Emollient structure and chemical functionality effects on the biomechanical function of human stratum corneum.

OBJECTIVE: Cosmetic emollients are widely used in skincare formulations due to their ability to 'soften' the skin and modulate formulation spreadability. Though emollients are commonly used, little is known about their effects on the biomechanical barrier properties of human stratum corneum (SC), which play a critical role in consumer perception of formulation efficacy. Accordingly, our objective was to provide new insights with a study involving fourteen cosmetic emollient molecules with widely varying structures, molecular weights, SC diffusivities, topological polar surface areas (TPSAs), viscosities and chemical functionalities. METHODS: Mechanical stress in the SC was measured in vitro using a substrate curvature measurement technique. Stress development due to SC drying was measured before and after topical treatment with cosmetic emollients. Emollient diffusivity and alterations to lipid content in SC after treatment were measured via ATR-FTIR spectroscopy. The maximum penetration volume of emollient in SC was characterized to elucidate mechanisms underlying emollient effects on stress. RESULTS: The application of all cosmetic emollients caused a reduction in SC mechanical stress under dehydrating conditions, and a linear correlation was discovered between emollient penetration volume and the degree of stress reduction. These molecules also induced increases in stress equilibration rate, signalling changes to SC transport kinetics. Stress equilibration rate increases linearly correlated with decreasing intensity of the νCH2 band, indicating a previously unknown interaction between cosmetic emollients and SC lipids. Stress and penetration volume results were rationalized in terms of a multi-parameter model including emollient molecular weight, diffusivity, TPSA and viscosity. CONCLUSION: We provide a new rational basis for understanding the effects of cosmetic emollient choice on biomechanical properties affecting SC barrier function and consumer perception. We demonstrate for the first time that emollients very likely reduce SC mechanical stress through their ability to take up volume when penetrating the SC, and how molecular weight, SC diffusivity, TPSA and viscosity are predictive of this ability. As cosmetic formulations continue to evolve to meet the needs of customers, emollient molecules can be selected that not only contribute to formulation texture and/or spreadability but that also leverage this novel connection between emollient penetration and SC biomechanics.

OBJECTIF: Les émollients cosmétiques sont largement utilisés dans les formulations de soins de la peau en raison de leur capacité à «adoucir¼ la peau et à moduler la capacité d'étalement de la formulation. Bien que les émollients soient couramment utilisés, on en sait peu sur leurs effets sur les propriétés de barrière biomécanique de la couche cornée humaine (SC), qui jouent un rôle essentiel dans la perception par les consommateurs de l'efficacité de la formulation. En conséquence, notre objectif était de fournir de nouvelles perspectives avec une étude impliquant quatorze molécules émollientes cosmétiques avec des structures, des poids moléculaires, des diffusivités SC, des surfaces polaires topologiques (TPSA), des viscosités et des fonctionnalités chimiques très variables. MÉTHODES: La contrainte mécanique dans le SC a été mesurée in vitro en utilisant une technique de mesure de la courbure du substrat. Le développement du stress dû au séchage SC a été mesuré avant et après un traitement topique avec des émollients cosmétiques. La diffusivité émolliente et les altérations de la teneur en lipides dans la SC après le traitement ont été mesurées par spectroscopie ATR-FTIR. Le volume de pénétration maximal de l'émollient dans SC a été caractérisé pour élucider les mécanismes sous-jacents aux effets émollients sur le stress. RÉSULTATS: L'application de tous les émollients cosmétiques a entraîné une réduction de la contrainte mécanique SC dans des conditions de déshydratation, et une corrélation linéaire a été découverte entre le volume de pénétration de l'émollient et le degré de réduction de la contrainte. Ces molécules ont également induit des augmentations du taux d'équilibrage des contraintes, signalant des changements dans la cinétique de transport SC. Le taux d'équilibrage des contraintes augmente linéairement en corrélation avec la diminution de l'intensité de la bande νCH2 , indiquant une interaction jusque-là inconnue entre les émollients cosmétiques et les lipides SC. Les résultats du stress et du volume de pénétration ont été rationalisés en termes d'un modèle multi-paramètres comprenant le poids moléculaire émollient, la diffusivité, le TPSA et la viscosité. CONCLUSION: Nous fournissons une nouvelle base rationnelle pour comprendre les effets du choix des émollients cosmétiques sur les propriétés biomécaniques affectant la fonction de barrière SC et la perception du consommateur. Nous démontrons pour la première fois que les émollients réduisent très probablement la contrainte mécanique SC grâce à leur capacité à prendre du volume lors de la pénétration du SC, et comment le poids moléculaire, la diffusivité SC, le TPSA et la viscosité sont prédictifs de cette capacité. Alors que les formulations cosmétiques continuent d'évoluer pour répondre aux besoins des clients, des molécules émollientes peuvent être sélectionnées qui contribuent non seulement à la texture et / ou à l'étalement de la formulation, mais qui exploitent également cette nouvelle connexion entre la pénétration des émollients et la biomécanique SC.

