Effects of a very low fat, high fiber diet on serum hormones and menstrual function. Implications for breast cancer prevention

Age at natural menopause and its associated characteristics among Brazilian women: cross-sectional results from ELSI-Brazil

OBJECTIVES

This study aimed to determine the median age at natural menopause and analyze lifestyle, anthropometric, and dietary characteristics associated with the age at natural menopause among Brazilian women.

METHODS

This cross-sectional study involved 2,731 women 50 years and over, drawn from the baseline of the Brazilian Longitudinal Study of Aging (ELSI-Brazil, 2015/16). Nonparametric Kaplan-Meier cumulative survivorship estimates were used to assess the median timing of natural menopause. Cox proportional hazards regression models were employed to estimate the associations between age at natural menopause and exposure variables.

RESULTS

The overall median age at natural menopause was 50 years. In the adjusted Cox model, current smoking (hazard ratio [HR], 1.11; 95% CI, 1.01-1.23) and underweight (HR, 1.34; 95% CI, 1.12-1.61) were associated with earlier natural menopause. Conversely, performing recommended levels of physical activity in the last week (HR, 0.88; 95% CI, 0.80-0.97), being overweight (HR 0.86; 95% CI, 0.74-0.99), and adhering to two or three healthy eating markers (HR, 0.80; 95% CI, 0.66-0.97; HR, 0.76; 95% CI, 0.61-0.94, respectively) were associated with later age at natural menopause. Binge drinking and waist circumference were not associated with age at natural menopause.

CONCLUSIONS

Lifestyle, anthropometric, and dietary characteristics are significant factors that affect the age at natural menopause. Our findings can contribute to public policies targeted at Brazilian women's health.

A whole-food, plant-based randomized controlled trial in metastatic breast cancer: weight, cardiometabolic, and hormonal outcomes

PURPOSE

Breast cancer treatment is associated with weight gain, and obesity and its related cardiometabolic and hormonal risk factors have been associated with poorer outcomes. Dietary intervention may address these risk factors, but limited research has been done in the setting of metastatic breast cancer requiring systemic therapy.

METHODS

Women with metastatic breast cancer on stable treatment were randomized 2:1 to an 8-week intervention (n = 21) or control (n = 11). The intervention included weekly assessment visits and an ad libitum whole-food, plant-based (WFPB) diet with provided meals. Cardiometabolic, hormonal, and cancer markers were assessed at baseline, 4 weeks, and 8 weeks.

RESULTS

Within the intervention group, mean weight decreased by 6.6% (p < 0.01) after 8 weeks. Fasting insulin decreased from 16.8 uIU/L to 11.2 uIU/L (p < 0.01), concurrent with significantly reduced insulin resistance. Total cholesterol decreased from 193.6 mg/dL to 159 mg/dL (p < 0.01), and low-density lipoprotein (LDL) cholesterol decreased from 104.6 mg/dL to 82.2 mg/dL (p < 0.01). Total testosterone was unchanged, but free testosterone trended lower within the intervention group (p = 0.08) as sex hormone binding globulin increased from 74.3 nmol/L to 98.2 nmol/L (p < 0.01). There were no significant differences in cancer progression markers at week 8, although mean CA 15-3, CA 27.29, and CEA were lower in the intervention group (p = 0.53, p = 0.23, and p = 0.54, respectively) compared to control, when adjusted for baseline.

CONCLUSION

WFPB dietary changes during treatment for metastatic breast cancer are well tolerated and significantly improve weight, cardiometabolic and hormonal parameters. Longer studies are warranted to assess the durability of changes. Trial registration First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.

A Whole-Food, Plant-Based Randomized Controlled Trial in Metastatic Breast Cancer: Weight, Cardiometabolic, and Hormonal Outcome

Purpose

Breast cancer treatment is associated with weight gain, and obesity and its related cardiometabolic and hormonal risk factors have been associated with poorer outcomes. Dietary intervention may address these risk factors, but limited research has been done in the setting of metastatic breast cancer requiring systemic therapy.

Methods

Women with metastatic breast cancer on stable treatment were randomized 2:1 to an 8-week intervention (n = 21) or control (n = 11). The intervention included weekly assessment visits and an ad libitum whole food, plant-based (WFPB) diet with provided meals. Cardiometabolic, hormonal, and cancer markers were assessed at baseline, 4 weeks, and 8 weeks.

Results

Within the intervention group, mean weight decreased by 6.6% (p < 0.01) after 8 weeks. Fasting insulin decreased from 16.8 uIU/L to 11.2 uIU/L (p < 0.01), concurrent with significantly reduced insulin resistance. Total cholesterol decreased from 193.6 mg/dL to 159 mg/dL (p < 0.01) and low-density lipoprotein (LDL) cholesterol decreased from 104.6 mg/dL to 82.2 mg/dL (p < 0.01). Total testosterone was unchanged, but free testosterone trended lower within the intervention group (p = 0.08) as sex hormone binding globulin increased from 74.3 nmol/L to 98.2 nmol/L (p < 0.01). There were no significant differences in cancer progression markers at week 8, although mean CA 15 - 3, CA 27.29, and CEA were lower in the intervention group (p = 0.53, p = 0.23, and p = 0.54, respectively) compared to control, when adjusted for baseline.

Conclusion

WFPB dietary changes during treatment for metastatic breast cancer are well tolerated and significantly improve weight and cardiometabolic and hormonal parameters. Longer studies are warranted to assess the durability of changes.

Trial registration

First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.

A dietary intervention for vasomotor symptoms of menopause: a randomized, controlled trial

OBJECTIVE

Postmenopausal vasomotor symptoms disrupt quality of life. This study tested the effects of a dietary intervention on vasomotor symptoms and menopause-related quality of life.

METHODS

Postmenopausal women (n = 84) reporting at least two moderate-to-severe hot flashes daily were randomly assigned, in two successive cohorts, to an intervention including a low-fat, vegan diet and cooked soybeans (½ cup [86 g] daily) or to a control group making no dietary changes. During a 12-week period, a mobile application was used to record hot flashes (frequency and severity), and vasomotor, psychosocial, physical, and sexual symptoms were assessed with the Menopause-Specific Quality of Life questionnaire. Between-group differences were assessed for continuous ( t tests) and binary ( χ2 /McNemar tests) outcomes. In a study subsample, urinary equol was measured after the consumption of ½ cup (86 g) of cooked whole soybeans twice daily for 3 days.

RESULTS

In the intervention group, moderate-to-severe hot flashes decreased by 88% ( P < 0.001) compared with 34% for the control group ( P < 0.001; between-group P < 0.001). At 12 weeks, 50% of completers in the intervention group reported no moderate-to-severe hot flashes at all. Among controls, there was no change in this variable from baseline ( χ2 test, P < 0.001). Neither seasonality nor equol production status was associated with the degree of improvement. The intervention group reported greater reductions in the Menopause-Specific Quality of Life questionnaire vasomotor ( P = 0.004), physical ( P = 0.01), and sexual ( P = 0.03) domains.

CONCLUSIONS

A dietary intervention consisting of a plant-based diet, minimizing oils, and daily soybeans significantly reduced the frequency and severity of postmenopausal hot flashes and associated symptoms.

