Consumption of dairy products and the risk of breast cancer: a review of the literature

Theoretical attributable risk analysis and Disability Adjusted Life Years (DALYs) based on increased dairy consumption

BACKGROUND

Identification of modifiable risk factors that may impact chronic disease risk is critical to public health. Our study objective was to conduct a theoretical population attributable risk analysis to estimate the burden of disease from low dairy intake and to estimate the impact of increased dairy intake on United States (US)-based disability adjusted life years (DALYs).

METHODS

We conducted a comprehensive literature review to identify statistically significant summary relative risk estimates (SRREs) from recent meta-analyses of dairy consumption and key chronic disease outcomes. The SRREs were applied to preventive fractions using a range of categories (low to high) for population consumption of dairy products. The preventive fraction estimates were then applied to the number of DALYs for each health outcome in the US based on 2019 WHO estimates. The population attributable risk proportion estimates were calculated using the inverse of the SRRE from each meta-analysis using the same range of categories of consumption. These values were subsequently applied to the DALYs estimates to estimate the theoretical burden of disease attributable to low dairy intake.

RESULTS

Statistically significant SRREs were identified in recent meta-analyses of total dairy consumption in relation to breast cancer, colorectal cancer, cardiovascular disease (CVD), type 2 diabetes (T2D), stroke, and hypertension. In this theoretical analysis, nearly 850,000 DALYs (or 5.0% of estimated years of healthy life lost) due to CVD and 200,000 DALYs (4.5%) due to T2D may be prevented by increased dairy consumption. Approximately 100,000 DALYs due to breast cancer (7.5%) and approximately 120,000 DALYs (8.5%) due to colorectal cancer may be prevented by high dairy intake. The numbers of DALYs for stroke and hypertension that may be prevented by increased dairy consumption were approximately 210,000 (6.0%) and 74,000 (5.5%), respectively.

CONCLUSIONS

Consumption of dairy products has been associated with decreased risk of multiple chronic diseases of significant public health importance. The burden of disease that may potentially be prevented by increasing dairy consumption is substantial, and population-wide improvement in meeting recommended daily dairy intake goals could have a notable public health impact. However, this analysis is theoretical, and thus additional studies providing empirical evidence are needed to further clarify potential relationships between dairy intake and various health outcomes.

Insights on the bioremediation technologies for pesticide-contaminated soils

The fast pace of increasing human population has led to enhanced crop production, due to which a significant increase in the application of pesticides has been recorded worldwide. Following the enhancement in the utilization of pesticides, the degree of environmental pollution, particularly soil pollution, has increased. To address this challenge, different methods of controlling and eliminating such contaminants have been proposed. Various methods have been reported to eradicate or reduce the degree of contamination of pesticides in the soil. Several factors are crucial for soil contamination, including pH, temperature, the number, and type/nature of soil microorganisms. Among the accessible techniques, some of them respond better to contamination removal. One of these methods is bioremediation, and it is one of the ideal solutions for pollution reduction. In this innovative technique, microorganisms are utilized to decompose environmental pollutants or to curb pollution. This paper gives detailed insight into various strategies used for the reduction and removal of soil pollution.

Consumption of dairy products and odds of breast cancer: an Iranian case-control study

BACKGROUND

Data on the link between total and individual dairy product consumption and risk of breast cancer are controversial, especially in Middle Eastern populations.

OBJECTIVE

This study aimed to evaluate the association between total and individual dairy product consumption and odds of breast cancer among Iranian women.

METHODS

In the context of a population-based case-control study on 350 patients with pathologically confirmed cases of breast cancer and 700 age-matched controls, we assessed dietary intakes using a 106-item semi-quantitative dish-based food frequency questionnaire. Consumption of low- and high-fat dairy products as well as dietary intakes of pasteurized milk, cheese and yogurt were computed.

RESULTS

Mean (± SD) age and BMI of study participants was 62.4 ± 10.8 y and 24.3 ± 5.2 kg/m², respectively. After controlling for potential covariates, individuals in the top quartile of low-fat dairy product intake were less likely to have breast cancer than those in the bottom quartile (OR 0.08; 95% CI 0.05-0.16), while those with the highest intake of high-fat dairy intake had greater odds for breast cancer than those with the lowest intake (OR 8.62; 95% CI 4.78-15.55). Despite lack of a significant association between yogurt and cheese consumption and odds of breast cancer, we found a positive association between total milk intake (OR 1.76; 95% CI 1.16-2.65) and breast cancer, after controlling for potential confounders.

CONCLUSION

Low-fat dairy intake was inversely and high-fat dairy consumption was positively associated with breast cancer. No significant association was found between yogurt and cheese consumption and breast cancer, while total milk intake was associated with a greater odds of breast cancer.

In Vivo Study of The Oestrogenic Activity of Milk

Introduction

Milk has been suggested to be a possible source of oestrogenically active compounds. In order to assess the health risk for milk consumers and ensure the safety of this staple part of the human diet, it is important to study the effect of xenooestrogen mixtures present in milk. This investigation used the available in vivo model to learn to what extent such compounds may be endocrine disruptors.

Material and Methods

The recommended immature golden hamster uterotrophic bioassay was chosen. A total of 132 animals were divided into nine groups of experimental animals and positive and negative control groups, each of 12 animals. The experimental females received ad libitum either one of five samples of raw cow’s milk from individual animals or one of four samples of pasteurised or ultra-high temperature treated cow’s milk as retail products. After 7 days, the animals were sacrificed and necropsied. Uterine weight increases were measured as the endpoint of oestrogenic activity in milk.

Results

The milk samples from individual cows and the retail milk samples did not show oestrogenic activity. However, in three groups, decreased uterine weights were observed.

Conclusion

Considering that milk supplies are beneficial to health, contamination in this food should be avoided. There is a need for further animal experiments and epidemiological studies are warranted to evaluate any causative role of milk in human endocrinological disorders.

Consumption of Dairy Products and the Risk of Developing Breast Cancer in Polish Women

Lack of consistency in the relationship between dairy products consumption and breast cancer (BC) risk motivated us to evaluate this association in a case-control study of BC among Polish women. The study includes 1699 women 26–79 years of age, 823 BC cases identified in Cancer Registries and 876 randomly selected controls from the national population registry. Using a validated, semiquantitative food frequency questionnaire (FFQ), the consumption of dairy products was collected for a time period of 10–15 years prior to BC diagnosis. We used logistic regression, adjusting for potential confounders, to assess the relationship between total dairy consumption as well as individual dairy groups of milk, cottage cheese and hard cheese and BC risk for premenopausal and postmenopausal women. For total consumption, a significant decrease in BC risk was observed with increased consumption of one serving/week, OR _trend = 0.98, 2% decrease in risk, for premenopausal women only. For milk, a significant decrease in BC risk was observed for an increase in consumption of one glass/week, OR _trend = 0.95, 5% decrease, in both strata of menopause. In contrast, for hard cheese, a significant increase in the risk of 10% was observed only in premenopausal women, OR _trend = 1.10. Cottage cheese consumption significantly reduced BC risk by 20%, OR _trend = 0.80, for an increase in one serving/week for postmenopausal women only. Our results show that individual dairy products have a statistically significant but bi-directional relationship with BC risk, which differs for premenopausal and postmenopausal women.

