Consumption of animal products, their nutrient components and postmenopausal circulating steroid hormone concentrations

17β-estradiol biosensors based on different bioreceptors and their applications

17β-Estradiol (E2) is a critical sex steroid hormone, which has significant effects on the endocrine systems of both humans and animals. E2 is also believed to play neurotrophic and neuroprotective roles in the brain. Biosensors present a powerful tool to detect E2 because of their small, efficient, and flexible design. Furthermore, Biosensors can quickly and accurately obtain detection results with only a small sampling amount, which greatly meets the detection of the environment, food safety, medicine safety, and human body. This review focuses on previous studies of biosensors for detecting E2 and divides them into non-biometric sensors, enzyme biosensors, antibody biosensors, and aptamer biosensors according to different bioreceptors. The advantages, disadvantages, and design points of various bioreceptors for E2 detection are analyzed and summarized. Additionally, applications of different bioreceptors of E2 detection are presented and highlight the field of environmental monitoring, food and medicine safety, and disease detection in recent years. Finally, the development of E2 detection by biosensor is prospected.

Mediterranean Diet and Oxidative Stress: A Relationship with Pain Perception in Endometriosis

BACKGROUND

Endometriosis is a chronic and inflammatory disease associated with pelvic pain. Dietary changes may be therapeutic for chronic inflammatory processes, reducing visceral input. The aim was to evaluate the role of dietary changes according to the Mediterranean Diet (MD) on pain perception in endometriosis and their relationship with oxidative stress.

METHODS

in this prospective study, we included 35 endometriosis women. At baseline (T0) and after 3 (T1) and 6 (T2) months from the start of the diet, we investigated pain intensity with VAS (Visual Analogue Scale, from 0 to 10), vitamin profile, and oxidative stress.

RESULTS

we found a significant increase in the diet score (p < 0.001). At T1, patients reduced pain in terms of dyspareunia (p = 0.04), non-menstrual pelvic pain (p = 0.06), dysuria (p = 0.04), and dyschezia (p < 0.001). Dyspareunia (p = 0.002) and dyschezia (p < 0.001) were further significantly reduced also at T2. We observed a significant positive correlation between lipid peroxidation and VAS non-menstrual pelvic pain and dysuria and a significant negative correlation between Oxygen radical absorbance capacity and VAS non-menstrual pain and dyschezia.

CONCLUSIONS

our findings show a clear tendency toward a relationship between pain relief in endometriosis and MD. This appears promising to treat endometriosis-related symptoms and could be considered a new effective strategy for chronic pain management in the long term.

Diet associations in endometriosis: a critical narrative assessment with special reference to gluten

Endometriosis is characterized by the presence of endometrium-like tissue outside the uterus. The etiology remains largely unknown. Despite adequate treatment, patients can still experience symptoms or side effects resulting in therapy incompliance and in self-management strategies such as dietary measures is increasing. A gluten free diet is thought to be contributory in reducing endometriosis-related pain, thereby optimizing quality of life. However, data is conflicting and currently provides no evidence for causality. This narrative review aims to put the effect of dietary self-management strategies on endometriosis in a balanced perspective, especially the effect of gluten and a gluten free diet. Several studies have found a strong overlap in symptoms, metabolic and immune responses associated with endometriosis and those associated with celiac disease, ulcerative colitis, Crohn's disease, irritable bowel syndrome and non-celiac wheat sensitivity. However, it remains unclear whether these diseases and/or disorders are causal to an increased risk of endometriosis. Some studies have found a positive effect on the risk of endometriosis, endometriosis-related symptoms and quality of life (QoL) when women either avoided certain nutrients or foods, or applied a specific nutrient supplementation. This includes the avoidance of red meat, an increasing intake of foods rich in anti-oxidants, omega-3, micronutrients and dietary fibers (e.g., fruit, vegetables) and the appliance of a gluten free diet. However, data from the available studies were generally graded of low quality and it was noted that placebo and/or nocebo effects influenced the reported positive effects. In addition, such effects were no longer seen when adjusting for confounders such as overweight, when a translation was made from in vitro to in vivo, or when the nutrients were not supplemented as isolated sources but as part of a mixed daily diet. Finally, some studies showed that long-term adherence to a gluten free diet is often associated with an impaired diet quality and nutrient intake, leading to negative health outcomes and reduced QoL. Concluding, scientific evidence on the efficacy of dietary interventions on well-defined clinical endpoints of endometriosis is lacking and recommending a gluten free diet to women solely diagnosed with endometriosis should therefore not be advised.

The relationship between endometriosis and diet

Endometriosis is an oestrogen dependent, benign, chronic inflammatory disease characterised by ectopic endometrial implants. Current medical practices for the treatment of the disease are associated with several side effects over long periods, making the effect of diet on endometriosis an important aspect. To alleviate this need, we review related literature to identify the association between nutrients and endometriosis and to find the probable therapeutic effects of the nutrients and foods on endometriosis. Despite variations among the findings, several of the prior studies point to an inverse relationship between endometriosis and the consumption of fruits, vegetables, dairy products, and omega-3 fatty acids. Another common finding among the studies is the increased risk of endometriosis with higher consumption of trans-unsaturated fatty acids and red meat. Due to the limited size of the samples in existing literature, however, significance of the association between diet and endometriosis is not conclusive. Further research is needed to better identify the role of diet on endometriosis.