Dietary Inflammatory Index and Epithelial Ovarian Cancer in Southern Chinese Women: A Case-Control Study

The association between inflammatory properties of diet and ovarian cancer risk has been investigated in some Western populations. However, little evidence is available from Asian women whose ovarian cancer incidence rates are low and dietary and lifestyle patterns are very different from their Western counterparts. We aimed to examine whether more pro-inflammatory diets, as indicated by higher dietary inflammatory index (DII®) scores, are associated with increased odds of epithelial ovarian cancer in southern China. A case-control study was conducted during 2006-2008 in Guangzhou, Guangdong Province. Energy-adjusted DII (E-DII) scores were calculated based on dietary intake assessed by a validated food frequency questionnaire administered to 500 incident epithelial ovarian cancer patients and 500 hospital-based controls. Logistic regression models were used to assess the relationship between E-DII scores and odds of ovarian cancer. Positive associations were observed between higher E-DII scores and ovarian cancer odds, using both continuous DII scores (odds ratio (OR) 1.87; 95% confidence interval (CI) 1.65, 2.13) and by DII tertiles (OR_tertile3vs1 7.04, 95% CI: 4.70, 10.54, p for trend < 0.001). Likewise, a more pro-inflammatory diet was associated with a higher chance of serous and mucinous ovarian tumors. Our results suggest that a pro-inflammatory diet was associated with increased odds of developing epithelial ovarian cancer in southern Chinese women. The findings add to epidemiological evidence for the role of dietary inflammatory potential in ovarian cancer development.

Dietary factors and serum antimüllerian hormone concentrations in late premenopausal women

OBJECTIVE

To study the associations between dietary factors and circulating antimüllerian hormone (AMH) concentrations among late premenopausal women.

DESIGN

AMH concentrations were measured in serum samples collected at enrollment from 296 women (aged 35-45 years) in the Sister Study cohort. Usual dietary intakes in the past 12 months were assessed using a validated food frequency questionnaire. Dietary exposures of interest included macronutrients, dietary fat subtypes, fiber, and glycemic index. Multivariable linear regression was used to evaluate associations between dietary variables and serum AMH concentrations. We also used nutrient density models to examine isocaloric replacement of macronutrients.

SETTING

Not applicable.

PATIENTS

Women aged 35-45 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Serum AMH concentrations in nanograms per milliliter (ng/mL).

RESULTS

AMH concentrations were positively associated with percentage of energy from carbohydrates (β per 5% calories = 0.141 [95% CI 0.023, 0.259]; P trend = .019), and inversely associated with percentage of energy from fat (β per 5% calories = -0.152 [95% CI -0.299, -0.004]; P trend = .044). In analyses of dietary fat subtypes, AMH decreased with increasing monounsaturated fatty acids (P trend = .082) and polyunsaturated fatty acids (P trend = .043), particularly ω-6 fatty acids (P trend = .044), whereas no strong trend was observed for saturated fatty acids. Protein and alcohol intake were not strongly associated with AMH.

CONCLUSIONS

Our cross-sectional analyses in a sample of late premenopausal women suggest that dietary fat intake may be inversely associated with circulating AMH concentrations. Further research in prospective studies is warranted to evaluate dietary factors as potential modifiers of ovarian reserve.

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.

Menstrual characteristics, disorders and associated risk factors among female international students in Zhejiang Province, China: a cross-sectional survey

Background

Until now, no previous study has addressed the menstrual patterns among female international students in China. In this present study, our objectives are to ascertain the menstrual characteristics and address the menstrual problems together with their associated risk factors among international students in China.

Methods

A cross-sectional survey was carried out with 500 previously piloted self-structured questionnaires which were administered to female international students enrolled in 15 universities in Zhejiang Province, China from May 2–August 31, 2016. Participants were required to provide answers to a semi-structured questionnaire which asked questions about their socio-demographics and their menstrual characteristics while in their home countries. Relevant changes in their menstrual pattern in terms of amount of flow and duration, regularity, length and suggestive symptoms for premenstrual syndrome in the months after coming to reside in China were also inquired. Respondents indicated changes in eating habits and selected stressors relevant to them from a given list. Their stress levels were assessed and further categorized with the help of the Perceived Stress Scale (PSS). Measurements for the main outcomes included the characteristics of menstrual patterns after arrival in China, stress levels, stressors and new lifestyle patterns.

Results

Four hundred and nine (81.8%) out of the 500 questionnaires met the criteria and constituted the population for this study. The respondents’ mean age was 21.405 years. Almost half of our respondents (49.1%) reported varying changes in their menstrual pattern after arrival to China. Although, menstrual regularity, normal menstrual length (21-35 days) and duration of flow (3–7 days) remained fairly normal among most of the respondents, disorders like premenstrual symptoms (PMS) (33.82%); abnormal amount (17.97%) and dysmenorrhea (16.38%) were prevalent. There was a significant association between high stress (PSS > 20) and menstrual change 0R = 1.636, 95% CI 1.051–2.547, p = 0.029) and dysmenorhea (p = 0.037). Common stressors included language barrier 81(25.88%), food 64(20.45%), and loneliness 56(17.89%).

Conclusion

Menstrual disorders are high among international students in China. We established premenstrual symptoms as the most common menstrual disorder. High levels of stress (PSS > 20) emanating from factors including the language barrier, diet and loneliness was significantly related to the disruptions in their menstruation.

Plant-Based Diet, Cholesterol, and Risk of Gallstone Disease: A Prospective Study

Vegetarian diets may lower symptomatic gallstone disease via cholesterol lowering. This study aimed to examine the risk of symptomatic gallstone disease (GSD) in Taiwanese vegetarians vs. nonvegetarians in a prospective cohort and to explore if this association is related to cholesterol concentration. We prospectively followed 4839 participants, and in the 29,295 person-years of follow-up, 104 new incident GSD cases were confirmed. Diet was assessed through a validated food frequency questionnaire. Symptomatic GSD was ascertained through linkage to the Taiwan National Health Insurance Research Database. Blood cholesterol profiles were measured at recruitment. Cox regression was applied to assess the effect of diet on symptomatic GSD, adjusting for age, education, smoking, alcohol, physical activities, diabetes, kidney diseases, body mass index, lipid-lowering medication, and hypercholesterolemia. Vegetarian diet was associated with a decreased risk of symptomatic GSD compared with nonvegetarian diet in women (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.28⁻0.96) but not in men. In women, nonvegetarians with hypercholesterolemia had 3.8 times the risk of GSD compared with vegetarians with normal cholesterol (HR, 3.81, 95% CI, 1.61⁻9.01). A vegetarian diet may therefore protect against GSD independent of baseline hypercholesterolemia. A nonvegetarian diet and hypercholesterolemia may have an additive effect in increasing GSD risk in women.

Diet, menopause and the risk of ovarian, endometrial and breast cancer

Menopause, the permanent cessation of the menstrual cycle, marks the end of a woman's reproductive lifespan. In addition to changes in sex hormone levels associated with menopause, its timing is another predictor of future health outcomes such as duration of the presence of vasomotor symptoms (VMS) and the risk of hormone-related cancers. With ageing of the population, it is estimated that worldwide 1·2 billion women will be menopausal by the year 2030. Previously the effects of reproductive factors (e.g. parity, age at menarche, pregnancy) and socio-demographic factors on intermediate and long-term health outcomes of menopause have been widely documented. However, little is known about whether diet could have an impact on these. Therefore, we review current evidence on the associations of diet with menopause, presence of VMS and the risk of hormone-related cancers such as ovarian, endometrial and breast cancer. Dietary factors could influence the lifespan of the ovaries and sex-hormones levels, hence the timing of natural menopause. Few studies reported an association between diet, in particular soya consumption, and a reduced risk of VMS. Sustained oestrogen exposure has been associated with a higher risk of hormone-related cancers and thus high-fat and meat diets have been linked with an increased risk of these cancers. However, to better understand the mechanistic pathways involved and to make stronger conclusions for these relationships, further studies investigating the associations of dietary intakes and dietary patterns with menopause, presence of VMS and the risk of hormone-related cancers are required.