Food Quality Score and Risk of Breast Cancer among Iranian Women: Findings from a Case Control Study

The quality of foods we consume may be an important risk factor for breast cancer (BrCa); however, relations between quality of food metrics and BrCa risk have not been systematically investigated. The purpose of this study was to examine the association between food quality score (FQS) by assessing the intake of healthy and unhealthy food and the odds of (BrCa) among Iranian women. This hospital-based case-control study was carried out on 150 women with pathologically confirmed breast cancer within the past three months and 150 healthy controls that were age-match from the Cancer Research Center, Imam Khomeini hospital, Iran. Participants were interviewed to obtain data relating to diet (using a 147-item validated FFQ) and BrCa risk factors. We found a significant association between adherence to the FQS and odds of breast cancer in the fully adjusted model (OR: 0.58; P = 0.04) and in premenopausal women in the fully adjusted model (OR: 0.45; P = 0.02); however, we did not observe any association between postmenopausal women in the adjusted model (OR: 0.76; P = 0.5). We also failed to observe any association between healthy (p = 0.3) and unhealthy subgroups (p = 0.3) of FQS. Our findings suggest that adherence to FQS may be associated with an increased risk of breast cancer in crude and adjusted models in overall and premenopausal women. However, we did not see any association between FQS and BrCa risk in postmenopausal women. Prospective cohort studies are needed to confirm these findings.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1957136 .

Dairy Consumption and Incidence of Breast Cancer in the 'Seguimiento Universidad de Navarra' (SUN) Project

Dairy products might influence breast cancer (BC) risk. However, evidence is inconsistent. We sought to examine the association between dairy product consumption-and their subtypes-and incident BC in a Mediterranean cohort. The SUN ("Seguimiento Universidad de Navarra") Project is a Spanish dynamic ongoing cohort of university graduates. Dairy product consumption was estimated through a previously validated 136-item food frequency questionnaire (FFQ). Incident BC was reported in biennial follow-up questionnaires and confirmed with revision of medical records and consultation of the National Death Index. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated with Cox regression models. Among 123,297 women-years of follow-up (10,930 women, median follow-up 12.1 years), we confirmed 119 incident BC cases. We found a nonlinear association between total dairy product consumption and BC incidence (p_nonlinear = 0.048) and a significant inverse association for women with moderate total dairy product consumption (HR_Q2vs.Q1 = 0.49 (95% CI 0.28-0.84); HR_Q3vs.Q1 = 0.49 (95% CI 0.29-0.84) p_trend = 0.623) and with moderate low-fat dairy product consumption (HR_Q2vs.Q1 = 0.58 (95% CI 0.35-0.97); HR_Q3vs.Q1 = 0.55 (95% CI 0.32-0.92), p_trend = 0.136). In stratified analyses, we found a significant inverse association between intermediate low-fat dairy product consumption and premenopausal BC and between medium total dairy product consumption and postmenopausal BC. Thus, dairy products, especially low-fat dairy products, may be considered within overall prudent dietary patterns.

Reproductive factors and breast cancer risk: A meta-analysis of case-control studies in Indian women

Background/Objective:

India is the world's most biodiverse region and is undergoing a period of dramatic social and economic change. Due to population's explosion, climate change and lax implementation of environmental policies, the incidence of breast cancer is increasing. From population-based cancer registry data, breast cancer is the most common cancer in women in urban registries where it constitutes more than 30% of all cancers in females. We conducted a meta-analysis of all breast cancer case–control studies conducted in India during 1991–2018 to find pooled estimates of odds ratio (OR).

Materials and Methods:

Eligible studies were identified through a comprehensive literature search of PubMed, EMBASE, and HINARI databases from 1991 to January 2018. This analysis included 24 observational studies out of 34 that reported the case–control distribution of reproductive factors, body mass index (BMI) and type of residence. The analysis was performed using RevMan 5.3 (Review Manager, 2017) applying the random-effects model.

Results:

A total of 21,511 patients (9889 cases and 11,622 controls) were analyzed, resulting in statistically significant association between breast cancer and the following reproductive factors: never breastfeed (OR: 3.69; 95% confidence interval [CI]: 1.70, 8.01), menopausal age >50 years (OR: 2.88; 95% CI: 1.85, 3.85), menarche age <13 years (OR: 1.83; 95% CI: 1.34, 2.51), null parity (OR: 1.58; 95% CI: 1.21, 2.06), postmenopause (OR: 1.35; 95% CI: 1.13, 1.62), and age at the 1^st pregnancy >25 years (OR: 1.57; 95% CI: 1.37, 1.80). Family history (FH) of breast cancer (OR: 5.33; 95% CI: 2.89, 9.82), obesity (OR: 1.19; 95% CI: 1.00, 1.42), and urban residence (OR: 1.22; 95% CI: 1.03, 1.44) were also found to be significant risk factors.

Conclusion:

The results of this meta-analysis are indicative of significant associations between reproductive factors and breast cancer risk, profoundly so among women experiencing menopause after the age of 50, women who never breastfeed and FH of breast cancer.

Hormones in Food as a Potential Risk for Human Reproductive and Health Disorders

In the last 60 years, milk, meat, and egg worldwide consumption per capita increased 2-, 3-, and 5-fold, respectively. In the same period, several studies have reported a drop of semen quality and an increased incidence of cryptorchidism, hypospadias, and some hormone-related cancers (testicular, prostate, breast, endometrial cancer) in humans. A possible reason for these disruptions is increased exposure to exogenous hormones in food of animal origin. Hormones in food are considered to affect the endocrine system and cell signaling and thus disrupt homeostasis in the consumers. Since food safety assurance is a part of the veterinary service, the risk assessment of hormones in food as potential disruptive compounds is a significant challenge. Numerous cohort and epidemiologic studies and meta-analyses have been performed with respect to find an association between the consumption of food of animal origin and particular health disorders. Additionally, several studies in animal models have been performed to explain the mechanisms of disruptive effects of exogenous hormones. Since contradictory results have been reported, there is no general conclusion about the disruptive effects of exogenous hormones. Further experiments on animals in which long-term treatment with exogenous hormones is performed and further comprehensive endocrinological, toxicological, and human epidemiological studies are needed to confirm or deny the role of exogenous hormones in human health disorders. Moreover, long-term exposure to a combination of several exogenous compounds, such as environmental pollutants and dietary hormones and their additive effects, are also not well known and should be a topic for further studies.