Food groups and nutrients consumption and risk of endometriosis: a systematic review and meta-analysis of observational studies

Dietary factors may play a role in the etiology of endometriosis and dietary intake of some food groups and nutrients could be associated with endometriosis risk. This systematic review and meta-analysis of observational studies was conducted to summarize the findings on the association between dietary intakes of selected food groups and nutrients (dairy, fats, fruits, vegetables, legumes, and animal-derived protein sources), and the risk of endometriosis among adult women. PubMed, Scopus, and ISI Web of Science were systematically searched up to September 2022. The inverse variance-weighted fixed-effect method was used to estimate the effect size and corresponding 95% CI. A total of 8 publications (4 studies) including 5 cohorts and 3 case-control with a sample size ranging from 156 to 116,607 were included in this study. A higher intake of total dairy [all low-fat and high-fat dairy foods] was associated with decreased risk of endometriosis (RR 0.90; 95% CI, 0.85 to 0.95; P < 0.001; I² = 37.0%), but these associations were not observed with intakes of low or high-fat dairy, cheese or milk. Increased risk of endometriosis was associated with higher consumption of red meat (RR 1.17; 95% CI, 1.08 to 1.26; P < 0.001; I² = 82.4%), trans fatty acids (TFA) (RR 1.12; 95% CI, 1.02 to 1.23; P = 0.019; I² = 73.0%), and saturated fatty acids (SFA) (RR 1.06; 95% CI, 1.04 to 1.09; P < 0.001; I² = 57.3%). The results of this meta-analysis suggest that there may be differing associations between dietary intake of dairy foods, red meat, SFAs, and TFAs and the risk of endometriosis. It may be useful to extend the analysis to other types of food groups and dietary patterns to obtain a complete picture. Additionally, further investigations are needed to clarify the role of diet in the incidence and progression of endometriosis.Trial registration: PROSPERO, CRD42020203939.

Dietary lactose and galactose intakes are associated with a later onset of natural menopause among women in a Japanese community

Galactose and its metabolites, primarily derived from lactose, may have toxic effects on the ovary. We aimed to prospectively examine the associations of galactose and lactose intakes with the onset of natural menopause. The data of a population-based cohort study in a Japanese community (the Takayama study) initiated in 1992 were analysed, with follow-up data collected in 2002. Among the participants of the Takayama study, premenopausal women (n 3115) aged 35-56 years at baseline were included in this study. Dietary intake, including lactose and galactose was assessed only at baseline using a FFQ. The menopausal status and age at menopause were determined based on the participants' self-reports, and natural menopause was defined as the absence of menstruation for 12 months or more. Cox proportional hazards models were used to estimate the hazard ratios (HR) and 95 % CI. A total of 1790 women experienced natural menopause within the 10-year follow-up. Lactose and galactose intakes were associated with a later onset of natural menopause after adjusting for potential confounding factors and the HR (95 % CI) for the highest v. lowest quartile were 0·80 (0·69, 0·92) (P-trend = 0·001) in lactose and 0·86 (0·74, 1·00) in galactose (P-trend = 0·036), respectively. High intakes of lactose and galactose were associated with a later onset of natural menopause. Despite the presumed ovotoxicity effects, lactose and galactose intakes at usual levels may not be deleterious to the ovarian aging process among Japanese community-dwelling women.

Dietary Protein Sources, Mediating Biomarkers, and Incidence of Type 2 Diabetes: Findings From the Women's Health Initiative and the UK Biobank

OBJECTIVE

Whether and how dietary protein intake is linked to type 2 diabetes (T2D) remains unclear. The aim of this study was to investigate the associations of protein intake with development of T2D and the potential mediating roles of T2D biomarkers.

RESEARCH DESIGN AND METHODS

We included 108,681 postmenopausal women without T2D at baseline from the Women's Health Initiative (WHI) (primary cohort) and 34,616 adults without T2D from the U.K. Biobank (UKB) (replication cohort). Cox proportional hazard models were used for estimation of protein-T2D associations. Mediation analysis was performed to assess the mediating roles of biomarkers in case-control studies nested in the WHI.

RESULTS

In the WHI, 15,842 incident T2D cases were identified during a median follow-up of 15.8 years. Intake of animal protein was associated with increased T2D risk (hazard ratio in comparing the highest to the lowest quintile = 1.31 [95% CI 1.24-1.37]) and plant protein with decreased risk (0.82 [0.78-0.86]). Intakes of red meat, processed meat, poultry, and eggs were associated with increased T2D risk and whole grains with decreased risk. Findings from the UKB were similar. These findings were materially attenuated after additional adjustment for BMI. Substituting 5% energy from plant protein for animal protein was associated with 21% decreased T2D risk (0.79 [0.74-0.84]), which was mediated by levels of hs-CRP, interleukin-6, leptin, and SHBG.

CONCLUSIONS

Findings from these two large prospective cohorts support the notion that substituting plant protein for animal protein may decrease T2D risk mainly by reducing obesity-related inflammation.

Low Intake of Vegetable Protein is Associated With Altered Ovulatory Function Among Healthy Women of Reproductive Age

CONTEXT

Diets high in plant-based protein have gained popularity due to increasing health concerns regarding consumption of animal products. Though links between intakes of certain protein-rich foods and reproductive disorders have been suggested, the relationship of overall animal and vegetable proteins with reproductive hormones among reproductive-aged women is unknown.

OBJECTIVE

To evaluate the associations between the intake of dietary protein with reproductive hormones and sporadic anovulation among reproductive-aged women.

DESIGN

A prospective cohort study, 2005-2007.

SETTING

University at Buffalo, western New York, United States.

PARTICIPANTS

A total of 259 premenopausal women (18-44 years) without dietary restrictions.

MAIN OUTCOME MEASURE(S)

Serum reproductive hormones were determined up to 8 times per cycle for 2 cycles. Protein intake was assessed the day prior to hormone assessment at 4 visits/cycle using 24-hour recalls.