Dietary intake and age at natural menopause: results from the UK Women's Cohort Study

BACKGROUND

Age at natural menopause is a matter of concern for women of reproductive age as both an early or late menopause may have implications for health outcomes.

METHODS

Study participants were women aged 40-65 years who had experienced a natural menopause from the UK Women's Cohort Study between baseline and first follow-up. Natural menopause was defined as the permanent cessation of menstrual periods for at least 12 consecutive months. A food frequency questionnaire was used to estimate diet at baseline. Reproductive history of participants was also recorded. Regression modelling, adjusting for confounders, was used to assess associations between diet and age at natural menopause.

RESULTS

During the 4-year follow-up period, 914 women experienced a natural menopause. A high intake of oily fish and fresh legumes were associated with delayed onset of natural menopause by 3.3 years per portion/day (99% CI 0.8 to 5.8) and 0.9 years per portion/day (99% CI 0.0 to 1.8), respectively. Refined pasta and rice was associated with earlier menopause (per portion/day: -1.5 years, 99% CI -2.8 to -0.2). A higher intake of vitamin B6 (per mg/day: 0.6 years, 99% CI 0.1 to 1.2) and zinc (per mg/day: 0.3 years, 99% CI -0.0 to 0.6) was also associated with later age at menopause. Stratification by age at baseline led to attenuated results.

CONCLUSION

Our results suggest that some food groups (oily fish, fresh legumes, refined pasta and rice) and specific nutrients are individually predictive of age at natural menopause.

Dietary fat intake and reproductive hormone concentrations and ovulation in regularly menstruating women

BACKGROUND

Emerging evidence suggests potential links between some dietary fatty acids and improved fertility, because specific fatty acids may affect prostaglandin synthesis and steroidogenesis.

OBJECTIVE

The objective of this exploratory study was to evaluate associations between total and specific types of dietary fat intake and 1) hormone concentrations and 2) the risk of sporadic anovulation in a cohort of 259 regularly menstruating women in the BioCycle Study.

DESIGN

Endogenous reproductive hormones were measured up to 8 times/cycle for up to 2 cycles, with visits scheduled with the use of fertility monitors. Dietary intake was assessed with up to four 24-h recalls/cycle. Linear mixed models and generalized linear models were used to evaluate the associations between dietary fatty acids and both reproductive hormone concentrations and ovulatory status. All models were adjusted for total energy intake, age, body mass index, and race.

RESULTS

Relative to the lowest levels of percentage of energy from total fat, the highest tertile was associated with increased total and free testosterone concentrations (total: percentage change of 4.0%; 95% CI: 0.7%, 7.3%; free: percentage change of 4.1%; 95% CI: 0.5%, 7.7%). In particular, the percentage of energy from polyunsaturated fatty acids (PUFAs) in the highest tertile was associated with increases in total and free testosterone (total: percentage change of 3.7%; 95% CI: 0.6%, 6.8%; free: percentage change of 4.0%; 95% CI: 0.5%, 7.5%). The PUFA docosapentaenoic acid (22:5n-3) was not significantly associated with testosterone concentrations (P-trend = 0.86 in energy substitution models) but was associated with increased progesterone and a reduced risk of anovulation (highest tertile compared with the lowest tertile: RR: 0.42; 95% CI: 0.18, 0.95). Fat intakes were not associated with other reproductive hormone concentrations.

CONCLUSIONS

These results indicate that total fat intake, and PUFA intake in particular, is associated with very small increases in testosterone concentrations in healthy women and that increased docosapentaenoic acid was associated with a lower risk of anovulation.

The Role of Steroid Hormones in the Modulation of Neuroinflammation by Dietary Interventions

Steroid hormones, such as sex hormones and glucocorticoids, have been demonstrated to play a role in different cellular processes in the central nervous system, ranging from neurodevelopment to neurodegeneration. Environmental factors, such as calorie intake or fasting frequency, may also impact on such processes, indicating the importance of external factors in the development and preservation of a healthy brain. The hypothalamic-pituitary-adrenal axis and glucocorticoid activity play a role in neurodegenerative processes, including in disorders such as in Alzheimer's and Parkinson's diseases. Sex hormones have also been shown to modulate cognitive functioning. Inflammation is a common feature in neurodegenerative disorders, and sex hormones/glucocorticoids can act to regulate inflammatory processes. Intermittent fasting can protect the brain against cognitive decline that is induced by an inflammatory stimulus. On the other hand, obesity increases susceptibility to inflammation, while metabolic syndromes, such as diabetes, are associated with neurodegeneration. Consequently, given that gonadal and/or adrenal steroids may significantly impact the pathophysiology of neurodegeneration, via their effect on inflammatory processes, this review focuses on how environmental factors, such as calorie intake and intermittent fasting, acting through their modulation of steroid hormones, impact on inflammation that contributes to cognitive and neurodegenerative processes.

Phytoestrogen and fiber intakes in relation to incident vasomotor symptoms: results from the Study of Women's Health Across the Nation

OBJECTIVE

Although reduction of vasomotor symptoms (VMS; hot flashes and night sweats) has been reported in postmenopausal women who used isoflavones, a clear dose response has not been shown, has largely not been reported for perimenopausal women, and has largely only been reported for reducing prevalent VMS, not preventing newly developing VMS. We analyzed longitudinal data from the Study of Women's Health Across the Nation for the relation of dietary phytoestrogen and fiber intake to incident VMS in this multiracial/ethnic cohort.

METHODS

The Study of Women's Health Across the Nation included 3,302 premenopausal and early perimenopausal women, 1,651 of whom reported no VMS at baseline and were followed with annual visits for 10 years. Dietary intakes of isoflavones, coumestrol, lignans, and fiber were assessed by a food frequency questionnaire at baseline and in annual visits 5 and 9 and interpolated for intervening years. The number of days experiencing VMS in the past 2 weeks was self-reported annually. Using multinomial logistic regression with generalized estimating equations, we modeled incident VMS in relation to isoflavones, lignans, fiber, coumestrol, or total phytoestrogen intake and covariates.

RESULTS

No consistent monotonic relations were observed between any dietary phytoestrogen or fiber and incident VMS, although adjusted odds ratios for some individual quartiles were statistically significant.

CONCLUSIONS

For certainty of any effect of dietary phytoestrogens or fiber on the prevention of incident VMS, a randomized, placebo-controlled, double-masked trial with sufficient numbers of women in different racial/ethnic, menopausal status, and metabolic groups over years of follow-up is required, but our results suggest that a clinically significant or large effect is improbable.

Effect of a six-week national cholesterol education program step 1 diet on plasma sex hormone-binding globulin levels in overweight premenopausal women

BACKGROUND

Low circulating sex hormone-binding globulin (SHBG) concentrations have been associated with the presence of several features of the metabolic syndrome in both men and women. Nutritional factors including dietary lipids and fibers in particular have been suggested to modulate plasma SHBG levels.

METHODS

The primary objective of the present study was to investigate the effect of an oat bran-rich supplement in conjunction with the National Cholesterol Education Program (NCEP) Step 1 diet (< 30% of total energy from fat, < 10% of energy from saturated fat, and < 300 mg cholesterol per day) on plasma SHBG levels in 35 overweight premenopausal women. Subjects (age 38.6 +/- 7.4 years) had normal menstrual cycles and were tested in the midluteal phase. Since no effect of the oat bran supplement was observed on plasma SHBG levels, data were analyzed according to the 6-week NCEP Step 1 diet.

