Dietary energy density is positively associated with breast density among young women.

BACKGROUND: Breast density is an established predictor of breast cancer risk, and there is considerable interest in associations of modifiable lifestyle factors, such as diet, with breast density. OBJECTIVE: To determine whether dietary energy density (ED) is associated with percent dense breast volume (%DBV) and absolute dense breast volume (ADBV) in young women. DESIGN: A cross-sectional analysis was conducted with women who participated in the Dietary Intervention Study in Children Follow-Up Study. %DBV and ADBV were measured by magnetic resonance imaging. Diet was assessed by three 24-hour recalls. Dietary ED (kilocalories/gram) was calculated using three methods: food only, food and caloric beverages, and food and all beverages. PARTICIPANTS/SETTING: One hundred seventy-two women (aged 25 to 29 years) who were enrolled in the Dietary Intervention Study in Children Follow-Up Study. Participants who reported breast augmentation or reduction surgery or were pregnant or lactating within 3 months before breast density assessment were excluded. MAIN OUTCOME MEASURES: ADBV and %DBV. STATISTICAL ANALYSES PERFORMED: Multivariable linear mixed effects models were used. Final models were adjusted for race, smoking status, education, parity, duration of sex hormone use, whole body percent fat, childhood body mass index z score, and energy from beverages. RESULTS: After adjustment, each 1 kcal/g unit increase in food-only ED was associated with a 25.9% (95% CI 6.2% to 56.8%) increase in %DBV (P=0.01). Childhood body mass index z score modified the association between food-only ED and %DBV such that a significant positive association was observed only in women who were heavier as children. Food-only ED was not associated with ADBV in all women, but a borderline significant positive association was observed in women who had higher childhood body mass index z scores. CONCLUSIONS: This is the first report to suggest a potential role for dietary ED in breast density; the effects of long-term exposure to high-ED diets on breast cancer risk remain unknown.

Youth and young adult physical activity and body composition of young adult women: findings from the dietary intervention study in children.

This study prospectively investigates associations between youth moderate-to-vigorous-intensity physical activity (MVPA) and body composition in young adult women using data from the Dietary Intervention Study in Children (DISC) and the DISC06 Follow-Up Study. MVPA was assessed by questionnaire on 5 occasions between the ages 8 and 18 years and at age 25-29 years in 215 DISC female participants. Using whole body dual-energy x-ray absorptiometry (DXA), overall adiposity and body fat distribution were assessed at age 25-29 years by percent body fat (%fat) and android-to-gynoid (A:G) fat ratio, respectively. Linear mixed effects models and generalized linear latent and mixed models were used to assess associations of youth MVPA with both outcomes. Young adult MVPA, adjusted for other young adult characteristics, was significantly inversely associated with young adult %fat (%fat decreased from 37.4% in the lowest MVPA quartile to 32.8% in the highest (p-trend = 0.02)). Adjusted for youth and young adult characteristics including young adult MVPA, youth MVPA also was significantly inversely associated with young adult %fat (ß=-0.40 per 10 MET-hrs/wk, p = .02) . No significant associations between MVPA and A:G fat ratio were observed. Results suggest that youth and young adult MVPA are important independent predictors of adiposity in young women.

Menstrual and reproductive characteristics and breast density in young women.

PURPOSE: Breast density is strongly related to breast cancer risk, but determinants of breast density in young women remain largely unknown. METHODS: Associations of reproductive and menstrual characteristics with breast density measured by magnetic resonance imaging were evaluated in a cross-sectional study of 176 healthy women, 25-29 years old, using linear mixed effects models. RESULTS: Parity was significantly inversely associated with breast density. In multivariable adjusted models that included non-reproductive variables, mean percent dense breast volume (%DBV) decreased from 20.5 % in nulliparous women to 16.0 % in parous women, while mean absolute dense breast volume (ADBV) decreased from 85.3 to 62.5 cm(3). Breast density also was significantly inversely associated with the age women started using hormonal contraceptives, whereas it was significantly positively associated with duration of hormonal contraceptive use. In adjusted models, mean %DBV decreased from 21.7 % in women who started using hormones at 12-17 years of age to 14.7 % in those who started using hormones at 22-28 years of age, while mean ADBV decreased from 86.2 to 53.7 cm(3). The age at which women started using hormonal contraceptives and duration of hormone use were inversely correlated, and mean %DBV increased from 15.8 % in women who used hormones for not more than 2.0 years to 22.0 % in women who used hormones for more than 8 years, while mean ADBV increased from 61.9 to 90.4 cm(3) over this interval. CONCLUSIONS: Breast density in young women is inversely associated with parity and the age women started using hormonal contraceptives but positively associated with duration of hormone use.

Height, adiposity and body fat distribution and breast density in young women.

