Mediation Effect of Physical Activity on Obesity in Black Women.

BACKGROUND AND OBJECTIVE: Sociodemographic and lifestyle factors, physical activity, diet, and nutrients are important in the understanding of obesity. The possibly direct or indirect nature of the associations among these factors and the eventual link to obesity is not well understood. In this study, we assess the indirect association between socio-demographic factors and obesity. DESIGN: A case-control study involving African American women conducted at Howard University Cancer Center. PARTICIPANTS AND METHODS: One hundred ninety eight participants gave information on anthropometric measurements, intake of dietary supplements and nutrients, socio-demographic factors (age, marital status, income and education) and physical activity. Path analysis was utilized to assess associations between socio-demographic factors and obesity through physical activity, dietary supplements and nutrients, smoking or alcohol consumption. MAIN RESULTS: The mean age of the participants was (55 ± 12 years), with 50% being obese (BMI ≥ 30 kg/m2). Obesity level decreased by approximately 7% for every one level increase in education via its prior effect on vigorous physical activity. Age had a significant positive indirect effect on obesity through vigorous physical activity - with obesity levels increasing by approximately 6% for every one year increase in age via its prior effect on vigorous physical activity. CONCLUSIONS: Vigorous physical activity mediates the association between education and age on obesity.

Cardiorespiratory Fitness and Metabolic Syndrome in Postmenopausal African-American Women.

We examined the association of cardiorespiratory fitness with metabolic syndrome in overweight/obese postmenopausal African-American women. Pooled baseline data on 170 African-American women from 2 exercise trials were examined. Metabolic syndrome was defined as at least 3 of the following: abdominal obesity, glucose intolerance, hypertension, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides. Cardiorespiratory fitness (VO2peak) was determined using the Bruce treadmill protocol and categorized as: Very Low (VLCRF<18 mL·kg(-1) min(-1)), Low (LCRF=18.0-220-22-22.0 mL·kg(-1) min(-1)), and Moderate (MCRF>22.0 mL·kg(-1) min(-1)). Associations of metabolic syndrome with cardiorespiratory fitness were analyzed using one-way ANOVA and linear regression. VO2peak was significantly lower in the VLCRF compared to the MCRF group. Lower cardiorespiratory fitness was associated with higher prevalence of metabolic syndrome, abdominal obesity, hypertriglyceridemia, and low HDL among overweight/obese postmenopausal African-American women. In fully adjusted models, higher waist circumference and triglycerides were associated with lower VO2peak levels (P<0.01) and higher HDL-C was associated with higher VO2peak levels (P=0.03). Overweight/obese postmenopausal African-American women with very low cardiorespiratory fitness are more likely to have metabolic syndrome, higher body mass index, and unhealthier levels of certain metabolic syndrome components than women with moderate cardiorespiratory fitness.

Longitudinal association of measures of adiposity with serum antioxidant concentrations in postmenopausal women.

BACKGROUND/OBJECTIVES: The relationship between obesity and circulating levels of antioxidants is poorly understood. Most studies that have examined the association of adiposity with blood or tissue concentrations of antioxidant micronutrients have been cross-sectional, and few have compared the associations for indices of overall obesity and central obesity. Our aim was to prospectively examine the longitudinal association of body mass index (BMI), waist circumference (WC), waist circumference-height ratio (WCHtR) and waist-hip ratio (WHR) with major serum antioxidants in a population of postmenopausal women. SUBJECTS/METHODS: We used a subsample of participants in the Women's Health Initiative aged 50-79 years at entry with available fasting blood samples and anthropometric measurements obtained at multiple time points over 12.8 years of follow-up (N=2672). Blood samples were used to measure α-carotene, ß-carotene, ß-cryptoxanthin, lutein+zeaxanthin, α-tocopherol, γ-tocopherol and retinol at baseline, and at years 1, 3 and 6. We used mixed-effects linear regression analyses to examine associations between anthropometric measures and serum antioxidants at baseline and over time, controlling for covariates. RESULTS: In longitudinal analyses, carotenoids, and particularly ß-carotene, were strongly and inversely associated with BMI, WC and WCHtR and less so with WHR. α-Tocopherol showed a strong positive association with WHR but not with other anthropometric measures, whereas γ-tocopherol was positively and strongly associated with BMI, WC, WCHtR and less so with WHR. Retinol was positively associated with WHR. The inverse association of several carotenoids with anthropometric measures was stronger in never and former smokers compared with current smokers and in women without the metabolic syndrome. The inverse association of carotenoids with obesity measures may reflect reduced micronutrient concentrations owing to inflammation associated with obesity. CONCLUSIONS: In the present study, the strongest observed associations between anthropometric variables and micronutrients were an inverse association of WC with serum ß-carotene and a positive association of WC with γ-tocopherol.