RESULTS

Overall, 84% of participants met the recommended dietary allowance for total protein set for reproductive-aged women. Neither total nor animal protein intake were associated with reproductive hormones or anovulation. However, vegetable protein intake in the lowest tertile was associated with lower luteal phase progesterone (-18.0%, 95% confidence interval [CI] -30.2, -3.6), higher follicle-stimulating hormone (3.8%, 95% CI 0.2, 7.6), and a higher risk of anovulation (risk ratio [RR] 2.53, 95% CI 1.21, 5.26), compared with the middle tertile. Nuts and seeds were the only protein-rich foods associated with an elevated risk of anovulation (RR 2.12, 95% CI 1.17, 3.85).

CONCLUSIONS

Findings suggest that among women who meet the recommended dietary allowance for total protein, low intake of vegetable, but not animal, protein may disturb normal ovulatory function.

Long-term exposure to PM1 and PM2.5 is associated with serum cortisone level and meat intake plays a moderation role

BACKGROUND

Although short-term exposure to particulate matter (PM) was associated with increased glucocorticoids (GCs) levels, available evidence on associations of long-term exposure to PM and GCs levels is still scant. Previous studies has showed that meat intake is associated with sex hormones levels, but it is unknown whether meat intake is associated with GCs levels. Furthermore, the role of meat intake in the associations between PM and GCs levels remains unclear.

AIMS

The aims of this study were to explore the associations of long-term exposure to PM and GCs levels among Chinese rural adults, and the role of meat intake in these associations.

MATERIALS AND METHODS

A total of 6223 subjects were recruited from the Henan Rural Cohort Study. Serum GCs levels were measured with liquid chromatography-tandem mass spectrometry. The concentrations of PM (PM₁ and PM_2.5) for each subject were assessed with machine learning algorithms. The food frequency questionnaire (FFQ) was used to obtain each participant' information on meat intake. The effects of PM and meat intake on GCs levels were assessed using generalized linear models. In addition, modification analyses were performed to identify the role of meat intake played in the associations of PM with serum GCs levels.

RESULTS

Per 1 μg/m³ increment in PM₁ or PM_2.5 concentration was associated with a 0.364 ng/ml (95% confidence interval (CI): 0.234, 0.494) or 0.227 ng/ml (95%CI: 0.110, 0.343) increase in serum cortisone, respectively. In addition, the moderation effects of total meat intake and red meat intake on the associations of long-term exposure to PM₁ or PM_2.5 with serum cortisone were observed (P < 0.05), indicating that individuals who had high levels of PM₁ or PM_2.5 and meat intake were more susceptible to have a higher state of serum cortisone.

CONCLUSIONS

Our findings suggested that long-term exposure to PM₁ or PM_2.5 was associated with serum cortisone. Moreover, meat intake was found to be a significant moderator in the association of PM₁ or PM_2.5 with serum cortisone levels.

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.

The Effects of Diet and Exercise on Endogenous Estrogens and Subsequent Breast Cancer Risk in Postmenopausal Women

Endogenous estrogens have been associated with overall breast cancer risk, particularly for postmenopausal women, and ways to reduce these estrogens have served as a primary means to decrease overall risk. This narrative review of clinical studies details how various nutritional and exercise lifestyle interventions have been used to modify estrogen levels and metabolism to provide a protective impact against breast cancer incidence. We also summarized the evidence supporting the efficacy of interventions, outcomes of interest and identified emerging research themes. A systematic PubMed MEDLINE search identified scholarly articles or reviews published between 2000-2020 that contained either a cohort, cross-sectional, or interventional study design and focused on the relationships between diet and/or exercise and overall levels of different forms of estrogen and breast cancer risk and occurrence. Screening and data extraction was undertaken by two researchers. Data synthesis was narrative due to the heterogeneous nature of studies. A total of 1625 titles/abstracts were screened, 198 full texts reviewed; and 43 met eligibility criteria. Of the 43 studies, 28 were randomized controlled trials, and 15 were observational studies. Overall, studies that incorporated both diet and exercise interventions demonstrated better control of detrimental estrogen forms and levels and thus likely represent the best strategies for preventing breast cancer development for postmenopausal women. Some of the strongest associations included weight loss via diet and diet + exercise interventions, reducing alcohol consumption, and consuming a varied dietary pattern, similar to the Mediterranean diet. More research should be done on the effects of specific nutritional components on endogenous estrogen levels to understand the effect that the components have on their own and in combination within the diet.

Pre- and post-diagnostic intake of whole grain and dairy products and breast cancer prognosis: the Danish Diet, Cancer and Health cohort

PURPOSE

Fiber rich foods and dairy products have been suggested to be associated with breast cancer prognosis, though existing research is limited and either report on pre- or post-diagnostic dietary intake in relation to breast cancer prognosis. We investigated the associations between intake of whole grain (WG) and dairy products assessed both pre- and post-diagnostically in relation to breast cancer prognosis.

METHODS

A total of 1965 women from the Diet, Cancer and Health cohort who were diagnosed with breast cancer between baseline (1993-1997) and December 2013 were included and followed for a median of 7 years after diagnosis. During follow-up, 309 women experienced breast cancer recurrence and 460 women died, of whom 301 died from breast cancer. Dietary assessment by food frequency questionnaires was obtained up to three times, pre- and post-diagnostic, over a period of 18 years. Cox proportional hazard models were used to estimate hazard ratios.

RESULTS

No associations were observed between pre- or post-diagnostic intake of total WG or total dairy products and breast cancer prognosis. A high pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality (HR 0.76, 95% CI 0.59-0.99), whereas high post-diagnostic intake of rye bread was associated with higher breast cancer-specific mortality (HR 1.29, 95% CI 1.02-1.63). A generally high intake of cheese was associated with a higher recurrence rate.

CONCLUSION

Pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality, and post-diagnostic intake of rye bread was associated with higher breast cancer specific mortality.

