Diet and the excretion and enterohepatic cycling of estrogens

The impact of vegetarian diet on sperm quality, sex hormone levels and fertility: a systematic review and meta-analysis

BACKGROUND

An increasing number of people have adhered to a vegetarian diet for several years. Nowadays, the favourable effect of this dietary pattern on metabolic diseases is well established, but its impact on fertility and reproductive health as a serious health concern is not clear yet. Therefore, we aim to summarise existing evidence regarding the possible association between a vegetarian diet and fertility as measured by key indicators such as sperm quality and sex hormone levels.

METHODS

We systematically searched online databases, including PubMed, ISI, Scopus and Google Scholar, up to 1 December 2022 using relevant keywords. We included observational studies that compared semen quality, sex hormone levels and infertility in people who adhered to a vegetarian diet versus an omnivore diet. Heterogeneity between studies was assessed using I2 and Q tests. Standardised mean differences (SMD) using a random/fixed model were calculated to assess outcomes between vegetarians and omnivores in included articles.

RESULTS

Finally, out of 972 documents that were retrieved, 20 articles met our inclusion criteria, and 16 were eligible for quantitative synthesis. Results of meta-analyses showed that there were no significant differences between vegetarians and omnivores in terms of semen quality parameters, including total sperm count, total and progressive sperm motility, sperm morphology and sperm concentration. Seven studies on female sex hormone profiles were eligible for meta-analysis. The only significant difference was the lower level of plasma oestrone in vegetarians (pooled SMD: -0.56; 95% confidence interval [CI]: -1.08, -0.05; p-value = 0.03) compared to omnivores. Furthermore, our meta-analysis revealed significantly higher sex-hormone-binding globulin levels in vegetarian men than in omnivores (pooled SMD: 0.52; 95% CI: 0.18, 0.86; p-value = 0.002).

CONCLUSION

Despite the numerous health benefits of a vegetarian diet, our review suggested that there were no conclusive positive or negative associations between vegetarian diet and semen quality, sex hormone levels and infertility. Further studies are recommended to better understand vegetarian dietary pattern effect on infertility and reproductive health.

The Effects of Different Types of Diets on Steroid Hormone Concentrations

The great popularity of various diets in recent years has led us to reflect on their suitability for our health. The aim of this communication is to review current knowledge on the influence of the most well-known diets on the concentrations of the main steroids and to consider possible mechanisms. The influence of diet on hormone concentrations is expected, but the literature data on this topic are inconsistent and yield conflicting results. The main problem in evaluating these influences is the change in weight that a change in diet induces. This effect needs to be filtered out in order to discover interesting associations between diet and steroid hormones. This is illustrated by the example of the effects of ketogenic diets on testosterone levels in men, where the direct effect of the diet is to reduce testosterone levels, but a number of papers have described increases that are due to diet-related weight loss and the modification of obesity-induced changes. A second major driver is the change in circadian rhythm, and it is necessary to assess hormonal changes induced by changing the time of day of the diet. Such shifts within the circadian rhythm rather than due to a particular type of diet itself are documented by changes in the circadian rhythm of cortisol.

Endocrine Disruptors in Food, Estrobolome and Breast Cancer

The microbiota is now recognized as one of the major players in human health and diseases, including cancer. Regarding breast cancer (BC), a clear link between microbiota and oncogenesis still needs to be confirmed. Yet, part of the bacterial gene mass inside the gut, constituting the so called "estrobolome", influences sexual hormonal balance and, since the increased exposure to estrogens is associated with an increased risk, may impact on the onset, progression, and treatment of hormonal dependent cancers (which account for more than 70% of all BCs). The hormonal dependent BCs are also affected by environmental and dietary endocrine disruptors and phytoestrogens which interact with microbiota in a bidirectional way: on the one side disruptors can alter the composition and functions of the estrobolome, ad on the other the gut microbiota influences the metabolism of endocrine active food components. This review highlights the current evidence about the complex interplay between endocrine disruptors, phytoestrogens, microbiome, and BC, within the frames of a new "oncobiotic" perspective.

A digital health intervention to improve nutrition and physical activity in breast cancer survivors: Rationale and design of the Cook and Move for Your Life pilot and feasibility randomized controlled trial

BACKGROUND

The design of a randomized pilot trial evaluating the feasibility of two doses of a digital health intervention promoting changes in nutrition and physical activity in breast cancer (BC) survivors is described.

METHODS

Eligible women were adults with history of early-stage breast cancer and > 60 days post-treatment, consumed <5 servings/day of fruits/vegetables and/or engaged in <150 min/week of aerobic moderate-to-vigorous physical activity, and had internet access. Participants were randomized to 6 months of either a "low" (1 session) or "high" (12 sessions) dose digital health intervention. Zoom-delivered sessions focused on improving diet and physical activity through didactic and experiential classes delivered by a registered dietitian, chef, exercise physiologist, and culinary educator. All study participants received weekly motivational texts, a Fitbit, and study website access. Diet, accelerometry, anthropometric, psychosocial, and biospecimen data were collected remotely at baseline and six months. Primary outcome was feasibility measured via accrual rate, adherence, retention, and acceptability.

RESULTS

Recruitment began in December 2019, was suspended in March 2020 due to the COVID-19 pandemic, resumed September 2020, and concluded in January 2021. Women were identified from the local BC registry and flyers posted in the oncology clinic. Of 929 women recruited, 321 completed the screening assessment, and of these, 138 were eligible. A total of 74 women were enrolled and randomized to the study.

CONCLUSION

BC survivors were successfully enrolled in a digital health nutrition and physical activity intervention. If feasible, this intervention will be tested in larger and more diverse populations of cancer survivors.

TRIAL REGISTRATION

ClinicalTrials.govNCT04200482.

Relations between the time of ovulation and fecal estrogen concentration in sows

Artificial insemination (AI) is the most important biotechnology in pig reproduction. To achieve the best possible fertility results, appropriate timing of the insemination is essential. The optimal time for AI is 12 h before to 4 h after ovulation. This time-frame, unlike in estrus, is not recognizable through external indicators. It would, therefore, be beneficial to find simple and economical methods that support manual estrus checks and are able to determine the time of ovulation more accurately. On this basis, starting 80 h after weaning, 14 DanBred sows (parity: 5.2 ± 2.4) were checked for ovulation via ultrasound scans every 8 h over a period of 72 h. Additionally, rectal fecal samples were taken and analyzed for their estrogen concentration to assess possible relations to ovulation time. On average, sows ovulated 121 ± 10 h after weaning and 16 ± 9 h after onset of heat. There was a prominent drop in fecal estrogen levels 4 h before ovulation when compared to almost all other points in time (before ovulation: 20 h (P = 0.056), 12 h (P = 0.006); after ovulation: 4 h and 12 h (P < 0.001)). There are, however, significant differences in the sow-individual fecal estrogen concentrations for which several influencing factors must be considered.