Anthropometric predictors of elevated prostate specific antigen among rural and urban Nigerians: a population-based study.

BACKGROUND: Obesity has been associated with incidence and mortality of carcinoma of the prostate (CaP), but the relationship of BMI to CaP risk remains controversial across populations. OBJECTIVE: To describe the anthropometric correlates of elevated prostate specific antigen in Nigeria, a low-incidence region for CaP that currently reports rising incidence. SUBJECTS AND METHODS: Weight, height and skin fold thickness were measured for men, aged 40 years and older. Waist-to-hip ratio (WHR) and body mass index (BMI) were computed. Prostate specific antigen (PSA) status and prostate size were determined. Mean anthropometric indices were compared across groups using Student's t-test, association between anthropometry and PSA was by Spearman's correlation, and mean PSA was tested for linearity across tertiles of anthropometry. Prediction of elevated PSA was determined by multivariate logistic regression controlling for age and prostate size. RESULTS: Of 350 consecutive men contacted, 281(80.3%) completed the survey, mean age 56.9(13.5) years, and elevated PSA prevalence 31(11.0 %). WHR was 0.92 for rural and urban men, BMI (22.9 vs 24.7, p<0.002, and skin fold thickness was lower for rural men. PSA correlated directly with age, r=0.360, p<0.0001 and negatively with height, r=-0.136, p<0.023. WHR remained a significant predictor of elevated PSA,[OR 3.04 (95% CI 1.13 - 8.15)], after adjusting for age and enlarged prostate. CONCLUSION: Central adiposity may be a more important predictor of elevated PSA than BMI in this population. There is need to investigate the role of hormonal, metabolic, and genetic correlates of central adiposity in carcinoma of the prostate risk in this population.

Follow-up of a large cohort of Black women.

High retention rates in follow-up studies reduce the potential for biased data due to selective losses. The Black Women's Health Study began in 1995 when 64,500 participants aged 21-69 years enrolled by completing postal health questionnaires. Follow-up is carried out biennially. On the basis of data collected between enrollment and completion of the first follow-up, the authors assessed the usefulness of various follow-up methods and compared the characteristics of respondents, nonrespondents, and women lost to follow-up because of an unknown address. The 1997 questionnaire was completed by 82.8% of the participants. The study population was highly mobile: 56.5% moved at least once, and 1.5% moved at least four times. Moving was associated with younger age: A total of 71.7% of participants aged 21-29 years moved at least once compared with 43.2% of women aged 50-69. The most successful and cost-effective method for eliciting completed questionnaires from participants was sending multiple waves of questionnaires. Telephone calls to nonrespondents were successful but were highly labor intensive. Demographic and health characteristics of the women were similar regardless of which mailing was completed, except that early respondents had higher levels of education. Respondents were more highly educated and older than were nonrespondents and lost subjects but were quite similar in all other characteristics. These data suggest that follow-up of a mobile population of African-American women can be successful.

Strenuous physical activity and breast cancer risk in African-American women.

OBJECTIVES: Some studies of white women suggest that exercise reduces the incidence of breast cancer. There are no data on black women. We assessed the relationship between strenuous physical activity and prevalent breast cancer among participants in the Black Women's Health Study. METHODS: Data on strenuous recreational physical activity at various ages and other factors were collected in 1995 by mail questionnaire from 64,524 United States black women aged 21 to 69 years. The 704 women who reported breast cancer (cases) were matched on age and on menopausal status at the time of the breast cancer diagnosis with 1408 women who did not report breast cancer (controls). Odds ratios for levels of physical activity at various ages were derived from conditional logistic regression with control for potential confounding factors. RESULTS: Odds ratios for > or =7 h per week relative to < 1 were significantly reduced for strenuous activity at age 21 for breast cancer overall and premenopausal breast cancer, at age 30 for breast cancer overall, and at age 40 for postmenopausal breast cancer. There was no evidence of a reduction associated with exercise in high school. CONCLUSIONS: The findings of the present study suggest that strenuous physical activity in early adulthood is associated with a reduced risk of breast cancer in African-American women.

Recent mammography use among African-American women.