Dairy Consumption in Adolescence and Early Adulthood and Risk of Breast Cancer

Background: Carcinogenic exposure in early life may be critical for subsequent breast cancer risk. Dairy consumption was examined during adolescence and early adulthood in relation to incident breast cancer in the Nurses' Health Study II cohort.Methods: For the analyses of early adulthood dairy consumption, we included 90,503 premenopausal women ages 27 to 44 years in 1991 who reported dairy consumption using a validated food-frequency questionnaire. From 1991 to 2013, 3,191 invasive breast cancer cases were identified. In 1998, 44,264 women recalled adolescent dairy consumption. This subgroup of women was followed up from 1998 to 2013; 1,318 invasive breast cancer cases were identified. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using the Cox proportional hazard regression.Results: Adolescent and early adulthood total dairy consumption was not associated with overall breast cancer risk (each serving/day during adolescence, total dairy HR = 1.02, 95% CI, 0.97-1.07; for early adulthood total dairy HR = 1.01, 95% CI, 0.97-1.04), as were intakes of calcium, vitamin D, and lactose. Adolescent consumption of total and high-fat dairy was associated with higher risk of estrogen and progesterone receptor negative (each serving/day: total dairy HR = 1.11, 95% CI, 1.00-1.24; high-fat dairy HR = 1.17, 95% CI, 1.04-1.31). However, higher adolescent high-fat dairy consumption was associated with lower risk of estrogen and progesterone receptor positive tumors (each serving/day HR = 0.91, 95% CI, 0.86-0.97).Conclusions: Our results suggest no overall association between dairy consumption during adolescence or early adulthood and breast cancer risk, but the findings may differ by hormone receptor status of tumors.Impact: Dairy consumption in adolescence or early adulthood may not be a significant predictor of breast cancer incidence. Cancer Epidemiol Biomarkers Prev; 27(5); 575-84. ©2018 AACR.

Recent advances in the detection of 17β-estradiol in food matrices: A review

Pollution of endocrine disrupting chemicals has become a global issue. As one of the hormonally active compounds, 17β-estradiol produces the strongest estrogenic effect when it enters the organism exogenously including food intakes, bringing potential harmfulness such as malfunction of the endocrine system. Therefore, in order to assure food safety and avoid potential risks of 17β-estradiol to humans, it is of great significance to develop rapid, sensitive and selective approaches for the detection of 17β-estradiol in food matrices. In this review, the harmfulness and main sources of 17β-estradiol are firstly introduced, followed by the description of the principles and applications of different approaches for 17β-estradiol detection including high performance liquid chromatography, electrochemistry, Raman spectroscopy, fluorescence and colorimetry. Particularly, applications in detecting 17β-estradiol in food matrices over the years of 2010-2018 are discussed. Finally, advantages and limitations of these detection methods are highlighted and perspectives on future developments in the detection methods for 17β-estradiol are also proposed. Although many detection approaches can achieve trace or ultratrace detection of 17β-estradiol, further studies should be focused on the development of in-situ and real-time methods to monitor and evaluate 17β-estradiol for food safety.

Interaction between diet- and exercise-lifestyle and phthalates exposure on sex hormone levels

Phthalate can affect sex hormones secretion. Exercise and diet habits affect sex hormones levels. However, interaction of phthalates exposure and diet or exercise habits with sex hormones is unclear. We enrolled 106 residents aged 11-88 years (48 males and 58 females) from two communities, Wuhan city, China during the winter of 2014 and summer of 2015. Data were collected on socio-demographic characteristics and lifestyle by a questionnaire in two seasons. Participants provided the blood and urine samples over 3 consecutive days for measuring sex hormones and urinary phthalate metabolites. We assessed the associations of urinary phthalate metabolites levels, lifestyle with hormones levels, the interaction of phthalate exposure and lifestyle with hormones levels using multivariate binary logistic regression models. High urinary mono-(2-ethyl-5-oxyhexyl) phthalate (MEOHP) levels and no exercise had an additive interaction on abnormal serum progesterone (PROG) levels in winter as well as on abnormal serum follicle-stimulating hormone (FSH) or luteinizing hormone (LH) levels in summer. High urinary MEOHP levels and red meat intake (>1 time/day) had an additive interaction with abnormal levels of serum FSH only in the winter. Phthalates exposure may confer differential susceptibility to abnormal hormones levels in individuals with no exercise or eating meat >1 time/day.

Diet and female fertility: doctor, what should I eat?

Fecundity is the capacity to produce offspring. Identifying dietary factors that influence human fecundity is of major clinical and public health significance. This review focuses on the evidence from epidemiologic literature for the relationships between key nutritional factors and female reproductive potential. According to existing data, women trying to achieve pregnancy are encouraged to increase consumption of whole grains, omega-3 fatty acids, fish, and soy and to reduce consumption of trans fats and red meat. In addition, a daily multivitamin that contains folic acid before and during pregnancy may not only prevent birth defects, but also improve the chance of achieving and maintaining a pregnancy. In contrast, there is limited evidence supporting an association between vitamin D and human fecundity outcomes despite promising evidence from nonhuman studies. Questions for future research included the roles of other types of fat (especially omega-6 and monounsaturated fats) and protein (especially white meat and seafood) on female fertility; particular attention should also be paid to exposure to environmental contaminants in foods. Although much work remains, this review accrued best available evidence to provide practical dietary recommendations for women trying to conceive.

Protein intake and the risk of premenstrual syndrome

OBJECTIVE

To examine the relationship between protein intake and the risk of incident premenstrual syndrome (PMS).

DESIGN

Nested case-control study. FFQ were completed every 4 years during follow-up. Our main analysis assessed protein intake 2-4 years before PMS diagnosis (for cases) or reference year (for controls). Baseline (1991) protein intake was also assessed.