Role of Gut Microbiota Dysbiosis in Breast Cancer and Novel Approaches in Prevention, Diagnosis, and Treatment

Breast cancer is the most common cause of cancer-related deaths in women. Breast cancer is still a major cause of morbidity and mortality among women despite all the available diagnostic and treatment modalities. The gut microbiota has drawn keen interest as an additional environmental risk factor in breast cancer, especially in sporadic cases. This article explores factors that disrupt the normal gut microbial composition and the role of gut microbial dysbiosis in the development of breast cancer. We finalized 40 relevant articles after searching Pubmed and Google Scholar using regular keywords and the Medical Subject Headings (MeSH) strategy. Gut microbiota dysbiosis has been shown to play a role in the development of breast cancer via estrogen-dependent mechanisms and non-estrogen-dependent mechanisms involving the production of microbial-derived metabolites, immune regulation, and effects on DNA. The gut microbiota influence estrogen metabolism hence estrogen levels. The metabolites that have demonstrated anticancer properties include lithocholic acid, butyrate, and cadaverine. New approaches targeting the gut microbiota have come up and may yield new advances in the prevention, diagnosis, and treatment of breast cancer. They include the use of prebiotics, probiotics, and hormone supplements to restore normobiosis in the prevention and treatment of breast cancer.

Probiotics for cancer alternative prevention and treatment

Cancer is a fatal malignancy with high clinical significance and remains one of the major causes of illness and death. It has no suitable cure existing till now. The safety and stability of the standard chemotherapeutics drugs and synthetic agents used to manage cancer are doubtful. These agents are affecting the quality of life or contributing for development of drug resistance and are not affordable to the majority of the patients. Therefore, scientists are looking into clinical management of the cancer with high efficiency. This review focuses on the role of probiotics as alternative prevention and treatment of cancer. In this regard, we discuss the alternative cancer biotherapeutic drugs including live or dead probiotics and their metabolites, such as short chain fatty acids, inhibitory compounds of protein, polysaccharide, nucleic acid and ferrichrome in in vitro, in vivo and clinical studies. We also discuss the effectiveness of these biotherapeutics in prevention and treatment of various types of cancer linked with probiotic bacterial or fungal strains, probiotic dose, and time of exposure. More in vivo mainly clinical trials are necessary to further reveal and approve the significant role of live and dead probiotics as well as their metabolic products in cancer prevention and treatment. Finally, the majority of the positive results provided by probiotic treatments are limited to experimental settings. To minimize side effects associated with probiotics, short and long term effect studies in the direction of methodology standardization are required.

The Microbiome-Estrogen Connection and Breast Cancer Risk

The microbiome is undoubtedly the second genome of the human body and has diverse roles in health and disease. However, translational progress is limited due to the vastness of the microbiome, which accounts for over 3.3 million genes, whose functions are still unclear. Numerous studies in the past decade have demonstrated how microbiome impacts various organ-specific cancers by altering the energy balance of the body, increasing adiposity, synthesizing genotoxins and small signaling molecules, and priming and regulating immune response and metabolism of indigestible dietary components, xenobiotics, and pharmaceuticals. In relation to breast cancer, one of the most prominent roles of the human microbiome is the regulation of steroid hormone metabolism since endogenous estrogens are the most important risk factor in breast cancer development especially in postmenopausal women. Intestinal microbes encode enzymes capable of deconjugating conjugated estrogen metabolites marked for excretion, pushing them back into the enterohepatic circulation in a biologically active form. In addition, the intestinal microbes also break down otherwise indigestible dietary polyphenols to synthesize estrogen-like compounds or estrogen mimics that exhibit varied estrogenic potency. The present account discusses the potential role of gastrointestinal microbiome in breast cancer development by mediating metabolism of steroid hormones and synthesis of biologically active estrogen mimics.

Potential effect of probiotics in the treatment of breast cancer

Breast cancer is one of the most important causes of cancerrelated morbidity and mortality in the world. Probiotics, as functional food, have the potential to act against breast cancer, as evidenced by cell-based and animal model experiments. Probiotic may be useful in prevention or treatment of breast cancer by modulating the gastrointestinal bacteria and the systemic immune system. However, large-scale clinical trials and intensive research are mandatory to confirm the in vitro and in vivo results and exploring the probiotics-related metabolic, immune, and molecular mechanisms in breast cancer. This current review summarizes the available data related to probiotics and their potential role in the treatment of breast cancer.

Diet quality in adolescents with premenstrual syndrome: A cross-sectional study

AIM

Premenstrual syndrome (PMS) is a complex of symptoms that can seriously affect the quality of life in women. It has been suggested that the nutritional status of adult women may influence the presence and/or severity of PMS symptoms. However, little is known about this association in adolescents. The present study aimed to examine the relationship between diet quality and the presence/severity of PMS symptoms in adolescents.

METHODS

A case-control study of 272 female students, aged 13-18 years, was conducted in a high school. PMS was diagnosed and the symptoms were recorded using Premenstrual Syndrome Scale (PMSS)-2006 in 2 consecutive months. Dietary intake was assessed with 24-hour-dietary intake recall method and Healthy Eating Index-2010 (HEI-2010) score was calculated as an indicator of diet quality. Anthropometric measurements, including body weight, height, waist circumference and hip circumference were taken.

RESULTS

PMS was diagnosed in 56.9% of the study sample. The mean HEI-2010 score was significantly lower in the PMS group (47.5 ± 23.95) when compared to the control group (53.5 ± 20.98), P = 0.034. The PMS symptoms, anxiety (P = 0.009), depressive feelings (P = 0.016) and changes in sleeping pattern (P = 0.000) were associated with lower diet quality scores in the PMS group. No significant difference in anthropometric measurements was observed between the groups.

CONCLUSIONS

The present study suggested that adolescents with a high-quality diet might experience depressive feelings, anxiety or changes in sleeping less when compared to those with a low quality diet. Therefore, the causal relationship between diet quality and presence/severity of PMS should be investigated in further studies.

Targeting gut microbiota with dietary components on cancer: Effects and potential mechanisms of action

Cancers are common chronic diseases worldwide and cause severe health burdens. There have been ongoing debates on the role of gut microbiota in the prevention and management of cancers, thus, it is worthwhile to pay high attention to the impacts of gut microbiota on several cancers, such as colon, liver, and breast cancers. In addition, it has been reported that gut microbiota may also affect the efficacy of cancer chemotherapy and immunotherapy. Among all the factors that influence gut microbiota, diet is the most influential and modifiable. The prebiotics, dietary fibers, short-chain fatty acids, and other bioactive compounds are all important dietary components to assist the growth of beneficial microbiota in the gut, which can protect against cancers and promote human health. Their beneficial effects can be due to the fermentation of dietary fibers, the metabolism of phytochemicals, the synthesis of estrogens, and interactions with chemotherapies and immunotherapies. In order to provide updated information of the relationships among dietary components, gut microbiota, and cancer, in this review, we summarize the reciprocal interactions between dietary components and gut microbiota, and highlight the impacts of dietary components on several common cancers by targeting gut microbiota, with the potential mechanisms of actions also intensively discussed. As a result, this review can be very helpful for healthy people as well as cancer patients to prevent or manage cancers via dietary factor-mediated regulation of gut microbiota.