OBJECTIVE: The incidence of breast cancer in Black women is lower, but their mortality rate is higher, compared to White women. Lower rates of mammography use among Black women in the past may have resulted in later diagnosis of breast cancer, leading to shorter survival periods and higher mortality rates. We assessed recent mammography use in a large national study, the Black Women's Health Study. DESIGN: In 1995, 27,632 US Black women aged 40-69 years completed mailed questionnaires, which included questions on mammography use. RESULTS: Seventy-three percent of women aged 40-49, and 82% of those aged 50-69, reported having had a mammogram within the previous three years. Use was greater among women with higher levels of education, and among those who had cystic breast disease or a mother or sister with breast cancer. CONCLUSIONS: The high rate of recent mammography use among participants in the Black Women's Health Study agrees with national data. If breast cancer mortality rates in Black women continue to exceed those in White women, despite the lower incidence among Black women, reasons other than differential mammography use must be sought.

Height and breast cancer risk: results from the Black Women's Health Study (United States).

OBJECTIVES: Numerous studies, but not all, have yielded positive associations between adult height and risk of breast cancer. There are few data on black women. We evaluated adult height in relation to breast cancer in data from the Black Women's Health Study, a prospective cohort study of 64,530 African-American women aged 18-69 years at baseline in 1995. METHODS: A total of 910 cases of breast cancer were analyzed: 700 prevalent cases reported at baseline and 210 incident cases that occurred during the first 2 years of follow-up. A comparison group of controls frequency-matched on 5-year category of birth year was chosen from among participants who had not developed breast cancer. Odds ratios (OR) were calculated for various categories of adult height compared to a reference category of height less than or equal to 61 inches (155 cm), with control for current age, age at menarche, and years of education. RESULTS: Increased height was associated with an increased risk of breast cancer overall (p trend = 0.001); the OR for the highest category of height, > 69 inches (175 cm), was 1.6 (95% confidence interval 1.1-2.3). The association was stronger among premenopausal women and women who had less than 16 years of education. Results were similar for prevalent and incident cases. CONCLUSION: The present findings indicate that height is associated with breast cancer risk in African-American women.

A comparison between BMI and Conicity index on predicting coronary heart disease: the Framingham Heart Study.

PURPOSE: This study examined the relationship of mortality and morbidity of coronary heart disease with body mass index (BMI) and Conicity index (CI). METHODS: Among 5209 Framingham Heart Study participants, 1882 men and 2373 women had waist and weight measurement at the 4th examination period and height measured on the 5th visit. These were used for BMI and CI. RESULTS: During a 24-year follow-up, 597 men and 468 women developed CHD and 248 men and 150 women died from CHD associated causes. In men the relative risks (RR) (95% confidence interval) adjusted for age, hypertension, diabetes, smoking status, and total cholesterol for CHD incidence in 2nd, 3rd, and 4th quartiles of BMI were 1.28 (1.0, 1.65), 1.45 (1.13, 1.86), and 1.53 (1.19, 1.96). The RR for CHD incidence in the 4th quartile of BMI in women was 1.56 (1.16, 2.08). No CI quartiles were risk factors for CHD incidence. There was 86% higher risk of CHD related death in the 4th quartile of BMI than the 1st quartile of BMI in women. In men no significantly higher risks of death were found across the quartiles of BMI. No associations were found between CI quartiles and CHD mortality. CONCLUSIONS: Obesity as measured by BMI is an important risk factor for CHD incidence in men and women and for CHD mortality in women. CI was not associated with an increase in CHD incidence or mortality. Thus, BMI is a better marker than CI for predicting CHD incidence and mortality.

Insulin-like growth factor-1 and breast cancer risk in postmenopausal African-American women.

We explored the relationship between insulin-like growth factor-1 (IGF-1) concentrations and breast cancer risk. Also, we examined whether obesity, sex hormone-binding globulin (SHBG), and estradiol influenced IGF-1 concentrations. A pilot study of 60 postmenopausal African-American women (30 cases and 30 controls) was used. Plasma concentrations of IGF-1 were higher among the cases, as compared to the controls. A negative trend was seen for plasma concentrations of IGF-1 and TNM (tumor-node-metastasis) stage and IGF-1 and body mass index. IGF-1 was found to be associated negatively with SHBG. After adjustment, plasma concentrations of IGF-1 remained significantly and positively associated with breast cancer risk (odds ratio, 1.183; 95% confidence interval, 1.167-1.201). No significant associations for breast cancer risk were observed for estradiol, SHBG, and body mass index. Further research with a larger sample is needed to clarify the relationships between obesity and IGF-1 concentrations to breast cancer risk in this population.

Addictive behaviors and depression among African Americans residing in a public housing community.