SETTING

Nurses' Health Study II (NHS2), a large prospective cohort study of registered female nurses in the USA.ParticipantsParticipants were premenopausal women between the ages of 27 and 44 years (mean: 34 years), without diagnosis of PMS at baseline, without a history of cancer, endometriosis, infertility, irregular menstrual cycles or hysterectomy. Incident cases of PMS (n 1234) were identified by self-reported diagnosis during 14 years of follow-up and validated by questionnaire. Controls (n 2426) were women who did not report a diagnosis of PMS during follow-up and confirmed experiencing minimal premenstrual symptoms.

RESULTS

In logistic regression models adjusting for smoking, BMI, B-vitamins and other factors, total protein intake was not associated with PMS development. For example, the OR for women with the highest intake of total protein 2-4 years before their reference year (median: 103·6 g/d) v. those with the lowest (median: 66·6 g/d) was 0·94 (95 % CI 0·70, 1·27). Additionally, intakes of specific protein sources and amino acids were not associated with PMS. Furthermore, results substituting carbohydrates and fats for protein were also null.

CONCLUSIONS

Overall, protein consumption was not associated with risk of developing PMS.

A Prospective Study of Dairy-Food Intake and Early Menopause

Early natural menopause, the cessation of ovarian function prior to age 45 years, affects approximately 10% of women and increases risk of cardiovascular disease and other adverse conditions. Laboratory evidence suggests a potential role of dairy foods in the ovarian aging process; however, no prior epidemiologic studies have evaluated how dairy-food intake is associated with risk of early menopause. We therefore evaluated how intakes of total, low-fat, high-fat, and individual dairy foods were associated with early menopause in Nurses' Health Study II. Women who were premenopausal at the start of follow-up in 1991 were followed until 2011 for early menopause. Food frequency questionnaires were used to assess dietary intake. In Cox proportional hazards models adjusting for age, smoking, and other factors, total baseline dairy-food intake of ≥4 servings/day versus <4 servings/week was associated with 23% lower risk of early menopause (hazard ratio = 0.77, 95% confidence interval: 0.64, 0.93; P for trend = 0.08). Associations appeared to be limited to low-fat dairy foods (for ≥2 servings/day vs. <3 servings/month, hazard ratio = 0.83, 95% confidence interval: 0.68, 1.01; P for trend = 0.02), whereas high-fat dairy-food intake was not associated with early menopause. Low-fat dairy foods may represent a modifiable risk factor for reducing risk of early menopause among premenopausal women.

A prospective cohort study of meat and fish consumption and endometriosis risk

BACKGROUND

Only 2 case-control studies have examined the associations between consumption of meat products and endometriosis risk with inconsistent results. Consumption of animal products has the potential to influence endometriosis risk through effects on steroid hormones levels.

OBJECTIVE

We sought to determine whether higher intake of red meat, poultry, fish, and seafood are associated with risk of laparoscopically confirmed endometriosis.

STUDY DESIGN

A total of 81,908 participants of the prospective Nurses' Health Study II were followed up from 1991 through 2013. Diet was assessed via food frequency questionnaire every 4 years. Cox proportional hazards models were used to calculate rate ratios and 95% confidence intervals.

RESULTS

During 1,019,294 person-years of follow-up, 3800 cases of incident laparoscopically confirmed endometriosis were reported. Women consuming >2 servings/d of red meat had a 56% higher risk of endometriosis (95% confidence interval, 1.22-1.99; P_trend < .0001) compared to those consuming ≤1 serving/wk. This association was strongest for nonprocessed red meats (rate ratio, 1.57; 95% confidence interval, 1.35-1.83 for ≥2 servings/d vs ≤1 servings/wk; P_trend < .0001), particularly among women who had not reported infertility (P_interaction = .0004). Women in the highest category of processed red meat intake also had a higher risk of endometriosis (rate ratio, 1.20; 95% confidence interval, 1.06-1.37 for ≥5 servings/wk vs <1 serving/mo; P_trend = .02). Intakes of poultry, fish, shellfish, and eggs were unrelated to endometriosis risk.

CONCLUSION

Our prospective analysis among premenopausal US nurses suggests that red meat consumption may be an important modifiable risk factor for endometriosis, particularly among women with endometriosis who had not reported infertility and thus were more likely to present with pain symptoms. Well-designed dietary intervention studies among women with endometriosis could help confirm this observation.

Prey cortisol affects the usefulness of fecal glucocorticoid metabolite concentration as an indicator of stress in a carnivore

The noninvasive nature of sample collection makes analysis of fecal hormone concentrations useful for examining endocrine responses in free-living wild animals. Glucocorticoid hormones (i.e., cortisol and corticosterone) are frequently measured as an indicator of activation of the endocrine stress axis. However, many factors may influence glucocorticoid concentrations in feces, and the influence of prey glucocorticoids on concentrations in the feces of predators is rarely considered. We tested whether cortisol consumption influenced concentrations of glucocorticoid metabolites in feces of captive Arctic foxes (Vulpes lagopus (Linnaeus, 1758)) by adding cortisol (5 mg cortisol per kg fox body mass) to the foxes’ diet. Food supplemented with supraphysiological concentrations of cortisol increased fecal glucocorticoid metabolite concentrations of Arctic foxes by 97% in males and 51% in females, compared with controls. In addition, fecal metabolite concentrations in nontreatment samples were higher for females (22.2 ± 3.3 ng·g−1, mean ± SE) than males (13.3 ± 1.5 ng·g−1), suggesting female Arctic foxes may have higher baseline cortisol concentrations or females may be more sensitive to captivity or relocation. These results indicate that prey cortisol can influence measurement of glucocorticoid metabolites in carnivore feces and suggest caution may be needed when interpreting such measurements in wild carnivores.

