropriate controls, potential biases, and experimental design issues. The remaining 455 papers were independently reviewed by both authors and 108 studies were included in the final review. The authors met regularly to concur, through consensus, on relevance, methods, findings, quality, and conclusions. The included studies were published between 1979 and 2017. From the 108 included studies, 76 reported a favorable outcome of fermented milks on health and 67 of these were considered to be positive or neutral quality according to the Academy of Nutrition and Dietetics’ Quality Criteria Checklist. Of the 32 remaining studies, the study outcomes were either not significant (28) or unfavorable (4), and most studies (18) were of neutral quality. A causal relationship exists between lactose digestion and tolerance and yogurt consumption, and consistent associations exist between fermented milk consumption and reduced risk of breast and colorectal cancer and type 2 diabetes, improved weight maintenance, and improved cardiovascular, bone, and gastrointestinal health. Further, an association exists between prostate cancer occurrence and dairy product consumption in general, with no difference between fermented and unfermented products. This article argues that yogurt and other fermented milk products provide favorable health outcomes beyond the milk from which these products are made and that consumption of these products should be encouraged as part of national dietary guidelines.

Systematic review registration: PROSPERO registration no. CRD42017068953.

A Health-Conscious Food Pattern Is Associated with Prediabetes and Gut Microbiota in the Malmö Offspring Study

BACKGROUND

Diet is a determinant of gut microbiota. Both diet and gut microbiota have been linked to metabolic diseases.

OBJECTIVE

We aimed to examine data-driven food patterns in relation to the prevalence of prediabetes and gut microbiota composition and food pattern-associated bacteria in relation to prediabetes.

METHODS

Food patterns were extracted using principal component analysis in 1726 individuals (aged 18-71 y, 55% women, mean BMI = 25.5 kg/m2) without diabetes from the population-based Malmö Offspring Study. The gut (fecal) microbiota was analyzed by sequencing the 16S ribosomal RNA gene (V1-V3 region). Prediabetes classification was based on fasting glucose ≥6.0 mmol/L and/or glycated hemoglobin ≥42 mmol/L at baseline and/or type 2 diabetes diagnosis during follow-up (0-3.8 y). Logistic regression was used to investigate cross-sectional associations with prediabetes, and the general linear model to examine associations between food patterns and bacterial genera.

RESULTS

Two food patterns, the Health-conscious and the Sugar and High-Fat Dairy patterns, were identified. Adherence to the Health-conscious pattern was associated with a lower prevalence of prediabetes (OR comparing highest quintile with lowest: 0.54; 95% CI: 0.32, 0.92; P-trend = 0.03) and with the abundance of several gut bacterial genera, of which the most robust findings were with a higher abundance of Roseburia and Lachnospira and with a lower abundance of Eubacterium. Roseburia was also associated with a lower prevalence of prediabetes (OR comparing highest quintile with lowest: 0.56; 95% CI: 0.35, 0.92; P-trend = 0.01) and the association between the Health-conscious pattern and prediabetes was attenuated after adjustment for abundance of Roseburia and BMI. Adherence to the Sugar and High-Fat Dairy pattern was associated with a higher prevalence of prediabetes in women (P-trend across food pattern quintiles = 0.03).

CONCLUSIONS

In this Swedish population-based study, a Health-conscious food pattern showed an inverse association with the prevalence of prediabetes. Potential underlying explanations may involve links between healthy diet and BMI, as well as gut microbiota, especially a higher abundance of Roseburia.

Reversal of age-associated oxidative stress in mice by PFT, a novel kefir product

INTRODUCTION

Oxidative stress is a key contributor to aging and age-related diseases. In the present study, we examine the protective effects of PFT, a novel kefir product, against age-associated oxidative stress using aged (10-month-old) mice.

METHODS

Mice were treated with PFT orally at a daily dose of 2 mg/kg body weight over 6 weeks, and antioxidant status, protein oxidation, and lipid peroxidation were studied in the brain, liver, and blood.

RESULTS

PFT supplementation significantly reduced the oxidative stress biomarkers malondialdehyde (MDA) and nitric oxide; reversed the reductions in glutathione (GSH) levels, total antioxidant capacity (TAC), and anti-hydroxyl radical (AHR) content; enhanced the antioxidant enzyme activities of glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD); inhibited the liver enzyme levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT); significantly reduced triglyceride (TG), total cholesterol (TC), and low density lipoprotein (LDL) levels; and significantly elevated high density lipoprotein (HDL) levels. Interestingly, PFT supplementation reversed the oxidative changes associated with aging, thus bringing levels to within the limits of the young control mice in the brain, liver, and blood. We also note that PFT affects the redox homeostasis of young mice and that it is corrected post-treatment with PFT.

CONCLUSION

Our findings show the effectiveness of dietary PFT supplementation in modulating age-associated oxidative stress in mice and motivate further studies of PFT's effects in reducing age-associated disorders where free radicals and oxidative stress are the major cause.

Cho W, Soleimanpour S. Bacteriotherapy in Breast Cancer

Breast cancer is the second most common cause of cancer-related mortality among women around the world. Conventional treatments in the fight against breast cancer, such as chemotherapy, are being challenged regarding their effectiveness. Thus, strategies for the treatment of breast cancer need to be continuously refined to achieve a better patient outcome. We know that a number of bacteria are pathogenic and some are even associated with tumor development, however, recent studies have demonstrated interesting results suggesting some bacteria may have potential for cancer therapy. Therefore, the therapeutic role of bacteria has aroused attention in medical and pharmaceutical studies. Furthermore, genetic engineering has been used in bacterial therapy and may led to greater efficacy with few side effects. Some genetically modified non-pathogenic bacterial species are more successful due to their selectivity for cancer cells but with low toxicity for normal cells. Some live, attenuated, or genetically modified bacterias are capable to multiply in tumors and inhibit their growth. This article aims to review the role of bacteria and their products including bacterial peptides, bacteriocins, and toxins for the treatment of breast cancer.