RESULTS

The NCEP Step 1 nutritional intervention caused a significant decrease in energy intake ( -11%, p < 0.05), percent fat intake (-10%, p < 0.005), as well as saturated (-20%, p < 0.005) and monounsaturated (-10%, p < 0.05) fatty acid intake. Body mass index (BMI) decreased slightly but significantly (from 29.2 +/- 4.5 to 28.8 +/- 4.3 kg/m(2), p < 0.005). Plasma SHBG levels increased significantly (from 70.6 +/- 17.7 to 79.9 +/- 15.3 pmol/L, p < 0.0005) following the 6-week NCEP Step 1 diet, whereas plasma insulin levels were not modified significantly. Significant correlations were observed between the change in plasma SHBG levels and baseline BMI (r = 0.36, p < 0.04), as well as baseline (r = -0.42, p < 0.05) and postintervention (r = -0.35, p < 0.05) HDL cholesterol levels.

CONCLUSIONS

We observed that a 6-week NCEP Step 1 diet significantly increased plasma SHBG levels, despite the finding that fasting insulin was not modified. Further studies are needed to elucidate physiological mechanisms underlying a direct effect of dietary composition on SHBG production by the liver.

Body mass index, exercise, and other lifestyle factors in relation to age at natural menopause: analyses from the breakthrough generations study

The authors examined the effect of women's lifestyles on the timing of natural menopause using data from a cross-sectional questionnaire used in the United Kingdom-based Breakthrough Generations Study in 2003-2011. The analyses included 50,678 women (21,511 who had experienced a natural menopause) who were 40-98 years of age at study entry and did not have a history of breast cancer. Cox competing risks proportional hazards models were fitted to examine the relation of age at natural menopause to lifestyle and anthropometric factors. Results were adjusted for age at reporting, smoking status at menopause, parity, and body mass index at age 40 years, as appropriate. All P values were 2-sided. High adult weight (P(trend) < 0.001), high body mass index (P(trend) < 0.001), weight gain between the ages of 20 and 40 years (P(trend) = 0.01), not smoking (P < 0.001), increased alcohol consumption (P(trend) < 0.001), regular strenuous exercise (P < 0.01), and not being a vegetarian (P < 0.001) were associated with older age at menopause. Neither height nor history of an eating disorder was associated with menopausal age. These findings show the importance of lifestyle factors in determining menopausal age.

Genetic and environmental determinants of menstrual characteristics

BACKGROUND

The impact of women's menstrual cycle on her quality of life, health, work, and community is substantial. Menstrual disturbance is linked with general ill conditions such as migraine, asthma, and endocrinopathies. The clinical significance of medical interventions to prevent these conditions becomes clear if the role of genetic or environment is clarified.

AIMS

To identify the genetic and environmental contribution on menstrual characteristics.

SETTING AND DESIGN

This was a cross-sectional study in 2 Asian countries.

MATERIALS AND METHODS

2 cohorts of monozygotic and dizygotic twins born between (1945-1988, n = 122) and (1951-1993, n = 71) were taken. A standard questionnaire was designed inclusive of socio- demographic characteristics of subjects as well as menstrual history (duration, interval, amount, irregularity). Subjects were interviewed by phone.

STATISTICAL ANALYSIS

Quantitative variables were analyzed using Falconars' formula as well as maximum likelihood analysis. Structural modeling was then applied to twin correlations to provide estimates of the relative genetic and/or environmental factors contribution in determining the measured trait.

RESULTS

Menstrual characteristics were found to be under environmental influence where the best fitting model for menstrual interval and duration was common environment. CDF plotting confirmed the results for both variables. Proband-wise concordance analysis for amount of menstruation, amenorrhea, and irregular menstruation revealed no genetic influence. The best fitting model for menstrual irregularity was CE (C73%, E27%). The same model was defined for amenorrhea (C48%, E52%).

CONCLUSIONS

Environmental factors are most likely responsible to determine the menstrual flow, its integrity, and regularity. These factors need to be studied further.

Generalized Degrees of Freedom and Adaptive Model Selection in Linear Mixed-Effects Models

Linear mixed-effects models involve fixed effects, random effects and covariance structure, which require model selection to simplify a model and to enhance its interpretability and predictability. In this article, we develop, in the context of linear mixed-effects models, the generalized degrees of freedom and an adaptive model selection procedure defined by a data-driven model complexity penalty. Numerically, the procedure performs well against its competitors not only in selecting fixed effects but in selecting random effects and covariance structure as well. Theoretically, asymptotic optimality of the proposed methodology is established over a class of information criteria. The proposed methodology is applied to the BioCycle study, to determine predictors of hormone levels among premenopausal women and to assess variation in hormone levels both between and within women across the menstrual cycle.

Realignment and multiple imputation of longitudinal data: an application to menstrual cycle data

Reproductive hormone levels are highly variable among premenopausal women during the menstrual cycle. Accurate timing of hormone measurement is essential, especially when investigating day- or phase-specific effects. The BioCycle Study used daily urine home fertility monitors to help detect the luteinising hormone (LH) surge in order to schedule visits with biologically relevant windows of hormonal variability. However, as the LH surge is brief and cycles vary in length, relevant hormonal changes may not align with scheduled visits even when fertility monitors are used. Using monitor data, measurements were reclassified according to biological phase of the menstrual cycle to more accurate cycle phase categories. Longitudinal multiple imputation methods were applied after reclassification if no visit occurred during a given menstrual cycle phase. Reclassified cycles had more clearly defined hormonal profiles, with higher mean peak hormones (up to 141%) and reduced variability (up to 71%). We demonstrate the importance of realigning visits to biologically relevant windows when assessing phase- or day-specific effects and the feasibility of applying longitudinal multiple imputation methods. Our method has applications in settings where missing data may occur over time, where daily blood sampling for hormonal measurements is not feasible, and in other areas where timing is essential.

Effect of daily fiber intake on luteinizing hormone levels in reproductive-aged women

PURPOSE

To evaluate whether the association between fiber intake and LH levels is driven by the association between fiber and estradiol, or whether there is an independent association.

METHODS

A prospective cohort of 259 premenopausal women were followed for up to 2 menstrual cycles. Estrogen and LH were measured ≤8 times per cycle at visits scheduled using fertility monitors. Diet was assessed ≤4 times per cycle by 24-h recall. Linear mixed models on the log scale of hormones were utilized to evaluate the total effects of fiber intake. Inverse probability weights were utilized to estimate the independent effect of fiber on LH levels.

RESULTS

In unweighted analyses, we observed a significant, inverse association between fiber intake (in 5 g/day increments) and log LH levels (β, -0.051, 95% confidence interval (CI), -0.100, -0.002). No association was observed in the weighted analyses, after estradiol levels were taken into account (β, -0.016, 95% CI, -0.060, 0.027).

CONCLUSIONS

The decreased levels of LH associated with high fiber intake were attenuated after taking estradiol levels into account, suggesting that the association between fiber and LH is most likely a consequence of fiber's impact on estradiol and not due to an independent mechanism.