Milk and yogurt intake and breast cancer risk: A meta-analysis

Different patterns of milk and breast cancer rates across countries suggest that several components of milk could affect breast cancer risk. However, the components of diet are complex including milk that could potentially influence risk. Some milk products such as whole milk and cheese have a high fat content which may increase risk. Moreover, milk products may contain pesticides which have carcinogenic potential. In contrast, some contents of milk such as calcium and vitamin D have been hypothesized to reduce breast cancer risk. Therefore, we performed this meta-analysis to derive a more precise estimation of the association between dairy food intake and breast cancer risk. Using the data from 8 available publications, we examined low-fat/skim milk, whole milk, and yogurt in relation to risk of breast cancer by meta-analysis. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. However the results of all milk models and the available epidemiologic evidence do not support a strong association between the consumption of milk or milk products and breast cancer risk. Further studies with larger participants worldwide are needed to validate the relationship of dairy food intake and breast cancer.

MECHANISMS IN ENDOCRINOLOGY: Estrogens in consumer milk: is there a risk to human reproductive health?

Possible effects of xenoestrogens on human health, in particular on male reproductive health, have attracted considerable attention in recent years. Cow's milk was suggested in numerous publications as one of possible sources of xenoestrogens that could affect human health. Although milk has undoubtedly many beneficial health effects and could even have a role in reducing incidence of some cancers, concerns were raised about presumably high levels of estrogens in cow's milk. In intensive farming, concentrations of estrogens in milk are higher due to long milking periods that today extend long into the pregnancy, when concentrations of estrogens in the cow's body rise. Numerous studies examined potential effects of milk on reproductive health and endocrine-related cancers in both experimental studies with laboratory animals, and in human epidemiological studies. In the present review article, we compiled a review of recently published literature about the content of estrogens in cow's milk and potential health effects, in particular on reproductive system, in humans. Although results of published studies are not unequivocal, it seems that there is stronger evidence suggesting that amounts of estrogens in cow's milk are too low to cause health effects in humans.

A descriptive study of vitamin D and other nutritional factors in breast cancer patients in Saudi Arabia

Objectives:

To assess the role of serum vitamin D and other nutritional factors in women with breast cancer in Saudi.

Methods:

A total of 500 women (250 patients with breast cancer and 250 controls) aged 30-60 years were recruited from King Saud Medical City and King Fahad Medical City, Riyadh, Saudi Arabia, between May 2015 and June 2016. In this cross-sectional study, blood pressure, plasma concentrations of vitamin D, and calcium levels were evaluated. A 3-day dietary record was used to assess dietary intake.

Results:

The mean body mass index was 31.2±7.0 kg/m² for the breast cancer group and 30.7±7.6 kg/m² for the control group. More than 80% of the participants had insufficient vitamin D levels (<75.0 nmol/L). The mean cholesterol intake was significantly (p=0.001) lower in the control group (233.1±75.1 mg) than in the breast cancer group (257.2±84.8 mg). Breast density was found to be significantly associated with vitamin D deficiency-symptoms. Severe paresthesia was also significantly associated with breast cancer. The incidence of other vitamin D deficiency-symptoms was significantly higher in the control group.

Conclusion:

Due to prevalence of vitamin D deficiency in Saudi Arabia, it is difficult to determine the relationship to breast cancer. The incidence of it is associated with old age and high cholesterol intake, and paresthesia may be a symptom of breast cancer.

Dietary Habits and Physical Activity are Associated With the Risk of Breast Cancer Among Young Iranian Women: A Case-control Study on 1010 Premenopausal Women

BACKGROUND

Several studies conducted in developed countries introduced diet and physical inactivity as major risk factors for several types of cancers. However, the impact of diet and physical inactivity on the risk of breast cancer (BC) is understudied, and the limited findings are controversial. In addition, no or limited knowledge is available from the developing world.

PATIENTS AND METHODS

This case-control study was performed from November 2014 to March 2016 on 1010 young women aged 20 to 50 years who were newly diagnosed with BC. Data was obtained via a validated questionnaire and the global physical activity questionnaire (GPAQ2). Also, patients' medical and histopathology reports were reviewed.

RESULTS

The results of multiple logistic regression suggested that, except for the common risk factors for BC (older marital age, family history of BC, smoking, and being a passive smoker), eating red meat (adjusted odds ratio [aOR] >8 portions/week [p/w] vs. 0-2 p/w, 1.15; 95% confidence interval [CI], 1.04-1.28); eating fish (aOR >8 p/w vs. 0-2 p/w, 1.55; 95% CI, 1.12-2.76), fruit consumption (aOR 0-4 p/w vs. >8 p/w, 1.96; 95% CI, 1.07-3.82), pickle consumption (aOR >8 p/w vs. 7-8 p/w, 1.46; 95% CI, 1.31-1.70), and intensity of physical activity (aOR light vs. vigorous, 1.68; 95% CI, 1.47-1.98) were directly associated with a higher risk of BC in young women.

CONCLUSION

Our study supported the hypothesis that unhealthy dietary habits and physical inactivity are risk factors for BC. We found that a healthy diet containing low fat and high fruits and vegetables with regular exercise are effective ways to reduce the risk of BC among young women.

Serial measures of circulating biomarkers of dairy fat and total and cause-specific mortality in older adults: the Cardiovascular Health Study

Background

Controversy has emerged about the benefits compared with harms of dairy fat, including concerns over long-term effects. Previous observational studies have assessed self-reported estimates of consumption or a single biomarker measure at baseline, which may lead to suboptimal estimation of true risk.

Objective

The aim of this study was to investigate prospective associations of serial measures of plasma phospholipid fatty acids pentadecanoic (15:0), heptadecanoic (17:0), and trans-palmitoleic (trans-16:1n-7) acids with total mortality, cause-specific mortality, and cardiovascular disease (CVD) risk among older adults.

Design

Among 2907 US adults aged ≥65 y and free of CVD at baseline, circulating fatty acid concentrations were measured serially at baseline, 6 y, and 13 y. Deaths and CVD events were assessed and adjudicated centrally. Prospective associations were assessed by multivariate-adjusted Cox models incorporating time-dependent exposures and covariates.