INTRODUCTION: Breast density is one of the strongest risk factors for breast cancer, but determinants of breast density in young women remain largely unknown. METHODS: Associations of height, adiposity and body fat distribution with percentage dense breast volume (%DBV) and absolute dense breast volume (ADBV) were evaluated in a cross-sectional study of 174 healthy women, 25 to 29 years old. Adiposity and body fat distribution were measured by anthropometry and dual-energy X-ray absorptiometry (DXA), while %DBV and ADBV were measured by magnetic resonance imaging. Associations were evaluated using linear mixed-effects models. All tests of statistical significance are two-sided. RESULTS: Height was significantly positively associated with %DBV but not ADBV; for each standard deviation (SD) increase in height, %DBV increased by 18.7% in adjusted models. In contrast, all measures of adiposity and body fat distribution were significantly inversely associated with %DBV; a SD increase in body mass index (BMI), percentage fat mass, waist circumference and the android:gynoid fat mass ratio (A:G ratio) was each associated significantly with a 44.4 to 47.0% decrease in %DBV after adjustment for childhood BMI and other covariates. Although associations were weaker than for %DBV, all measures of adiposity and body fat distribution also were significantly inversely associated with ADBV before adjustment for childhood BMI. After adjustment for childhood BMI, however, only the DXA measures of percentage fat mass and A:G ratio remained significant; a SD increase in each was associated with a 13.8 to 19.6% decrease in ADBV. In mutually adjusted analysis, the percentage fat mass and the A:G ratio remained significantly inversely associated with %DBV, but only the A:G ratio was significantly associated with ADBV; a SD increase in the A:G ratio was associated with an 18.5% decrease in ADBV. CONCLUSION: Total adiposity and body fat distribution are independently inversely associated with %DBV, whereas in mutually adjusted analysis only body fat distribution (A:G ratio) remained significantly inversely associated with ADBV in young women. Research is needed to identify biological mechanisms underlying these associations.

Adolescent diet and metabolic syndrome in young women: results of the Dietary Intervention Study in Children (DISC) follow-up study.

CONTEXT: Childhood diet is hypothesized to influence development of chronic disease in adulthood. OBJECTIVE: Our objective was to evaluate the long-term effects of a dietary intervention to reduce fat and increase fiber intake during childhood and adolescence on the prevalence of metabolic syndrome in young adult women. DESIGN: A follow-up study was conducted in 2006-2008, 9 yr after termination of the Dietary Intervention Study in Children (DISC). SETTING: The study took place at six DISC clinical centers in the United States. PARTICIPANTS: A total of 230 (76%) DISC female participants who were 25-29 yr old and had not been pregnant or breastfeeding in the previous 3 months participated in the follow-up study. INTERVENTION: There was no intervention between the end of the DISC trial and the follow-up visit. MAIN OUTCOME MEASURE: Metabolic syndrome was the primary study endpoint planned before data collection and was hypothesized to be less common in the intervention group participants. RESULTS: Metabolic syndrome was uncommon, and its prevalence did not differ by treatment group. However, after adjustment for nondietary variables, mean systolic blood pressures of intervention and control group participants were 107.7 and 110.0 mm Hg, respectively (P = 0.03), whereas mean fasting plasma glucose levels were 87.0 and 89.1 mg/dl, respectively (P = 0.01). Intervention group participants also had lower concentrations of large very-low-density lipoprotein particles, a marker of hepatic insulin resistance, compared with control group participants. Adjustment for current diet did not materially alter results. CONCLUSION: Consumption of a diet lower in fat and higher in fiber during childhood and adolescence may benefit glycemic control and blood pressure long term.

Adolescent diet and subsequent serum hormones, breast density, and bone mineral density in young women: results of the Dietary Intervention Study in Children follow-up study.

BACKGROUND: Adolescent diet is hypothesized to influence breast cancer risk. We evaluated the long-term effects of an intervention to lower fat intake among adolescent girls on biomarkers that are related to breast cancer risk in adults. METHODS: A follow-up study was conducted on 230 girls who participated in the Dietary Intervention Study in Children (DISC), in which healthy, prepubertal, 8 to 10 year olds were randomly assigned to usual care or to a behavioral intervention that promoted a reduced fat diet. Participants were 25 to 29 years old at follow-up visits. All tests of statistical significance are two-sided. RESULTS: In analyses that did not take account of diet at the time of the follow-up visit, the only statistically significant treatment group difference was higher bone mineral content in intervention group participants compared with usual care group participants; their mean bone mineral contents were 2,444 and 2,377 g, respectively. After adjustment for current diet, the intervention group also had statistically significantly higher bone mineral density and luteal phase serum estradiol concentrations. Serum progesterone concentrations and breast density did not differ by treatment group in unadjusted or adjusted analyses. CONCLUSIONS: Results do not support the hypothesis that consumption of a lower fat diet during adolescence reduces breast cancer risk via effects on subsequent serum estradiol and progesterone levels, breast density, or bone mineral density. It remains unclear, however, if the results are specific to the DISC intervention or are more broadly applicable. IMPACT: Modest reductions in fat intake during adolescence are unlikely to lower later breast cancer risk via long-term effects on the biomarkers measured.

Galvanic skin responses from asking stressful questions.