Significance of Leydig Cell Neoplasia in Rats Fed Lactitol or Lactose

Lactitol is a disaccharide sugar alcohol (polyol) which is derived from lactose by catalytic hydrogenation and which may be used as a noncariogenic, reduced calorie sugar substitute in different foods. In the context of the safety evaluation of lactitol, a chronic carcinogenicity/toxicity study was conducted in a Wistar-derived strain of rats. In addition to effects that occur commonly in rats fed high doses of polyols, an increased incidence of Leydig cell tumors was observed in rats fed a diet with 10% lactitol for their lifetime. A comparison group receiving a diet with 20% lactose exhibited the same effect. At the 5% dose level of lactitol, no testicular changes were seen. Although lactitol is not genotoxic in standard in vitro tests and was also not associated with tumor formation in female rats and mice of either sex, it was necessary to assess the relevance of the testicular neoplastic growth for human safety. A comparative evaluation of the spontaneous and chemically induced formation of Leydig cell tumors in rats and humans demonstrates that the spontaneous occurrence is extremely low in humans but rather high in rats. Chemical agents or experimental conditions that in rats are associated with interstitial cell hyperplasia or neoplasia have not been associated with similar effects in humans. This is also true for lactose which, in Western countries, is consumed regularly and in substantial amounts with dairy products. Since lactitol is essentially not hydrolyzed in the small intestine, it gains access to the metabolism only after fermentation by the intestinal flora. It is therefore reasonable to assume that the testicular effects of lactitol and lactose were mediated by changes in the digestive tract such as by the known increase of calcium absorption which occurs in lactitol- and lactose-fed rats but not in humans or by effects of these compounds on the enterohepatic cycling of steroid hormones. Although these mechanisms are not yet elucidated, the available data on Leydig cell tumors indicate that the effects seen in male rats are not relevant to humans. The major lines of evidence supporting the human safety of lactitol and lactose are: (1) the lack of genotoxicity of lactitol, (2) the rat specificity of the testicular effects of lactose and lactitol, (3) the long history of safe consumption of lactose in humans, (4) the insensitivity of the human Leydig cells to agents and conditions that are known to cause neoplastic growth of Leydig cells in rats, (5) the generally very low spontaneous incidence of Leydig cell tumors in the human population, and (6) the absence of any epidemiological evidence establishing a link between nutritional factors and the occurrence of Leydig cell tumors in humans.

The Intestinal Microbiome and Estrogen Receptor-Positive Female Breast Cancer

The huge communities of residential microbes, including bacteria, viruses, Archaea, and Eukaryotes, that colonize humans are increasingly recognized as playing important roles in health and disease. A complex populous ecosystem, the human gastrointestinal (GI) tract harbors up to 10(11) bacterial cells per gram of luminal content, whose collective genome, the gut metagenome, contains a vastly greater number of individual genes than the human genome. In health, the function of the microbiome might be considered to be in dynamic equilibrium with the host, exerting both local and distant effects. However, 'disequilibrium' may contribute to the emergence of disease, including malignancy. In this review, we discuss how the intestinal bacterial microbiome and in particular how an 'estrobolome,' the aggregate of enteric bacterial genes capable of metabolizing estrogens, might affect women's risk of developing postmenopausal estrogen receptor-positive breast cancer. Estrobolome composition is impacted by factors that modulate its functional activity. Exploring variations in the composition and activities of the estrobolome in healthy individuals and in women with estrogen-driven breast cancer may lead to development of microbiome-based biomarkers and future targeted interventions to attenuate cancer risk.

Role of enterohepatic recirculation in drug disposition: cooperation and complications

Enterohepatic recirculation (EHC) concerns many physiological processes and notably affects pharmacokinetic parameters such as plasma half-life and AUC as well as estimates of bioavailability of drugs. Also, EHC plays a detrimental role as the compounds/drugs are allowed to recycle. An in-depth comprehension of this phenomenon and its consequences on the pharmacological effects of affected drugs is important and decisive in the design and development of new candidate drugs. EHC of a compound/drug occurs by biliary excretion and intestinal reabsorption, sometimes with hepatic conjugation and intestinal deconjugation. EHC leads to prolonged elimination half-life of the drugs, altered pharmacokinetics and pharmacodynamics. Study of the EHC of any drug is complicated due to unavailability of the apposite model, sophisticated procedures and ethical concerns. Different in vitro and in vivo methods for studies in experimental animals and humans have been devised, each having its own merits and demerits. Involvement of the different transporters in biliary excretion, intra- and inter-species, pathological and biochemical variabilities obscure the study of the phenomenon. Modeling of drugs undergoing EHC has always been intricate and exigent models have been exploited to interpret the pharmacokinetic profiles of drugs witnessing multiple peaks due to EHC. Here, we critically appraise the mechanisms of bile formation, factors affecting biliary drug elimination, methods to estimate biliary excretion of drugs, EHC, multiple peak phenomenon and its modeling.

Western dietary pattern is related to premenstrual syndrome: a case-control study

Although premenstrual syndrome (PMS) affects a large number of women of reproductive age, the aetiology of this disorder has not yet been fully elucidated. The relationship between food intake and PMS morbidity has been investigated in several studies, but dietary patterns of PMS patients have not been taken into consideration up to now. We examined dietary patterns of 320 nurses with (n 160) and without (n 160) PMS in a case-control study. Food intakes over the past year were determined using semi-quantitative FFQ. Factor analysis was used to identify the main dietary patterns, and logistic regression was used to model the relationship between dietary patterns and PMS morbidity. Three dietary patterns were identified in the analysis: healthy, Western and traditional. After adjustment for age, BMI, menstrual cycles, physical activity and energy intake, participants in the second (OR 2·53; 95 % CI 1·18, 5·43) and third (OR 4·39; 95 % CI 1·97, 9·81) quintiles of the Western dietary pattern were more likely to experience PMS compared with those in the first quintile. The study findings therefore reveal that Western dietary pattern might be associated with PMS morbidity. However, this result should be interpreted with caution as there was no evidence of a dose-response relationship. Future studies are needed to confirm our findings in other populations.

Mediterranean diet and risk of endometrial cancer: a pooled analysis of three Italian case-control studies

BACKGROUND

Some components of the Mediterranean diet have favourable effects on endometrial cancer, and the Mediterranean diet as a whole has been shown to have a beneficial role on various neoplasms.