Screening sunscreens: protecting the biomechanical barrier function of skin from solar ultraviolet radiation damage.

OBJECTIVE: Solar ultraviolet (UV) radiation is ubiquitous in human life and well known to cause skin damage that can lead to harmful conditions such as erythema. Although sunscreen is a popular form of protection for some of these conditions, it is unclear whether sunscreen can maintain the mechanical barrier properties of skin. The objective of this study was to determine whether in vitro thin-film mechanical analysis techniques adapted for biological tissue are able to characterize the efficacy of commonly used UV inhibitors and commercial sunscreens to protect the biomechanical barrier properties of stratum corneum (SC) from UV exposure. METHODS: The biomechanical properties of SC samples were assayed through measurements of the SC's drying stress profile and delamination energy. The drying stresses within SC were characterized from the curvature of a borosilicate glass substrate onto which SC had been adhered. Delamination energies were characterized using a double-cantilever beam (DCB) cohesion testing method. Successive DCB specimens were prepared from previously separated specimens by adhering new substrates onto each side of the already tested specimen to probe delamination energies deeper into the SC. These properties of the SC were measured before and after UV exposure, both with and without sunscreens applied, to determine the role of sunscreen in preserving the barrier function of SC. RESULTS: The drying stress in SC starts increasing sooner and rises to a higher plateau stress value after UVA exposure as compared to non-UV-exposed control specimens. For specimens that had sunscreen applied, the UVA-exposed and non-UV-exposed SC had similar drying stress profiles. Additionally, specimens exposed to UVB without protection from sunscreen exhibited significantly lower delamination energies than non-UV-exposed controls. With commercial sunscreen applied, the delamination energy for UV-exposed and non-UV-exposed tissue was consistent, even up to large doses of UVB. CONCLUSION: In vitro thin-film mechanical analysis techniques can readily characterize the effects of SC's exposure to UV radiation. The methods used in this study demonstrated commercial sunscreens were able to preserve the biomechanical properties of SC during UV exposure, thus indicating the barrier function of SC was also maintained.

The protease inhibitor PI*S allele and COPD: a meta-analysis.

In many countries, the protease inhibitor (SERPINA1) PI*S allele is more common than PI*Z, the allele responsible for most cases of chronic obstructive pulmonary disease (COPD) due to severe alpha 1-antitrypsin deficiency. However, the risk of COPD due to the PI*S allele is not clear. The current authors located studies that addressed the risk of COPD or measured lung function in individuals with the PI SZ, PI MS and PI SS genotypes. A separate meta-analysis for each genotype was performed. Aggregating data from six studies, the odds ratio (OR) for COPD in PI SZ compound heterozygotes compared with PI MM (normal) individuals was significantly increased at 3.26 (95% confidence intervals (CI): 1.24-8.57). In 17 cross-sectional and case-control studies, the OR for COPD in PI MS heterozygotes was 1.19 (95%CI: 1.02-1.38). However, PI MS genotype was not associated with COPD risk after correcting for smoking. Furthermore, mean forced expiratory volume in one second, a measure of airflow obstruction and a defining feature of COPD, did not differ between PI MS and PI MM individuals. There were not enough cases to summarise the risk of COPD in PI SS homozygotes. In conclusion, the results show that the PI SZ genotype is a significant risk factor for chronic obstructive pulmonary disease. The risk of chronic obstructive pulmonary disease due to the PI MS genotype is not substantially elevated.