Results

During 22 y of follow-up, 2428 deaths occurred, including 833 from CVD, 1595 from non-CVD causes, and 1301 incident CVD events. In multivariable models, circulating pentadecanoic, heptadecanoic, and trans-palmitoleic acids were not significantly associated with total mortality, with extreme-quintile HRs of 1.05 for pentadecanoic (95% CI: 0.91, 1.22), 1.07 for heptadecanoic (95% CI: 0.93, 1.23), and 1.05 for trans-palmitoleic (95% CI: 0.91, 1.20) acids. Circulating heptadecanoic acid was associated with lower CVD mortality (extreme-quintile HR: 0.77; 95% CI: 0.61, 0.98), especially stroke mortality, with a 42% lower risk when comparing extreme quintiles of heptadecanoic acid concentrations (HR: 0.58; 95% CI: 0.35, 0.97). In contrast, heptadecanoic acid was associated with a higher risk of non-CVD mortality (HR: 1.27; 95% CI: 1.07, 1.52), which was not clearly related to any single subtype of non-CVD death. No significant associations of pentadecanoic, heptadecanoic, or trans-palmitoleic acids were seen for total incident CVD, coronary heart disease, or stroke.

Conclusions

Long-term exposure to circulating phospholipid pentadecanoic, heptadecanoic, or trans-palmitoleic acids was not significantly associated with total mortality or incident CVD among older adults. High circulating heptadecanoic acid was inversely associated with CVD and stroke mortality and potentially associated with higher risk of non-CVD death.

Donkey milk kefir induces apoptosis and suppresses proliferation of Ehrlich ascites carcinoma by decreasing iNOS in mice

Donkey milk and donkey milk kefir exhibit antiproliferative, antimutagenic and antibacterial effects. We investigated the effects of donkey milk and donkey milk kefir on oxidative stress, apoptosis and proliferation in Ehrlich ascites carcinoma (EAC) in mice. Thirty-four adult male Swiss albino mice were divided into four groups as follows: group 1, administered 0.5 ml water; group 2, administered 0.5 ml water + EAC cells; group 3, administered 0.5 ml donkey milk + EAC cells; group 4, administered 0.5 ml donkey milk kefir + EAC cells. We introduced 2.5 x 10⁶ EAC cells into each animal by subcutaneous injection. Tap water, donkey milk and donkey milk kefir were administered by gavage for 10 days. Animals were sacrificed on day 11. After measuring the short and long diameters of the tumors, tissues were processed for histology. To determine oxidative stress, cell death and proliferation iNOS and eNOS, active caspase-3 and proliferating cell nuclear antigen were assessed using immunohistochemistry. A TUNEL assay also was used to detect apoptosis. Tumor volume decreased in the donkey milk kefir group compared to the control and donkey milk groups. Tumor volume increased in the donkey milk group compared to the control group. Proliferating cell nuclear antigen levels were higher in the donkey milk kefir group compared to the control and donkey milk groups. The number of apoptotic cells was less in the donkey milk group, compared to the control, whereas it was highest in the donkey milk kefir group. Donkey milk administration increased eNOS levels and decreased iNOS levels, compared to the control group. In the donkey milk kefir group, iNOS levels were significantly lower than those of the control and donkey milk groups, while eNOS levels were similar to the control group. Donkey milk kefir induced apoptosis, suppressed proliferation and decreased co-expression of iNOS and eNOS. Donkey milk promoted development of the tumors. Therefore, donkey milk kefir appears to be more beneficial for treating breast cancer than donkey milk.

Assessment of Risk Factors of Obesity and Diet on Breast Cancer in Ankara, Turkey

OBJECTIVE

To determine the risk factors of obesity and diet on breast cancer in Ankara, Turkey.

METHODS

A case-controlled study was carried out on newly diagnosed 40 breast cancer patients [patient group (PC)] and 40 volunteer individuals [control group (CG)] with no diagnosis of cancer and history of cancer in the family with similar characteristics to the age and gender-matched patient group between March and July 2016. All the individuals were administered a questionnaire by face-to-face interview method.

RESULTS

The mean menarche age, age at first birth and menopause age were 13.0±1.17, 22.6±3.78 and 44.33±2.39 years in PG and 12.3±0.95, 21.6±2.99, 46.71±2.41 years in CG, respectively. The mean BMI values were determined as 28.1±6.75 kg/m² in PG and 30.1±6.18 kg/m² in CG (p>0.05). It was determined that intake of vitamin C and fiber decreases the risk of breast cancer. Also, eating quickly and smoking were risk factors for breast cancer (p<0.05).

CONCLUSION

This study indicated that there are relationships between menarche age, menopause age, and age at first birth, eating quickly, smoking and breast cancer. Conversely, there are significant negative relationships between dietary fiber, vitamin C intake and breast cancer. As a result, it can be said that there is a link between breast cancer and lifestyle factors and a reduction in the risk of developing breast cancer can be achieved through changes in diet, one of the lifestyle factors.

Association of Milk and Meat Consumption with the Development of Breast Cancer in a Western Mexican Population

BACKGROUND

Breast cancer is a public health problem and it is the most common gynecologic neoplasia worldwide. The risk factors for its development are of both hereditary and environmental origin. Certain foods have been clearly associated with modifying the breast cancer risk. The aim of the present analysis was to evaluate the effects of cow's milk and meat consumption on the development of breast cancer in a population from Western Mexico (Colima).

MATERIAL AND METHODS

We studied 97 patients presenting with a histopathologic diagnosis of breast cancer and 104 control individuals who did not present with the disease (Breast Imaging Report and Data System (BI-RADS) 1-2). 80% of the population belonged to a low socioeconomic stratum. The main clinical characteristics were analyzed along with the lifetime consumption of meat and milk.

RESULTS

High milk consumption increased the breast cancer risk by 7.2 times (p = 0.008) whereas the consumption of meat was not significantly associated with the disease.

CONCLUSIONS

High consumption of cow's milk was a risk factor for the development of breast cancer. Further studies are needed to evaluate the effects of dietary patterns on the development of breast cancer in diverse populations with ethnic, cultural, and economic differences.

Risk factors for breast cancer in women residing in urban and rural areas of eastern China

OBJECTIVE

To investigate breast cancer risk factors in Chinese women residing in urban and rural areas of eastern China using a large-scale cross-sectional survey.

METHODS

In this multistage, stratified cluster sampling epidemiological survey, information on demographic characteristics, diet and lifestyle variables were gathered using a carefully designed questionnaire. Multivariate logistic regression analysis and subgroup analyses of the data were performed, including separate analyses of data from women residing in urban and rural areas.

RESULTS

A total of 122,058 women were included in the survey. Age, body mass index, number of miscarriages, family history of breast cancer and menopausal status were found to be risk factors for breast cancer, while the consumption of soya bean products was a protective factor. Among women residing in urban areas, high or moderate intake of soya bean products and red meat were protective factors. Among women residing in rural areas, obesity and a high intake of milk were identified as risk factors for breast cancer, while a moderate intake of soya bean products was a protective factor.