METHODS

We analysed this issue pooling data from three case-control studies carried out between 1983 and 2006 in various Italian areas and in the Swiss Canton of Vaud. Cases were 1411 women with incident, histologically confirmed endometrial cancer, and controls were 3668 patients in hospital for acute diseases. We measured the adherence to the Mediterranean diet using a Mediterranean Diet Score (MDS), based on the nine dietary components characteristics of this diet, that is, high intake of vegetables, fruits/nuts, cereals, legumes, fish; low intake of dairy products and meat; high monounsaturated to saturated fatty acid ratio; and moderate alcohol intake. We estimated the odds ratios (OR) and the corresponding 95% confidence intervals (CI) for increasing levels of the MDS (varying from 0, no adherence, to 9, maximum adherence) using multiple logistic regression models, adjusted for major confounding factors.

RESULTS

The adjusted OR for a 6-9 components of the MDS (high adherence) compared with 0-3 (low adherence) was 0.43 (95% CI 0.34-0.56). The OR for an increment of one component of MDS diet was 0.84 (95% CI 0.80-0.88). The association was consistent in strata of various covariates, although somewhat stronger in older women, in never oral contraceptive users and in hormone-replacement therapy users.

CONCLUSIONS

Our study provides evidence for a beneficial role of the Mediterranean diet on endometrial cancer risk, suggesting a favourable effect of a combination of foods rich in antioxidants, fibres, phytochemicals, and unsaturated fatty acids.

Whole grain, dietary fiber, and incidence of endometrial cancer in a Danish cohort study

Whole grains and dietary fiber might be inversely associated with endometrial cancer risk through their effects on sex hormone metabolism and body fat. We investigated whether a higher intake of whole grains and dietary fiber was associated with a lower incidence of endometrial cancer in the Diet, Cancer and Health cohort of 29,875 women aged 50-64 years at enrollment in 1993-1997. Information on diet and lifestyle was derived from self-administered questionnaires. The incidence rate ratios and 95% confidence intervals were estimated based on a Cox proportional hazards model. Of the 24,418 women included as cohort members, 217 had a diagnosis of endometrial cancer. No clear associations were found between intake of whole grains or dietary fiber and the incidence of endometrial cancer.

Impact of cabbage pectin-protein complex on microbial β-glucuronidase activity

We previously demonstrated that pectin-protein complex (PPC) isolated from white cabbage adsorbs the β-glucuronidase (βG) enzyme of E. coli. Concurrently, we discovered a significant increase in βG activity in the presence of PPC. The aim of this study is to identify the structural components of PPC that are responsible for βG adsorption and activation. PPC was isolated from white cabbage using a saline solution containing hydrochloric acid (pH 1.5) at 37 °C for 4 h. PPC proteins were precipitated by aqueous 10% (m/v) trichloroacetic acid to yield the pectin-protein fractions PPC1 and PPC2. PPC was digested using 1,4-α-d-galacturonase, yielding the PPC6 fraction. Partial acid hydrolysis of PPC revealed the galacturonan fraction, PPC3, to be the core of the macromolecule. The purified PPC4 and PPC5 fractions were isolated from PPC by ion-exchange chromatography on DEAE-cellulose. βG activity and its adsorption in the PPC fractions were studied in vitro. Crystalline cellulose was used as a control. This study found that the PPC3 fraction (the galacturonan core) does not adsorb βG and does not affect its activity. The adsorption of βG in the PPC samples is inversely proportional to the degree of methyl esterification of its carbohydrate component. The PPC4 and PPC5 fractions adsorb the highest proportion of βG (51.2% and 54%, respectively). The stimulation of βG enzyme activity is directly proportional to the protein content of the PPC sample. The PPC and PPC1 samples have the greatest ability to increase βG activity (57.6% and 52.1%, respectively).

Intake of food groups and idiopathic asthenozoospermia: a case-control study

STUDY QUESTION

Is there any association between the intake of different food groups and the risk of idiopathic asthenozoospermia?

SUMMARY ANSWER

A high intake of processed meat and sweets was positively associated with a higher risk of asthenozoospermia, whereas a high intake of fruits, vegetables, poultry, skim milk and sea foods was associated with a lower risk.

WHAT IS KNOWN ALREADY

A high intake of lipophilic foods like meat products or milk may be negatively associated with semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.

STUDY DESIGN, SIZE, DURATION

A case-control study including 72 asthenozoospermic men and 169 normozoospermic men all from infertile couples who underwent face-to-face private interviews, from January 2011 to December 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Semen was assessed by volume, sperm concentration, motility and morphology. Usual dietary intakes were assessed using a semi-quantitative food frequency questionnaire. Odds ratios (ORs), 95% confidence intervals (CIs) and evaluation of trends were calculated using logistic regression. The first tertile served as the reference category for regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

After adjusting for potential confounders, the risk of asthenozoospermia was significantly higher in the highest tertiles of processed meat (OR: 2.03, 95% CI: 1.70-2.44) and sweets intake (OR: 2.05, 95% CI: 1.09-2.26). Conversely, being in the highest tertile of total fruits and vegetables, the intake of dark green vegetables, skim milk, poultry and sea food intake was associated with a lower risk of asthenozoospermia (P for trend = 0.04, 0.01, 0.02, 0.03 and 0.04, respectively).

LIMITATIONS, REASONS FOR CAUTION

Recall bias, selection bias and measurement bias are inevitable in this kind of study and residual confounding due to omission or imprecise measurement of important covariates remains possible.

WIDER IMPLICATIONS OF THE FINDINGS

Patients with asthenozoospermia should be advised to adhere to a diet rich in fruits, vegetables, poultry, skim milk and sea foods while low in processed meat and sweets.

STUDY FUNDING/COMPETING INTEREST(S)

This study was financially supported by the National Nutrition and Food Technology Research Institute, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Science, Tehran, Iran. No conflict of interests to declare.

Microbiome and malignancy

Current knowledge is insufficient to explain why only a proportion of individuals exposed to environmental carcinogens or carrying a genetic predisposition to cancer develop disease. Clearly, other factors must be important, and one such element that has recently received attention is the human microbiome, the residential microbes including Bacteria, Archaea, Eukaryotes, and viruses that colonize humans. Here, we review principles and paradigms of microbiome-related malignancy, as illustrated by three specific microbial-host interactions. We review the effects of the microbiota on local and adjacent neoplasia, present the estrobolome model of distant effects, and discuss the complex interactions with a latent virus leading to malignancy. These are separate facets of a complex biology interfacing all the microbial species we harbor from birth onward toward early reproductive success and eventual senescence.

