Perfluorooctanoate and changes in anthropometric parameters with age in young girls in the Greater Cincinnati and San Francisco Bay Area.

METHODS: We conducted a study of per- and polyfluoroalkyl substance biomarkers, including PFOA, in girls from Greater Cincinnati (CIN, N = 353) and the San Francisco Bay Area (SFBA, N = 351). PFOA was measured in the baseline serum sample collected in 2004-2007 of 704 girls at age 6-8 years. Mixed effects models were used to derive the effect of PFOA on BMI, waist-to-height and waist-to-hip ratios over increasing age in this longitudinal cohort. RESULTS: Median PFOA serum concentrations were 7.3 (CIN) and 5.8 (SFBA) ng/mL, above the U.S. population median for children 12-19 years in 2005-2006 (3.8 ng/mL). Log-transformed serum PFOA had a strong inverse association with BMIz in the CIN girls (p = 0.0002) and the combined two-site data (p = 0.0008); the joint inverse effect of PFOA and Age*PFOA weakened at age at 10-11 years. However, in the SFBA group alone, the relationship was not significant (p = 0.1641) with no evidence of changing effect with age. The effect of PFOA on waist:height ratio was similar to BMIz at both sites, but we did not find a significant effect of PFOA on waist:hip ratio in either the CIN or SFBA girls. CONCLUSIONS: PFOA is associated with decreased BMI and waist:height ratio in young girls, but the strength of the relationship decreases with age. Site heterogeneity may be due to greater early life exposure in Cincinnati. DISCLAIMER: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. Use of trade names is for identification only and does not imply endorsement by the CDC, the Public Health Service, or the US Department of Health and Human Services.

Phthalate exposure and pubertal development in a longitudinal study of US girls.

STUDY QUESTION: Does phthalate exposure during early childhood alter the timing of pubertal development in girls? SUMMARY ANSWER: Urinary concentrations of high-molecular weight phthalate (high-MWP) metabolites are associated with later pubarche. WHAT IS KNOWN ALREADY: Phthalates are anti-androgenic environmental agents known to alter early development, with possible effects on pubertal onset. STUDY DESIGN, SIZE, AND DURATION: This multi-ethnic study included 1239 girls from New York City, greater Cincinnati, and the San Francisco Bay Area who were 6-8 years old at enrollment (2004-2007) and who were followed until 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS Phthalate metabolites were measured in urine collected at enrollment from 1170 girls; concentrations ranged from <1 to >10,000 µg/l. Breast and pubic hair stages and body size were assessed one to two times annually to determine the age at transition from stage 1 to 2 for breast and pubic hair development. Associations between exposures and pubertal ages were estimated using Cox proportional hazard ratios (HR) with 95% confidence intervals (CI) and survival analyses. Associations were examined with respect to age-specific body mass-index percentile, one of the strongest predictors of pubertal onset. MAIN RESULTS AND THE ROLE OF CHANCE: Urinary concentrations of high-MWP including di(2-ethylhexyl) phthalate (ΣDEHP) metabolites were associated with later pubic hair development during 7 years of observation. The relationship was linear and was stronger among normal-weight girls. Among normal-weight girls, age at pubic hair stage 2 (PH2) was 9.5 months older for girls in the fifth compared with the first quintile of urinary ΣDEHP (medians: 510 and 59 µg/g creatinine, respectively; adjusted HR 0.70, CI 0.53-0.93, P-trend 0.005. Age at first breast development was older for fifth quintile of mono-benzyl phthalate versus first (HR 0.83, CI 0.68-1.02; P-trend 0.018). No associations were observed between low-molecular weight phthalate urinary metabolite concentrations and age at pubertal transition in adjusted analyses. LIMITATIONS, REASONS FOR CAUTION: While there is evidence that phthalate exposures are fairly consistent over time, the exposure measure in this study may not reflect an earlier, more susceptible window of exposure. We investigated alternative explanations that might arise from exposure misclassification or confounding. WIDER IMPLICATIONS OF THE FINDINGS: Phthalates are widespread, hormonally active pollutants that may alter pubertal timing. Whether exposures delay or accelerate pubertal development may depend on age at exposure as well as other factors such as obesity and exposures earlier in life. Whether exposures act independently or as part of real life mixtures may also change their effects on maturation from birth through childhood. STUDY FUNDING/COMPETING INTEREST(S): This project was supported by the US National Institutes of Health, Environmental Protection Agency, New York State Empire Clinical Research Investigator Program and the Avon Foundation. L.H.K. is employed by Kaiser Permanente. The remaining authors declare they have no actual or potential competing financial interests.