CONCLUSIONS

This type of data is crucial for understanding the risk factors for breast cancer and could facilitate the development and targeting of effective intervention strategies, with the ultimate aim of breast cancer prevention.

Dietary habits contributing to breast cancer risk among Iranian women

BACKGROUND

The aim of this study was to investigate demographic features, dietary habits, and some possible risk factors for being susceptible to breast cancer in Iranian women.

MATERIALS AND METHODS

A study of dietary habits and breast cancer was conducted among 53 Iranian women with histological confirmed disease and 40 matched controls. A dietary habits questionnaire was used to evaluate the pattern of selected food intakes. The risk of cancer was analyzed after adjustment for confounding factors. Age, weight, body mass index (BMI), waist circumference, educational status, parity, lactation, marital status, menopause, history of estrogen therapy, and family history of breast disease or cancer were assessed among participants. Special attention was given to the relationship between consumption of high fat meat, milk, yogurt and cheese as well use of frying oils for frying foods, use of olive/liquid oils for cooking, removing fat from meat and poultry, removing chicken skin and not use of mayonnaise as salad dressing and the risk of breast cancer. Moreover, salad, vegetable and fruit consumption, and eating outdoors owere investigated.

RESULTS

Our results revealed significant lower education and higher BMI and waist circumference levels in patients with breast cancer. There was significantly increased breast cancer risk in overweight women in comparison with normal weight (OR=2.91, 95%CI 1.24 to 6.82). High intake of fat dairy products including milk and cheese was found to be a statistically significant factor for increasing breast cancer risk in models adjusting for age, BMI and education. Use of olive/liquid oils for cooking and avoidance of mayonnaise as salad dressing are related to lower risk of breast cancer. The frequency of vegetable and fruit consumption was significantly lower in patients with breast cancer compared to healthy women.

CONCLUSIONS

Dietary habits might be risk factors for breast cancer among Iranian women. Adoption of a prudent diet could be an appropriate strategy for preventing breast cancer.

Lifestyle, nutrition and breast cancer: facts and presumptions for consideration

Breast cancer is the most common cancer in women worldwide, and the high incidence of this cancer coupled with improvements in initial treatments has led to an ever-increasing number of breast cancer survivors. Among the prospective epidemiological studies on diet and breast cancer incidence and recurrence, to date, there is no association that is strong, reproducible and statistically significant, with the exception of alcohol intake, overweight, and weight gain. Nevertheless, many beliefs about food and breast cancer persist in the absence of supporting scientific evidence.

After a comprehensive review regarding the role of lifestyle on breast cancer outcomes and a thorough study of the dissemination field including mass media, clinical institutions, and academic figures, we briefly reported the most common presumptions and also facts from the literature regarding lifestyle, nutrition, and breast cancer.

The randomised controlled trial is the best study-design that could provide direct evidence of a causal relationship; however, there are methodological difficulties in applying and maintaining a lifestyle intervention for a sufficient period; consequently, there is a lack of this type of study in the literature. Instead, it is possible to obtain indirect evidence from observational prospective studies. In this article, it becomes clear that for now the best advice for women’s health is to follow the World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) recommendations on diet, nutrition, physical activity, and weight management for cancer prevention, because they are associated with a lower risk of developing most types of cancer, including breast cancer. Despite current awareness of the role of nutrition in cancer outcomes, there is inadequate translation from research findings into clinical practice. We suggest the establishment of a multidisciplinary research consortium to demonstrate the real power of lifestyle interventions.

TLR2∆22 (-196-174) significantly increases the risk of breast cancer in females carrying proline allele at codon 72 of TP53 gene: a case-control study from four ethnic groups of North Eastern region of India

Breast cancer (BC) is the second most common cancer in women. In the North Eastern Region (NER) of India, BC is emerging as an important concern as evidenced by the data available from population and hospital-based cancer registries. Studies on genetic susceptibility to BC are important to understand the increase in the incidence of BC in NER. The present case control study was conducted to investigate the association between tumour suppressor gene TP53 codon 72 polymorphism and innate immune pathway gene TLR2∆22 (-196-174) polymorphism with BC in females of NER of India for the identification of novel biomarker of BC. Four hundred sixty-two histopathologically confirmed BC cases from four states of NER of India, and 770 healthy controls were included by organizing community surveys from the neighbourhood of cases. In our study, no significant association between TP53 codon 72 polymorphisms and the risk of BC was found. However, our study has shown that TP53 codon 72 polymorphism is an important effect modifier. In the present study it was found that females carrying 22 base-pair deletion in the promoter region of their TLR2 gene had two times (AOR= 2.18, 95 % CI 1.13-4.21, p=0.019 in dominant model; AOR= 2.17, 95 % CI 1.09-4.34, p=0.027 in co-dominant model) increased risk of BC whwn they also carry proline allele at codon 72 of their TP53 gene.

Associations between dairy products consumption and risk of type 2 diabetes: Tehran lipid and glucose study

We aimed to examine the relationship between total dairy and dairy subtypes with the risk of type 2 diabetes (T2DM) in an Asian population. A nested case-control study of 178 cases of incident T2DM and 520 matched controls was conducted within the Tehran lipid and glucose study (TLGS). A 27% lower risk of T2DM was found per 100 g/d total dairy consumption that tend to be significant (95% CI: 0.52-1.02). Milk intake was inversely associated with diabetes after adjustment for confounders (p-trend: 0.042). Milk intake was associated with decreased T2DM risk in men (p-trend: 0.025), but not in women (p-trend: 0.527). Each 100 g/d increase in milk intake corresponded to 41% lower T2DM risk in fully adjusted model (95% CI: 0.39-0.89) in men. In conclusion, there is no significant association between diabetes and total dairy intake in the present study, but high intake of milk may reduce T2DM risk among men.

Dietary components and uterine leiomyomas: a review of published data

Some studies have considered the association between diet and uterine fibroid risk, but the issue is largely unsettled. To identify potential modifiable risk factors for fibroid development, we have herein systematically reviewed prior publications dealing with this aspect. Comprehensive searches in electronic databases were conducted to collect studies published on association between uterine leiomyomas and both nutrients and food groups. We identified 13 publications deriving from 4 case-control, 3 cross-sectional, and 4 cohort studies. A protective effect has been demonstrated for consumption of fruits and green vegetables in both case-control and cohort studies. Moreover, very recent cross-sectional and case-control studies evaluating serum levels of 25-hydroxyvitamin-D3 tend to indicate that vitamin D insufficiency, which may in part be due to the diet intake, may play an important role in the development of uterine fibroids. No association was found with the intake of fibers, vitamin C and E, phytoestrogens and carotenoids, whereas association was controversial for the consumption of meat, fish, dairy products, and vitamin A. Most data have also been discussed herein in light of the available experimental and animal model results. These findings may be useful in devising nutritional strategies to reduce leiomyoma risk in humans.