Interaction of microbial β-glucuronidase with vegetable pectins

The purpose of this study was to investigate the in vitro effects of vegetable carbohydrates on the activity of microbial β-glucuronidase (βG) and the adsorption of the enzyme on carbohydrates. This study used pectin-protein complexes (PPCs) with molecular weights of 300 kDa isolated under conditions simulating a gastric environment from cabbage (HCl-PPCC and HCl+pepsin-PPCCP) and sweet pepper (PPCP and PPCPP). As a sample for comparison, microcrystalline cellulose was used. The activity of βG from Escherichia coli was determined spectrophotometrically by the formation of the colored product from the breakdown of phenolphthalein-β-D-glucuronide. Adsorption of βG on biopolymers was studied by the retention of the enzyme on the membrane of a concentrator with a pore diameter of 300 kDa and by native PAGE. PPCCP and PPCC were established to increase the activity of βG by 50 and 100%, respectively. Cellulose had a weak effect, whereas pepper PPC had no effect. All studied carbohydrates adsorb on βG. The maximum βG adsorption (15%) was observed with PPCC, whereas PPCCP absorbed 5% of the enzyme. Pepper PPCs and cellulose adsorbed up to 10% of the enzyme. There was a positive correlation between the increase of βG activity in the presence of carbohydrates and enzyme adsorption on the polymers (r=0.80; P<0.01). The activity of the enzyme in the gel after electrophoresis of the PPCC+βG mixture was inversely proportional to the concentration of PPCC in the mixture. A model explaining the effects of cabbage PPCs on the excretion of estrogens is proposed.

Non-invasive methods for estradiol recovery from infant fecal samples

While the activation of the infant hypothalamic-pituitary-gonadal axis and the existence of a postnatal gonadotropin surge were first documented in the early 1970s, study of the longitudinal development of gonadal hormones in infancy, and the potential physiological and behavioral correlates of this development, have been hampered by reliance on infrequent serum sampling. The present study reports the validation of a non-invasive method for repeated assessment of steroid hormones in infant fecal samples. Fecal samples were collected in and excised from cotton diaper liners and extracted using methanol. Extracts were analyzed for estradiol using a diluted assay modification. Method validity was supported by a steroid recovery rate of at least 80%, a sensitivity of 0.35 pg/ml, and inter- and intra-assay coefficients of variations of less than 10 and 20%, respectively. Variation in estradiol concentration was assessed across (1) sample type (scraped vs. cut from diaper liner), (2) time of day (morning vs. afternoon/evening samples), (3) time interval between samples, and (4) time-to-assay (1 day vs. 489 days after collection). Of these characteristics, only the time interval between samples within an individual was significantly associated with estradiol concentration. This is the first report of human infant fecal estradiol levels. The results support fecal recovery as a novel and powerful non-invasive tool for longitudinal studies of human infants, expanding research opportunities for investigating development of sex-specific behaviors in infancy, and the potential effects of endocrine disruptors on development.

Legume intake and the risk of cancer: a multisite case-control study in Uruguay

BACKGROUND

Previous studies have suggested that a high intake of legumes may decrease the risk of stomach and prostate cancer and some other cancers. However, the evidence is still limited. To further explore the association between legume intake and cancer risk we conducted a case-control study of 11 cancer sites in Uruguay between 1996 and 2004, including 3,539 cancer cases and 2,032 hospital controls.

RESULTS

The highest versus the lowest tertile of legume intake was associated with a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.48, 95% CI: 0.34-0.68), esophagus (OR = 0.54, 95% CI: 0.38-0.77), larynx (OR = 0.55, 95% CI: 0.40-0.77), upper aerodigestive tract (OR = 0.50, 95% CI: 0.40-0.63), stomach (OR = 0.69, 95% CI: 0.49-0.97), colorectum (OR = 0.43, 95% CI: 0.32-0.59), kidney (OR = 0.41, 95% CI: 0.24-0.71), and all sites combined (OR = 0.68, 95% CI: 0.59-0.78). No significant association was observed between legume intake and cancers of the lung (OR = 1.03, 95% CI: 0.83-1.27), breast (OR = 0.89, 95% CI: 0.65-1.20), prostate (OR = 0.87, 95% CI: 0.64-1.18) or bladder (OR = 0.82, 95% CI: 0.57-1.17). Similar results were found for both beans and lentils.

CONCLUSION

Higher intake of legumes was associated with a decreased risk of several cancers including those of the upper aerodigestive tract, stomach, colorectum, and kidney, but not lung, breast, prostate or bladder. Further investigations of these associations in prospective cohort studies are warranted.

Association between dietary fiber and endometrial cancer: a dose-response meta-analysis

BACKGROUND

Endometrial cancer is the most common female gynecologic cancer in the United States. Excessive and prolonged exposure of the endometrium to estrogens unopposed by progesterone and a high body mass are well-established risk factors for endometrial cancer. Although dietary fiber has been shown to beneficially reduce estrogen concentrations and prevent obesity, its role in endometrial cancer has received relatively little attention.

OBJECTIVE

The objective was to summarize and quantify the current evidence of a role of dietary fiber consumption in endometrial cancer risk and to identify research gaps in this field.

DESIGN

We conducted a systematic literature review of articles published through February 2007 to summarize the current evidence of a relation between dietary fiber consumption and endometrial cancer risk and to quantify the magnitude of the association by conducting a dose-response meta-analysis.

RESULTS

Ten articles representing 1 case-cohort study and 9 case-control studies that evaluated several aspects of fiber consumption and endometrial cancer risk were identified through searches in various databases. On the basis of 7 case-control studies, the random-effects summary risk estimate was 0.82 (95% CI: 0.75, 0.90) per 5 g/1000 kcal dietary fiber, with no evidence of heterogeneity (I(2): 0%, P for heterogeneity: 0.55). The random-effects summary estimate was 0.71 (95% CI: 0.59, 0.85) for the comparison of the highest with the lowest dietary fiber intake in 8 case-control studies, with little evidence of heterogeneity (I(2): 20.8%, P for heterogeneity: 0.26). In contrast, the only prospective study that evaluated this association did not find an association.

CONCLUSIONS

Although the current evidence, based on data from case-control studies, supports an inverse association between dietary fiber and endometrial cancer, additional population-based studies, particularly cohort studies, are needed before definitive conclusions can be drawn.

A high-saturated fat diet enriched with phytosterol and pectin affects the fatty acid profile in guinea pigs

This paper presents the results of a study whose aim was to test the effects of several doses of pectin and phytosterols on the body weight gain and the FA content in female guinea pigs. The treatments resulted from supplementing with pectin and plant sterol a guinea pig diet (rich in saturated FA), following a 3 x 3 factorial design, with three levels of pectin (0, 3.67 and 6.93%) and three levels of phytosterols (0, 1.37, and 2.45%). Seventy-two female Dunkin Hartley guinea pigs were randomly assigned to the treatment groups (8 animals/group), the duration of the treatment being 4 wk. Pectin dietary intake led to a significant increase in body weight (P < 0.001), food consumption (P = 0.025), and feed efficiency (P < 0.001), but no influence of phytosterols on weight gain or food consumption was detected. We found a significant negative effect of the addition of phytosterols on lauric, myristic, and palmitic acid contents in feces, and a positive effect on their concentration in plasma and liver, but no significant effect on stearic acid content. Apparent FA absorption was assessed by calculating the ratio of FA in feces and diets that the absorption of the different FA could be compared, and the negative effect of phytosterol supplementation on these ratios, especially for lauric and myristic acids, was established.