Chronic obstructive pulmonary disease in alpha1-antitrypsin PI MZ heterozygotes: a meta-analysis.

BACKGROUND: Severe alpha(1)-antitrypsin deficiency, usually related to homozygosity for the protease inhibitor (PI) Z allele, is a proven genetic risk factor for chronic obstructive pulmonary disease (COPD). The risk of COPD in PI MZ heterozygous individuals is controversial. METHODS: A search of MEDLINE from January 1966 to May 2003 identified studies that examined the risk of COPD in PI MZ individuals and studies that measured forced expiratory volume in 1 second (FEV(1)) in heterozygotes. RESULTS: In 16 studies that reported COPD as a categorical outcome, the combined odds ratio (OR) for PI MZ versus PI MM (normal genotype) was 2.31 (95% CI 1.60 to 3.35). The summary OR was higher in case-control studies (OR 2.97; 95% CI 2.08 to 4.26) than in cross sectional studies (OR 1.50; 95% CI 0.97 to 2.31) and was attenuated in studies that adjusted for cigarette smoking (OR 1.61; 95% CI 0.92 to 2.81). In seven studies that reported FEV(1) as a continuous outcome there was no difference in mean FEV(1) between PI MM and PI MZ individuals. CONCLUSIONS: Case-control studies showed increased odds of COPD in PI MZ individuals, but this finding was not confirmed in cross sectional studies. Variability in study design and quality limits the interpretation. These results are consistent with a small increase in risk of COPD in all PI MZ individuals or a larger risk in a subset. Future studies that adjust for smoking and include other COPD related phenotypes are required to conclusively determine the risk of COPD in PI MZ heterozygotes.

Longitudinal study of skipping breakfast and weight change in adolescents.

BACKGROUND: Several cross-sectional studies reported that heavier children eat breakfast less often. However, no longitudinal studies have addressed whether skipping breakfast leads to excessive weight gain. OBJECTIVE: To investigate whether skipping breakfast was prospectively associated with changes in body fatness. METHODS: A cohort of >14000 boys and girls from all over the US, 9- to 14-y-old in 1996, returned annual mailed questionnaires (1996-1999) for the Growing Up Today Study. We analyzed change in body mass index (BMI; kg/m(2)) over three 1-y periods among children who reported breakfast frequency. RESULTS: Children who reported that they never eat breakfast had lower energy intakes than those who eat breakfast nearly every day. Children who were more physically active reported higher energy intakes, as did those who reported more time watching television/videos and playing videogames. Like previous studies, skipping breakfast was associated with overweight, cross-sectionally. However, overweight children who never ate breakfast lost BMI over the following year compared to overweight children who ate breakfast nearly every day (boys: -0.66 kg/m(2) (s.e.=0.22); girls: -0.50 kg/m(2) (s.e.=0.14)). But normal weight children who never ate breakfast gained weight relative to peers who ate breakfast nearly every day (boys: +0.21 kg/m(2) (s.e.=0.13); girls: +0.08 kg/m(2) (s.e.=0.05)). Breakfast frequency was positively correlated with self-reported quality of schoolwork. CONCLUSIONS: Overweight children who never eat breakfast may lose body fat, but normal weight children do not. Since numerous studies link skipping breakfast to poorer academics, children should be encouraged to eat breakfast.

Cross-sectional measurement of nutrient intake among adolescents in 1996.