Lactose intolerance and risk of lung, breast and ovarian cancers: aetiological clues from a population-based study in Sweden

Background:

Individuals with lactose intolerance are recommended to avoid milk or dairy products, which may affect the development of cancer.

Methods:

We identified individuals with lactose intolerance from several Swedish Registers linked to the Swedish Cancer Registry to calculate standardised incidence ratios (SIRs) for cancers in the breast, lung, and ovary.

Results:

A total of 22 788 individuals with lactose intolerance were identified, and their risks of lung (SIR=0.55), breast (SIR=0.79), and ovarian (SIR=0.61) cancers were significantly decreased. Cancer incidences in the siblings and parents of individuals with lactose intolerance were similar to those in the general population.

Conclusions:

In this large cohort study, people with lactose intolerance, characterised by low consumption of milk and other dairy products, had decreased risks of lung, breast, and ovarian cancers, but the decreased risks were not found in their family members, suggesting that the protective effects against these cancers may be related to their specific dietary pattern.

Milk, dairy products, and their functional effects in humans: a narrative review of recent evidence

Milk is a widely consumed beverage that is essential to the diet of several millions of people worldwide because it provides important macro- and micronutrients. Milk is recognized as being useful during childhood and adolescence because of its composition; however, its relatively high saturated fat proportion raises issues of potential detrimental effects, namely on the cardiovascular system. This review evaluates the most recent literature on dairy and human health, framed within epidemiologic, experimental, and biochemical evidence. As an example, the effects of milk (notably skimmed milk) on body weight appear to be well documented, and the conclusions of the vast majority of published studies indicate that dairy consumption does not increase cardiovascular risk or the incidence of some cancers. Even though the available evidence is not conclusive, some studies suggest that milk and its derivatives might actually be beneficial to some population segments. Although future studies will help elucidate the role of milk and dairy products in human health, their use within a balanced diet should be considered in the absence of clear contraindications.

The administration of milk fermented by the probiotic Lactobacillus casei CRL 431 exerts an immunomodulatory effect against a breast tumour in a mouse model

Antitumour activity is one of the health-promoting effects attributed to probiotics specially analysed from preclinical models, mostly murine. Here, the effect of milk fermented by the probiotic bacterium Lactobacillus casei CRL 431, on a murine breast cancer model was analysed. Mice were fed with milk fermented by Lactobacillus casei or unfermented milk before and after tumour injection. Rate of tumour development, cytokines in serum, IgA, CD4, CD8, F4/80 and cytokines positive cells in mammary glands were determined. Microvasculature in the tumour tissues was monitored. The effect of fermented milk administration after tumour injection was also evaluated. It was observed that probiotic administration delayed or blocked tumour development. This effect was associated to modulation of the immune response triggered by the tumour. The area occupied by blood vessels decreased in the tumours from mice given fermented milk which agrees with their small tumours, and fewer side effects. Finally, it was observed that probiotic administration after tumour detection was also beneficial to delay the tumour growth. In conclusion, we showed in this study the potential of milk fermented by the probiotic Lactobacillus casei CRL431 to stimulate the immune response against this breast tumour, avoiding or delaying its growth when it was preventively administrated and also when the administration started after tumour cells injection.

Breast cancer and dietary patterns: a systematic review

This systematic review collates research on the topic of dietary patterns and breast cancer risks. The literature search targeted epidemiological studies published up to December 2012 and was conducted using the Medline (U.S. National Library of Medicine, Bethesda MD, USA) and Lilacs (Latin American and Caribbean Health Sciences, São Paulo, Brazil) databases. The following search terms were used: breast cancer, breast neoplasm, breast carcinoma, diet, food, eating habits, dietary patterns, factor analysis, and principal component analysis. Only studies that used factor analysis techniques and/or principal component analysis were eligible, and a total of 26 studies were included. The findings of these studies suggest the Mediterranean dietary pattern and diets composed largely of vegetables, fruit, fish, and soy are associated with a decreased risk of breast cancer. There was no evidence of an association between traditional dietary patterns and risk of breast cancer, and only one study showed a significant increase in risk associated with the Western dietary pattern. Diets that include alcoholic beverages may be associated with increased risk.

Milk nutritional composition and its role in human health

Dairy and milk consumption are frequently included as important elements in a healthy and balanced diet. It is the first food for mammals and provides all the necessary energy and nutrients to ensure proper growth and development, being crucial in respect to bone mass formation. However, several controversies arise from consumption of dairy and milk products during adulthood, especially because it refers to milk from other species. Despite these controversies, epidemiologic studies confirm the nutritional importance of milk in the human diet and reinforce the possible role of its consumption in preventing several chronic conditions like cardiovascular diseases (CVDs), some forms of cancer, obesity, and diabetes. Lactose malabsorption symptoms and cow milk protein allergy are generally considered to be the adverse reactions to milk consumption. The present article reviews the main aspects of milk nutritional composition and establishes several associations between its nutritious role, health promotion, and disease prevention.

High- and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis

BACKGROUND

Dietary fat in dairy is a source of estrogenic hormones and may be related to worse breast cancer survival. We evaluated associations between high- and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis.

METHODS

We included 1893 women from the Life After Cancer Epidemiology study diagnosed with early-stage invasive breast cancer from 1997 to 2000, who completed the Fred Hutchinson Cancer Research Center Food Frequency Questionnaire after diagnosis. A total of 349 women had a recurrence and 372 died during a median follow-up of 11.8 years, with 189 deaths from breast cancer. We used delayed entry Cox proportional hazards regression to evaluate associations between categories of the cumulative average of dairy fat at baseline and at follow-up 5 to 6 years later and subsequent outcomes. Tests of statistical significance were two-sided.

RESULTS

In multivariable-adjusted analyses, overall dairy intake was unrelated to breast cancer-specific outcomes, although it was positively related to overall mortality. Low-fat dairy intake was unrelated to recurrence or survival. However, high-fat dairy intake was positively associated with outcomes. Compared with the reference (0 to <0.5 servings/day), those consuming larger amounts of high-fat dairy had higher breast cancer mortality (0.5 to <1.0 servings/day: hazard ratio [HR] = 1.20, 95% confidence interval [CI] = 0.82 to 1.77; and ≥1.0 servings/day: HR = 1.49, 95% CI = 1.00 to 2.24, P trend = .05), higher all-cause mortality (P trend < .001), and higher non-breast cancer mortality (P trend = .007); the relationship with breast cancer recurrence was positive but not statistically significant. The higher risk appeared consistent across different types of high-fat dairy products.