Effect of dietary fiber intake on lipoprotein cholesterol levels independent of estradiol in healthy premenopausal women

High-fiber diets are associated with improved lipid profiles. However, pre- and postmenopausal women respond differently to fiber intake, suggesting that endogenous estradiol mediates the effect. The authors' objective was to determine the direct effect of fiber intake on lipoprotein cholesterol levels independent of estradiol among premenopausal women. The BioCycle Study, a prospective cohort study conducted at the State University of New York at Buffalo from 2005 to 2007, followed 259 healthy women for up to 2 complete menstrual cycles. Serum lipoprotein and hormone levels were measured at 16 visits timed using fertility monitors. Fiber intake was assessed by 8 24-hour recalls. Marginal structural models with inverse probability weights for both lipoprotein and estradiol levels were used to estimate controlled direct effects of the highest category of fiber intake (≥22 g/day vs. <22 g/day) while accounting for age, body mass index, total energy, vitamin E intake, physical activity, luteinizing hormone, follicle-stimulating hormone, and progesterone. Reductions were observed in total and low density lipoprotein cholesterol in women with higher fiber intakes. Direct effects were greater than total effects. These analyses suggested that estradiol mediates at least part of the association between fiber and cholesterol among premenopausal women. More research is needed to elucidate the biologic mechanisms driving these associations.

Carbohydrate intake, glycemic load, glycemic index, and risk of ovarian cancer

BACKGROUND

Our objective was to determine the relationship between dietary glycemic load (GL), glycemic index (GI), carbohydrate intake, and ovarian cancer risk in a population-based case-control study.

PATIENTS AND METHODS

A self-administered questionnaire was used to collect data on demographic and lifestyle factors, and a food frequency questionnaire was used to collect dietary information from 1366 women with ovarian cancer and 1414 population controls.

RESULTS

GL was positively associated with ovarian cancer. The adjusted odds ratio (OR) for the highest versus the lowest quartile of intake was 1.24 [95% confidence interval (CI) 1.00-1.55, P for trend = 0.03]. Fiber intake was inversely associated with risk. The OR comparing women in the highest fiber-intake group with those in the lowest was 0.78 (95% CI 0.62-0.98, P for trend = 0.11). We found no association between GI, carbohydrate intake, and ovarian cancer. In analyses stratified by body mass index, the risk estimates for GL, carbohydrate, and sugar were higher among overweight/obese women; however, the interaction term was only significant for sugar (P for interaction = 0.004).

CONCLUSIONS

Our results suggest that diets with a high GL may increase the risk of ovarian cancer, particularly among overweight/obese women, and a high intake of fiber may provide modest protection.

Adolescent diet and subsequent serum hormones, breast density, and bone mineral density in young women: results of the Dietary Intervention Study in Children follow-up study

BACKGROUND

Adolescent diet is hypothesized to influence breast cancer risk. We evaluated the long-term effects of an intervention to lower fat intake among adolescent girls on biomarkers that are related to breast cancer risk in adults.

METHODS

A follow-up study was conducted on 230 girls who participated in the Dietary Intervention Study in Children (DISC), in which healthy, prepubertal, 8 to 10 year olds were randomly assigned to usual care or to a behavioral intervention that promoted a reduced fat diet. Participants were 25 to 29 years old at follow-up visits. All tests of statistical significance are two-sided.

RESULTS

In analyses that did not take account of diet at the time of the follow-up visit, the only statistically significant treatment group difference was higher bone mineral content in intervention group participants compared with usual care group participants; their mean bone mineral contents were 2,444 and 2,377 g, respectively. After adjustment for current diet, the intervention group also had statistically significantly higher bone mineral density and luteal phase serum estradiol concentrations. Serum progesterone concentrations and breast density did not differ by treatment group in unadjusted or adjusted analyses.

CONCLUSIONS

Results do not support the hypothesis that consumption of a lower fat diet during adolescence reduces breast cancer risk via effects on subsequent serum estradiol and progesterone levels, breast density, or bone mineral density. It remains unclear, however, if the results are specific to the DISC intervention or are more broadly applicable.

IMPACT

Modest reductions in fat intake during adolescence are unlikely to lower later breast cancer risk via long-term effects on the biomarkers measured.

Diet, physical activity and energy balance and their impact on breast and prostate cancers

Obesity, physical activity status and circulating levels of sex steroid hormones and growth factor proteins are intrinsically linked to energy balance. Epidemiological studies have previously reported associations between these factors and the risk of hormone-related cancers such as prostate and breast cancer in men and postmenopausal women. An increasing number of intervention studies in 'at-risk' populations and cancer survivors are now investigating the effects of lifestyle interventions that promote negative energy balance on circulating levels of sex hormones and growth factor proteins as surrogate markers of cancer risk. Evidence from these studies suggests that lifestyle interventions can improve insulin sensitivity, alter the balance of circulating sex steroid hormones and insulin-like growth factor (IGF) axis proteins (including IGF-1 and the IGF binding proteins 1 and 3) and change the functioning of immune cells in peripheral blood. Such changes could influence the risk of developing hormone-related cancers, as well as having the potential to improve disease-free survival in patients recovering from cancer treatment. However, despite promising results, the methodological quality of most intervention studies has been limited due to small subject numbers, lack of adequate control groups or non-randomised designs and the absence of long-term follow-up measures. More intervention studies with randomised controlled designs, higher numbers of subjects and longer-term follow-up measures are needed to establish which combination of specific dietary and physical activity interventions work best for reducing risk in 'at-risk' populations and survivors, optimal dose-response relationships and the magnitude of change in surrogate markers of cancer risk that is required to induce a protective effect.

Effect of daily fiber intake on reproductive function: the BioCycle Study

BACKGROUND

High-fiber diets have been associated with decreased breast cancer risk, likely mediated by the effect of fiber on lowering circulating estrogen concentrations. The influence of fiber on aspects of reproduction, which include ovulation, has not been well studied in premenopausal women.

OBJECTIVE

The objective was to determine if fiber consumption is associated with hormone concentrations and incident anovulation in healthy, regularly menstruating women.

DESIGN

The BioCycle Study was a prospective cohort study conducted from 2004 to 2006 that followed 250 women aged 18-44 y for 2 cycles. Dietary fiber consumption was assessed < or =4 times/cycle by using 24-h recall. Outcomes included concentrations of estradiol, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), which were measured < or =8 times/cycle, and incident anovulation.

RESULTS

Dietary fiber consumption was inversely associated with hormone concentrations (estradiol, progesterone, LH, and FSH; P < 0.05) and positively associated with the risk of anovulation (P = 0.003) by using random-effects models with adjustment for total calories, age, race, and vitamin E intake. Each 5-g/d increase in total fiber intake was associated with a 1.78-fold increased risk (95% CI: 1.11, 2.84) of an anovulatory cycle. The adjusted odds ratio of 5 g fruit fiber/d was 3.05 (95% CI: 1.07, 8.71).

CONCLUSIONS

These findings suggest that a diet high in fiber is significantly associated with decreased hormone concentrations and a higher probability of anovulation. Further study of the effect of fiber on reproductive health and of the effect of these intakes in reproductive-aged women is warranted.