Emerging Roles of Probiotics in Prevention and Treatment of Breast Cancer: A Comprehensive Review of Their Therapeutic Potential

Breast cancer is the most common cancer among women. Need for novel preventive and curative approaches with more safety than the present one seems inevitable. This review is devoted to potentially favorable role of probiotics in prevention and treatment of breast cancer as well as their alleviating role regarding chemotherapy-induced side effects. Literature was searched for human, animal, and in vitro studies about the role of probiotics in breast cancer. In vitro studies showed that probiotic intervention induces cancer cells apoptosis and inhibits their proliferation. In animal models, treatment with probiotics inhibited tumor growth and reduced tumor size; also, the immunomodulatory, antiangiogenesis and antimetastatic activities of probiotics were illustrated. Human studies showed that intake of Lactobacillus casei shirota reduced the breast cancer incidence and consumption of fermented milk products and yogurt was inversely associated with breast cancer incidence; however, no study regarding the curative role of probiotics in breast cancer is available. Studies on the effect of probiotics on chemotherapy-induced side effects in breast cancer were contradictory but showed potential for more investigation. Probiotics seem to have a potential role in both prevention and treatment of breast cancer. However, more clinical studies are needed to elucidate their efficacy and safety.

Polyunsaturated fatty acid interactions and breast cancer incidence: a population-based case-control study on Long Island, New York

PURPOSE

Experimental studies demonstrate that ω-3 polyunsaturated fatty acids (PUFAs) inhibit inflammatory eicosanoids generated by ω-6 PUFAs. Epidemiologic studies on dietary ω-3 PUFA intake show consistent inverse associations with breast cancer incidence among Asian populations, where ω-3, relative to ω-6, intake is high. In contrast, associations are inconsistent among Western populations, where intake of ω-3, relative to ω-6, is low. We hypothesized that examining interactions between ω-3 and ω-6 would help elucidate the PUFA-breast cancer association in the United States.

METHODS

In a Long Island, New York, population-based study of 1463 breast cancer cases and 1500 controls, we estimated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression to examine interactions between ω-3 and ω-6 intake.

RESULTS

We observed a super-additive interaction (relative excess risk due to interaction = 0.41; 95% confidence interval = 0.06-0.76) between ω-3 and ω-6 intake in association with breast cancer incidence, although the CIs for the joint exposure of low ω-3/high ω-6 compared to high ω-3/low ω-6 intake were wide (odds ratio = 1.20; 95% confidence interval = 0.85-1.69).

CONCLUSIONS

Breast cancer risk reduction may be possible for U.S. women with dietary consumption of higher ω-3, which has anti-inflammatory properties, in concert with lower ω-6, which induces inflammation. Replication from future U.S.-based investigations is needed.

Apoptotic effect of a novel kefir product, PFT, on multidrug-resistant myeloid leukemia cells via a hole-piercing mechanism

We examined the apoptotic effect of a novel Probiotics Fermentation Technology (PFT) kefir grain product; PFT is a natural mixture composed primarily of Lactobacillus kefiri P-IF, a specific strain of L. kefiri with unique growth characteristics. The aim of this study was to examine the apoptotic effect of PFT on human multidrug-resistant (MDR) myeloid leukemia (HL60/AR) cells in vitro and explore the mechanistic approach underlying its effect. HL60/AR cells were cultured with PFT (0.6–5.0 mg/ml) for 3 days. The apoptotic effect of PFT was assessed through examination of percent apoptosis, caspase 3 activation, Bcl-2 expression levels and changes in mitochondrial membrane potential (MMP). PFT induced apoptosis in HL60/AR cells in a dose-dependent manner which was maximal at 67.5% for 5 mg/ml. Induction of apoptosis was associated with activation of caspase 3, decreased expression of Bcl-2 and decreased polarization of MMP. In addition, PFT showed a unique characteristic of piercing holes in HL60/AR cells, as indicated by AFM studies. This hole induction may be responsible for the apoptotic effect on cancer cells. These results suggest that PFT may act as a potential therapy for the treatment of MDR leukemia.

Breast Cancer Risk - Genes, Environment and Clinics

The information available about breast cancer risk factors has increased dramatically during the last 10 years. In particular, studies of low-penetrance genes and mammographic density have improved our understanding of breast cancer risk. In addition, initial steps have been taken in investigating interactions between genes and environmental factors. This review concerns with actual data on this topic. Several genome-wide association studies (GWASs) with a case-control design, as well as large-scale validation studies, have identified and validated more than a dozen single nucleotide polymorphisms (SNPs) associated with breast cancer risk. They are located not only in or close to genes known to be involved in cancer pathogenesis, but also in genes not previously associated with breast cancer pathogenesis, or may even not be related to any genes. SNPs have also been identified that alter the lifetime risk in BRCA mutation carriers. With regard to nongenetic risk factors, studies of postmenopausal hormone replacement therapy (HRT) have revealed important information on how to weigh up the risks and benefits of HRT. Mammographic density (MD) has become an accepted and important breast cancer risk factor. Lifestyle and nutritional considerations have become an integral part of most studies of breast cancer risk, and some improvements have been made in this field as well. More than 10 years after the publication of the first breast cancer prevention studies with tamoxifen, other substances such as raloxifene and aromatase inhibitors have been investigated and have also been shown to have preventive potential. Finally, mammographic screening systems have been implemented in most Western countries during the last decade. These may be developed further by including more individualized methods of predicting the patient's breast cancer risk.

Association between vitamin D and calcium intake and breast cancer risk according to menopausal status and receptor status in Japan

Although several studies have investigated the possible association between elevated vitamin D and calcium intake and low breast cancer risk, findings have been inconsistent. We conducted a case-control study to clarify the association between vitamin D and calcium intake and breast cancer risk among pre- and post- menopausal women in Japan. We also investigated whether these effects were modified by tumor receptor status, specifically estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor-2 (HER2) status. We examined 1803 breast cancer patients and 3606 age- and menopausal status-matched noncancer controls. Among cases, 713 were assessed for ER, PR, and HER2 status. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using conditional or unconditional logistic models adjusted for potential confounders. A significant inverse association was observed between vitamin D and calcium intake and breast cancer risk among all subjects, with top quartile ORs of 0.76 (95% CI, 0.63-0.90; trend P = 0.001) and 0.83 (95% CI, 0.69-0.99; trend P = 0.038), respectively. In analyses stratified by menopausal status, a significant association between risk and vitamin D was observed only among premenopausal women (trend P < 0.001), whereas that between risk and calcium intake was seen only among postmenopausal women (trend P = 0.022). Heterogeneity by menopausal status for these associations was statistically significant. This association was modified by tumor receptor status. These findings suggest that the protective effects of vitamin D and calcium intake against breast cancer risk may differ by menopausal status and receptor status.

Dietary patterns and breast cancer risk: a systematic review and meta-analysis

BACKGROUND

Dietary patterns, which represent whole-diet and possible food and nutrient interactions, have been linked to the risk of various cancers. However, the associations of these dietary patterns with breast cancer remain unclear.