BACKGROUND: Many components are involved in an assessment of diet and health among youth. To address these issues and document the major contributions of fat, fiber, vitamins, and minerals to the diet, we analyzed baseline cross-sectional data from a cohort of 16,882 youth. METHODS: Cross-sectional analyses were conducted on the Growing Up Today Study dietary data reported by 16,882 9- to 14-year-olds in 1996. The adolescent food frequency questionnaire was used to assess this age group's eating habits. Arithmetic means and standard deviations were calculated on energy-adjusted and unadjusted data. RESULTS: Mean intake (including vitamin/mineral supplementation) for all nutrients met 100% of the RDAs, except calcium for girls. Comparing the servings of foods with the USDA Food Pyramid, neither boys nor girls met recommended number of servings except for dairy. Overweight participants consumed fewer kilocalories and lower levels of nutrients than their nonoverweight peers. CONCLUSION: These cross-sectional data from 1996 indicate that this cohort is consuming foods and nutrients comparable with national data of less fat and more carbohydrates in their diet. Overweight participants have similar dietary patterns except for total energy. The cohort's diet (with vitamin/mineral supplementation) is meeting the RDAs, but actual foods consumed suggest a lack of balance in the diet.

Comparing physical activity questionnaires for youth: seasonal vs annual format.

BACKGROUND: In large cohort studies of older children, self-report is the only practical way to assess physical activity. Assessing usual activity over the entire year is desirable, but children and adolescents may overestimate activities with high seasonal variability. Use of questionnaires in which individuals report each activity by season may improve accuracy. METHODS: A total of 6782 girls and 5110 boys, aged 9-14 years in 1996, completed self-administered activity questionnaires in 1996 and in 1997. In 1996, participants reported the average time spent in each of 17 activities during the previous 12 months; in 1997, we also asked for the average time spent in the previous year, but within each of the four seasons. RESULTS: Girls reported a median of 12.8 hours/week total activity in 1996 and 10.4 hours/week in 1997. For boys, the estimates were 15.5 hours/week and 13.4 hours/week, respectively. Girls and boys within 1-year age strata (e.g., comparison of 10-year olds in 1996 with 10-year olds in 1997) reported an average of 3.7 and 3.1 fewer hours per week, respectively, on the 1997 seasonal format versus the 1996 annual format questionnaire. In longitudinal analyses, the difference between the annual and the seasonal estimates was greater if participants did the activity in fewer seasons in 1997. CONCLUSIONS: In comparison to an annual format questionnaire, a seasonal format questionnaire may improve accuracy of self-report of physical activity by reducing over-reporting of activities in which pre-adolescents and adolescents engage in fewer seasons.

Risk of overweight among adolescents who were breastfed as infants.

CONTEXT: Overweight during adolescence predicts short- and long-term morbidity as well as obesity in adulthood. The prevalence of overweight among adolescents is high and continues to increase. Physiological and behavioral mechanisms and preliminary epidemiologic data suggest that breastfeeding could lower the risk of subsequent obesity in adolescence. OBJECTIVE: To examine the extent to which overweight status among adolescents is associated with the type of infant feeding (breast milk vs infant formula) and duration of breastfeeding. DESIGN, SETTING, AND SUBJECTS: Survey of 8186 girls and 7155 boys, aged 9 to 14 years, who are participants in the Growing Up Today Study, a nationwide cohort study of diet, activity, and growth. In the fall of 1996 we mailed a questionnaire to each of the subjects, and in the spring of 1997, we mailed a supplemental questionnaire to their mothers, who are participants in the Nurses' Health Study II. MAIN OUTCOME MEASURE: Overweight status defined as body mass index exceeding the 95th percentile for age and sex from US national data. RESULTS: In the first 6 months of life, 9553 subjects (62%) were only or mostly fed breast milk, and 4744 (31%) were only or mostly fed infant formula. A total of 7186 subjects (48%) were breastfed for at least 7 months while 4613 (31%) were breastfed for 3 months or less. At ages 9 to 14 years, 404 girls (5%) and 635 boys (9%) were overweight. Among subjects who had been only or mostly fed breast milk, compared with those only or mostly fed formula, the odds ratio (OR) for being overweight was 0.78 (95% confidence interval [CI], 0.66-0.91), after adjustment for age, sex, sexual maturity, energy intake, time watching television, physical activity, mother's body mass index, and other variables reflecting social, economic, and lifestyle factors. Compared with subjects who had been breastfed for 3 months or less, those who had been breastfed for at least 7 months had an adjusted OR for being overweight of 0.80 (95% CI, 0.67-0.96). Timing of introduction of solid foods, infant formula, or cow's milk was not related to risk of being overweight. CONCLUSION: Infants who were fed breast milk more than infant formula, or who were breastfed for longer periods, had a lower risk of being overweight during older childhood and adolescence.