Dietary lipids and endometrial cancer: the current epidemiologic evidence

BACKGROUND

Because dietary fat has been postulated to affect obesity and estrogen levels, two important risk factors for endometrial cancer, its association with this disease has received some attention. We summarize here the current evidence for several dietary lipids.

METHODS

Searches were conducted to identify peer-reviewed manuscripts up to December 2006. Two cohort studies and nine case-control studies were included in meta-analyses.

RESULTS

Random-effects summary estimates for case-control studies were 1.24 (95% CI: 1.10, 1.41) per 10% kcal from total fat and 1.28 (95% CI: 1.12, 1.47) per 10 g/1,000 kcal of saturated fat. The only cohort study evaluating total fat and saturated fat did not find an association. We estimated a 35% increased risk (95% CI: 0.96, 1.90) per 150 mg/1,000 kcal of cholesterol intake, based on six case-control studies. For animal fat (per 10 g/1,000 kcal) the summary estimates were 0.78 (95% CI: 0.63, 0.96) and 1.34 (95% CI: 1.06, 1.69) for two cohort and four case-control studies, respectively.

CONCLUSIONS

Case-control data suggest an increased risk for total, saturated, and animal fat. However, the limited available cohort data do not support these associations. Additional data, particularly from prospective studies, are needed before conclusions can be drawn.

Dietary Fiber Intake and Endogenous Serum Hormone Levels in Naturally Postmenopausal Mexican American Women: The Multiethnic Cohort Study

This study investigated dietary fiber intake in association with serum estrogen levels in naturally postmenopausal Latina women with a wide range of fiber intake. Estrone (E1), estradiol (E2), and sex-hormone-binding globulin (SHBG) were measured in 242 women. Associations between estrogen levels and intake of dietary fiber, including insoluble and soluble fractions, quantified from a food frequency questionnaire, were examined. The biomarker enterolactone was also measured. After adjustment for age, weight, and other nondietary factors, dietary fiber intake was inversely associated with E1 and E2; there was a 22% and 17% decrease (2Ptrend=0.023 and 0.045) among subjects in the highest quintile of intake compared with the lowest. Fitting dietary fiber together with soluble and insoluble nonstarch polysaccharides (NSP) showed a much greater decrease in E1 and E2 (47% and 41%, respectively) while increased soluble NSP intake showed increases in E1 and E2 (64% and 69%, respectively). Two foods, avocado and grapefruit, showed significant positive associations with E1 (2Ptrend=0.029 and 0.015, respectively). This study suggests that different components of dietary fiber may have very significant different effects on serum estrogen levels. The suggestive findings relating increased estrogen levels to avocado and grapefruit intakes need confirmation.

Nutritional factors in relation to endometrial cancer: a report from a population-based case-control study in Shanghai, China

We evaluated the role of dietary nutrients in the etiology of endometrial cancer in a population-based case-control study of 1,204 newly diagnosed endometrial cancer cases and 1,212 age frequency-matched controls. Information on usual dietary habits was collected during an in-person interview using a validated, quantitative food frequency questionnaire. Logistic regression analysis was conducted to evaluate the association of nutrients with endometrial cancer risk using an energy density method (e.g., nutrient intake/1,000 kilocalories of intake). Higher energy intake was associated with increased risk, which was attributable to animal source energy and a high proportion of energy from protein and fat. Odds ratios comparing highest versus lowest quintiles of intake were elevated for intake of animal protein (Odds ratio (OR) = 2.0, 95% confidential interval: 1.5-2.7) and fat (OR = 1.5, 1.2-2.0), but reduced for plant sources of these nutrients (OR = 0.7, 0.5-0.9 for protein and OR = 0.6, 0.5-0.8 for fat). Further analysis showed that saturated and monounsaturated fat intake was associated with elevated risk, while polyunsaturated fat intake was unrelated to risk. Dietary retinol, beta-carotene, vitamin C, vitamin E, fiber, and vitamin supplements were inversely associated with risk. No significant association was observed for dietary vitamin B1 or vitamin B2. Our findings suggest that associations of dietary macronutrients with endometrial cancer risk may depend on their sources, with intake of animal origin nutrients being related to higher risk and intake of plant origin nutrients related to lower risk. Dietary fiber, retinol, beta-carotene, vitamin C, vitamin E, and vitamin supplementation may decrease the risk of endometrial cancer.

Animal food intake and cooking methods in relation to endometrial cancer risk in Shanghai

We evaluated animal food intake and cooking methods in relation to endometrial cancer risk in a population-based case–control study in Shanghai, China. A validated food frequency questionnaire was used to collect the usual dietary habits of 1204 cases and 1212 controls aged 30–69 years between 1997 and 2003. Statistical analyses were based on an unconditional logistic regression model adjusting for potential confounders. High intake of meat and fish was associated with an increased risk of endometrial cancer, with adjusted odds ratios for the highest vs the lowest quartile groups being 1.7 (95% confidence interval: 1.3–2.2) and 2.4 (1.8–3.1), respectively. The elevated risk was observed for all types of meat and fish intake. Intake of eggs and milk was not related to risk. Cooking methods and doneness levels for meat and fish were not associated with risk, nor did they modify the association with meat and fish consumption. Our study suggests that animal food consumption may play an important role in the aetiology of endometrial cancer, but cooking methods have minimal influence on risk among Chinese women.

Potential Impact of Nutritional Strategy on Noninvasive Measurements of Hormones in Birds

The dietary preferences, gastrointestinal anatomy, digestive physiology, biochemical capabilities, and commensal microflora of a bird are collectively known as its nutritional strategy. Measurement of hormones in droppings requires an appreciation of an animal's nutritional strategy in order to optimize collection protocols, validate techniques, interpret results, and minimize variability and artifacts. Foods of animal origin, nectar, and seeds are highly digestible by relatively simple digestive tracts and result in low rates of feces production. Most frugivorous species also have simple digestive tracts, and they digest the fruit's simple sugars and proteins, but not the fiber in its pulp. Consequently, retention time of food in the digestive tract is short, and their droppings are voluminous. Herbivorous species possess enlarged ceca that house microorganisms that aid in the digestion of fibrous components of their food. Part of the digesta enters the ceca and is subjected to lengthy microbial fermentation. The rest is excluded and quickly passes through the rectum, and is quickly defecated. For measurement of hormones in droppings it appears prudent to collect only rectal feces and to avoid cecal feces. One-third of the avian families are omnivorous and consume a wide variety of foods. Their digestive strategies are highly variable and change with diet, as does the amount and composition of feces and the rate of passage.

Etiology and pathogenesis of uterine leiomyomas: a review

Uterine leiomyomas, or fibroids, represent a major public health problem. It is believed that these tumors develop in the majority of American women and become symptomatic in one-third of these women. They are the most frequent indication for hysterectomy in the United States. Although the initiator or initiators of fibroids are unknown, several predisposing factors have been identified, including age (late reproductive years), African-American ethnicity, nulliparity, and obesity. Nonrandom cytogenetic abnormalities have been found in about 40% of tumors examined. Estrogen and progesterone are recognized as promoters of tumor growth, and the potential role of environmental estrogens has only recently been explored. Growth factors with mitogenic activity, such as transforming growth factor- (subscript)3(/subscript), basic fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I, are elevated in fibroids and may be the effectors of estrogen and progesterone promotion. These data offer clues to the etiology and pathogenesis of this common condition, which we have analyzed and summarized in this review.