CONCLUSIONS

Intake of high-fat dairy, but not low-fat dairy, was related to a higher risk of mortality after breast cancer diagnosis.

Diet and endometriosis risk: a literature review

A connection between dietary factors and endometriosis onset has become a topic of interest mostly due to the observation that physiological and pathological processes of the disease can be influenced by diet. This paper systematically reviews prior publications dealing with this aspect in order to identify potentially modifiable risk factors. Comprehensive searches in the electronic databases MEDLINE, EMBASE and Science Citation Index Expanded were conducted to identify published studies evaluating the association between food intake (nutrients and food groups) and endometriosis. Eleven studies were identified: 10 case-control and one cohort study. Information on diet was collected using food frequency questionnaires in seven studies, while in one study the questionnaire focused on caffeine and alcohol intake. Women with endometriosis seem to consume fewer vegetables and omega-3 polyunsaturated fatty acids and more red meat, coffee and trans fats but these findings could not be consistently replicated. Most data have also been discussed herein in light of the available experimental and animal model results. At present, evidence supporting a significant association between diet and endometriosis is equivocal. Further studies are needed to clarify the role of diet on endometriosis risk and progression.

Calcium sensing receptor signalling in physiology and cancer

The calcium sensing receptor (CaSR) is a class C G-protein-coupled receptor that is crucial for the feedback regulation of extracellular free ionised calcium homeostasis. While extracellular calcium (Ca(2+)o) is considered the primary physiological ligand, the CaSR is activated physiologically by a plethora of molecules including polyamines and l-amino acids. Activation of the CaSR by different ligands has the ability to stabilise unique conformations of the receptor, which may lead to preferential coupling of different G proteins; a phenomenon termed 'ligand-biased signalling'. While mutations of the CaSR are currently not linked with any malignancies, altered CaSR expression and function are associated with cancer progression. Interestingly, the CaSR appears to act both as a tumour suppressor and an oncogene, depending on the pathophysiology involved. Reduced expression of the CaSR occurs in both parathyroid and colon cancers, leading to loss of the growth suppressing effect of high Ca(2+)o. On the other hand, activation of the CaSR might facilitate metastasis to bone in breast and prostate cancer. A deeper understanding of the mechanisms driving CaSR signalling in different tissues, aided by a systems biology approach, will be instrumental in developing novel drugs that target the CaSR or its ligands in cancer. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.

The role of vitamin D deficiency and osteoporosis in breast cancer

AIM

Epidemiological studies suggest an association between vitamin D and calcium intake and breast cancer. The aim of this study was to determine the association of breast cancer with vitamin D deficiency and osteoporosis according to menopausal status and to examine vitamin D and bone mineral density (BMD) levels in breast cancer patients.

METHODS

This was an observational cohort hospital-based study. It included 635 patients with breast cancer. Socio-demographic information, type of consanguinity, menopause status, medical history, lifestyle habits, dietary intake, BMD measurements and vitamin D levels were collected. Descriptive and univariate analyses were performed.

RESULTS

Of the studied patients, 36.1% were Qataris, 63.9% non-Qatari Arabs, 40% premenopausal women, 20.9% university graduates and 37.2% housewives. Overall, 31.8% of breast cancer women were affected with osteopenia/osteoporosis. Vitamin D deficiency (10.7% vs. 7.9%) and severe vitamin D insufficiency (39.2% vs. 32.5%) were higher in postmenopausal women than premenopausal women (P < 0.001). Low physical activity (< 30 min/day) was observed among vitamin D deficient (46.8%) and osteoporotic (45%) women. Dietary intake of vitamin D was significantly lower in vitamin D deficient women; these included dairy products (33.1%), milk (38.6%), seafood (39.6%), (P < 0.001) and for osteoporotic women, dairy products (46%), calcium (21.3%), milk (36.1%), yoghurt (37.6%), cheese (37.6%) and sea food (34.7%) (P < 0.001).

CONCLUSION

The present study findings revealed a high prevalence of vitamin D deficiency and osteoporosis in breast cancer patients. Also, the dietary intake of vitamin D and calcium was significantly lower in breast cancer women.

Effects of maternal exposure to cow's milk high or low in isoflavones on carcinogen-induced mammary tumorigenesis among rat offspring

We investigated whether maternal exposure during pregnancy to cow's milk containing endogenous estrogens and insulin-like growth factor 1 (IGF-1) and either high or low levels of isoflavones from dietary legumes (HIM and LIM, respectively) affected carcinogen-induced mammary carcinogenesis in female rat offspring. Pregnant Sprague-Dawley rats were given HIM, LIM, or tap water (control) from gestational day (GD) 11 until birth; hereafter all rats received tap water. Mammary tumorigenesis was induced by administrating 7,12-dimethylbenz[a]anthracene (DMBA) on postnatal day 50. No differences in maternal serum estradiol (P = 0.19) and IGF-1 levels (P = 0.15) at GD 19 or birth weight among the milk and water groups were seen, but estradiol, and IGF-1 levels and birth weight were numerically higher in the LIM group than in the HIM group. Puberty onset occurred earlier in the LIM offspring than in controls (P = 0.03). Although the high isoflavone content seemed to prevent the effect on circulating estradiol and IGF-1 levels and advanced puberty onset seen in the LIM group, HIM increased DMBA-DNA adducts in the mammary gland and tended to increase mammary tumorigenesis. In contrast, offspring exposed to LIM in utero, did not exhibit increased breast cancer risk, despite having higher estradiol and IGF-1 environment and consequently earlier puberty onset. These results indicate that the phytochemical content in the cow's milk, consumed by a pregnant dam, determines how milk affects the offspring.

Healthy lifestyle on the risk of breast cancer

BACKGROUND

Many studies have analyzed the effect of behavioral risk factors such as common lifestyle patterns on the risk of disease. The aim of this study was to assess the effect of a healthy lifestyle index on the risk of breast cancer.

METHODS

A population-based case-control study was conducted in Mexico from 2004 to 2007. One thousand incident cases and 1,074 controls, matched to cases by 5-year age category, region, and health institution, participated in the study. A healthy lifestyle index was developed by means of principal components by using dietary pattern, physical activity, alcohol consumption, and tobacco smoking. A conditional logistic regression model was used to assess this association.

RESULTS

The healthy lifestyle index was defined as the combined effect of moderate and/or vigorous-intensity physical activity, low consumption of fat, processed foods, refined cereals, complex sugars, and the avoidance of tobacco smoking and alcohol consumption. Results showed a protective effect on both pre- (OR = 0.50, 95% CI: 0.29-0.84) and postmenopausal women (OR = O.20, 95% CI: 0.11-0.37) when highest versus lowest index quintiles were compared.