OBJECTIVE

We critically appraised the literature and conducted meta-analyses to pool the results of studies to clarify the relation between dietary patterns and breast cancer risk.

DESIGN

MEDLINE and EMBASE were searched for relevant articles that identified common dietary patterns published up to November 2009. Multivariable-adjusted odds ratios (ORs) comparing highest and lowest categories of dietary pattern scores and multivariable-adjusted ORs for a 20th-percentile increase in dietary pattern scores were combined by using random-effects meta-analyses.

RESULTS

Case-control and cohort studies were retrieved that identified prudent/healthy (n = 18), Western/unhealthy (n = 17), and drinker (n = 4) dietary patterns. There was evidence of a decrease in the risk of breast cancer in the highest compared with the lowest categories of prudent/healthy dietary patterns (OR = 0.89; 95% CI: 0.82, 0.99; P = 0.02) in all studies and in pooled cohort studies alone. An increase in the risk of breast cancer was shown for the highest compared with the lowest categories of a drinker dietary pattern (OR = 1.21; 95% CI: 1.04, 1.41; P = 0.01). There was no evidence of a difference in the risk of breast cancer between the highest and the lowest categories of Western/unhealthy dietary patterns (OR = 1.09; 95% CI: 0.98, 1.22; P = 0.12).

CONCLUSION

The results of this systematic review and meta-analysis indicate that some dietary patterns may be associated with breast cancer risk.

Probiotics for preventive health

Gut flora and probiotics have potential to affect health and disease far beyond the gut. There is increasing evidence that probiotics have beneficial effects in preventing a wide range of conditions and improving health. Randomized, double-blind studies have provided evidence of the effectiveness of probiotics for preventing various diarrheal illnesses as well as allergic disorders. Evidence for their efficacy for use in the prevention and treatment of bacterial vaginosis and urinary tract infections is also mounting. In addition, probiotics may be useful for preventing respiratory infections, dental caries, necrotizing enterocolitis, and certain aspects of inflammatory bowel disease. Data also suggest that probiotics may promote good health in day care and work settings, and may enhance growth in healthy as well as ill and malnourished children. Results from meta-analyses and systematic reviews that combine results of studies from different types of probiotics to examine the effects in any disease state should be interpreted with caution. Specific strains are effective in specific disease states. No 2 probiotics are exactly alike; we should not expect reproducible results from studies that employ different species or strains, variable formulations, and diverse dosing schedules.

The role of the calcium-sensing receptor in the development and progression of cancer

The calcium-sensing receptor (CaR) is responsive to changes in the extracellular Ca(2+) (Ca(2+)(o)) concentration. It is a member of the largest family of cell surface receptors, the G protein-coupled receptors, and it has been shown to be involved in Ca(2+)(o) homeostasis. Apart from its primary role in Ca(2+)(o) homeostasis, the CaR may be involved in phenomena that allow for the development of many types of benign or malignant tumors, from parathyroid adenomas to breast, prostate, and colon cancers. For example, whereas the CaR is expressed in both normal and malignant breast tissue, increased CaR levels have been reported in highly metastatic primary breast cancer cells and breast cancer cell lines, possibly contributing to their malignancy and associated alterations in their biological properties. In these settings the CaR exhibits oncogenic properties. Enhanced CaR expression and altered proliferation of prostate cancer cells in response to increased Ca(2+)(o) have also been described. In contrast, colon and parathyroid cancers often present with reduced or absent CaR expression, and activation of this receptor decreases cell proliferation, suggesting a role for the CaR as a tumor suppressor gene. Thus, the CaR may play an important role in the development of many types of neoplasia. Herein, we review the role of the CaR in various benign and malignant tumors in further detail, describing its contribution to parathyroid tumors, breast, prostate, and colon cancers, and we evaluate how pharmacological manipulations of this receptor may be of interest for the treatment of certain cancers in the future.

Vitamin D receptor polymorphisms (FokI, BsmI) and breast cancer risk: association replication in two case-control studies within French Canadian population

Vitamin D has been associated with reduced breast cancer risk. We studied the association of two vitamin D receptor (VDR) gene single nucleotide polymorphisms restriction enzyme detecting SNP of VDR (FokI and BsmI) with breast cancer risk in two independent case-control studies carried out in the same population. The modifying effect of family history of breast cancer on this relationship was also evaluated. The first and second studies included respectively 718 (255 cases/463 controls) and 1596 (622 cases/974 controls) women recruited in Quebec City, Canada. FokI and BsmI genotypes were assessed. Relative risks of breast cancer were estimated by multivariate logistic regression. Compared with homozygotes for the common F allele (FF genotype), FokI ff homozygotes had a higher breast cancer risk (study 1: odds ratio (OR)=1.22, 95% confidence interval (CI)=0.76-1.95; study 2: OR=1.44, 95% CI=1.05-1.99; and combined studies: OR=1.33, 95% CI=1.03-1.73). Significant interactions were observed between FokI and family history of breast cancer in the two studies as well as in the combined analysis (P interaction=0.031, 0.050 and 0.0059 respectively). Among women without family history, odds ratios were 1.00, 1.27 (95% CI=1.02-1.58) and 1.57 (95% CI=1.18-2.10) respectively for FF, Ff and ff carriers (P(trend)=0.0013). BsmI Bb+bb genotypes were associated with a weak non-significant increased risk in the two studies (combined OR=1.22, 95% CI=0.95-1.57) without interaction with family history. Results support the idea that vitamin D, through its signalling pathway, can affect breast cancer risk. They also suggest that variability in observed associations between VDR FokI and breast cancer from different studies may partly be explained by the proportion of study subjects with a family history of breast cancer.

Levels of zinc, selenium, calcium, and iron in benign breast tissue and risk of subsequent breast cancer

Previous studies that have assessed breast cancer in relation to zinc, selenium, calcium, and iron have yielded inconsistent results but have not measured breast tissue levels. In a case-control study involving 252 matched pairs nested in a cohort of 9,315 women with benign breast disease, we investigated these associations by directly measuring elemental levels in breast tissue using X-ray fluorescence spectroscopy. Quintile analyses revealed positive associations of breast cancer, of borderline statistical significance, with zinc [highest versus lowest quintile: odds ratio (OR), 1.37; 95% confidence limit (95% CL), 0.91, 2.05; P(trend) = 0.04], iron (highest versus lowest quintile: OR, 1.58; 95% CL, 1.02, 2.44; P(trend) = 0.07), and calcium (highest versus lowest quintile: OR, 1.46; 95% CL, 0.98, 2.17; P(trend) = 0.14), but little association with selenium (highest versus lowest quintile: OR, 1.10; 95% CL, 0.72, 1.68; P(trend) = 0.76). The associations were weakened by mutual adjustment. Furthermore, after stratification by menopausal status, the positive association between iron and breast cancer was confined to postmenopausal women (highest versus lowest quintile: OR, 2.77; 95% CL, 1.25, 6.13; P(trend) = 0.008), whereas the associations for zinc, calcium, and selenium did not differ by menopausal stratum. In conclusion, our data raise the possibility that relatively high levels of zinc, iron, and calcium in benign breast tissue may be associated with a modest increase in risk of subsequent breast cancer.