Association of childhood and adolescent anthropometric factors, physical activity, and diet with adult mammographic breast density.

Early-life exposures may influence the development of breast cancer. The authors examined the association of childhood and adolescent anthropometric factors, physical activity levels, and diet with adult mammographic breast density, a strong risk factor for breast cancer. Women in the Minnesota Breast Cancer Family Study cohort who had undergone mammograms but had not had breast cancer (n=1,893) formed the sample. Information on adolescent exposures, including relative height, weight, and physical activity at ages 7, 12, and 18 years and diet at age 12-13 years, was self-reported during two follow-up studies (1990-2003). Mammographic percent density was estimated using a computer-assisted thresholding program. Statistical analyses were performed using linear mixed-effects models with two-sided tests. Positive associations with height at ages 7 (p<0.001), 12 (p<0.001), and 18 (p<0.001) years and percent density were evident overall and within menopausal status categories. The minimum difference in percent density between the tallest and shortest girls was 3 percent, with a maximum of 7 percent. Weight at age 12 years (p=0.005) and adiposity at age 12 years (p=0.005) were both inversely associated with adult percent density. Adolescent physical activity and diet were unrelated to percent density. These results suggest that adolescent height, a known risk factor for breast cancer, is also associated with mammographic percent density.

Recall of diet during a past pregnancy.

The authors conducted a study of women's ability to recall diet during a past pregnancy. For a prospective study, women completed self-administered food frequency questionnaires (FFQs) before and during pregnancy (1989-1992). These women, mostly White and well-educated, were contacted 3-7 years later (1996-1997) for a retrospective dietary assessment performed by either telephone interview (n = 154) or self-administered FFQ (n = 115). Energy-adjusted Pearson correlations ranged from 0.10 to 0.49 for the telephone interview group and from 0.02 to 0.67 for the self-administered questionnaire group. When participants' intakes were ranked, quintile agreement (within one quintile) between original diet and recalled diet ranged from 60% to 69% in the telephone interview group and from 69% to 79% in the self-administered questionnaire group. Correlations and percentages of agreement were higher among women who used the same questionnaire for both dietary assessments than among those who used different questionnaires. These results suggest that diet during pregnancy is recalled with similar accuracy as or perhaps slightly lower accuracy than adult diet generally. This may reflect, in part, the influence of current (nonpregnancy) diet on recall of past (pregnancy) diet. While the results of this study may not be generalizable to those obtained from other populations, to the authors' knowledge it is the first study of recall of diet during pregnancy.

The macrobiotic diet in cancer.

Macrobiotics is one of the most popular alternative or complementary comprehensive lifestyle approaches to cancer. The centerpiece of macrobiotics is a predominantly vegetarian, whole-foods diet that has gained popularity because of remarkable case reports of individuals who attributed recoveries from cancers with poor prognoses to macrobiotics and the substantial evidence that the many dietary factors recommended by macrobiotics are associated with decreased cancer risk. Women consuming macrobiotic diets have modestly lower circulating estrogen levels, suggesting a lower risk of breast cancer. This may be due in part to the high phytoestrogen content of the macrobiotic diet. As with most aspects of diet in cancer therapy, there has been limited research evaluating the effectiveness of the macrobiotic diet in alleviating suffering or prolonging survival of cancer patients. The few studies have compared the experience of cancer patients who tried macrobiotics with expected survival rates or assembled series of cases that may justify more rigorous research. On the basis of available evidence and its similarity to dietary recommendations for chronic disease prevention, the macrobiotic diet probably carries a reduced cancer risk. However, at present, the empirical scientific basis for or against recommendations for use of macrobiotics for cancer therapy is limited. Any such recommendations are likely to reflect biases of the recommender. Because of its popularity and the compelling evidence that dietary factors are important in cancer etiology and survival, further research to clarify whether the macrobiotic diet or similar dietary patterns are effective in cancer prevention and treatment is warranted.

Population-based case-control study of soyfood intake and breast cancer risk in Shanghai.

