Association of intakes of fat, dietary fibre, soya isoflavones and alcohol with uterine fibroids in Japanese women

Serum micronutrient concentrations and risk of uterine fibroids

BACKGROUND

Although uterine fibroids are among the most common gynecologic conditions affecting women in the United States, research on uterine fibroids is sparse. This study explored the association between micronutrients and uterine fibroids.

METHODS

We conducted a population-based, cross-sectional analysis of 887 women aged 20-49 who participated in the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Serum micronutrient levels were collected during the health examinations, and information on uterine fibroids was assessed on self-reported questionnaires. Multivariate logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) while controlling for confounders.

RESULTS

A statistically significant dose-response relationship was observed between vitamin A and uterine fibroids, after adjustment for age, race, education, body mass index (BMI), and oral contraceptive (OC) use (middle vs. low: OR 2.43, 95% CI 1.35-4.37; high vs. low: OR 2.66, 95% CI 1.16-6.10, p for trend=0.02). After adjustment, a dose-response relationship also emerged for vitamin C, although these associations were not statistically significant.

CONCLUSIONS

It is possible that certain micronutrients affect uterine fibroid development. If this is confirmed in large prospective studies, clinicians could advise susceptible populations on dietary changes to reduce their risk of uterine fibroids.

The role of soy isoflavones in menopausal health: report of The North American Menopause Society/Wulf H. Utian Translational Science Symposium in Chicago, IL (October 2010)

OBJECTIVES

If and to what extent soy protein, soy isoflavones, and their metabolites, including S(--)-equol, have beneficial effects on women's health is currently unclear. The North American Menopause Society (NAMS)/Utian Translational Science Symposium on Soy and Soy Isoflavones convened October 9-10, 2010, to clarify basic and clinical research findings as they relate to the risk and benefits of soy products for peri- and postmenopausal women.

METHODS

A working group of faculty and panelists composed of clinical and research experts in the fields of women's health and botanicals met during a 2-day translational symposium to cover the latest evidence-based science on isoflavones as they affect menopausal symptoms, breast and endometrial cancer, atherosclerosis, bone loss, and cognition. Full descriptions of the bioavailability and pharmacokinetics of isoflavones were also presented. Subspecialty groups then broke off with the goal of translating the information into a report for general medical practice and identifying further research areas. All faculty and panelists reviewed the final report, which was then approved by the NAMS Board of Trustees.

RESULTS

From the hundreds of studies reviewed in this report, there are mixed results of the effects on midlife women. Soy-based isoflavones are modestly effective in relieving menopausal symptoms; supplements providing higher proportions of genistein or increased in S(--)-equol may provide more benefits. Soy food consumption is associated with lower risk of breast and endometrial cancer in observational studies. The efficacy of isoflavones on bone has not been proven, and the clinical picture of whether soy has cardiovascular benefits is still evolving. Preliminary findings on cognitive benefit from isoflavone therapy support a "critical window" hypothesis wherein younger postmenopausal women derive more than older women.

CONCLUSIONS

Several areas for further research have been identified on soy and midlife women. More clinical studies are needed that compare outcomes among women whose intestinal bacteria have the ability to convert daidzein to equol (equol producers) with those that lack that ability (equol nonproducers) in order to determine if equol producers derive greater benefits from soy supplementation. Larger studies are needed in younger postmenopausal women, and more research is needed to understand the modes of use of soy isoflavone supplements in women. The interrelations of other dietary components on soy isoflavones consumed as a part of diet or by supplement on equol production also require further study, as do potential interactions with prescription and over-the-counter medications. And finally, greater standardization and documentation of clinical trial data of soy are needed.

Associations of body size and reproductive factors with circulating levels of sex hormones and prolactin in premenopausal Japanese women

OBJECTIVE

Body size and reproductive factors are important risk factors of breast cancer. The aim of the present study was to examine the associations of these factors with blood concentrations of sex hormones and prolactin in premenopausal Japanese women.

METHODS

We measured the plasma concentrations of estradiol, estrone, testosterone, dehydroepiandrosterone sulfate (DHEAS), sex hormone-binding globulin (SHBG), follicle-stimulating hormone, luteinizing hormone, and prolactin among 436 women who had regular menstrual cycles less than 40 days long. Information on menstrual and reproductive factors including history of breastfeeding was obtained using a self-administered questionnaire. Height and weight were measured.

RESULTS

After controlling for age and the phase of the menstrual cycle, the body mass index (BMI) was significantly inversely associated with total estradiol, estrone and SHBG and significantly positively associated with total and free testosterone and DHEAS. Nulliparous women had significantly higher levels of total and free testosterone, DHEAS, and prolactin than parous women. Duration of breastfeeding for the first child was significantly inversely associated with free testosterone and prolactin levels.

CONCLUSIONS

The data suggest that an increased risk of premenopausal breast cancer associated with low BMI is partially mediated by an increased total estradiol. Androgens and prolactin may explain the breast cancer protection provided by giving birth and breastfeeding.