Dietary beta-tocopherol and linoleic acid, serum insulin, and waist circumference predict circulating sex hormone-binding globulin in premenopausal women

Reduced levels of circulating sex hormone-binding globulin (SHBG) are implicated in the etiology of sex steroid-related pathologies and the metabolic syndrome. Dietary correlates of serum SHBG remain unclear and were studied in a convenient cross-sectional sample of healthy 30- to 40-y-old women (n = 255). By univariate analyses, serum SHBG correlated negatively with several indices of the metabolic syndrome, such as BMI, waist circumference, hip circumference (r = -0.36 to -0.44; P < 0.0001), fasting serum insulin (r = -0.41; P < 0.0001), serum triglycerides (r = -0.27; P < 0.0001), serum glucose (r = -0.23; P < 0.001), and plasma testosterone (r = -0.19; P = 0.002). Serum SHBG correlated positively with serum HDL-cholesterol (r = 0.33; P < 0.0001), plasma progesterone (r = 0.17; P = 0.007), and dietary intake of beta-tocopherol (r = 0.17; P = 0.006), and negatively with that of fructose (r = -0.13; P = 0.04). Principal component analysis (PCA) extracted 12 nutrient factors with eigenvalues > 1.0 from 54 nutrients and vitamins in food records. Multivariate regression analyses showed that the PCA-extracted nutrient factor most heavily loaded with beta-tocopherol and linoleic acid (P = 0.03) was an independent positive predictor of serum SHBG. When individual nutrients were the predictor variables, beta-tocopherol (P = 0.002), but not other tocopherols or fatty acids (including linoleic acid), was an independent positive predictor of serum SHBG. Circulating insulin (P = 0.02) and waist circumference (P = 0.002), but not serum lipids, were negative independent predictors of SHBG in all regression models. Additional studies are needed in women of other age groups and men to determine whether consumption of foods rich in beta-tocopherol and/or linoleic acid may increase serum SHBG concentrations and may thereby decrease the risk for metabolic syndrome and reproductive organ cancer.

Higher intakes of vegetables and vegetable-related nutrients are associated with lower endometrial cancer risks

A limited number of studies have investigated diet in association with endometrial cancer (EC). We examined the association between intakes of selected food groups and nutrients with EC risk among 541 women with histologically confirmed EC and 541 women with an intact uterus and noncancer diagnoses seen at Roswell Park Cancer Institute between 1982 and 1998. Self-reported dietary and other epidemiologic data were collected by questionnaire. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% CI, adjusting for age, BMI, hormone replacement therapy use, cigarette smoking, lifetime duration of menstruation, and total energy intake. We observed significant inverse associations for women in the highest vs. lowest quartiles of intake of total vegetables (OR, 0.51; 95% CI, 0.34-0.75), vitamin E (OR, 0.44; 95% CI, 0.27-0.70), dietary fiber (OR, 0.60; 95% CI, 0.39-0.94), beta-carotene (OR, 0.55; 95% CI, 0.37-0.82), lutein (OR, 0.52; 95% CI, 0.34-0.78), and folate (OR, 0.57; 95% CI, 0.36-0.91). Our results support that vegetables and related nutrients are associated with decreased risk of EC.

Dietary fiber intake and ovarian cancer risk: a prospective cohort study

There is some evidence from case-control studies that dietary fiber intake might be inversely associated with ovarian cancer risk, but there are limited prospective data. Therefore, we examined ovarian cancer risk in association with intake of dietary fiber in a prospective cohort of 49,613 Canadian women enrolled in the National Breast Screening Study (NBSS), who completed a self-administered food frequency questionnaire between 1980 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000. Data from the food frequency questionnaire were used to estimate intake of total dietary fiber, of fiber fractions, and of fiber from various sources. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between energy-adjusted quartile levels of fiber intake and ovarian cancer risk. During a mean 16.4 years of follow-up, we observed 264 incident ovarian cancer cases. Total dietary fiber and fiber fractions were not associated with ovarian cancer risk in this study population.

Alcohol and dietary fibre intakes affect circulating sex hormones among premenopausal women

Background

The association of alcohol and fibre intake with breast cancer may be mediated by circulating sex hormone levels, which are predictors of breast cancer risk.

Objective

To evaluate the relationship of alcohol and dietary fibre intake with circulating sex hormone levels among premenopausal women.

Methods

A total of 205 premenopausal women completed a validated food-frequency questionnaire at baseline and after 2 years; blood samples taken at the same time were analysed for circulating sex hormone concentrations, including oestrone (E1), oestradiol (E2), free E2, progesterone, androstenedione and sex hormone-binding globulin, by radioimmunoassay. We used mixed models to estimate least-square means of sex hormone concentrations for alcohol intake categories and quartiles of dietary intake.

Results

After adjustment for covariates, alcohol consumption was moderately associated with higher circulating oestrogen levels; those who consumed more than one drink per day had 20% higher E2 (Ptrend = 0.07) levels than non-drinkers. In contrast, higher dietary fibre intake was associated with lower serum levels of androstenedione (−8% between the lowest and highest quartiles of intake, Ptrend = 0.06), but not oestrogens. Similarly, consumption of fruits (−12%, Ptrend = 0.03), vegetables (−9%, Ptrend = 0.15) and whole grains (−7%, Ptrend = 0.07) showed inverse associations with androstenedione levels.

Conclusions

The consistency of the observed differences in sex hormone levels associated with alcohol and fibre-rich foods indicates that these nutritional factors may affect sex hormone concentrations and play a role in breast cancer aetiology and prevention.

Associations of menstrual cycle length with intake of soy, fat, and dietary fiber in Japanese women

A decreased risk of breast cancer has been reported among women who have longer menstrual cycles or anovulatory cycles. The present study examined the relationships between intake of fat, soy, and dietary fiber and length of menstrual cycle among 341 Japanese women aged 18 to 29 yr old at two colleges and three nursing schools. Intake of nutrients and foods including fats, dietary fiber, and soy products was estimated through the use of a validated semi-quantitative food frequency questionnaire. The mean cycle length was determined for each women based on a prospective record of menstruation. Polyunsaturated fat intake was significantly inversely associated with cycle length; the means of cycle length were 33.2 and 31.0 days for the lowest and the highest quintiles of intake, respectively, after controlling for covariates (trend = 0.03). The odds ratio of a long cycle (> 35 days) for the highest vs. lowest quintile of dietary fiber intake was 2.12 (95% confidence interval 1.00-4.47), although the trend was not statistically significant. The data suggest that polyunsaturated fat and dietary fiber intake are associated with the parameters of menstrual cycle length, but further studies are required to better characterize these associations.

Effects of a Low-Fat, High-Fiber Diet and Exercise Program on Breast Cancer Risk Factors In Vivo and Tumor Cell Growth and Apoptosis In Vitro

The present study investigated the effects of a diet and exercise intervention on known breast cancer (BCa) risk factors, including estrogen, obesity, insulin, and insulin-like growth factor-I (IGF-I), in overweight/obese, postmenopausal women. In addition, using the subjects' pre- and postintervention serum in vitro, serum-stimulated growth and apoptosis of three estrogen receptor-positive BCa cell lines were studied. The women where placed on a low-fat (10-15% kcal), high-fiber (30-40 g per 1,000 kcal/day) diet and attended daily exercise classes for 2 wk. Serum estradiol was reduced in the women on hormone treatment (HT; n = 28) as well as those not on HT (n = 10). Serum insulin and IGF-I were significantly reduced in all women, whereas IGF binding protein-1 was increased significantly. In vitro growth of the BCa cell lines was reduced by 6.6% for the MCF-7 cells, 9.9% for the ZR-75-1 cells, and 18.5% for the T-47D cells. Apoptosis was increased by 20% in the ZR-75-1 cells, 23% in the MCF-7 cells, and 30% in the T-47D cells (n = 12). These results show that a very-low-fat, high-fiber diet combined with daily exercise results in major reductions in risk factors for BCa while subjects remained overweight/obese. These in vivo serum changes slowed the growth and induced apoptosis in serum-stimulated BCa cell lines in vitro.

Effect of flaxseed and wheat bran on serum hormones and lignan excretion in premenopausal women

OBJECTIVE

To examine the effects of flaxseed consumption (a lignan-rich plant food) alone and in combination with wheat bran on serum hormones and urinary lignan excretion in premenopausal women.