Macronutrient intakes and serum oestrogen, and interaction with polymorphisms in CYP19A1 and HSD17B1 genes: a cross-sectional study in postmenopausal Japanese women

Although higher circulating levels of oestrogen are related to postmenopausal breast cancer risk, limited information is available regarding effects of diet on endogenous oestrogen. Thus, we examined associations between macronutrient intakes and serum oestrogen with consideration of polymorphisms in oestrogen-metabolising genes. In this cross-sectional study, 784 naturally menopaused Japanese women aged 47–69 years were selected from participants of the Japan Multi-Institutional Collaborative Cohort Study. We documented dietary intakes, measured serum concentrations of oestrone (E1) and oestradiol (E2) and genotyped polymorphisms in oestrogen-metabolising CYP19A1 (rs4441215 and rs936306) and HSD17B1 (rs605059) genes. Trends and interactions were examined using linear regression models. In addition, we calculated the ratios of the oestrogen concentrations of the second to the highest quartiles (Q2–Q4) of dietary intake to those of the lowest quartiles (Q1). After adjustment for potential confounders, E2 was significantly associated with intake of carbohydrate and noodles; ratios of Q4 v. Q1 were 1·15 (95 % CI 1·04, 1·28) and 1·15 (95 % CI 1·04, 1·26), respectively. In contrast, E2 levels were inversely associated with intake of total energy, SFA and n-3 highly unsaturated fatty acids (n-3 HUFA); ratios of Q4 v. Q1 were 0·90 (95 % CI 0·82, 0·99), 0·89 (95 % CI 0·81, 0·98) and 0·91 (95 % CI 0·83, 1·00), respectively. In stratified analysis by polymorphisms, the rs605059 genotype of HSD17B1 significantly modified associations of E2 with intake of n-3 HUFA and fish; the associations were limited to those with the CC genotype. Macronutrient intakes were associated with serum E2 level, and these associations may be modified by HSD17B1 polymorphism in postmenopausal women.

Vitamin D and calcium intake and risk of early menopause

Background: Early menopause, defined as the cessation of ovarian function before the age of 45 y, affects ∼10% of women and is associated with higher risk of cardiovascular disease, osteoporosis, and other conditions. Few modifiable risk factors for early menopause have been identified, but emerging data suggest that high vitamin D intake may reduce risk.Objective: We evaluated how intakes of vitamin D and calcium are associated with the incidence of early menopause in the prospective Nurses' Health Study II (NHS2).Design: Intakes of vitamin D and calcium from foods and supplements were measured every 4 y with the use of a food-frequency questionnaire. Cases of incident early menopause were identified from all participants who were premenopausal at baseline in 1991; over 1.13 million person-years, 2041 women reported having natural menopause before the age of 45 y. We used Cox proportional hazards regression to evaluate relations between intakes of vitamin D and calcium and incident early menopause while accounting for potential confounding factors.Results: After adjustment for age, smoking, and other factors, women with the highest intake of dietary vitamin D (quintile median: 528 IU/d) had a significant 17% lower risk of early menopause than women with the lowest intake [quintile median: 148 IU/d; HR: 0.83 (95% CI: 0.72, 0.95); P-trend = 0.03]. Dietary calcium intake in the highest quintile (median: 1246 mg/d) compared with the lowest (median: 556 mg/d) was associated with a borderline significantly lower risk of early menopause (HR: 0.87; 95% CI: 0.76, 1.00; P-trend = 0.03). Associations were stronger for vitamin D and calcium from dairy sources than from nondairy dietary sources, whereas high supplement use was not associated with lower risk.Conclusions: Findings suggest that high intakes of dietary vitamin D and calcium may be modestly associated with a lower risk of early menopause. Further studies evaluating 25-hydroxyvitamin D concentrations, other dairy constituents, and early menopause are warranted.

The association of protein intake (amount and type) with ovarian antral follicle counts among infertile women: results from the EARTH prospective study cohort

OBJECTIVE

To evaluate the association between protein intake (amount and type) and antral follicle count (AFC).

DESIGN

Prospective cohort.

SETTING

Academic fertility centre.

POPULATION

Two hundred and sixty-five women undergoing fertility treatments at an academic fertility centre and participating in an ongoing study on environment and reproductive health.

METHODS

We measured AFC in ultrasonographic evaluation among women undergoing infertility treatments. Women completed a previously validated semi-quantitative food frequency questionnaire. We used Poisson regression to evaluate the relation between protein intake and AFC while adjusting for age, body mass index, race, smoking status, and total energy intake.

MAIN OUTCOME MEASURES

Antral follicle count.

RESULTS

Among 265 women (mean age: 35.0 ± 3.9 years, 85% Caucasian), total protein intake (% energy) was unrelated to AFC. When protein from different food sources was considered separately, we found a negative association between dairy protein intake and AFC. The mean AFC was 14.4% (3.9-23.7%) lower for women in the highest quintile of dairy protein intake than for women in the bottom quintile after adjusting for potential confounders (P-trend = 0.04). This association was stronger among women who had never smoked (P-trend = 0.002) but was not observed among previous smokers (P-trend = 0.36). There were no associations between protein intake from either non-dairy animal or vegetable sources and AFC.

CONCLUSION

Higher dairy protein intake (≥5.24% of energy) was associated with lower antral follicle counts among women presenting for infertility treatment. These findings should be further investigated in prospective studies also designed to clarify the biology underlying the observed associations.

TWEETABLE ABSTRACT

Higher dairy protein intake was associated with lower antral follicle counts in an infertile population.