Peer, parent, and media influences on the development of weight concerns and frequent dieting among preadolescent and adolescent girls and boys.

OBJECTIVE: To assess prospectively the influence of peers, parents, and the media on the development of weight concerns and frequent dieting. DESIGN: Prospective cohort study. SETTING: Questionnaires mailed annually to participants throughout the United States. PARTICIPANTS: One-year follow-up of 6770 girls and 5287 boys who completed questionnaires in 1996 and 1997 and were between 9 and 14 years of age in 1996. MAIN OUTCOME MEASURE: Onset of high levels of concern with weight and dieting frequently to control weight. RESULTS: During 1 year of follow-up, 6% of girls and 2% of boys became highly concerned with weight and 2% of girls and 1% of boys became constant dieters. Peer influence was negligible. Independent of age and body mass index, both girls (odds ratio [OR]): 1.9; 95% confidence interval [CI]: 1.1-3.1) and boys (OR: 2.7; 95% CI: 1.1-6. 4) who were making a lot of effort to look like same-sex figures in the media were more likely than their peers to become very concerned with their weight. Moreover, both girls (OR: 2.3; 95% CI: 1.1-5.0) and boys (OR: 2.6; 95% CI: 1.1-6.0) who reported that their thinness/lack of fat was important to their father were more likely than their peers to become constant dieters. CONCLUSIONS: Our results suggest that parents and the media influence the development of weight concerns and weight control practices among preadolescents and adolescents. However, there are gender differences in the relative importance of these influences.

Relation of childhood diet and body size to menarche and adolescent growth in girls.

Adolescent growth and development may be affected by factors such as dietary intake and body size from much earlier in childhood. In a longitudinal study of 67 Caucasian girls in Boston, Massachusetts, data were collected prospectively from birth during the 1930s and 1940s. Heights and weights were measured semiannually, and dietary history interviews were conducted with mothers. Stepwise linear regression methods were used to seek factors which best predicted age at menarche, adolescent peak height growth velocity, and the age at which peak growth velocity occurred. Girls who consumed more (energy-adjusted) animal protein and less vegetable protein at ages 3-5 years had earlier menarche, and girls aged 1-2 years with higher dietary fat intakes and girls aged 6-8 years with higher animal protein intakes became adolescents with earlier peak growth. Controlling for body size, girls who consumed more calories and animal protein 2 years before peak growth had higher peak growth velocity. These findings may have implications regarding adult diseases whose risks are associated with adolescent growth and development factors.

Meta-analysis of dietary essential fatty acids and long-chain polyunsaturated fatty acids as they relate to visual resolution acuity in healthy preterm infants.

OBJECTIVE: To derive combined estimates of visual resolution acuity differences between healthy preterm infants consuming different compositions and ratios of essential fatty acids (EFAs) and docosahexaenoic acid (DHA), an omega-3 (n-3) long-chain polyunsaturated fatty acid (LCPUFA). DATA SOURCES: Electronic biomedical reference database (Medline and Health Star from 1965 to July 1999) searches with index terms omega-3, n-3, infant, vision, acuity, and human. Current review article, monograph, and book chapter bibliography/reference section hand searches. STUDY SELECTION: A total of 5 original articles and 4 review chapters were reviewed for details on study design, conduct, and outcome. Four prospective trials of EFA/LCPUFA supplementation were included in these analyses. For behaviorally based outcomes, there were 2 randomized comparisons each at

Activity, dietary intake, and weight changes in a longitudinal study of preadolescent and adolescent boys and girls.