Numerous studies have indicated that there is an association between cigarette smoking, alcohol use, and depression. However, little attention has been devoted to understanding how demographic factors, such as socioeconomic status and ethnicity, influence these relationships. To address this gap in the literature, cigarette and alcohol use were examined in a sample of African Americans from an urban area. A single public-housing community in Washington, DC was selected for complete ascertainment of the adult population. A total of 126 African American subjects were recruited. Semi-structured interviews were conducted to assess depressive symptoms and to characterize cigarette and alcohol use patterns. Cigarette smoking was not related to the severity of depressive symptoms. By contrast, increased symptoms of depression were related to alcohol use patterns. Light drinkers had a mean score of 5.77 on the Centers for Epidemiologic Studies Depression Scale, compared to a mean of 8.30 for abstainers and 10.07 for heavy drinkers (F = 4.968, p < .003). An analysis of patterns of substance use revealed that subjects were more likely to either abstain from both substances (30.2%) or to use both substances (32.5%) (chi2 = 8.516, df = 1. p < .004). It is unclear which specific processes work to link alcohol use and depressive symptoms in this group of urban African Americans from a low-income community. What is clear is that alcohol use is clearly related to depressive symptoms in the sample. It is hypothesized that both self-medicating processes and substance-induced depressive symptoms may be responsible for these findings. Important factors to consider in developing effective intervention programs that target this specific population are discussed.

Descriptive epidemiology of physical activity in African-American women.

OBJECTIVES: We assessed walking for exercise and moderate and strenuous physical activity in relation to both demographic and health-related characteristics among African-American women from various parts of the United States who participate in the Black Women's Health Study. METHODS: The data were collected in 1995 by mail questionnaire from 64,524 U.S. black women aged 21 to 69 years. The 64,101 women who provided data on physical activity are the subjects of the present report. RESULTS: The present study revealed low levels of physical activity among the African-American women: 57% reported an hour or less per week walking for exercise, 18% reported moderate activity, and 61% reported strenuous physical activity. Strenuous physical activity increased with education. Higher levels of walking for exercise and moderate and strenuous activity were associated with higher levels of participation in strenuous exercise in high school. CONCLUSION: Physical activity levels are low in African-American women. Based on the findings of the present study it may be suggested that educational efforts to increase levels of physical activity should start at an early age.

Correlates of hysterectomy among African-American women.

Hysterectomy is the second most common surgery performed on US women. Baseline data from a large study of African-American women were used to examine correlates of premenopausal hysterectomy. Analyses were conducted on participants aged 30-49 years; 5,163 had had a hysterectomy and 29,787 were still menstruating. Multiple logistic regression was used to compute prevalence odds ratios for the association of hysterectomy with various factors. Hysterectomy was associated with region of residence: Odds ratios for living in the South, Midwest, and West relative to the Northeast were 2.63 (95% confidence interval (CI): 2.38, 2.91), 2.02 (95% CI: 1.81, 2.25), and 1.89 (95% CI: 1.68, 2.12), respectively. Hysterectomy was inversely associated with years of education and age at first birth: Odds ratios were 1.96 (95% CI: 1.74, 2.21) for < or =12 years of education relative to >16 years and 4.33 (95% CI: 3.60, 5.22) for first birth before age 20 relative to age 30 or older. Differences in the prevalence of major indications for hysterectomy did not explain the associations. This study indicates that the correlates of hysterectomy among African-American women are similar to those for White US women. The associations with geographic region and educational attainment suggest that there may be modifiable factors which could lead to reduced hysterectomy rates.

Risk factors for coronary heart disease in African American women.

There have been few studies of risk factors for coronary heart disease in African American women. The authors investigated factors associated with prevalent coronary heart disease in data provided by participants in the Black Women's Health Study. In 1995, 64,530 US Black women aged 21-69 years completed postal health questionnaires. The 352 women who reported having had a heart attack (cases) were frequency matched 5:1 on age with 1,760 women who had not (controls); medical record review for 35 cases indicated that two-thirds had had a heart attack and the remainder had other coronary heart disease. Odds ratios, obtained from multiple logistic regression analyses, were significantly elevated for cigarette smoking, drug-treated hypertension, drug-treated diabetes mellitus, elevated cholesterol level, and history of heart attack in a parent. High body mass index (kg/m2) was associated with coronary heart disease in the absence of control for hypertension, diabetes mellitus, and elevated cholesterol but not when they were controlled, suggesting that obesity may influence risk as a result of its effects on blood pressure, glucose tolerance, and cholesterol levels. Odds ratios increased with increasing parity and with decreasing age at first birth. These data suggest that important risk factors for coronary heart disease are similar in Black women and White women.

Cardiovascular reactivity in Zimbabwe.