Effect of diet and housing on growth, body weight, survival and tumor incidences of B6C3F1 mice in chronic studies

Diet is one of the most important environmental factors influencing growth, body weight, survival, and age-related diseases of rodents in chronic studies. NIH-07 open formula diet was the selected diet for the NTP studies from 1980 to 1994. A new diet designated as NTP-2000 diet is the current diet for mice in the NTP studies beginning in 1994. This report is a summary of results of untreated control groups of B6C3F1 mice fed NTP-2000 or NIH-07 diet from several retrospective 2-year dosed-feed and inhalation studies for differences in growth, body weight, survival, and tumor incidences. The dosed-feed studies were conducted in 3 different facilities located in the United States, and all the inhalation studies were conducted in 1 facility. During dosed-feed studies, male and female mice housed in polycarbonate cages and fed the NTP-2000 diet had lower maximum body weights than those fed NIH-07 diet. However, during inhalation studies, mice housed in wire mesh cages and fed the NTP-2000 diet had higher maximum body weights than the mice fed NIH-07 diet. Survival was higher in groups fed NTP-2000 diet irrespective of sex, housing conditions, or body weight compared to the corresponding groups fed NIH-07 diet. Survival was higher in mice housed in polycarbonate cages irrespective of diet and sex compared to the respective sex and diet groups housed in wire mesh cages. During inhalation studies, survival of male and female mice fed NTP-2000 diet was higher than that of the groups fed NIH-07 diet, although the body weights of NTP-2000 diet groups were higher than those of the groups fed NIH-07 diet. When the NTP-2000 diet was used, male and female mice in dosed-feed studies and male mice in inhalation studies had markedly lower incidences of liver tumors than the corresponding groups fed NIH-07 diet. Significant decreases in the incidences of lung tumors were observed only in the male groups fed NTP-2000 diet during dosed-feed studies. These results suggest that body weight may not be the major contributing factor for mortality and liver tumors and that an interaction between diet and housing conditions appears to affect the growth, survival and tumor incidences of B6C3F1 mice.

Diet and cancer

The large differences in cancer rates among countries, striking changes in these rates among migrating populations, and rapid changes over time within countries indicate that some aspect of lifestyle or environment is largely responsible for the common cancers in Western countries. Dietary fat has been hypothesized to be the key factor because national consumption is correlated with the international differences. However, detailed analyses in large prospective studies have not supported an important role of dietary fat. Instead, positive energy balance, reflected in early age at menarche and weight gain as an adult, is an important determinant of breast and colon cancers, consistent with numerous studies in animals. As a contributor to positive energy balance, and possibly by other mechanisms, physical inactivity has also been shown to be a risk factor for these diseases and in part accounts for the international differences. Although the percentage of calories from fat in the diet does not appear related to risk of colon cancer, greater risks have been seen with higher consumption of red meat, suggesting that factors other than fat per se are important. In many case-control studies, a high consumption of fruits and vegetables has been associated with reduced risks of numerous cancers, but recent prospective studies suggest these associations may have been overstated. Among the factors in fruits and vegetables that have been examined in relation to cancer risk, present data most strongly support a benefit of higher folic acid consumption in reducing risks of colon and breast cancers. These findings have been bolstered by an association between incidence of colon cancer and a polymorphism in the gene for methylenetetrahydrofolate reductase, an enzyme involved in folic acid metabolism. The benefits of folic acid appear strongest among persons who regularly consume alcohol, which itself is associated with risk of these cancers. Numerous other aspects of diet are hypothesized to influence the risks of cancers in Western countries, but for the moment the evidence is unclear.

Potential mechanisms of diet therapy for fibrocystic breast conditions show inadequate evidence of effectiveness

Fibrocystic breast conditions, formerly referred to as fibrocystic breast disease, affect about half of all women and typically present as any combination of breast nodularity, swelling, and pain. We reviewed the literature to evaluate evidence supporting nutrition interventions commonly recommended for fibrocystic breast conditions by health care providers. Randomized, controlled studies of the effectiveness of caffeine restriction fail to support any benefit in fibrocystic breast conditions. Similarly, evidence supporting evening primrose oil, vitamin E, or pyridoxine as treatments for the discomforts of fibrocystic breast conditions is insufficient to draw conclusions about effectiveness. Dietary alterations that influence the intermediate markers for fibrocystic breast conditions include low-fat (15% to 20% energy), high-fiber (30 g/day), and soy isoflavone regimens. However, our findings provide no solid evidence for secondary prevention or treatment of fibrocystic breast conditions through a dietary approach. Health care providers should limit recommendations to proven diet therapies supported by randomized, placebo-controlled trials, given the instability inherent in fibrocystic breast conditions and the near 20% placebo effect associated with intervention. Because excessive estrogen or altered sensitivity to estrogen is the dominant theory of etiology, interventions that may modulate endogenous steroid hormones warrant further investigation as potential treatments for symptomatic fibrocystic breast conditions.

Epidemiologic correlates with menstrual cycle length in middle aged women

While irregular menstruations have been associated with lower cumulative exposure to the ovarian steroids, shorter regular cycles have been postulated to increase the cumulative exposure. Epidemiological correlates with menstrual patterns were analyzed among 4900 premenopausal women aged 45 or younger from the New York University Women's Health Study. The length of regular menstrual cycles increased with increasing age at menarche, body mass index and parity, but decreased with age, nonwhite racial background and current smoking. The likelihood of irregular cycles increased with increasing age, body mass index and number of cigarettes smoked per day. With adjustment for age, body mass index and number of cigarettes smoked per day, the risk of irregular cycles was marginally positively associated with total fat intake.

The metabolic consequences of slow colonic transit

Intestinal transit has a substantial influence on the enterohepatic circulation of bile acids and steroid hormones, on colonic pH, and on short chain fatty acid concentrations in the distal colon. Slow transit is likely to favor disease processes that are related to over-efficient enterohepatic recirculation and to lack of short chain fatty acid in the distal colon. These include gallstones, large bowel cancer, and possibly breast cancer. The best-documented influence of slow colonic transit is on bile acid metabolism. Slowing colonic transit increases deoxycholate and raises cholesterol saturation of bile, making gallstone formation more likely. In this review, we also examine the evidence that slow colonic transit may be important in the etiology of large bowel and breast cancer. There is a lack of data pertaining to the relationship between colonic transit and diseases such as colon and breast cancer. Should slow colonic transit prove to be a significant factor in the etiology of such diseases, then the health of the population might benefit from dietary and lifestyle changes that speed up intestinal transit.