We evaluated the association of soyfood intake and breast cancer risk in a population-based case-control study among Chinese women in Shanghai. Included in the study were 1459 cases and 1556 age-matched controls, with respective response rates of 91.1% and 90.3%. Usual soyfood intake was assessed using a food frequency questionnaire (FFQ). Separate analyses were performed for all subjects and for the subset who reported no recent change in soyfood intake. The intake levels of soyfoods among women in Shanghai are high, with 96.6% women reporting soyfood consumption at least once a week. A statistically non-significant reduced risk (odds ratio (OR) = 0.78 95% CI = 0.52-1.16) of breast cancer was observed among those who reported eating soyfood at least once a week. Compared to those in the lowest decile intake group, women in the highest decile intake group had a 30% reduced risk of breast cancer (OR = 0.66, 95% CI = 0.46-0.95), but no monotonic dose-response relation was observed (P for trend, 0.28). Stratified analyses showed that the inverse association was restricted primarily among women who had a high body mass index (BMI), with an adjusted OR of 0.30 (95% CI = 0.10-0.94) observed for the highest intake group. The reduction in risk was stronger for breast cancer positive for both oestrogen receptor (ER) and progesterone receptor (PR) (OR = 0.44, 95% CI = 0.25-0.78) than those with other ER/PR status. More pronounced inverse associations were observed in analyses among those who reported no recent change in soyfood intake than those conducted in all subjects. A dose-response relation between soyfood intake and breast cancer risk was observed in this subset of women (P for trend, 0.02), with an OR of 0.46 (95%CI = 0.28-0.75) for those in the highest decile intake group. No clear monotonic dose-response relation was found between soyfood intake and breast cancer risk among regular soy eaters, but nevertheless the results suggest that regular soyfood consumption may reduce the risk of breast cancer, particularly for those positive for ER and PR; the effect may be modified by body mass index.

Dietary fat and incidence of type 2 diabetes in older Iowa women.

OBJECTIVE: To examine the associations between reported intakes of dietary fat and incident type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied the relation between dietary fatty acids and diabetes in a prospective cohort study of 35,988 older women who initially did not have diabetes. Diet was assessed with a food frequency questionnaire at baseline, and 1,890 incident cases of diabetes occurred during 11 years of follow-up. RESULTS: After adjusting for age, smoking, alcohol consumption, BMI, waist-to-hip ratio, physical activity, demographic factors, and dietary magnesium and cereal fiber, diabetes incidence was negatively associated with dietary polyunsaturated fatty acids, vegetable fat, and trans fatty acids and positively associated with omega-3 fatty acids, cholesterol, and the Keys score. After simultaneous adjustment for other dietary fat, only vegetable fat remained clearly related to diabetes risk. Relative risks across quintiles of vegetable fat intake were 1.00, 0.90, 0.87, 0.84, and 0.82 (P = 0.02). Diabetes risk was also inversely related to substituting polyunsaturated fatty acids for saturated fatty acids and positively correlated to the Keys dietary score. CONCLUSIONS: These data support an inverse relation between incident type 2 diabetes and vegetable fat and substituting polyunsaturated fatty acids for saturated fatty acids and cholesterol.

Dietary folate intake, alcohol, and risk of breast cancer in a prospective study of postmenopausal women.

Low B-vitamin intake may increase risk of breast cancer through decreased DNA repair capacity. Alcohol intake increases risk for breast cancer, with evidence from prospective studies of an interaction between alcohol and folate. We explored dietary intake of folate and other B vitamins with risk of breast cancer in a cohort study of 34,387 postmenopausal women. To measure diet, we mailed a food frequency questionnaire; we estimated nutrient intakes and categorized them into four levels: <10th, 11th-30th, 31st-50th, and >50th percentiles. Through 12 years of follow-up, we identified 1,586 cases of breast cancer in the cohort at risk. We estimated relative risks (RRs) and 95% confidence intervals (CIs) through Cox regression models adjusted for age, energy, and other risk factors. Women in the lowest 10th percentile of folate intake from diet alone were at modestly increased risk of breast cancer relative to those above the 50th percentile: RR = 1.21 (95% CI = 0.91--1.61). We examined the joint association of folate intake and alcohol use on risk of breast cancer, with the reference group defined as women with high folate (>50th percentile) and no alcohol use. The RRs of breast cancer associated with low dietary folate intake were 1.08 (95% CI = 0.78--1.49) among nondrinkers, 1.33 (95% CI = 0.86--2.05) among drinkers of < or = 4 gm per day, and 1.59 (95% CI = 1.05--2.41) among drinkers of > 4 gm per day. These results suggest that the risks of postmenopausal breast cancer may be increased among women with low intakes of folate if they consume alcohol-containing beverages.