Metabolism of ethanol to acetaldehyde by rat uterine horn subcellular fractions

Controversial studies from others suggested that alcohol intake could be associated with some deleterious effects in the uterus. Not all the effects of alcohol drinking on female reproductive organs can be explained in terms of endocrine disturbances. Deleterious effect of alcohol or its metabolites in situ could also play a role. Accordingly, we found a metabolism of alcohol to acetaldehyde in the rat uterine horn tissue cytosolic fraction mediated by xanthine oxidoreductase, requiring a purine cosubstrate and inhibited by allopurinol. This activity was detected by histochemistry in the epithelium and aldehyde dehydrogenase activity was detected in the muscular layer and in the serosa. There was a microsomal process, not requiring NADPH and of enzymatic nature, oxygen-dependent and inhibited by diethyldithiocarbamate, diphenyleneiodonium and partially sensitive to esculetin and nordihydroguaiaretic acid. The presence of metabolic pathways in the uterine horn able to generate acetaldehyde, accompanied by a low capacity to destroy it through aldehyde dehydrogenase, led to acetaldehyde accumulation in the uterus during ethanol exposure. Results suggest that any acetaldehyde produced in situ or arriving to the uterine horn via blood would remain in this organ sufficiently to have the opportunity to react with critical molecules to cause deleterious effects.

The role of soy in vegetarian diets

Soyfoods have long been prized among vegetarians for both their high protein content and versatility. Soybeans differ markedly in macronutrient content from other legumes, being much higher in fat and protein, and lower in carbohydrate. In recent years however, soyfoods and specific soybean constituents, especially isoflavones, have been the subject of an impressive amount of research. Nearly 2,000 soy-related papers are published annually. This research has focused primarily on the benefits that soyfoods may provide independent of their nutrient content. There is particular interest in the role that soyfoods have in reducing risk of heart disease, osteoporosis and certain forms of cancer. However, the estrogen-like effects of isoflavones observed in animal studies have also raised concerns about potential harmful effects of soyfood consumption. This review addresses questions related to soy and chronic disease risk, provides recommendations for optimal intakes, and discusses potential contraindications. As reviewed, the evidence indicates that, with the exception of those individuals allergic to soy protein, soyfoods can play a beneficial role in the diets of vegetarians. Concerns about adverse effects are not supported by the clinical or epidemiologic literature. Based on the soy intake associated with health benefits in the epidemiologic studies and the benefits noted in clinical trials, optimal adult soy intake would appear to be between two and four servings per day.

New directions in the epidemiology of uterine fibroids

Although uterine leiomyomata (fibroids) have been the leading indication for hysterectomy in the United States for decades, the epidemiological data on fibroid prevalence and risk factors are limited. Given the hormonal dependence of fibroids, most earlier studies focused on reproductive or hormonal factors. Recent analyses have extended that focus to other areas. We present previously unpublished data on the association between reproductive tract infections and fibroids that highlight the need for more detailed studies. Our review suggests that metabolic, dietary, stress, and environmental factors may also play a role in fibroid development.

Association of dietary fat, vegetables and antioxidant micronutrients with skin ageing in Japanese women

Daily diet may have implications for skin ageing. However, data on the relationship between diet and the parameters of skin conditions are scarce. The present study aimed to examine the associations of biophysical properties of the skin of women with intakes of fats and antioxidant micronutrients as well as food groups as sources of these nutrients. In a cross-sectional study, we measured the hydration, surface lipids and elasticity of the skin of 716 Japanese women using non-invasive techniques. The extent of facial wrinkles in the crow's-foot area was determined by observation using the Daniell scale. Each subject's usual diet was determined with the use of a validated FFQ. After controlling for covariates including age, smoking status, BMI and lifetime sun exposure, the results showed that higher intakes of total fat, saturated fat and monounsaturated fat were significantly associated with increased skin elasticity. A higher intake of green and yellow vegetables was significantly associated with a decreased Daniell wrinkling score. Intake of saturated fat was significantly inversely associated with the Daniell wrinkling score after additional adjustment for green and yellow vegetable intake. Further studies with more accurate measurement methods are needed to investigate the role of daily diet in skin ageing.

A prospective study of dairy intake and risk of uterine leiomyomata

Rates of uterine leiomyomata are 2-3 times higher among black women than white women. Dietary factors that differ in prevalence between these populations that could contribute to the disparity include dairy intake. During 1997-2007, the authors followed 22,120 premenopausal US Black Women's Health Study participants to assess dairy intake in relation to uterine leiomyomata risk. Because soy may be substituted for dairy, the effect of soy intake was also evaluated. Diet was estimated by using food frequency questionnaires in 1995 and 2001. Incidence rate ratios and 95% confidence intervals were estimated with Cox regression. There were 5,871 incident cases of uterine leiomyomata diagnosed by ultrasound (n = 3,964) or surgery (n = 1,907). Multivariable incidence rate ratios comparing 1, 2, 3, and > or =4 servings/day with <1 serving/day of total dairy were 0.94 (95% confidence interval (CI): 0.88, 1.00), 0.87 (95% CI: 0.78, 0.98), 0.84 (95% CI: 0.70, 1.01), and 0.70 (95% CI: 0.58, 0.86), respectively (P-trend <0.001). Incidence rate ratios comparing the highest (> or =2 servings/day) with the lowest (<1 serving/week) intake categories were 0.81 (95% CI: 0.66, 0.99) for high-fat dairy, 0.80 (95% CI: 0.70, 0.91) for low-fat dairy, and 0.78 (95% CI: 0.68, 0.89) for milk. Soy intake was unrelated to uterine leiomyomata risk. This large prospective study of black women provides the first epidemiologic evidence of reduced uterine leiomyomata risk associated with dairy consumption.