This study considers the effects of stress on interviewers as they ask challenging questions to interviewees. A convenience sample of 40 subjects was drawn from health and social care professionals and divided into a study group and a control group. Instrumentation was by unobtrusive galvanic skin response monitors. Data calibrations were checked against heart rate and finger temperature monitors for accuracy. The findings showed that when the interviewer asked a challenging question which they had designed themselves, it triggered a measurable stress response in 80% of interviewers. The respondents did not show stress responses to the same challenging question.

Higher self-reported physical activity is associated with lower systolic blood pressure: the Dietary Intervention Study in Childhood (DISC).

OBJECTIVE: Children participating in a dietary clinical trial were studied to (1) assess physical activity patterns in boys and girls longitudinally from late childhood through puberty and (2) determine the association of level of physical activity on systolic blood pressure, low-density lipoprotein cholesterol, and BMI. PATIENTS AND METHODS: In the Dietary Intervention Study in Childhood, a randomized clinical trial of a reduced saturated fat and cholesterol diet in 8- to 10-year-olds with elevated low-density lipoprotein, a questionnaire that determined time spent in 5 intensity levels of physical activity was completed at baseline and at 1 and 3 years. An estimated-metabolic-equivalent score was calculated for weekly activity; hours per week were calculated for intense activities. We hypothesized that weekly self-reported physical activity would be associated with lower systolic blood pressure, low-density lipoprotein, and BMI over 3 years. Longitudinal data analyses were performed for each outcome (systolic blood pressure, low-density lipoprotein, and BMI) by using generalized estimating equations with estimated-metabolic-equivalent score per week as the independent variable adjusted for visit, gender, and Tanner stage (BMI was included in models for systolic blood pressure and low-density lipoprotein). RESULTS: The initial study cohort comprised 663 youths (362 boys [mean age: 9.7 years] and 301 girls [mean age: 9.0 years], of whom 623 (94%) completed the 3-year visit. For every 100 estimated-metabolic-equivalent hours of physical activity, there was a decrease of 1.15 mmHg of systolic blood pressure. There was a 1.28 mg/dL decline in low-density lipoprotein for a similar energy expenditure. For BMI, an analysis of intense physical activity showed that for every 10 hours of intense activity, there was a trend toward significance with a 0.2 kg/m2 decrease. CONCLUSIONS: Children with elevated cholesterol levels who lead a more physically active lifestyle have lower systolic blood pressure and a trend toward lower low-density lipoprotein over a 3-year interval. Long-term participation in intense physical activity may reduce BMI as well.

Diet and sex hormones in boys: findings from the dietary intervention study in children.

CONTEXT: Diet reportedly alters serum sex hormone concentrations in adults, but little is known about the influence of diet during puberty on these hormones. OBJECTIVE: We aimed to determine whether an intervention to lower fat intake during adolescence alters serum sex hormone concentrations and progression through puberty. DESIGN: In 1990-1997, we conducted an ancillary study to the Dietary Intervention Study in Children, a multicenter, randomized, controlled clinical trial to test the safety and efficacy of a cholesterol-lowering dietary intervention in children. PARTICIPANTS: Healthy, prepubertal, 8 to 10 yr olds with elevated low-density lipoprotein cholesterol were randomized to usual care or a behavioral intervention. Of 362 randomized Dietary Intervention Study in Children boys, 354 participated in the ancillary study. Eighty-four percent of boys attended last visits when their median time on trial was 7.1 yr. INTERVENTION: The behavioral intervention continued throughout the duration of the trial and promoted a diet with 28% energy from total fat, less than 8% from saturated fat, 9% or less from polyunsaturated fat, and less than 75 mg cholesterol per 1000 kcal. OUTCOME MEASURES: The main outcome measure for boys formulated before study initiation was non-SHBG bound testosterone concentration. Secondary outcomes included serum total testosterone, dihydrotestosterone, androstenedione, estradiol, estrone, SHBG, and Tanner stage. RESULTS: There were no significant treatment group differences in boys' serum hormone levels, SHBG, or Tanner stages at any individual visit or over the course of the trial when evaluated by longitudinal models. CONCLUSION: Modest reductions in total fat, saturated fat, and possibly energy intake do not alter progression through puberty or serum sex hormone concentrations in adolescent boys.

A summary of results of the Dietary Intervention Study in Children (DISC): lessons learned.

Prevention of cardiovascular disease must begin in childhood, preferably before risk factors develop. Elevated low-density lipoprotein cholesterol levels in children are likely to track over time and become high-risk levels in adults. The Dietary Intervention Study in Children (DISC) was a multicenter, collaborative randomized trial in pre-adolescent children designed to test the efficacy and safety of a dietary intervention to lower saturated fat and cholesterol intake among growing children with elevated low-density lipoprotein cholesterol. Numerous DISC results, which include findings on lipids-lipoproteins, genetics, and nutrient adequacy, as well as descriptions of the behavioral intervention strategies, have been reported. A summary of practical findings and their potential clinical applications have not previously been published. Highlights of key lessons learned from DISC and translational applications of potential interest to nurses and other health care providers are presented.