Vitamin D, Calcium, and Breast Cancer Risk: A Review

Vitamin D and calcium are metabolically interrelated and highly correlated dietary factors. Experimental studies have shown their anticarcinogenic effects due to their participation in regulating cell proliferation, differentiation, and apoptosis in normal and malignant breast cells. Given the emerging interest in their potential roles in the etiology of breast cancer, we review the current epidemiologic literature on dietary and/or supplemental intakes of vitamin D, endogenous circulating levels of vitamin D, and dietary and/or supplemental intakes of calcium in relation to breast cancer risk. To place these studies in context, we also provide a brief review of other supporting epidemiologic evidence. Despite inconsistent results from the epidemiologic studies, several lines of evidence suggest that vitamin D and calcium may be involved in the development of breast cancer. Specifically, (a) there is some epidemiologic evidence for inverse associations between vitamin D and calcium intakes and breast cancer; (b) serum, plasma, and/or blood levels of vitamin D metabolites have been inversely associated with breast cancer risk in some studies; (c) high sunlight exposure, presumably reflecting vitamin D synthesis in the skin, has been associated with a reduced risk of breast cancer; (d) vitamin D and calcium intakes have been inversely related to breast density, an intermediate end point for breast cancer; (e) calcium has been associated with a reduced risk of benign proliferative epithelial disorders of the breast, putative precursors of breast cancer; and (f) certain polymorphisms of the vitamin D receptor might modify breast cancer susceptibility. To further confirm the potential protective effects of calcium and vitamin D on breast cancer, well-designed cohort studies and clinical trials are warranted.

Roles for the calcium sensing receptor in primary and metastatic cancer

AIM

To review the role of the calcium sensing receptor (CASR) in colorectal, breast and parathyroid cancers and related cell lines, and to discuss the effects of CASR in the setting of bone metastases from breast cancer.

METHODS

We performed a literature search of the PubMed database of the National Library of Medicine (NLM) to identify articles concerning the CASR's involvement in different cancers. Further relevant papers were obtained from the references of those identified in the original search.

RESULTS

Loss of CASR expression is understood to be associated with abnormal differentiation and progression of colorectal carcinoma. It is expressed in both normal and malignant breast tissues and has been implicated in the vicious cycle of bone metastases through its interactions with the parathyroid hormone related peptide (PTHrP). In parathyroid tissue, CASR expression has been linked to proliferation of both parathyroid adenomas and carcinomas.

CONCLUSION

Apart from its role in calcium homeostasis, the CASR has many diverse functions in a variety of tissue types throughout the body, and is involved in various signalling pathways relating to cell proliferation and differentiation. CASR has been shown to be involved in the progression and spread of a variety of cancers such as colorectal, breast and parathyroid, and is likely to be the focus of much research to further elucidate its precise role.

Lipids isolated from bone induce the migration of human breast cancer cells

Bone is the most common site to which breast cancer cells metastasize. We found that osteoblast-like MG63 cells and human bone tissue contain the bile acid salt sodium deoxycholate (DC). MG63 cells take up and accumulate DC from the medium, suggesting that the bone-derived DC originates from serum. DC released from MG63 cells or bone tissue promotes cell survival and induces the migration of metastatic human breast cancer MDA-MB-231 cells. The bile acid receptor farnesoid X receptor (FXR) antagonist Z-guggulsterone prevents the migration of these cells and induces apoptosis. DC increases the gene expression of FXR and induces its translocation to the nucleus of MDA-MB-231 cells. Nuclear translocation of FXR is concurrent with the increase of urokinase-type plasminogen activator (uPA) and the formation of F-actin, two factors critical for the migration of breast cancer cells. Our results suggest a novel mechanism by which DC-induced increase of uPA and binding to the uPA receptor of the same breast cancer cell self-propel its migration and metastasis to the bone.

Fat From Different Foods Show Diverging Relations With Breast Cancer Risk in Postmenopausal Women

The aim was to explore previous findings within the Malmö Diet and Cancer cohort (Sweden) that omega6-fatty acid intakes are positively associated with breast cancer risk among women 50 yr of age and older and specifically examine relations between breast cancer risk and fat from different food groups. Incident breast cancer cases (n = 237) were matched to controls (n = 673) on age and screening date. A modified diet history method, a structured questionnaire, and anthropometric measurements provided data. Fat-food variables from 24 food groups were computed. Conditional logistic regression examined breast cancer risk associated with energy-adjusted exposure categories of fat-food variables. Fat from fermented milk products was negatively associated with breast cancer risk (trend, P = 0.003). The highest quartiles of vegetable oil-based dietary fats (odds ratio, OR = 1.74; confidence interval, CI = 1.12-2.72) and dried soup powders (OR = 1.59; CI = 1.04-2.43) showed positive associations. Dietary fiber did not influence associations.

Towards a dietary prevention of hereditary breast cancer

Inheritance of a deleterious mutation in BRCA1 or BRCA2 confers a high lifetime risk of developing breast cancer. Variation in penetrance between individuals suggests that factors other than the gene mutation itself may influence the risk of cancer in susceptible women. Several risk factors have been identified which implicate estrogen-induced growth stimulation as a probable contributor to breast cancer pre-disposition. The protein products of both of these genes appear to help preserve genomic integrity via their participation in the DNA damage response and repair pathways. To date, the evidence for a cancer-protective role of dietary nutrients, for the most part those with antioxidant properties, has been based on women without any known genetic pre-disposition and it is important to identify and evaluate dietary factors which may modify the risk of cancer in BRCA carriers. Here we propose that diet modification may modulate the risk of hereditary breast cancer by decreasing DNA damage (possibly linked to estrogen exposure) or by enhancing DNA repair. The prevention of hereditary breast cancer through diet is an attractive complement to current management strategies and deserves exploration.