CONCLUSIONS

Healthy lifestyle was associated with a reduction in the odds of having breast cancer. Primary prevention of this disease should be promoted in an integrated manner. Effective strategies need to be identified to engage women in healthy lifestyles.

IMPACT

This study is the first to assess a healthy lifestyle index in relation to the risk of breast cancer.

Vitamin D and breast cancer recurrence in the Women's Healthy Eating and Living (WHEL) Study

BACKGROUND

There is a paucity of research evaluating the relation between vitamin D and recurrence of breast cancer after treatment.

OBJECTIVE

This study was designed to evaluate the associations between circulating concentrations of 25-hydroxyvitamin D [25(OH)D] and dietary, supplemental, and total intake of vitamin D and recurrent or new breast cancer events within the Women's Healthy Eating and Living (WHEL) Study.

DESIGN

A prospective cohort study design (n = 3085) was used to evaluate the relation between dietary, supplemental, and total vitamin D intake and recurrent breast cancer, and a nested case-control study with 512 matched pairs was used for analysis of the association between 25(OH)D and breast cancer recurrence.

RESULTS

No relation between 25(OH)D and breast cancer recurrence was observed. Compared with women with serum concentrations of 25(OH)D ≥ 30 ng/mL, adjusted odds ratios (95% CI) for breast cancer recurrence were 1.14 (0.57, 2.31) for those with concentrations < 10 ng/mL, 1.00 (0.68-1.48) for concentrations ≥ 10 and < 20 ng/mL, and 1.05 (0.76, 1.47) for concentrations ≥ 20 and < 30 ng/mL. No significant associations were observed when analyses were stratified by pre- and postmenopausal status or for local, regional, or distant recurrence or death. Vitamin D intake was not related to breast cancer recurrence overall, although for premenopausal women there was a significant inverse association between dietary vitamin D intake and recurrence (P for trend = 0.02).

CONCLUSION

These results do not provide support for a relation between concentrations of 25(OH)D after treatment and the recurrence of breast cancer. This trial is registered at clinicaltrials.gov for the WHEL Study as NCT00003787.

Prepubertal exposure to cow's milk reduces susceptibility to carcinogen-induced mammary tumorigenesis in rats

Cow's milk contains high levels of estrogens, progesterone and insulin-like growth factor 1 (IGF-1), all of which are associated with breast cancer. We investigated whether prepubertal milk exposure affects mammary gland development and carcinogenesis in rats. Sprague-Dawley rats were given either whole milk or tap water to drink from postnatal day (PND) 14 to PND 35, and thereafter normal tap water. Mammary tumorigenesis was induced by administering 7,12-dimethylbenz[a]anthracene on PND 50. Milk exposure increased circulating E2 levels on PND 25 by 10-fold (p < 0.001) and accelerated vaginal opening, which marks puberty onset, by 2.5 days (p < 0.001). However, rats exposed to milk before puberty exhibited reduced carcinogen-induced mammary carcinogenesis; that is, their tumor latency was longer (p < 0.03) and incidence was lower (p < 0.05) than in the controls. On PND 25 and 50, mammary glands of the milk-exposed rats had significantly less terminal end buds (TEBs) than the tap water-exposed controls (p < 0.019). ER-α protein levels were elevated in the TEBs and lobules of milk rats, compared to rats given tap water (p < 0.019), but no changes in cyclin D1 expression, cell proliferation or apoptosis were seen. IGF-1 mRNA levels were reduced on PND 50 in the mammary glands of rats exposed to milk at puberty. Our results suggest that drinking milk before puberty reduces later risk of developing mammary cancer in rats. This might be mediated by a reduction in the number of TEBs and lower expression of IGF-1 mRNA in the mammary glands of milk-exposed animals.

Joint effects of dietary vitamin D and sun exposure on breast cancer risk: results from the French E3N cohort

BACKGROUND

Ecological studies have suggested that vitamin D production through ultraviolet (UV) solar irradiance could reduce breast cancer (BC) risk. Although studies restricted to dietary vitamin D intake have provided inconsistent results, little is known about the relationship between pre- and postmenopausal BC and combined intakes from diet, supplements, and sun exposure.

METHODS

Cox proportional hazards regression models evaluated the association between vitamin D intakes, mean daily ultraviolet radiation dose (UVRd) at the place of residence and risk of BC among 67,721 women of the French E3N cohort. All analyses were stratified on menopausal status taking into account important confounders including calcium consumption.

RESULTS

During 10 years of follow-up, a total of 2,871 BC cases were diagnosed. Dietary and supplemental vitamin D intakes were not associated with BC risk; however, in regions with the highest UVRd, postmenopausal women with high dietary or supplemental vitamin D intake had a significantly lower BC risk as compared with women with the lowest vitamin D intake (HR = 0.68, 95% CI: 0.54-0.85, and HR = 0.57, 95% CI: 0.36-0.90, respectively).

CONCLUSION

Our results suggest that a threshold of vitamin D exposure from both sun and diet is required to prevent BC and this threshold is particularly difficult to reach in postmenopausal women at northern latitudes where quality of sunlight is too poor for adequate vitamin D production.

IMPACT

Prospective studies should further investigate associations between BC risk, vitamin D status and sunlight exposure.

Diet and risk of endometriosis in a population-based case-control study

Diet plausibly has a role in the aetiology of endometriosis through effects on steroid hormone levels; however, few published studies have examined the diet and endometriosis risk. We evaluated dietary risk factors for endometriosis in a population-based case-control study. Cases were 284 Group Health (GH) enrollees aged 18-49 years with newly diagnosed, surgically confirmed endometriosis between 1996 and 2001. Controls were 660 randomly selected age-matched female GH enrollees without a history of endometriosis. Nutrients and selected food groups were assessed using the Women's Health Initiative FFQ. OR of endometriosis risk associated with dietary exposures were estimated using unconditional logistic regression and adjusted for identified covariates. Increased total fat consumption was associated with decreased endometriosis risk (fourth quartile v. lowest: OR 0·5, 95% CI 0·2, 1·0, P-trend = 0·12). Increased β-carotene consumption and servings/d of fruit were associated with increased risk (β-carotene third quartile v. lowest: OR 1·7, 95% CI 1·1, 2·6; fourth quartile v. lowest: OR 1·6, 95% CI 1·0, 2·5, P-trend 0·16; fruit >2 servings/d v. < 1: OR 1·5, 95% CI 1·0, 2·3, P-trend = 0·04). We also found a suggestion of decreased endometriosis risk associated with the consumption of dairy products (2 servings/d v. ≤ 1: OR 0·6, >2 servings/d v. ≤ 1: OR 0·7), but this association was not statistically significant for the highest tertile. The present study suggests that specific dietary components may be associated with endometriosis risk.