Diabetes and endometrial cancer in the Iowa women's health study.

Diabetes has been associated with increased risk of endometrial cancer in some epidemiological studies. Body mass index (BMI) and other measures of obesity have been associated positively with both diabetes and endometrial cancer. It is not clear whether or not the association of diabetes with endometrial cancer is explained entirely by obesity. Thus, we sought to test the hypothesis that diabetes is not associated with endometrial cancer independent of obesity. We examined the association between self-reported diabetes (onset at >30 years of age) and incident endometrial cancer in a prospective cohort study of 24,664 postmenopausal women in Iowa. Over 12 years of follow-up, 346 cases occurred among the cohort at risk. Data were analyzed using proportional hazards regression models. Diabetes was analyzed as reported at baseline and as a time-dependent variable using information obtained during follow-up. After adjustment for BMI, waist:hip ratio, and other covariates, the relative risk (RR) for women with diabetes versus women without diabetes was 1.43 [95% confidence interval (CI), 0.98-2.1]. The diabetes association was confined to women in the upper two BMI quintiles (RR, 1.47; 95% CI, 0.98-2.20), but a formal test of interaction was not statistically significant. Analyses that included diabetes ascertained at baseline and at follow-up gave similar results; the diabetes-associated RR in the higher BMI strata was 1.64 (95% CI, 1.16-2.31). We conclude that after adjustment for other risk factors, diabetes is associated with a modestly increased risk for endometrial cancer among women in this cohort.

Types of dietary fat and breast cancer: a pooled analysis of cohort studies.

Recently, there has been interest in whether intakes of specific types of fat are associated with breast cancer risk independently of other types of fat, but results have been inconsistent. We identified 8 prospective studies that met predefined criteria and analyzed their primary data using a standardized approach. Holding total energy intake constant, we calculated relative risks for increments of 5% of energy for each type of fat compared with an equivalent amount of energy from carbohydrates or from other types of fat. We combined study-specific relative risks using a random effects model. In the pooled database, 7,329 incident invasive breast cancer cases occurred among 351,821 women. The pooled relative risks (95% confidence intervals [CI]) for an increment of 5% of energy were 1.09 (1.00-1.19) for saturated, 0.93 (0.84-1.03) for monounsaturated and 1.05 (0.96-1.16) for polyunsaturated fat compared with equivalent energy intake from carbohydrates. For a 5% of energy increment, the relative risks were 1.18 (95% CI 0.99-1.42) for substituting saturated for monounsaturated fat, 0.98 (95% CI 0.85-1.12) for substituting saturated for polyunsaturated fat and 0.87 (95% CI 0.73-1.02) for substituting monounsaturated for polyunsaturated fat. No associations were observed for animal or vegetable fat intakes. These associations were not modified by menopausal status. These data are suggestive of only a weak positive association with substitution of saturated fat for carbohydrate consumption; none of the other types of fat examined was significantly associated with breast cancer risk relative to an equivalent reduction in carbohydrate consumption.

Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women.

Many experimental but few epidemiological studies have suggested that soyfoods and their constituents have cancer-inhibitory effects on breast cancer. No epidemiological study has evaluated the association of adolescent soyfood intake with the risk of breast cancer. To evaluate the effect of soyfood intake during adolescence, one of the periods that breast tissue is most sensitive to environmental stimuli, on subsequent risk of breast cancer, we analyzed data from a population-based case-control of 1459 breast cancer cases and 1556 age-matched controls (respective response rates were 91.1% and 90.3%). Information on dietary intake from ages 13-15 years was obtained by interview from all study participants and, in addition, from mothers of subjects less than 45 years of age (296 cases and 359 controls). Odds ratios (ORs) and 95% confidence intervals (CIs) derived from unconditional logistic models were used to measure soyfood intake and breast cancer risk. After adjustment for a variety of other risk factors, adolescent soyfood intake was inversely associated with risk, with ORs of 1.0 (reference), 0.75 (95% CI, 0.60-0.93), 0.69 (95% CI, 0.55-0.87), 0.69 (95% CI, 0.55-0.86), and 0.51 (95% CI, 0.40-0.65), respectively, for the lowest to highest quintiles of total soyfood intake (trend test, P < 0.001). The inverse association was observed for each of the soyfoods examined and existed for both pre- and postmenopausal women. Adolescent soyfood intakes reported by participants' mothers were also inversely associated with breast cancer risk (P for trend < 0.001), with an OR of 0.35 (95% CI, 0.21-0.60) for women in the highest soyfood intake group. Adjustment for rice and wheat products, the major energy source in the study population, and usual adult soyfood intake did not change the soyfood associations. Our study suggests that high soy intake during adolescence may reduce the risk of breast cancer in later life.