Vitamin D and Calcium Intakes from Food or Supplements and Mammographic Breast Density

BACKGROUND

A better understanding of factors that affect breast density, one of the strongest breast cancer risk indicators, may provide important clues about breast cancer etiology and prevention. This study evaluates the association of vitamin D and calcium, from food and/or supplements, to breast density in premenopausal and postmenopausal women separately.

METHODS

A total of 777 premenopausal and 783 post-menopausal women recruited at two radiology clinics in Quebec City, Canada, in 2001 to 2002, completed a food frequency questionnaire to assess vitamin D and calcium. Breast density from screening mammograms was assessed using a computer-assisted method. Associations between vitamin D or calcium and breast density were evaluated using linear regression models. Adjusted means in breast density were assessed according to the combined daily intakes of the two nutrients using generalized linear models.

RESULTS

In premenopausal women, total intakes of vitamin D and calcium were inversely related to breast density (beta = -1.4; P = 0.004 for vitamin D; beta = -0.8; P = 0.0004 for calcium). In multivariate linear regression, simultaneous increments in daily total intakes of 400 IU vitamin D and 1,000 mg calcium were associated with an 8.5% (95% confidence interval, 1.8-15.1) lower mean breast density. The negative association between dietary vitamin D intake and breast density tended to be stronger at higher levels of calcium intake and vice versa. Among postmenopausal women, intakes of vitamin D and calcium were not associated with breast density.

CONCLUSION

These findings show that higher intakes of vitamin D and calcium from food and supplements are related to lower levels of breast density among premenopausal women. They suggest that increasing intakes of vitamin D and calcium may represent a safe and inexpensive strategy for breast cancer prevention.

Probiotics and human health: a clinical perspective

There is unequivocal evidence that administration of probiotics could be effective in the treatment of acute infectious diarrhoea in children and the prevention of antibiotic associated diarrhoea and nosocomial/community acquired diarrhoea. Encouraging evidence is also emerging for the effectiveness of probiotics in the prevention and management of pouchitis and paediatric atopic diseases, and the prevention of postoperative infections. There is also strong evidence that certain probiotic strains are able to enhance immune function, especially in subjects with less than adequate immune function such as the elderly. Efficacy of probiotics in the prevention of traveller's diarrhoea, sepsis associated with severe acute pancreatitis, and cancers, the management of ulcerative colitis, and lowering of blood cholesterol remains unproven. In addition to firm evidence of efficacy (for a range of conditions), major gaps exist in our knowledge regarding the mechanisms by which probiotics modulate various physiological functions and the optimum dose, frequency, and duration of treatment for different probiotic strains.

Vitamin D, Calcium, and Mammographic Breast Densities

Vitamin D and calcium are being evaluated as potential breast cancer prevention agents. This study reports on the relation of dietary vitamin D and calcium to mammographic breast densities, one of the strongest breast cancer risk factors. Participants were women ages 40 to 60 years who had had a screening mammogram in Rhode Island and eastern Massachusetts (1989–1990). Diet was assessed by semiquantitative food frequency questionnaire, and the percentage of the breast showing densities was estimated visually by a single observer without information on subjects. Multivariate logistic regression was used to compare dietary intakes of vitamin D and calcium between women classified as having few densities (≤30% of the breast with density, n = 287) and extensive densities (≥70% of the breast with density, n = 256). For categories of increasing vitamin D intake (&lt;50, 50–99, 100–199, and ≥200 IU/d), adjusted odds ratios (OR) for extensive densities were 1.00 (reference), 0.51, 0.37, and 0.24, respectively (P for trend = 0.0005). For increasing calcium intake (&lt;500, 500–749, 750–999, and ≥1,000 mg/d), adjusted ORs were 1.00 (reference), 0.63, 0.25, and 0.24, respectively (P for trend = 0.0006). Combination of higher intakes of vitamin D and calcium (≥100 IU/d and ≥750 mg/d, respectively) were associated with a reduction of breast densities (OR, 0.28; 95% confidence interval, 0.15–0.54) compared with those consuming &lt;100 IU/d and &lt;750 mg/d. Increases in vitamin D and calcium intakes were associated with decreases in breast densities, suggesting that dietary vitamin D and calcium could reduce breast cancer risk possibly through influences on breast tissue morphology.

Intakes of plant foods, fibre and fat and risk of breast cancer--a prospective study in the Malmö Diet and Cancer cohort

The objective of this study was to investigate prospectively the associations between intakes of plant foods, fibre and relative fat and risk of breast cancer in a subsample of 11 726 postmenopausal women in the Malmö Diet and Cancer cohort. Data were obtained by an interview-based diet history method, a structured questionnaire, anthropometrical measurements and national and regional cancer registries. During 89 602 person-years of follow-up, 342 incident cases were documented. Cox regression analysis examined breast cancer risks adjusted for potential confounders. High fibre intakes were associated with a lower risk of postmenopausal breast cancer, incidence rate ratio=0.58, 95% CI: 0.40, 0.84, for the highest quintile of fibre intake compared to the lowest quintile. The combination high fibre–low fat had the lowest risk when examining the effect in each cell of cross-classified tertiles of fibre and fat intakes. An interaction (P=0.049) was found between fibre- and fat-tertiles. There was no significant association between breast cancer risk and intakes of any of the plant food subgroups. These findings support the hypothesis that a dietary pattern characterised by high fibre and low fat intakes is associated with a lower risk of postmenopausal breast cancer.

Dietary calcium intake and breast cancer risk among Chinese women in Shanghai

Limited epidemiological evidence suggests that calcium intake may be related to breast cancer risk. Data from a large, population-based, case-control study (n = 1,459 cases, 1,556 controls) conducted in Shanghai, China, between 1996 and 1998 were used to investigate the association between calcium intake and risk for breast cancer. Diet was assessed using a quantitative food-frequency questionnaire. The multivariate-adjusted odds ratio (OR) comparing all women combined in the highest to lowest deciles of total calcium intake was 0.74 (95% confidence interval [CI] = 0.46-1.20). Whereas calcium primarily derived from poultry was inversely associated with risk for breast cancer (comparing the highest to lowest quintile OR = 0.71, 95% CI = 0.55-0.93) with a statistically significant test for trend, calcium derived from milk, seafood, fruit, and vegetables was not associated with risk of breast cancer. Given that breast cancer is one of the top contributors to cancer incidence worldwide, even a moderate inverse association between calcium and breast cancer risk, if confirmed, could have important public health implications in breast cancer prevention.

