Binding of steroid hormones in vitro by water-insoluble dietary fiber

Effect of dietary fiber on fecal androgens levels: An experimental analysis in brown brocket deer (Mazama gouazoubira)

Non-invasive endocrinology is an important tool for animal conservation, but its success depends on many factors (e.g. adequate hormonal extraction, diet, antibody used in the assay). Dietary fiber is one of the main sources that can lead to erroneous interpretation of the endocrine status provided by EIA analysis. This study aimed to evaluate the dietary fiber effect on the fecal androgen metabolites (FAM) detection, on the daily defecation rate and fecal production, as well as to analyze the gastrointestinal passage and retention time of the experimental diets. Eight brown brocket deer (Mazama gouazoubira) males were randomly assigned to two groups and submitted to both isocaloric and isoproteic experimental diets for 10 days, in a crossover system: low fiber percentage feed (LF, 7% fiber) and high fiber percentage feed (HF, 19% fiber). Such groups were alternated in the middle of this period, with an interval of 10 days between them. In addition, there was a five-day adaptation phase at the beginning of each diet. Fecal collection for FAM measurement was performed during 10 days of treatment, whereas,the defecation rate and fecal production were performed every two hours, for 6 days. The mean FAM level in the HF group was 5038.0 ± 1529.1 ng/g, while for LF, 2178.7 ± 824.9 ng/g (p < 0.05). The mean HF fecal production was 182.6 ± 36.2 g DM/day and 117.5 ± 12.6 g DM/day for LF (p < 0.05). There were no differences in terms of mean defecation rate, passage, and retention times between groups. The results suggest that dietary fiber affects the FAM detection, and this should be taken into consideration before conducting experiments using fecal samples as a source of reproductive hormones profiling.

The Impact of Macronutrient Intake on Sex Steroids During Onset of Puberty

INTRODUCTION

Increased fiber intake has been associated with decreased breast cancer risk, while increased animal protein intake with increased risk. The objective of this study is to examine the relationship of dietary fiber and protein intake to estrogen and sex hormone-binding globulin (SHBG) concentrations at puberty onset.

METHODS

These analyses were conducted using the Cincinnati puberty cohort of the Breast Cancer and the Environment Research Program, with girls followed every 6 months from ages 6 and 7. The analyses included serum measurements at 6-month intervals for estrogen and SHBG concentrations, from 18 months prior to breast stage 2 (onset of puberty). Dietary intake was documented via 24-hour dietary recalls every 3 months. Dietary factors of interest included total energy intake; total and animal protein; total, soluble, and insoluble fiber; and lignan and flavanol intake.

RESULTS

This study included 260 participants who generated 871 serum specimens and 3,000 days of diet intake. In longitudinal models, estradiol was associated inversely with insoluble fiber intake; estrone positively with animal protein intake; SHBG with greater insoluble fiber and lower total protein intake; and ratio of estrone to SHBG, a measure of bioavailable estrogen, positively with animal protein.

CONCLUSIONS

Greater protein intake, especially animal protein, led to greater estrogen concentrations and lower SHBG; greater animal protein and greater caloric intake led to increased bioavailable estrogen. This relationship may have served an evolutionary advantage in the past for greater fertility with adequate high-quality protein; in contemporary women, a modest decrease in animal protein may be beneficial in reducing breast cancer risk.

A Review of Nonpharmacological Strategies in the Treatment of Relative Energy Deficiency in Sport

Relative energy deficiency in sport (RED-S) can result in negative health and performance outcomes in both male and female athletes. The underlying etiology of RED-S is low energy availability (LEA), which occurs when there is insufficient dietary energy intake to meet exercise energy expenditure, corrected for fat-free mass, leaving inadequate energy available to ensure homeostasis and adequate energy turnover (optimize normal bodily functions to positively impact health), but also optimizing recovery, training adaptations, and performance. As such, treatment of RED-S involves increasing energy intake and/or decreasing exercise energy expenditure to address the underlying LEA. Clinically, however, the time burden and methodological errors associated with the quantification of energy intake, exercise energy expenditure, and fat-free mass to assess energy availability in free-living conditions make it difficult for the practitioner to implement in everyday practice. Furthermore, interpretation is complicated by the lack of validated energy availability thresholds, which can result in compromised health and performance outcomes in male and female athletes across various stages of maturation, ethnic races, and different types of sports. This narrative review focuses on pragmatic nonpharmacological strategies in the treatment of RED-S, featuring factors such as low carbohydrate availability, within-day prolonged periods of LEA, insufficient intake of bone-building nutrients, lack of mechanical bone stress, and/or psychogenic stress. This includes the implementation of strategies that address exacerbating factors of LEA, as well as novel treatment methods and underlying mechanisms of action, while highlighting areas of further research.