Frequent nut intake and risk of death from coronary heart disease and all causes in postmenopausal women: the Iowa Women's Health Study.

BACKGROUND AND AIM: Recent epidemiological studies suggest that there is an inverse association between the frequent consumption of nuts and the risk of coronary heart disease (CHD), and clinical investigations suggest that diets high in nuts may reduce serum cholesterol levels. This study assessed whether the risk of death due to CHD and all causes is reduced in postmenopausal women who frequently consume nuts. METHODS AND RESULTS: In 1986, 34,111 postmenopausal women with no known cardiovascular disease reported the frequency of their consumption of nuts and other foods, as well as other CHD risk factors. During approximately 12 years of follow-up, 3726 women died, 657 from CHD. After adjustment for multiple risk factors for CHD and dietary variables, there was an inverse but not statistically significant association between frequent nut consumption (two or more 28.5 g servings per week compared with less than one serving per month) and death from CHD (relative risk 0.81; 95% confidence interval: 0.60-1.11). There was also a weak inverse association between frequent nut intake and all-cause mortality (relative risk 0.88; 95% confidence interval: 0.77-0.99, p for trend = 0.047). CONCLUSIONS: Frequent nut consumption may offer postmenopausal women modest protection against the risk of death from all causes and CHD.

Association of fractures with caffeine and alcohol in postmenopausal women: the Iowa Women's Health Study.

OBJECTIVE: To assess whether alcoholic and caffeinated beverages are associated with risk of fractures in women. SETTING: Population-based sample surveyed by post. SUBJECTS: A total of 34 703 postmenopausal Iowan women aged 55-69 years were surveyed. DESIGN: A cohort of women reported alcoholic and caffeinated beverage intake and were followed for 6.5 years for fracture occurrence. Relative risks (RR) and 95% confidence intervals (CI) were computed using Cox proportional hazards regression. Covariates included age, tobacco use, physical activity, body mass index (BMI), waist to hip ratio (WHR), oestrogen use and calcium intake. RESULTS: At least one fracture was reported by 4378 women (389 upper arm, 288 forearm, 1128 wrist, 275 hip, 416 vertebral and 2920 other fractures). The adjusted RR for highest versus lowest caffeine intake quintiles was 1.09 (95% CI 0.99-1.21) for combined fracture sites. Wrist fractures were associated positively (RR for extreme quintiles 1.37, 95% CI 1.11-1.69) and upper arm fractures were negatively associated (RR 0.67, 95% CI 0.48-0.94) with caffeine intake. The age-adjusted RR of total fractures for highest versus lowest frequency of beer usage was 1.55 (95% CI 1.25-1.92) and for liquor was 1.25 (95% CI 1.03-1.54). No other association was found between any specific fracture site and alcohol intake. CONCLUSIONS: We found a modest increase in fracture risk associated with highest caffeine intake, varying by site. Alcohol intake was low, but it also showed a weak positive association with fracture risk.

Intake of antioxidant vitamins and risk of death from stroke in postmenopausal women.

BACKGROUND: Antioxidant vitamins may play a role in the prevention of stroke because they scavenge free radicals and prevent LDL oxidation. Epidemiologic studies that have examined this relation produced conflicting results. OBJECTIVE: We examined the association between antioxidant vitamin intakes and death from stroke. DESIGN: This was a prospective cohort study of 34492 postmenopausal women. RESULTS: During follow-up, 215 deaths from stroke were documented. Total vitamin A, carotenoid, and vitamin E intakes were not associated with death from stroke after multivariate adjustment. Relative risks (RRs) and 95% CIs of the highest compared with the lowest category were 0.79 (0.45, 1.38; P for trend = 0.33) for vitamin A, 0.80 (0.45, 1.40; P for trend = 0.40) for carotenoids, and 0.91 (0.55, 1.52; P for trend = 0.86) for vitamin E. The test for trend for total vitamin C intake was significant, although the association appeared somewhat U-shaped, not monotonic. An inverse association was seen between death from stroke and vitamin E intake from food. RRs (and 95% CIs) of death from stroke from the lowest to highest intake categories were 1.0, 0.80 (0.51, 1.26), 0.93 (0.58, 1. 49), 0.67 (0.39, 1.14), 0.40 (0.20, 0.80); P for trend = 0.008. The results suggest inverse associations between death from stroke and intakes of the most concentrated vitamin E food sources consumed by this cohort: mayonnaise, nuts, and margarine. CONCLUSIONS: Our results suggest a protective effect of vitamin E from foods on death from stroke but do not support a protective role for supplemental vitamin E or other antioxidant vitamins. However, given the number of deaths from stroke in the present cohort, a small-to-moderate association could not be ruled out.