The Role of Nutrition in the Prevention of Breast Cancer

Nutrition has been widely studied as a leading environmental factor in the prevention of breast cancer (BC). Despite the challenges in relating consumption of specific nutrients to BC risk, particularly in the context of a total diet, many investigators have contributed valuable information. Dietary fat has received the most attention and also created the most uncertainty. Specific types of fat, particularly monounsaturated fat and the ratio of omega-3 to omega-6 fatty acids, demonstrate more potential to influence BC risk. A wide variety of other dietary factors have been studied in relation to BC including total energy, dietary fiber, alcohol, micronutrients, phytochemicals, specific foods, and food constituents. Results of epidemiological studies relating consumption of these dietary factors to BC have increased the knowledge base that provides rationale for various nutritional strategies to contribute to BC prevention.

Dietary fat and breast cancer risk revisited: a meta-analysis of the published literature

Animal experiments and human ecological studies suggest that dietary fat intake is associated with a risk of breast cancer, but individual-based studies have given contradictory results. We have carried out a meta-analysis of this association to include all papers published up to July 2003. Case–control and cohort studies that examined the association of dietary fat, or fat-containing foods, with risk of breast cancer were identified. A total of 45 risk estimates for total fat intake were obtained. Descriptive data from each study were extracted with an estimate of relative risk and its associated 95% confidence interval (CI), and were analysed using the random effects model of DerSimonian and Laird. The summary relative risk, comparing the highest and lowest levels of intake of total fat, was 1.13 (95% CI: 1.03–1.25). Cohort studies (N=14) had a summary relative risk of 1.11 (95% CI: 0.99–1.25) and case–control studies (N=31) had a relative risk of 1.14 (95% CI 0.99–1.32). Significant summary relative risks were also found for saturated fat (RR, 1.19; 95% CI: 1.06–1.35) and meat intake (RR, 1.17; 95% CI 1.06–1.29). Combined estimates of risk for total and saturated fat intake, and for meat intake, all indicate an association between higher intakes and an increased risk of breast cancer. Case–control and cohort studies gave similar results.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

Dairy foods and risk of breast cancer: a case-control study in Montevideo, Uruguay

In order to investigate possible associations of milk and dairy products and the risk of breast cancer (BC) in Montevideo, the authors performed a case-control study in the period 1999-2001. A total of 333 women were interviewed with a specific questionnaire; 111 of them had been diagnosed with BC and 222 were frequency-matched healthy women, with a recent normal mammography (BIRADS 1). The questionnaire included a detailed 120-item food-frequency section, as well as questions related to socio-demographic, reproductive, familial, medical and lifestyle variables. There was particular emphasis on types of milk and dairy products. After controlling for age, years of urban status, education, body mass index, age at menarche, menopausal status, family history of BC, number of childbirths, total energy and total fruits, a multivariate analysis found that high intakes of whole milk, chocolate milk and Gruyère cheese were associated with significant increased risk of BC, whereas ricotta cheese and skim yoghurt were associated with significant decreased risks. Low-fat and fermented products combined appear to be the most protective dairy foods. The results suggest that separate analyses for types of milk and cheese, as well as for dairy products in general should be performed in the future.

The comprehensive approach to diet: a critical review

Recent disappointing results have challenged the earlier results of ecological studies that launched the hypothesis of a strong relationship between diet and cancer. The present state of knowledge regarding the relationship between cancer and diet is considered and discussed here. Steps for improving the understanding of the relationship and the content of recommendations for cancer prevention and survival are proposed, such as determining the possible food effect at each step of the carcinogenesis process, considering the dietary pattern instead of a single nutrient or food, introducing the diet quality index for evaluating cancer risk and developing more comprehensive statistical methods in nutritional epidemiology. In support of these propositions, previous, recent and on-going studies are reviewed and discussed. A holistic model of diet is described as a conclusion.

Profiles of a healthful diet and its relationship to biomarkers in a population sample from Mediterranean southern France

OBJECTIVES

The failure of single-nutrient supplementation to prevent disease in intervention studies underlines the necessity to develop a holistic view of food intake. The objectives of this study were to devise a diet quality index (DQI) and identify biomarkers of multidimensional dietary behavior.

DESIGN

A nutrition survey was conducted in Mediterranean southern France by means of a food frequency questionnaire. The DQI was based on current dietary recommendations for prevention of diet-related diseases such as cardiovascular disease and some cancers. A second DQI included tobacco use.

STATISTICAL ANALYSES

performed Spearman rank correlations, cross-classifications and intraclass correlations were computed between the DQI and biomarkers.

RESULTS

Of the 146 subjects, 10 had a healthful diet and 18 had a poor diet. Erythrocyte omega-3 fatty acids-eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)-beta carotene, and vitamin E concentrations were lower and cholesterol concentrations were higher in the poor diet; the difference was significant for EPA and DHA and borderline significant for vitamin E. Significant correlation was found between the DQI and vitamin E (-0.12), EPA (-0.30), and DHA (-0.28), and beta carotene (-0.17) when tobacco use was considered, but not between the DQI and cholesterol. The correlation coefficient reached 0.58 (P0.01) for a composite index based on all biomarkers except cholesterol.

CONCLUSIONS

Subjects with a beta carotene levels greater thanl micromol/L, vitamin E greater than 30 micromol/L and EPA greater than 0.65% and DHA greater than 4% of fatty acids in erythrocytes were likely to have a healthful diet. Each biomarker indicated the quality of diet, but correlation was higher with a composite index.

Immunologic effects of yogurt

Many investigators have studied the therapeutic and preventive effects of yogurt and lactic acid bacteria, which are commonly used in yogurt production, on diseases such as cancer, infection, gastrointestinal disorders, and asthma. Because the immune system is an important contributor to all of these diseases, an immunostimulatory effect of yogurt has been proposed and investigated by using mainly animal models and, occasionally, human subjects. Although the results of these studies, in general, support the notion that yogurt has immunostimulatory effects, problems with study design, lack of appropriate controls, inappropriate route of administration, sole use of in vitro indicators of the immune response, and short duration of most of the studies limit the interpretation of the results and the conclusions drawn from them. Nevertheless, these studies in toto provide a strong rationale for the hypothesis that increased yogurt consumption, particularly in immunocompromised populations such as the elderly, may enhance the immune response, which would in turn increase resistance to immune-related diseases. This hypothesis, however, needs to be substantiated by well-designed randomized, double-blind, placebo-controlled human studies of an adequate duration in which several in vivo and in vitro indexes of peripheral and gut-associated immune response are tested.