Influence of diet on mammary cancer in transgenic mice bearing an oncogene expressed in mammary tissue

Breast cancer is one of the most common cancers in women. The laboratory rat treated with strong carcinogen is the most commonly used animal model for study of breast cancer. Transgenic mouse lines with homologues of human breast cancer oncogenes have been developed. The transgenic mouse line TG.NK with c-neu, the human breast cancer oncogene homologue of erbB2, was evaluated to determine its suitability for study of intervention strategies to delay/prevent the development of breast cancer. There were no palpable mammary tumor masses up to 22-weeks of age, and almost all mice fed a purified diet developed palpable mammary tumors by 28-weeks of age. Nonpurified diets decreased the incidence and multiplicity, and delayed the development of mammary tumors as compared to a purified diet. Increasing the fiber content of nonpurified diet decreased the tumor incidence further. There is approximately a 19-week interval between weaning and development of palpable mammary masses to evaluate intervention strategies to delay or prevent the development of mammary cancer in the TG.NK mouse model. Fiber from nonpurified cereal ingredients appears to be highly beneficial in delaying the development of mammary cancer in TG.NK mice, and this observation is in agreement with human epidemiological findings. Therefore, the TG.NK transgenic mouse with oncogene c-neu (erbB2), appears to be a useful animal model for evaluation of dietary intervention strategies.

Lower serum oestrogen concentrations associated with faster intestinal transit

Increased fibre intake has been shown to reduce serum oestrogen concentrations. We hypothesized that fibre exerts this effect by decreasing the time available for reabsorption of oestrogens in the colon. We tested this in volunteers by measuring changes in serum oestrogen levels in response to manipulation of intestinal transit times with senna and loperamide, then comparing the results with changes caused by wheat bran. Forty healthy premenopausal volunteers were placed at random into one of three groups. The first group took senna for two menstrual cycles then, after a washout period, took wheat bran, again for two menstrual cycles. The second group did the reverse. The third group took loperamide for two menstrual cycles. At the beginning and end of each intervention a 4-day dietary record was kept and whole-gut transit time was measured; stools were taken for measurement of pH and beta-glucuronidase activity and blood for measurement of oestrone and oestradiol and their non-protein-bound fractions and of oestrone sulphate. Senna and loperamide caused the intended alterations in intestinal transit, whereas on wheat bran supplements there was a trend towards faster transit. Serum oestrone sulphate fell with wheat bran (mean intake 19.8 g day(-1)) and with senna; total- and non-protein-bound oestrone fell with senna. No significant changes in serum oestrogens were seen with loperamide. No significant changes were seen in faecal beta-glucuronidase activity. Stool pH changed only with senna, in which case it fell. In conclusion, speeding up intestinal transit can lower serum oestrogen concentrations.

Fat and fiber intakes in relation to serum estrogen concentration in premenopausal Japanese women

It has been implied that fat and fiber intakes influence breast cancer risk. The effects of these dietary factors may be mediated by hormonal changes. We evaluated the relationships between fat or fiber intake and serum concentration of estradiol (E2) or sex hormone-binding globulin in premenopausal women. In 1994 blood samples were collected from each of 50 premenopausal healthy Japanese women on Days 11 and 22 of the menstrual cycle. Nutrient intakes were assessed by food frequency questionnaire in which the subjects were asked about their diets during one year before the study. Each nutrient intake was categorized into tertile after adjustment for total energy. Linear regression models, including age and cycle length as covariates, were utilized to evaluate the association between the nutrient intakes and the hormone concentrations. A statistically significant trend was observed between increasing fat intake and increasing E2 on Day 11 of the cycle (p = 0.05). The positive trend for increasing sex hormone-binding globulin on Day 22 with fat intake was of borderline significance (p = 0.06). There was a statistically significant inverse trend for E2 on Day 11 of the cycle with fiber intake (p = 0.05). It was suggested that fat as well as fiber intake should affect the hormone status.

Bone density and cyclic ovarian function in trained runners and active controls

This study was conducted to determine whether rigorous exercise training adversely affects ovarian hormone levels and bone health in cyclically menstruating trained runners. Ovarian hormones, bone mineral density (BMD), body composition, 3-d diet records, 3-d estimated energy expenditure, and menstrual histories were evaluated in 10 trained collegiate runners and 10 moderately active controls. The trained runners had lower total body calcium per kg of soft lean tissue measured by DEXA (P = 0.045). Half of the trained runners had experienced stress fractures compared with only one of the moderately active controls. The trained runners' lumbar (L2-L4) BMD (1.178 g.cm-2) was not significantly different from that of the active controls (1.283 g.cm-2) (P = 0.074) but, for all subjects combined, there wasa significant inverse relation between L2-L4 BMD and distance run per week (P = 0.036). Further, adding age, body weight, percent body fat, daily energy intake, and daily calcium intake to a stepwise multiple regression analysis did not significantly improve predictive precision. The trained runners consumed nearly twice the amount of calcium (1089 mg.d-1 vs 641 mg.d-1, respectively; P = 0.036), while intake of other nutrients did not differ significantly between groups. Urinary estrone conjugates (E1C) were lower in the trained runners during the early follicular phase (P = 0.028), while pregnanediol-3-glucuronide (PdG) was not significantly different between groups during the luteal phase (P = 0.213). Thus, it appears that lower estrogen production, especially during the early follicular phase, and not progesterone, is associated with lower whole body calcium per kg of soft lean tissue and, probably, L2-L4 BMD. Results of this study also suggest that regular menstrual cycles do not imply normal ovarian hormone function in young women who are engaged in either recreational or competitive running.

Intake of selected micronutrients and the risk of endometrial carcinoma

BACKGROUND

There is some evidence that dietary habits independent of body mass may influence endometrial carcinoma risk, but the specific aspects of this hypothesis are not yet clear.

METHODS

A case-control study was conducted between 1988 and 1994 in the Swiss Canton of Vaud and Northern Italy including 368 patients with histologically confirmed endometrial carcinoma and 713 controls in hospital for acute, nonneoplastic conditions, unrelated to known or potential risk factors for endometrial carcinoma. Multiple logistic regression was used to estimate the odds rations of carcinoma of the corpus uteri according to quintile of intake of the micronutrients considered, and adjusted for potential confounding factors.

RESULTS

Total energy intake was directly related to endometrial carcinoma risk. Adjustment for energy substantially modified the estimated odds ratios. After allowance for calories, the relative risk of endometrial carcinoma in the highest quintile of intake, compared with the lowest quintile of intake, was 1.2 for retinol, 0.5 for beta-carotene, 0.6 for ascorbic acid, 1.8 for vitamin D, 0.9 for vitamin E, 2.9 for methionine, 0.7 for folate, and 1.5 for calcium. Allowance for other micronutrients significantly associated with endometrial carcinoma did not substantially modify the risks estimated for beta-carotene, while associations with ascorbic acid were weaker and nonsignificant.

CONCLUSIONS

This study suggests that some micronutrients, including beta-carotene, may have a protective effect against endometrial carcinoma.