Impacts of linseed meal and estradiol-17β on cellularity, angiogenic and vasoactive factor mRNA expression, and vascularity of the uterus in ovariectomized ewes

Ilse, B. R., O'Neil, M. R., Lardy, G. P., Reynolds, L. P. and Vonnahme, K. A. 2012. Impacts of linseed meal and estradiol-17β on cellularity, angiogenic and vasoactive factor mRNA expression, and vascularity of the uterus in ovariectomized ewes. Can. J. Anim. Sci. 92: 297–306. The objective of the current study was to determine the estrogenic potential of the phytoestrogen secoisolariciresinol diglycoside (SDG) found in linseed meal (LSM) on uterine cell proliferation, vascularity, and angiogenic factor mRNA expression. Ovariectomized ewes (n=48) were fed a diet containing 12.5% LSM for 0, 1, 7, or 14 d and implanted with estradiol-17β (E2) for 0, 6, or 24 h before tissue collection. There was an interaction of LSM×E2 on uterine mass (grams; P=0.03; percentage change; P<0.003). Uterine mass increased (P≤0.02) after 24 h of E2 exposure on days 1, 7, and 14 of LSM feeding, with the greatest mass occurring in ewes exposed to E2 for 24 h and 1 d LSM feeding. Regardless of days fed LSM, after 24 h of E2 exposure uterine mass was greatest. The greatest percentage increase in uterine mass occurred in ewes exposed to E2 for 24 h and fed 1 d of LSM. Cell proliferation within the uterine luminal epithelium was greatest (P<0.01) with 24 h of E2 exposure compared with 0 h and 6 h. When expressed as the percentage change in uterine cell proliferation, feeding LSM for 14 d negated these effects. Only length of E2 exposure impacted vascularity with capillary number density at 6 h of E2 exposure being greater (P=0.02) than at 24 h. While mRNA expression of several angiogenic factors was influenced by E2, there was a LSM×E2 interaction (P≤0.03) only on vascular endothelial growth factor receptor 2 and fibroblast growth factor receptor 2C. It appears that growth and angiogenesis of E2 sensitive tissues may be influenced by the duration of LSM feeding.

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.

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.

Associations between coronary heart disease, obesity and histological prostate cancer

OBJECTIVE

The present study investigates the possible associations between coronary heart disease and histological prostate carcinoma in autopsy material.

MATERIAL AND METHOD

The material of our study, were 116 men between 55 years and 98 years of age, who died in the period of August 2002-January 2005. The initial segment of the aorta and the prostate glands of all cadavers were removed while the initial 30 mm of the left and right coronary arteries and the peripheral zone of the prostate gland underwent pathologic examination.

RESULTS

Of all subjects examined 71.8% had pathological findings suggesting advanced coronary heart disease. Twenty out of 116 cadavers were found with histological carcinoma in their prostate specimen. Among subjects positive for prostate cancer, 12 had died of cardiovascular diseases, while 16 had macroscopic evidence of advanced coronary artery obstructive disease, a finding that was confirmed on pathologic examination. Although most of the subjects had atheromatous lesions on the coronary arteries, the percentage of men with prostate cancer, which had advanced atheromatosis, was greater when compared to those of subjects without prostate cancer. The relation between the coronary artery obstructive disease severity and the presence of latent prostate cancer was statistically significant (P = 0.02). No statistically significant correlation was obtained between body mass index and the presence of prostate cancer.

CONCLUSIONS

Our results indicate that there could be an association between coronary artery obstructive disease and prostate cancer, however due to the relatively low sample further studies are needed in order to confirm such findings.

Isoflavonas en mujeres menopáusicas

Phytoestrogens are composed derivatives of vegetables. The 2 main classes of interest to human health are lignans and isoflavones. Isoflavones exist in at least 15 different chemical forms and their effect on human health has been investigated to some extent (particularly, genistein and daidzein as high levels of these compounds are present in soybean). Isoflavones have similar structure to oestrogen and have the capacity to exert both oestrogenic and anti oestrogenic effects. They may block the effects of oestrogen in some tissues (e. g., the breast and endometrium), but act like an oestrogen in providing possible protection against bone loss and heart disease. Lignans are much more widespread in plant foods but investigation has been limited due to the complexity of measurement. The increasing interest in the use of the soybean and the phytoestrogens derived from the soybean is due to the results published on experimental animal actions, and in human case-control studies. There are many observational and epidemiologists studies that suggest the potential benefit of isoflavones on the menopause symptoms, the cardiovascular system, the osteoporosis and the estrogen dependent cancers, but many open questions exist. We must be very strict with certain observational studies by the possible influences of collateral factors to the isoflavones (exercise, type of diet, etc.), and attribute the beneficial effects may be due to own treatment.