Diet and the risk of breast cancer in a case-control study: does the threat of disease have an influence on recall bias?

It has been suggested that recall bias may explain the discrepant results between case-control and cohort studies on diet and the risk of breast cancer. Two control groups were used for this case-control study of 25 to 75-year-old breast cancer cases (n = 310). The first group consisted of population controls drawn from the Finnish National Population Register (n = 454). The second group consisted of women who were referred to the same examinations as were the cases because of clinical suspicion of breast disease but who were later diagnosed as healthy (referral controls; n = 506). Because the diagnosis was unknown at the time of interview, it was possible to assess by comparing the two control groups whether the self-reporting of diet changed under the threat of disease. Dietary habits were examined using a validated, self-administered food-frequency questionnaire. Premenopausal women misreported their consumption of liquid milk products, tea, and sugar. Reporting bias was also associated with the intake of fat and vitamins. Postmenopausal women misreported consumption of milk products. When recall bias was taken into consideration, milk was associated with increased risk of premenopausal breast cancer, whereas high consumption of poultry or high intake of monounsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, and vitamin E were related to lower risk. The study suggested that oil, milk, cheese, coffee and beta-carotene may act as protective factors in postmenopausal women, whereas butter and cream may be risk factors for breast cancer. In summary, it is possible that some food items may be overreported or underreported under the threat of disease in health-conscious population. However, most of the results in this study were not modified by recall bias.

Understanding meta-analysis in cancer epidemiology: dietary fat and breast cancer

Meta-analyses of the relationship between dietary fat and breast cancer risk using different methodologies have reported conflicting results. This investigation compares methodologic aspects of meta-analyses of patient data (MAP) with meta-analyses of data from the literature (MAL), and computes relative risk (RR) estimates from a random effects model using 28 published studies of dietary fat and breast cancer. MAP and MAL results compare closely when homogeneity is verified. When statistical homogeneity is rejected, a random effects model adjusting for study design and location is appropriate. The highest RR was found for case-control studies of European women (RR: 1.46), followed by North American case-control studies (RR: 1.25), case-control studies of women on other continents (RR: 1.23), cohort studies in Europe (RR: 1.20), and cohort studies in North America (RR: 1.02). The overall risk estimate in a MAL with heterogeneous studies should be interpreted only in a conditional model.

Fiber and cancer protection--mechanisms

There is no reason to believe that a single lumenal or tissue factor will hold the key to understanding the of dietary fiber's effect on reducing the risk of colon cancer. In fact, the data suggest that multiple, interacting factors will be revealed. After years of research, it appears that the bile acid hypothesis is not nearly as strong as first envisaged. Additionally, the theory that SCFA protect against colon cancer has little clinical or experimental support. There is no doubt that identification of genetic alterations, and their controlling factors, will play a major role in our understanding of this issue. The appeal of the original fiber hypothesis has not diminished but simply requires updating based on discoveries made since it was first proposed. It is this author's opinion that dietary fiber will likely be found to modulate human colon cancer and the mechanisms of its beneficial effect will probably be through multiple actions within the lumen and at the level of the target tissue. Based on our current knowledge of the pathogenesis of colon cancer we cannot make definitive statements about what percentage of colon cancer might be prevented by a specific type or amount of dietary fiber but it is reasonable to conclude that consumption of fiber-rich diets is associated with reduced risk of colon cancer. It is quite plausible that the combination of dietary fiber, or its metabolites, in conjunction with other phytochemicals may be necessary to realize inhibition of the tumorigenic process.

Case-control study of phyto-oestrogens and breast cancer

BACKGROUND

Phyto-oestrogens are a group of naturally occurring chemicals derived from plants; they have a structure similar to oestrogen, and form part of our diet. They also have potentially anticarcinogenic biological activity. We did a case-control study to assess the association between phyto-oestrogen intake (as measured by urinary excretion) and the risk of breast cancer.

METHODS

Women with newly diagnosed early breast cancer were interviewed by means of questionnaires, and a 72 h urine collection and blood sample were taken before any treatment started. Controls were randomly selected from the electoral roll after matching for age and area of residence. 144 pairs were included for analysis. The urine samples were assayed for the isoflavonic phyto-oestrogens daidzein, genistein, and equol, and the lignans enterodiol, enterolactone, and matairesinol.

FINDINGS

After adjustment for age at menarche, parity, alcohol intake, and total fat intake, high excretion of both equol and enterolactone was associated with a substantial reduction in breast-cancer risk, with significant trends through the quartiles: equol odds ratios were 1.00, 0.45 (95% CI 0.20, 1.02), 0.52 (0.23, 1.17), and 0.27 (0.10, 0.69)--trend p = 0.009--and enterolactone odds ratios were 1.00, 0.91 (0.41, 1.98), 0.65 (0.29, 1.44), 0.36 (0.15, 0.86)--trend p = 0.013. For most other phytoestrogens there was a reduction in risk, but it did not reach significance. Difficulties with the genistein assay precluded analysis of that substance.

INTERPRETATION

There is a substantial reduction in breast-cancer risk among women with a high intake (as measured by excretion) of phyto-oestrogens-particularly the isoflavonic phyto-oestrogen equol and the lignan enterolactone. These findings could be important in the prevention of breast cancer.

Antimutagenicity of an acetone extract of yogurt

Reconstituted non-fat dry milk powder, fermented by a mixture of Streptococcus thermophilus CH3 and Lactobacillus bulgaricus 191R to produce yogurt, was freeze-dried and extracted in acetone. After evaporation of the acetone, the extract was dissolved in dimethyl sulfoxide (DMSO) and tested for antimutagenicity. In the Ames test, significant dose-dependent activity was observed against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitro-quinoline-N-oxide (4NQO), 3,2'-dimethyl-4-aminobiphenyl (DMAB), 9,10-dimethyl-1,2-benz[a]anthracene (DMBA), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). Weak activity was observed against 1,2,7,8-diepoxyoctane (DEO), and no activity was observed against methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), or aflatoxin B1 (AFB1). In a related assay (Saccharomyces cerevisiae D7), significant antimutagenic activity was detected against MNNG and 4NQO. Activity against the experimental colon carcinogens MNNG and DMAB was examined further, as assayed in the Ames test (Salmonella typhimurium TA100). Compounds responsible for both activities were less soluble in aqueous solutions than in DMSO. Adjustment of yogurt pH to 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the amount of anti-MNNG activity recovered. In contrast, extractability of anti-DMAB activity was significantly greater at acidic pH. Conjugated linoleic acid, a known dairy anticarcinogen, failed to inhibit mutagenesis caused by either mutagen, suggesting that other yogurt-derived compound(s) are responsible. Unfermented milk was treated with lactic acid, yogurt bacteria without subsequent growth, or both, to determine if formation of antimutagenic activity required bacterial growth. Extracts of the milk treatments exhibited the same weak antimutagenicity observed in unfermented milk, approximately 2.5-fold less than in the yogurt extracts, suggesting that antimutagenic activity is associated with bacterial growth.