The Western dietary pattern is associated with increased serum concentrations of free estradiol in postmenopausal women: implications for breast cancer prevention

Little is known about the possible influence of food consumption on the serum concentrations of endogenous sex hormones in postmenopausal women. We evaluated the relationships of the Western dietary pattern with serum concentrations of free estradiol and testosterone of postmenopausal women to test the hypothesis that a highly Western dietary pattern is associated with high serum concentrations of these hormones. We used data from a representative subsample of 305 women from the control group of a population-based case-control study conducted in Mexico from 2004 to 2007. A Western dietary pattern index value was compared with log natural serum concentrations of testosterone and estradiol using multiple linear regression models. The median values of serum concentrations of free estradiol and testosterone were 0.26 pg/mL (interquartile range, 0.14-0.43) and 0.40 pg/mL (interquartile range, 0.30-0.70), respectively. A multiple linear regression model showed that for each unit increase in the Western dietary pattern index, there was a 16.2% increase in the serum concentrations of free estradiol (β=0.15; 95% confidence interval [CI], 0.01-0.29); for each additional serving per week of chicken eggs, the increase was 31.0% (β=0.27; 95% CI, 0.106-0.441); for each additional serving per week of red meat, the increase was 64.9% (β=0.50; 95% CI, 0.01-1.01). There was no relationship found between dietary patterns and serum concentrations of free testosterone. The present findings suggest that intake of a Western diet, particularly of chicken eggs and meat, increases serum concentrations of free estradiol; these results have implications for breast cancer prevention.

An estrogen-associated dietary pattern and breast cancer risk in the Swedish Mammography Cohort

High endogenous hormone levels have been associated with breast cancer and dietary factors have the potential to influence breast cancer risk through effects on hormone levels. Dietary patterns derived from reduced rank regression provide a way to identify food groups correlated with hormones and subsequently examine food patterns that may be associated with breast cancer risk. We investigated whether a dietary pattern previously correlated with estradiol and estrone sulfate was associated with breast cancer in the prospective Swedish Mammography Cohort. Among 37,004 primarily postmenopausal women diet was assessed with a food frequency questionnaire. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). During 15 years of follow-up 1,603 cases of breast cancer were identified. A higher estrogen dietary pattern score was associated with an increased risk of breast cancer. Women in the highest quartile of estrogen pattern score had a 29% (95% CI = 1.08-1.55) increased risk of breast cancer compared to women in the lowest quartile (p(trend) = 0.006). When the association was examined by estrogen-receptor status, it was only significant for those with estrogen-receptor-positive tumors; however, in the competing risk analysis there were no significant differences in the effect estimates by receptor subtype (p(heterogeneity) = 0.65). Our findings suggest that a dietary pattern associated with higher estrogen levels may increase breast cancer risk. However, whether the influence of this dietary pattern is through a direct effect on estrogen levels deserves further study.

Oestrogen levels in serum and urine of premenopausal women eating low and high amounts of meat

OBJECTIVE

Based on the hypothesis that high-meat diets may increase breast cancer risk through hormonal pathways, the present analysis compared oestrogens in serum and urine by meat-eating status.

DESIGN

Intervention with repeated measures.

SETTING

Two randomized soya trials (BEAN1 and BEAN2) among premenopausal healthy women.

SUBJECTS

BEAN1 participants completed seven unannounced 24 h dietary recalls and donated five blood and urine samples over 2 years. BEAN2 women provided seven recalls and three samples over 13 months. Serum samples were analysed for oestrone (E₁) and oestradiol (E₂) using RIA. Nine oestrogen metabolites were measured in urine by LC-MS. Semi-vegetarians included women who reported consuming <30 g of red meat, poultry and fish daily, and pescatarians those who reported consuming <20 g of meat/poultry but >10 g of fish daily. All other women were classified as non-vegetarians. We applied mixed models to compute least-square means by vegetarian status adjusted for potential confounders.

RESULTS

The mean age of the 272 participants was 41·9 (SD 4·5) years. Serum E₁ (85 v. 100 pg/ml, P = 0·04) and E₂ (140 v. 154 pg/ml, P = 0·04) levels were lower in the thirty-seven semi-vegetarians than in the 235 non-vegetarians. The sum of the nine urinary oestrogen metabolites (183 v. 200 pmol/mg creatinine, P = 0·27) and the proportions of individual oestrogens and pathways did not differ by meat-eating status. Restricting the models to the samples collected during the luteal phase strengthened the associations.

CONCLUSIONS

Given the limitations of the study, the lower levels of serum oestrogens in semi-vegetarians than non-vegetarians need confirmation in larger populations.

Reproducibility of estradiol and testosterone levels in postmenopausal women over 5 years: results from the breakthrough generations study

Prospective cohort studies examining sex hormones in relation to cancer risk have generally collected blood samples at 1 time point, with an assumption that hormone levels measured in these samples will be reliable markers of true levels at other times. In postmenopausal women, body fat is a major source of estradiol; therefore, changes in adiposity may affect the correlation of single measurements to more relevant long-term averages. To estimate the intraclass correlation coefficient (ICC) for estradiol and testosterone, we collected repeat blood samples from 119 postmenopausal women (average age = 59.4 (standard deviation, 4.7) years) from the United Kingdom during 2004-2005 and again during 2010-2011. The ICCs (adjusted for assay variation) were 0.73 (95% confidence interval: 0.63, 0.82) for total estradiol and 0.59 (95% confidence interval: 0.47, 0.72) for total testosterone. The ICCs were 3%-5% larger after adjustment for change in body mass index (weight (kg)/height (m)(2)) or leptin, which are 2 markers of change in adiposity. There was no increase in ICCs after adjustment for change in age, alcohol consumption, smoking, exercise, time between waking and blood collection, or season. The results suggest that other factors account for within-woman variation in these sex hormones.

Racial disparities in red meat and poultry intake and breast cancer risk

PURPOSE

Research on the role of red meat and poultry consumption in breast carcinogenesis is inconclusive, but the evidence in African-American (AA) women is lacking. The association between consuming meat and breast cancer risk was examined in the Women's Circle of Health Study involving 803 AA cases, 889 AA controls, 755 Caucasian cases, and 701 Caucasian controls.

METHODS

Dietary information was collected using a Food Frequency Questionnaire. Odds ratios (OR) and 95 % confidence intervals (CI) were obtained from logistic regression models adjusting for potential covariates.