OBJECTIVE: In this study, we examined the effects of residency and gender on cardiovascular reactivity to a speech stressor in 50 rural Zimbabweans (24 males, 26 females) and 47 urban Zimbabweans (25 males and 22 females). METHODS: Participants were engaged in 4 periods: pre-task rest period, speech preparatory period, speaking task period, and the final recovery period. During each period, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were assessed. RESULTS: There was a significant interaction between area of residence and period for SBP and HR. Urban residents exhibited greater SBP and HR during the speaking phase of the speech task than did rural residents. However, rural residents displayed more exaggerated HR reactivity during the speech preparatory phase as compared to the urban residents. No gender differences were observed on blood pressure or heart rate reactivity. CONCLUSION: In conclusion, the more exaggerated SBP and HR reactivity to the speaking phase among urban residents as compared to rural residents may be influenced by factors associated with urbanization.

Perceptions and knowledge of breast cancer among African-American women residing in public housing.

OBJECTIVE: The purpose of this study, theoretically based on the Health Belief Model, was to assess breast cancer perceptions, knowledge, and screening behavior of low-income, African-American women residing in public housing. METHODS: One hundred twenty (120) randomly selected women were interviewed to determine their perceived susceptibility to breast cancer, perceived severity of the disease, perceived barriers to breast cancer screening, and perceived benefits of mammography. Knowledge about breast cancer causes, risk factors, symptoms, and screening was also assessed. Contingency tables and Student's t test were used to analyze the data. RESULTS: The results demonstrated that 80.7% of women aged 40 and older had a previous mammogram. Approximately 92% of women reported having a clinical breast examination, and 75.8% performed breast self-examination. Knowledge of breast cancer was poor among the women in this study. Most women did not perceive themselves or a particular racial or economic group to be more susceptible to breast cancer. Moreover, the women in the sample did not perceive breast cancer as a fatal disease. Overall, women in the sample endorsed the benefits of mammography and denied the relevance of commonly cited barriers to breast cancer screening. The constructs of the Health Belief Model were not significantly related to mammography or breast self-examination. However, perceived severity and perceived barriers were found to be significantly related to clinical breast examination. CONCLUSIONS: Rates of early detection behaviors in this sample are commendable. Future research should focus on actual determinants and facilitators of regular screening behavior within a theoretical framework that incorporates cultural, ethnic, and socioeconomic diversity.

Obesity and hypertension among college-educated black women in the United States.

It is established that obesity is an important risk factor for hypertension, but there is little information on this relationship among highly educated black women. We assessed the relationship of body mass index (weight (kg)/height2 (m)) to prevalent hypertension among US black women who had completed college, and among less educated women as well. The data were collected in 1995 in the Black Women's Health Study: 64530 African-American women aged 21 to 69 years enrolled by completing mailed health questionnaires; 44% of the participants had completed college. We compared the 9394 participants who reported a diagnosis of hypertension treated with a diuretic or antihypertensive drug (cases) with 9259 participants of similar ages who did not have hypertension (controls). Multivariate odds ratios were estimated by logistic regression. The odds ratio for treated hypertension increased with increasing body mass index at every educational level. Among college-educated women, the odds ratio for hypertension was 2.7 for overweight women (index 27.3-32.3) and 4.9 for severely overweight women (index > or =32.3), relative to women with a body mass index <22.8. The prevalences of obesity and hypertension were high among the college-educated women, although not as high as among women with fewer years of education. About a quarter of the difference in the prevalence of hypertension across educational levels was explained by the difference in the proportions who were overweight or severely overweight. These results document a high prevalence of obesity and hypertension, and a strong association of obesity with hypertension, among highly educated US black women.

Plasma lipid alterations in African-American women with breast cancer.

The purpose of this study was to examine the relationship between plasma lipid and lipoprotein levels, stage of disease and breast cancer risk in African-American women. The study population comprised 163 African-American women: patients (n = 58) and controls (n = 105), with mean ages of 57.2 years and 47.7 years respectively. Approximately 71% and 56% of the women with breast cancer and the control population, respectively, were postmenopausal. Those with cancer had significantly higher education levels, P < or = 0.01, and higher triglyceride levels compared to the controls, P < or = 0.001, but lower body mass index (BMI) levels, P < or = 0.01. There were no statistically significant differences observed in total cholesterol, high-density-lipoprotein-containing cholesterol and low-density-lipoprotein-containing cholesterol between the patients and controls. After adjustments for age, education, BMI, and menopausal status, triglycerides remained significantly and positively associated with breast cancer risk. The significant correlation between the high levels of triglycerides and breast cancer risk (odds ratio = 5.12) may be attributed to differences in lipid metabolism between the women with breast cancer and controls, or to the consequences of breast cancer.