Antimutagenicity of fermented milk

Reconstituted nonfat dry milk was fermented by Lactobacillus helveticus CH65, Lactobacillus acidophilus BG2FO4, Streptococcus salivarius ssp. thermophilus CH3, Lactobacillus delbrueckii ssp. bulgaricus 191R, and by a mixture of the latter two organisms. The fermented milks were then freeze-dried, extracted in acetone, dissolved in dimethylsulfoxide, and assayed for antimutagenicity in the Ames test (Salmonella typhimurium TA 100) against N-methyl, N'-nitro, N-nitroso-guanidine, and 3,2'-dimethyl-4-amino-biphenyl. Dose-dependent activity was significant against both mutagens in all extracts. Maximal inhibitory activity against 3,2'-dimethyl-4-aminobiphenyl and N-methyl, N'-nitro, N-nitroso-guanidine was 2- and 2.7-fold greater, respectively, than that exhibited by extracts of unfermented milk. Extracts of milk fermented by L. delbrueckii ssp. bulgaricus 191R were examined further. Compounds that were responsible for activity against both mutagens were less soluble in aqueous solutions than in dimethylsulfoxide. Adjustment of milk fermented by L. delbrueckii ssp. bulgaricus 191R to pH 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the activity specific for 3,2'-dimethyl-4-aminobiphenyl. In contrast, compounds with activity specific for N-methyl, N'-nitro, N-nitrosoguanidine were less extractable at pH 7.6. The weak antimutagenicity of unfermented milk was not increased by addition of 2% L-lactic acid.

Actual daily dietary intake of selenium in Belgium, using duplicate portion sampling

The dietary selenium (Se) intake in Belgium has been re-evaluated. Duplicate meal collection, wet acid destruction and flow injection hydride generation atomic absorption spectrometry were used as techniques. The daily intake ranged from 28.4 micrograms (Liège, Walloon part of the country) to 61.1 micrograms (Vilvoorde, central part of the country). Compared with intakes recently published for other countries, the actual Belgian value corresponds to intermediate ranges of Se intake.

Nutritional risk factors for breast cancer

The observation of large differences in breast cancer rates between countries has led to the hypothesis that excessive intake of dietary fat is an important risk factor for breast cancer in women. Case-control and prospective studies, however, generally have failed to show associations between dietary fat and breast cancer risk. There therefore is only weak evidence that modest reductions in fat intake (for instance to levels of 30% of caloric intake from fat) will reduce breast cancer risk. The possible benefits of lowering fat intake to levels substantially below 30% of calories will need to be tested in a randomized trial. In the meantime, the possible roles of micronutrient imbalances and childhood nutritional factors need to be studied better. Obesity is related to breast cancer in a complex way that suggests that a hormonal correlate of excessive body weight might affect breast cancer growth and metastasis. The potential benefit of intentional weight loss as an adjunct breast cancer treatment deserves further study. Many studies have suggested that drinking alcohol, even at modest levels, might increase breast cancer risk. Because the potential benefits of modest levels of alcohol for cardiovascular disease may outweigh the risk for breast cancer, recommendations for total alcohol abstinence may be premature for women with an average breast cancer risk. Women at unusually high risk for breast cancer who have a lower-than-average risk for cardiovascular disease, however, might make an informed decision to abstain from alcohol intake. Following current dietary advice to increase the amount of fruits, vegetables, and whole grains in the diet while reducing fats is certainly prudent for women to reduce their risk of several chronic disease, but current data points to the somber conclusion that such changes probably will have little effect on breast cancer risk.

A review of calcium preparations

There are more than a dozen commonly prescribed calcium supplements and hundreds of different formulations commercially available. Numerous factors need to be considered when selecting a calcium preparation. Physical properties such as solubility, interference from coingested medications or foodstuffs, dosage, and timing can all affect the bioavailability of calcium. Medical conditions such as lactose intolerance, impaired gastric acid secretion, and high risk profile for kidney stone formation may impact on selection of a calcium supplement. This article will review the available literature and make general recommendations for the optimal use of calcium preparations.

Alcoholic beverages and breast cancer: some observations on published case-control studies

We identified 38 case-control studies investigating possible associations between alcoholic beverage consumption and cancer of the female breast. Each study was characterized according to design features such as: control type (hospital or community based), risk factors controlled for, matching strategy, and statistical power. We examined the effect of these design variables on several outcome variables including identification of any significant elevation in odds ratio and characterization of any dose-response effect. The major finding of this study is that of a striking difference between hospital and community based controlled studies with respect to (1) the level of any estimated dose-response effect, and (2) the finding of statistically significant elevations in odds ratios at levels of consumption below 4 drinks per week. In summary, the generally weak associations reported in these case-control studies along with the measurement and/or selection biases implied by our findings would lead one to the conclusion that present evidence does not support a causal association. This conclusion seems to be in accord with results from cohort studies and with similar conclusions from several other reviews.

Antimutagens and anticarcinogens in foods

The role of dietary factors in the prevention of major chronic diseases, cancer in particular, is under intensive investigation by many laboratories around the world. Evidence from epidemiological studies and tests in laboratory animals suggests that food consumed by the general population contains certain ingredients that may have a role in reduction of the incidence of cancer. It has been observed that a number of regular food components, belonging to different chemical groups, do possess cancer preventive and/or beneficial outcomes for some other diseases; these chemicals, therefore, are frequently collectively known as 'chemopreventers'. The mode of action of most chemopreventers is still unknown, although it appears that many of them are antioxidants, and as such, they may scavenge free radicals, formed either during the preparation of food, or by biological processes in the body. As free radicals damage lipids, proteins, cell membranes and DNA, their removal could prevent development of certain chronic diseases, particularly cancer or atherosclerosis. This review summarizes recent developments in the search for beneficial effects of regular food ingredients in prevention of cancer.