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.

Isoflavones and postmenopausal women: a critical review

Isoflavonic phytoestrogens, or isoflavones, constitute a class of phytoestrogens that have properties similar to selective estrogen receptor modulators, and have attracted a substantial degree of attention in recent years, particularly as a possible alternative to the conventional hormone replacement therapy regimens used by postmenopausal women. Despite great promise, it is difficult to make many specific recommendations about their use at the current time, in light of the many outstanding questions that hopefully will be answered in the future by focused interventional studies involving humans. Studies to date indicate that the use of isoflavones to address vasomotor symptoms provides at most small benefits beyond a placebo effect, and no benefit for genital atrophy. As for postmenopausal women whose primary concern is cardiovascular disease, the recommendation of the American Heart Association to include soy protein foods as part of an otherwise healthy diet is well justified, and similarly the substitution of supplements containing soy protein for animal protein can also be recommended. The use of purified isoflavone supplements not containing soy protein may have some cardiovascular benefits, but these appear to be less substantial in degree than those provided by soy protein with isoflavones. In particular, more research is needed to assess the effects of isoflavones on osteoporosis, for which no recommendation regarding isoflavones can be made based on the current data. Also, isoflavones should not be taken by postmenopausal women for the specific purpose of decreasing their risk of breast or endometrial cancer, although, at least for those without pre-existing disease or at high risk, it seems quite unlikely that isoflavone use is harmful in this regard.

Dietary fiber, Hispanics, and breast cancer risk?

The cancer rates of immigrant populations in the United States must be taken into account when looking at the importance of diet and culture as it relates to cancer prevention. Unfortunately, some nutrition studies targeted toward nontraditional white populations have not adequately confronted the issue of cultural meaning in efforts to gather dietary data accurate enough to support nutritional analyses, identify marginal diets, or relate risk to dietary patterns. The study presented here resolves many of the culturally specific issues utilizing awareness, attention, and judicious combination of culturally sensitive qualitative and quantitative research techniques. The importance of such a study in an Hispanic population is based on the fact that the age-adjusted rate of breast cancer in countries such as Mexico is among the lowest in the world. In addition, although one of the fastest-growing minority groups in the United States, Hispanic women living in this country have been shown to have the lowest incidence of the mortality rates from this disease across most geographic regions of the United States. Therefore, one might speculate that dietary factors, which have been shown to play a role in breast cancer prevention, may account for this difference. It is well recognized that the traditional Hispanic diet is rich in protective nutrients such as dietary fiber. It is known that through complex mechanisms, dietary fiber works to reduce the amount of estrogens in the body. Research also indicates that it is the level of endogenous estrogen in the body that may influence the onset of breast cancer. In order to better understand how dietary factors may be associated with breast cancer in Hispanic women, it is important that one develop the proper tools to discern any potential differences. Therefore, we developed an approach to obtaining dietary fiber information from a small cohort of 22 Houston-area Hispanic women as a vanguard study for a larger breast cancer prevention trial. Two separate dietary assessment instruments were utilized, a three-day food record and the Southwest Food Frequency Questionnaire. The mean intake of dietary fiber was 16 g/day according to the food record and 21 g/day according to the SWFFQ. Fruits, vegetables, breads, cereals, and beans provided for most of the participants' dietary fiber intake. These results support evidence that the Hispanic population's dietary fiber intake is higher than that for other groups, and this may help explain the lower incidence of breast cancer among some Hispanic populations.

A diet high in wheat fiber decreases the bioavailability of soybean isoflavones in a single meal fed to women

The absorption of some dietary components may be inhibited by dietary fiber. To study the effect of dietary fiber on the bioavailability of Isoflavones, seven healthy women were randomly assigned in a crossover design to a control diet containing 15 g dietary fiber or a wheat fiber-supplemented diet containing 40 g dietary fiber, both fed with a single dose of 0.9 mg isoflavones/kg body weight from tofu or texturized vegetable protein (TVP). The fiber-rich diet produced 55% lower plasma genistein at 24 h after soy dosing (P < 0.05) and reduced total urinary genistein by 20% (P < 0.03). Urinary daidzein was not significantly related to fiber intake. Highly insoluble, dietary wheat fiber reduced the absorption of genistein probably by its bulking effect and hydrophobic binding to this compound. Urinary genistein was greater by 23% after tofu than after TVP consumption (P < 0.02), but the percentage of ingested genistein recovered in urine was not affected by soy product intake. The higher urinary genistein after tofu consumption compared with TVP was apparently due to differences in amount of genistein between these soy foods, not the different forms of genistein present in these two soy food products.