Associations of general and abdominal obesity with multiple health outcomes in older women: the Iowa Women's Health Study.

BACKGROUND: Recent clinical guidelines on the health risks of obesity use body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) and waist circumference, but the waist-hip ratio may provide independent information. METHODS: To assess the joint and relative associations of BMI, waist circumference, and waist-hip ratio with multiple disease end points, we conducted a prospective cohort study of 31,702 Iowa women, aged 55 to 69 years and free of cancer, heart disease, and diabetes, assembled by random sampling and mail survey in 1986. Study end points were total and cause-specific mortality and incidence of site-specific cancers and self-reported diabetes, hypertension, and hip fracture over 11 to 12 years. RESULTS: The waist-hip ratio was the best anthropometric predictor of total mortality, with the multivariable-adjusted relative risk for quintile 5 vs 1 of 1.2 (95% confidence interval, 1.1-1.4), compared with 0.91 (95% confidence interval, 0.8-1.0) for BMI and 1.1 (95% confidence interval, 1.0-1. 3) for waist circumference. The waist-hip ratio was also associated positively with mortality from coronary heart disease, other cardiovascular diseases, cancer, and other causes. The waist-hip ratio was associated less consistently than BMI or waist circumference with cancer incidence. All anthropometric indexes were associated with incidence of diabetes and hypertension. For example, women simultaneously in the highest quintiles of BMI and waist-hip ratio had a relative risk of diabetes of 29 (95% confidence interval, 18-46) vs. women in the lowest combined quintiles. CONCLUSION: The waist-hip ratio offers additional prognostic information beyond BMI and waist circumference.

Association of menstrual and reproductive factors with breast cancer risk: results from the Shanghai Breast Cancer Study.

The incidence of breast cancer among women in Shanghai, a traditionally low-risk population, has increased substantially over the past 20 years. To evaluate the association of menstrual and reproductive factors with breast cancer risk and the influence of these factors on the temporal trend of breast cancer incidence, we analyzed data from the Shanghai Breast Cancer Study, a population-based case-control study of breast cancer recently completed among Chinese women in urban Shanghai. In-person interviews were completed for 1,459 women newly diagnosed with breast cancer between ages 25 and 64 and for 1,556 controls frequency-matched to cases by age. Unconditional logistic regression was employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) related to menstrual and reproductive factors. Earlier menarcheal age, nulliparity, and later age at first live birth were associated with increased risk of breast cancer among both pre- and post-menopausal women, while never having breast-fed and later age at menopause were associated with elevated risk only among post-menopausal women. Among controls, 32% of younger women (40 years) reported starting menarche at age of 13 or younger, and this factor contributed to 44% of cases diagnosed among younger women and 26% to 28% of cases in older women. Older age at first live birth or at menopause explained a considerable portion of cases diagnosed in older, but not younger, women. Our study suggests that the changes in menstrual and reproductive patterns among women in Shanghai have contributed to the recent increase in breast cancer incidence, particularly among younger women.

Fiber from whole grains, but not refined grains, is inversely associated with all-cause mortality in older women: the Iowa women's health study.