RESULTS

Comparing the fourth versus the first quartiles, among Caucasian women, processed meat (OR = 1.48; 95 % CI 1.07-2.04), unprocessed red meat (OR = 1.40; 95 % CI 1.01-1.94), and poultry intakes (OR = 1.42; 95 % CI 1.01-1.99) increased breast cancer risk. Risk associated with poultry intake was more dominant in premenopausal women (OR = 2.33; 95 % CI 1.44-3.77) and for women with ER- tumors (OR = 2.55; 95 % CI 1.29-5.03) in the Caucasian group. Associations in AA women were mostly null except for a significant increased risk trend with processed meat consumption for ER+ tumors (OR = 1.36; 95 % CI 0.94-1.97, p trend = 0.04).

CONCLUSIONS

Overall, associations between breast cancer risk and consumption of red meat and poultry were of different magnitude in AA and Caucasian women, with further differences noted by menopausal and hormone receptor status in Caucasian women. This is the first study to examine racial differences in meat and breast cancer risk and represents some of the first evidence in AA women.

Consumption of low-fat dairy products may delay natural menopause

Later menopause is a risk factor for breast and endometrial cancer, yet few studies have investigated dietary predictors of this potentially modifiable event. In particular, dairy contains hormones and growth factors that could potentially affect menopausal timing. We therefore assessed the association between regular consumption of dairy foods and related nutrients and age at natural menopause. We conducted a prospective analysis with up to 20 y of follow-up in 46,059 participants in the Nurses' Health Study who were premenopausal in 1980. We observed 30,816 events of natural menopause over 401,754 person-years. In the total population, the estimated mean age at natural menopause was 51.5 y for women who consumed no low-fat dairy and 51.5, 51.6, 51.7, and 51.8 y for women who consumed 0.1-1.0, 1.1-2.0, 2.1-3.0, and >3 servings of low-fat dairy daily, respectively. Premenopausal women <51 y of age consuming >3 servings of low-fat dairy per day were 14% less likely (HR: 0.86; 95% CI: 0.77, 0.96; P-trend < 0.0001) to report natural menopause in the next month relative to those consuming 0.1-1 servings/d. Similar results were obtained for skim milk (for >6 servings/wk vs. 0-1 servings/mo: HR: 0.93; 95% CI: 0.89, 0.97; P-trend < 0.0001) but not for total high-fat dairy or whole milk. Dairy foods were not associated with age at menopause among women ≥51 y of age. These findings support the growing body of literature on the hormonally active nature of milk and dairy foods.

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.

A dietary pattern derived to correlate with estrogens and risk of postmenopausal breast cancer

Circulating estrogens are an established risk factor for breast cancer and some data suggest that diet may influence estrogen levels. Therefore, using a subsample (n = 550) of women from a large cohort, we applied reduced rank regression to identify a dietary pattern that was correlated with estradiol and estrone sulfate. We then adapted the pattern to be used with the full cohort (n = 67,802) and prospectively assessed its association with postmenopausal breast cancer. The estrogen food pattern, characterized by higher intakes of red meat, legumes, and pizza, but lower intakes of coffee and whole grains, was modestly but significantly correlated with estradiol (r = 0.14) and estrone sulfate (r = 0.20). During 22 years of follow-up, we ascertained 4,596 incident breast cancer, with 2,938 estrogen receptor-positive tumors and 689 estrogen receptor-negative tumors. However, after adjusting for potential confounders, we did not observe any association with overall estrogen receptor-positive or estrogen receptor-negative breast cancer. In conclusion, diet pattern appeared to only have modest association with estrogens, and was not associated with postmenopausal breast cancer risk. Although these results were null, it should be repeated in other populations as differences in food intake may yield a dietary pattern with stronger association with estrogens.

A meat, processed meat, and French fries dietary pattern is associated with high allostatic load in Puerto Rican older adults

BACKGROUND

Consumption of certain dietary patterns, such as a Western diet, has been associated with unfavorable physiologic outcomes. Diet has been proposed as a contributor to allostatic load, a composite measure of physiological dysregulation.

OBJECTIVE

To determine the association of dietary patterns, defined by "meat and french fries," "traditional Puerto Rican foods" (rice, beans, and oils), or "sweets," with allostatic load, and with the 10 individual physiologic parameters that comprise it.

PARTICIPANTS

Baseline data collected from participants of the Boston Puerto Rican Health Study (n=1,117; aged 45 to 75 years) was used to run linear and logistic regression models, adjusting for age, sex, alcohol intake, smoking, medications, energy intake, and body mass index or physical activity.

RESULTS

Significant trends across increasing quintiles of the meat and french fries pattern were observed for higher allostatic load score (P=0.002), waist circumference (P=0.032), systolic blood pressure (P=0.008), and diastolic blood pressure (P<0.0001). Participants in the highest quintile of the meat and french fries pattern had significantly higher allostatic load score than those in the lowest quintile (mean 4.3±0.11 vs 3.9±0.12, P=0.030), and had higher odds of having high allostatic load (odds ratio [95% confidence interval]: 1.8 [1.2 to 2.9]), low dehydroepiandrosterone sulfate (odds ratio 1.9 [95% confidence interval: 1.2 to 3.1]), and high glycosylated hemoglobin (odds ratio 1.7 (95% confidence interval: 1.0 to 2.9]). The traditional pattern was not associated with allostatic load, whereas a significant association between the sweets pattern and allostatic load disappeared after restricting analysis to participants without diabetes.

CONCLUSIONS

A meat, processed meat, and french fries dietary pattern may contribute to the deregulation of multiple physiologic parameters in Puerto Rican adults. Efforts to limit consumption of this pattern may help prevent further cumulative physiological dysregulation in this high risk population.