Antioxidants and hormone-mediated health benefits of whole grains

Lignans and phytoestrogens have been associated with protective effect against hormone-related diseases, for example, cancer of the breast and prostate, and potential mechanisms for this effect have been reported. Antioxidants also appear to have some protective effect against diseases associated with reactive free radicals such as coronary heart disease and cancer. Whole grains contain some of these substances particularly the mammalian lignan precursors, vitamin E, other phenolic compounds, Se, and phytic acid. These substances may in part be responsible for the reduced risk of cancer and coronary heart disease associated with intake of high-fiber diets containing whole grains. Because they are more associated with the fiber in the outer layers of the grain, the intake of whole vs. refined grain is emphasized for optimum health benefits.

Diet and breast cancer

It is a general opinion that the Western diet plays a significant role in increasing the risk of breast cancer in the Western World. Recently some likely mechanisms involved in increasing the risk have been disclosed. It has been found that a Western-type diet elevates plasma levels of sex hormones and decreases the sex hormone binding globulin concentration, increasing the availability of these steroids for peripheral tissues. The same diet results in low formation by intestinal bacteria of mammalian lignans and isoflavonoid phyotestrogens from plant precursors. These diphenolic compounds seem to affect hormone metabolism and production and cancer cell growth by many different mechanisms making them strong candidates for a role as cancer protective substances. The sex hormone pattern found in connection with a Western-type diet combined with low lignan and isoflavonoid excretion was found particularly in postmenopausal breast cancer patients and omnivores living in high-risk areas, and to a lesser degree in areas with less risk. However, the pattern observed was not entirely due to diet.

In vitro binding of estrogens by dietary fiber and the in vivo apparent digestibility tested in pigs

Within the framework of experiments related to the association between dietary fiber and breast cancer an in vitro test system was used to study the binding of estrogens to various fibers (e.g. cholestyramin, lignin and cellulose) and fiber sources (e.g. wheat bran, cereals, seeds and legumes). Furthermore, the in vivo apparent digestibility of the different fiber sources was tested using a mobile nylon bag technique in intestine-cannulated pigs. Estradiol-17 beta (E2) bound more strongly to the various fibers than did estrone (E1), estriol or estrone-3-glucuronide. At increasing pH (greater than 7) binding of both E1 and E2 to wheat bran decreased significantly. Cholestyramine and lignin bound almost all estrogens present in the medium. Linseed (91%), oats (83%), barley chaff (88%) and wheat bran (82%) are other excellent binders of E2. Corn, rye and white wheat flour showed lower binding capacity with a relatively low affinity. Cereals with the highest percentage of lignin in the fiber (greater than 3%) were also the fiber sources with the lowest apparent digestibility. Estrogens bound with the highest affinity (relative to bovine serum albumin) to these fiber sources. Together with wheat bran and lignin, oats, linseed and soybean seem to be products with good perspectives for in vivo evaluation of the lowering effect of dietary fiber on estrogen exposure of estrogen-sensitive tissues.

[Dietary fiber. Effect on colon carcinogenesis]

The etiopathogenesis of colon carcinogenesis is supposed to be a two-step process consisting of initiation and promotion. In human nutrition the range of xenobiotics acting possibly as initiators occurs mostly in very low concentrations. Therefore, performing a one-factorial consideration they are not claimed seriously to account for initiation. On the contrary, it can be taken for granted that bile acids exert promoting effects in connection with colon carcinogenesis. All factors influencing the promoting effect of bile acids are able to do so probably due to a decrease of pH and as a result the shift of the two bile acid fractions in favour of the soluble fraction, and/or due to the intensification of shift of bile acid metabolism (7-alpha-dehydroxylase). These processes are indirectly influenced to a large extent by the lipid content of food as a result of cholegenesis induction. The "protective Effect" of dietary fibre in colon carcinogenesis (reduced number of tumour carriers, and/or number of tumors per animal) cannot been interpreted as such. Only a delayed promotion phase could been proven. It can be reached only by plant products (bran, lupin), but not by dietary fibre in general.