BACKGROUND: Inconsistencies in epidemiologic findings relating grain fiber to chronic disease may be explained by differentiating nutrient-rich fiber derived from whole grain vs. nutrient-poor fiber derived from refined grain. OBJECTIVE: Given that phytochemicals are most varied and abundant in the outer layers of grains, we tested the hypothesis that whole grain fiber consumption is associated with a reduced mortality risk in comparison to a similar amount of refined grain fiber. DESIGN: 11,040 postmenopausal women enrolled in the Iowa Women's Health Study, matched on total grain fiber intake, but differing in the proportion of fiber consumed from whole vs. refined grain, were followed from baseline in 1986 through 31 December, 1997, during which time 1,341 deaths occurred in 124,823 observed woman-years. RESULTS: After multivariate adjustment in proportional hazards regression, women who consumed on average 1.9 g refined grain fiber/2,000 kcal and 4.7 g whole grain fiber/2,000 kcal had a 17% lower mortality rate (RR=0.83, 95% CI=0.73-0.94) than women who consumed predominantly refined grain fiber: 4.5 g/2,000 kcal, but only 1.3 g whole grain fiber/2,000 kcal. CONCLUSION: Inferences from studies that have reported associations between grain fiber intake and morbidity or mortality may be limited by not differentiating fiber sources. Future studies should distinguish fiber from whole vs. refined grains. Public health policy should differentiate whole grains from refined, and recommend increased consumption of the former.

Physical activity and incidence of postmenopausal breast cancer.

Whether physical activity reduces the risk of postmenopausal breast cancer is uncertain; few studies have addressed this issue. We examined the association of leisure physical activity with breast cancer incidence among 37,105 postmenopausal participants in the Iowa Women's Health Study. Women reporting the highest level of physical activity at baseline compared with women with the lowest level of activity had an age-adjusted relative risk of breast cancer of 0.92 (95% confidence interval = 0.80-1.05). Women reporting any regular leisure-time physical activity had a relative risk of 0.97 (95% confidence interval = 0.87-1.08) compared with those reporting no such regular physical activity. Adjustment for potential confounders did not appreciably alter the findings. There is little evidence from this study that physical activity later in life is associated to any appreciable extent with breast cancer incidence.

Carbohydrates, dietary fiber, and incident type 2 diabetes in older women.

BACKGROUND: Dietary carbohydrates may influence the development of type 2 (non-insulin-dependent) diabetes, for example, through effects on blood glucose and insulin concentrations. OBJECTIVE: We examined the relations of baseline intake of carbohydrates, dietary fiber, dietary magnesium, and carbohydrate-rich foods and the glycemic index with incidence of diabetes. DESIGN: This was a prospective cohort study of 35988 older Iowa women initially free of diabetes. During 6 y of follow-up, 1141 incident cases of diabetes were reported. RESULTS: Total grain, whole-grain, total dietary fiber, cereal fiber, and dietary magnesium intakes showed strong inverse associations with incidence of diabetes after adjustment for potential nondietary confounding variables. Multivariate-adjusted relative risks of diabetes were 1.0, 0.99, 0.98, 0.92, and 0.79 (P for trend: 0.0089) across quintiles of whole-grain intake; 1.0, 1.09, 1.00, 0.94, and 0.78 (P for trend: 0.005) across quintiles of total dietary fiber intake; and 1.0, 0.81, 0.82, 0.81, and 0.67 (P for trend: 0.0003) across quintiles of dietary magnesium intake. Intakes of total carbohydrates, refined grains, fruit and vegetables, and soluble fiber and the glycemic index were unrelated to diabetes risk. CONCLUSION: These data support a protective role for grains (particularly whole grains), cereal fiber, and dietary magnesium in the development of diabetes in older women.

Association of diet and mammographic breast density in the Minnesota breast cancer family cohort.

Mammographic breast density is a significant risk factor for breast cancer. The present report analyzes the association of breast density and dietary factors in 1508 women in a historical cohort study of breast cancer families in Minnesota. Diet was assessed by a semiquantitative food frequency questionnaire. Percent breast density was estimated visually by a radiologist experienced in mammography. The association of percent breast density with quartiles of energy-adjusted dietary intakes was examined in analysis of covariance models adjusting for potential confounding effects of age, body mass index, and other covariates as well as correcting for familial correlation. Analyses were performed on all women combined and were also stratified by menopausal status. Among premenopausal women, percent breast density was positively associated with intakes of polyunsaturated fat, polyunsaturated:saturated fat ratio, and vitamins C and E and was inversely associated with saturated fat and total dairy intake. Among postmenopausal women, vitamin B12 was linearly associated with increased breast density. The positive associations for vitamin C and B12 were attributable to supplement intake only. There was a suggestive positive trend between breast density and daily alcohol consumption in both premenopausal and postmenopausal women. After adjustment for other sources of alcohol, only wine intake among postmenopausal women was significant such that white wine showed a positive association and red wine an inverse association with percent breast density. There was no association with other examined dietary factors. The cross-sectional differences in breast density across levels of dietary factors were small in magnitude but may have implications for breast cancer risk.