METHODS

Sixteen subjects were studied for four feeding treatments lasting two menstrual cycles each in a randomized, crossover design. During each treatment, subjects consumed their habitual diets supplemented with baked goods containing no flaxseed or wheat bran, 10 g of flaxseed, 28 g of wheat bran, or 10 g of flaxseed plus 28 g of wheat bran/day. Serum samples collected during the mid-luteal phase of the second menstrual cycle of each diet treatment were analyzed for serum hormones and sex hormone binding globulin. Urine samples collected during the same time period were analyzed for urinary lignan excretion.

RESULTS

There were no changes in serum hormone concentrations or sex hormone binding globulin on any of the treatments. Urinary lignan excretion significantly increased on diet treatments that included flaxseed, but inclusion of wheat bran did not significantly alter lignan excretion.

CONCLUSIONS

Urinary lignan excretion increased with flaxseed consumption, but serum hormones did not change in this group of premenopausal women. Consumption of wheat bran with flaxseed did not alter urinary lignan excretion associated with flaxseed consumption.

Effects of exercise and diet on chronic disease

Currently, modern chronic diseases, including cardiovascular diseases, Type 2 diabetes, metabolic syndrome, and cancer, are the leading killers in Westernized society and are increasing rampantly in developing nations. In fact, obesity, diabetes, and hypertension are now even commonplace in children. Clearly, however, there is a solution to this epidemic of metabolic disease that is inundating today's societies worldwide: exercise and diet. Overwhelming evidence from a variety of sources, including epidemiological, prospective cohort, and intervention studies, links most chronic diseases seen in the world today to physical inactivity and inappropriate diet consumption. The purpose of this review is to 1) discuss the effects of exercise and diet in the prevention of chronic disease, 2) highlight the effects of lifestyle modification for both mitigating disease progression and reversing existing disease, and 3) suggest potential mechanisms for beneficial effects.

Prevention of Cancer Through Lifestyle Changes

Cancer is the second leading cause of death in the USA and an abundance of evidence suggests that lifestyle factors including smoking, the typical high-fat, refined-sugar diet and physical inactivity account for the majority of cancer. This review focuses on diet and inactivity as major factors for cancer promotion by inducing insulin resistance and hyperinsulinemia. Elevated levels of serum insulin impact on the liver primarily, increasing the production of insulin-like growth factor I (IGF-I) while reducing the production of insulin-like growth factor binding protein 1 (IGFBP-1) resulting in stimulation of tumor cell growth and inhibition of apoptosis (programmed cell death). Adopting a diet low in fat and high in fiber-rich starch foods, which would also include an abundance of antioxidants, combined with regular aerobic exercise might control insulin resistance, reduce the resulting serum factors and thus reduce the risk for many different cancers commonly seen in the USA.

Current problems of food intake in young women in Japan: Their influence on female reproductive function

Accumulating evidence suggests that food customs are associated with quality of life in women of the reproductive age. In Japan, dietary limitation for cosmetic purposes, skipping food intake, intake of processed foods and the shift from Japanese to Westernized style food have increased among young women. These changes in food habits can cause inadequate intake of calories, micronutrients, unsaturated fat, phytestrogens and fiber as well as increasing environmental toxins. Furthermore, these food habits increase risk as a result of intake of food additives, anti-oxidants, processing agents and sweeteners, which have been demonstrated to be harmful to human health. These factors are speculated to not only influence the present lifestyle, but also to induce gynecologic disorders such as dysmenorrhea and irregular menstruation. The adverse effects of these dietary habits on pregnancy outcome and carcinogenesis of breast and ovarian cancers have also been demonstrated. In addition, latent development of organic diseases such as endometriosis, which are accompanied by dysmenorrhea, is a concern under the current nutritional environment in young women. Thus, it is an urgent issue to evaluate the present situation of eating habits in young Japanese women and estimate the influence of these habits on the quality of life including reproductive functions. (Reprod Med Biol 2004; 3: 107-114).

Factors affecting menstrual cycle characteristics

This 1989-1991 study in California and Utah used daily urinary metabolites of estrogen and progesterone and computer algorithms to assess ovulatory status and day of ovulation. The authors examined the associations of risk factors with menstrual cycle characteristics for 309 working women aged 20-44 years who collected a median of five cycles each of daily urine samples. Linear mixed models were used to assess continuous menstrual outcomes. Compared with women less than age 35 years, women aged 35 years or older had a significantly decreased (-0.94 days, 95% confidence interval: -1.83, -0.05) adjusted mean cycle length. Age modified the effects of smoking, physical activity, ethnicity, and alcohol consumption on mean follicular phase length. Asian women had a significantly longer (1.65 days, 95% confidence interval: 0.54, 2.76) adjusted mean cycle length compared with Caucasian women. Compared with women who did not consume alcoholic drinks, women who did had a significantly shorter (-1.26 days, 95% confidence interval: -2.21, -0.31) adjusted mean cycle length. Mean cycle and phase lengths were significantly associated with length of the prior luteal phase. These results indicate that potentially modifiable risk factors, as well as immutable host factors, are associated with menstrual cycle characteristics that may in turn be related to subsequent disease risk.

Olive oil consumption during pregnancy and lactation in rats influences mammary cancer development in female offspring

This study examined the effects of variety and quantity of dietary fat consumed by rats during pregnancy and lactation on female offspring's response to chemically induced mammary cancer. Groups of six female rats were fed diets containing 7% corn oil (7-CO), 15% CO (15-CO), 7% olive oil (7-OO), or 15% OO (15-OO) for 5 wk prior to, and during, pregnancy and lactation. Female offspring (n = 15 per group) were fed a 7-CO diet, and mammary cancer was induced with 7,12-dimethylbenz[a]anthracene (DMBA). Three months following cancer induction tumor incidence and size were recorded, and markers of apoptosis, serum estrogen concentrations, and hepatic phase II enzymes were measured. Tumor incidence was 47% in offspring born to mothers fed the 7-OO diet, rose to 67% in 7-CO and 15-OO offspring, and reached 86% in 15-CO. A trend toward smaller tumors was observed in the 7-OO group, and offspring of mothers fed high-fat diets had significantly more tumors. Estradiol levels at the end of lactation were significantly lower in mothers fed 7-OO but were similar in all groups of offspring. In tumor tissue, Bcl-2 expression was highest in the 15-CO offspring, and Bak expression was significantly higher in rats exposed to OO. A distinct trend toward increased caspase-3 expression (20 kDa) was observed in the 7-OO offspring, and both low-fat diets significantly elevated caspase activity. In healthy mammary tissue, rats exposed to low-fat diets had significantly higher caspase-3 (32-kDa) levels, and caspase-3 activity was significantly higher in the healthy tissue from both OO groups. Hepatic quinone reductase activity was significantly lower in offspring of mothers fed the low-fat diets. These results indicate that perinatal exposure to OO may have a protective effect against future development of mammary cancer in female offspring, whereas high-fat diets fed to pregnant and lactating rats, in particular CO, may be deleterious.

Nutritional factors and breast cancer in Mexico

Breast cancer (BC) morbidity and mortality in Mexico are on the rise, affecting younger women with more frequency. Nutritional factors are often mentioned as determinants of BC but their relevance is not well established in Latin-American countries, where dietary habits show great variation. From a study population previously assembled in Mexico City, 141 histologically confirmed cases of BC were matched by age (+/-3 yr) to an equal number of hospital controls. A food frequency questionnaire was administered to all subjects and the risk of BC was estimated in relation to the intake of selected nutrients. The findings of this study show a protective effect against BC due to a high intake of polyunsaturated fat (odds ratio, OR = 0.10, 95% CI = 0.02-0.40, P for trend = 0.001) and vitamin E (OR = 0.10, 95% CI = 0.02-0.44, P for trend = 0.003) among postmenopausal women. In addition, our findings also suggest that a high intake of total fiber (OR = 0.29, 95% CI = 0.08-1.10, P for trend = 0.080) and carotenes (OR = 0.42, 95% CI = 0.16-1.14, P for trend = 0.088) lowers BC risk among premenopausal women. The relationship between the intake of nutrients and BC risk needs further confirmation.

The effects of a low-fat/high-fiber diet on sex hormone levels and menstrual cycling in premenopausal women: a 12-month randomized trial (the diet and hormone study)

BACKGROUND

Reduction of cumulative exposure to endogenous ovarian steroid hormones is a postulated method for reducing the risk of carcinoma of the breast and other malignancies. Although there are data from trials evaluating the effect of low-fat and high-fiber diets on sex hormone levels in premenopausal women, to the authors' knowledge none of these trials has combined a relatively large number of participants, follow-up of > 2-3 months, parallel controls receiving a usual diet, and careful timing of blood sampling within the menstrual cycle.

METHODS

A total of 213 healthy women, ages 20-40 years, were randomly assigned to follow their usual diet or to adopt an isocaloric diet with goals of 20% calories as fat, total fiber of 25 g/day, and at least 8 fruit or vegetable servings per day. Serum levels of total estradiol (E2), sex hormone-binding globulin (SHBG), non-SHBG-bound estradiol (NSBE2), SHBG, and progesterone were evaluated during a menstrual cycle at baseline, and at 4 cycles (C4) and 12 cycles (C12) after the start of the intervention. Serum was collected during each test cycle 7-9 days after the detection of an luteinizing hormone peak in the urine. One hundred eighty-nine women provided serum at C4 and 176 women at C12.

RESULTS

Serum E2 decreased by an average of 7.5% or 7.8 pg/mL (95% confidence interval [95% CI], -16.0-0.04) at C12 in the intervention group, versus a decrease of 0.9% or 0.9 pg/mL (95% CI, -9.5-7.7) in the control group (the P value for the difference between the treatment groups was 0.25). Results for NSBE2 were very similar to those for total estradiol. There were no material effects found to result from intervention with regard to SHBG or progesterone. The results did not differ by baseline age, body mass index, or baseline hormone level above or below the median, and were not likely to be affected by weight change, which amounted to a mean loss of only 0.23 kg in the diet group versus a gain of 0.17 kg in the control group. The decrease in serum E2 associated with intervention was not greater when subjects were stratified by self-reported adherence to the dietary goals.

CONCLUSIONS

The results of the current study suggest that the effects of this isocaloric low-fat, high-fiber diet pattern on circulating ovarian steroids were modest or nonexistent. However, the observed 7.5% reduction in estradiol could have biologic significance if it persisted over many years. Moreover, underestimation of the true dietary effect could have occurred because of incomplete adherence to assigned diets. Weight loss and weight control through midlife could be a more effective and feasible approach to dietary intervention in reducing the risk of breast carcinoma.

Association between vegetarian diet and menstrual problems in young women: a case presentation and brief review

In the last twenty years, several studies have suggested the existence of an association between vegan diets and adolescent menstrual disorders. We share our experience with this problem and a review of the literature on the subject. We conclude that despite the existence of some evidence to the possible association between vegetarian diet and menstrual disorders, it is still not clear if this association is due solely to the vegetarian diet or due to the overall inadequate nutrition with decreased proportions of fat and protein in the diet. We believe that more prospective, well controlled studies are needed to truly explain this association.

Risk of human ovarian cancer is related to dietary intake of selected nutrients, phytochemicals and food groups

Intakes of specific nutrients and food groups have been shown previously to be related to ovarian cancer risk, but no studies, to our knowledge, have emphasized the effect of phytochemical intakes on this cancer. We conducted a case-control study of diet and ovarian cancer in western New York involving 124 primary, histologically confirmed ovarian cancer cases and 696 population-based controls, frequency matched to cases on age and county of residence. Diet was assessed with a detailed food-frequency questionnaire. Nutrient and phytochemical intakes were calculated from published food composition data. The odds ratios (OR) and 95% CI for risk of ovarian cancer with each nutrient, phytochemical and food group were estimated with unconditional logistic regression adjusting for age, education, total months menstruating, difficulty becoming pregnant, oral contraceptive use, menopausal status and energy intake. Compared with women in the lowest quintile of intake, reduced risks were observed for women in the highest quintile of intake of dietary fiber (OR 0.43, 95% CI, 0.20-0.94), total carotenoids (OR 0.33, 95% CI, 0.16-0.68), stigmasterol (OR 0.42, 95% CI, 0.20-0.87), total lignans (OR 0.43, 95% CI, 0.21-0.85), vegetables (OR 0.47, 95% CI, 0.23-0.97) and poultry (OR 0.45, 95% CI, 0.22-0.92). These results support a protective effect on ovarian cancer of phytoestrogen intakes, and our results support the hypothesis that a plant-based diet may be important in reducing risks of hormone-related neoplasms.

Effects of prune consumption on the ratio of 2-hydroxyestrone to 16alpha-hydroxyestrone

BACKGROUND

A higher urinary ratio of the biologically inactive estrogen metabolite, 2-hydroxyestrone (2OHE1), to the biologically active metabolite, 16alpha-hydroxyestrone (16alphaOHE1), may be associated with a lower risk of breast cancer. High fiber intake is also associated with decreased breast cancer risk.

OBJECTIVE

We investigated the effects of prunes, which are naturally rich in both soluble and insoluble fiber, on the concentrations of 2OHE1 and 16alphaOHE1 and on the ratio of 2OHE1 to 16alphaOHE1.

DESIGN

Nineteen healthy premenopausal women consumed their habitual diets for 3 menstrual cycles and then consumed 100 g prunes/d for the next 3 cycles. Concentrations of urinary 2OHE1 and 16alphaOHE1 were determined during the follicular and luteal phases.

RESULTS

Prune supplementation increased total and soluble fiber intakes by 4 and 2 g/d, respectively (P < 0.001). Mean (+/- SEM) luteal 2OHE1 excretion decreased from 3.92 +/- 0.79 to 2.20 +/- 0.40 nmol/mmol creatinine during the third cycle (P = 0.017). Luteal 16alphaOHE1 excretion decreased from 1.38 +/- 0.24 to 0.87 +/- 0.10 and 0.87 +/- 0.15 nmol/mmol creatinine during the first and third cycles, respectively (P = 0.018 for both values). Follicular 16alphaOHE1 excretion decreased significantly only during the first cycle (from 0.82 +/- 0.12 to 0.45 +/- 0.09 nmol/mmol creatinine; P = 0.005). The 2OHE1-16alphaOHE1 ratio did not change significantly after prune supplementation.

CONCLUSIONS

Prune supplementation significantly decreased the excretion of 16alphaOHE1 during the follicular phase of the first menstrual cycle and during the luteal phases of both the first and third menstrual cycles. The 2OHE1-16alphaOHE1 ratio did not change significantly. The potential significance of the decrease in 16alphaOHE1 excretion, without a change in the 2OHE1-16alphaOHE1 ratio, on the prevention of estrogen-dependent cancers remains to be determined.