OBJECTIVE: To examine the role of physical activity, inactivity, and dietary patterns on annual weight changes among preadolescents and adolescents, taking growth and development into account. STUDY DESIGN: We studied a cohort of 6149 girls and 4620 boys from all over the United States who were 9 to 14 years old in 1996. All returned questionnaires in the fall of 1996 and a year later in 1997. Each child provided his or her current height and weight and a detailed assessment of typical past-year dietary intakes, physical activities, and recreational inactivities (TV, videos/VCR, and video/computer games). METHODS: Our hypotheses were that physical activity and dietary fiber intake are negatively correlated with annual changes in adiposity and that recreational inactivity (TV/videos/games), caloric intake, and dietary fat intake are positively correlated with annual changes in adiposity. Separately for boys and girls, we performed regression analysis of 1-year change in body mass index (BMI; kg/m(2)). All hypothesized factors were in the model simultaneously with several adjustment factors. RESULTS: Larger increases in BMI from 1996 to 1997 were among girls who reported higher caloric intakes (.0061 +/-.0026 kg/m(2) per 100 kcal/day; beta +/- standard error), less physical activity (-.0284 +/-.0142 kg/m(2)/hour/day) and more time with TV/videos/games (.0372 +/-.0106 kg/m(2)/hour/day) during the year between the 2 BMI assessments. Larger BMI increases were among boys who reported more time with TV/videos/games (.0384 +/-.0101) during the year. For both boys and girls, a larger rise in caloric intake from 1996 to 1997 predicted larger BMI increases (girls:.0059 +/-.0027 kg/m(2) per increase of 100 kcal/day; boys:.0082 +/-.0030). No significant associations were noted for energy-adjusted dietary fat or fiber. CONCLUSIONS: For both boys and girls, a 1-year increase in BMI was larger in those who reported more time with TV/videos/games during the year between the 2 BMI measurements, and in those who reported that their caloric intakes increased more from 1 year to the next. Larger year-to-year increases in BMI were also seen among girls who reported higher caloric intakes and less physical activity during the year between the 2 BMI measurements. Although the magnitudes of these estimated effects were small, their cumulative effects, year after year during adolescence, would produce substantial gains in body weight. Strategies to prevent excessive caloric intakes, to decrease time with TV/videos/games, and to increase physical activity would be promising as a means to prevent obesity.

Dietary essential fatty acids, long-chain polyunsaturated fatty acids, and visual resolution acuity in healthy fullterm infants: a systematic review.

BACKGROUND: Biologically active neural tissue is rich in docosahexaenoic acid (DHA), an omega-3 long-chain polyunsaturated fatty acid (LCPUFA). We conducted a systematic review to examine the nature of discordant results from studies designed to test the hypothesis that dietary DHA leads to better performance on visually-based tasks in healthy, fullterm infants. We also conducted a meta-analysis to derive combined estimates of behavioral- and electrophysiologic-based visual resolution acuity differences and sample sizes that would be useful in planning future research. STUDY DESIGN AND METHODS: Twelve empirical studies on LCPUFA intake during infancy and visual resolution acuity were identified through bibliographic searches, examination of monograph and review article reference lists, and written requests to researchers in the field. Works were reviewed for quality and completeness of information. Study design and conduct information was extracted with a standardized protocol. Acuity differences between groups consuming a source of DHA and groups consuming DHA-free diets were calculated as a common outcome from individual studies; this difference score was evaluated against a null value of zero and then used, with the method of DerSimonian and Laird (Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-188), to derive combined estimates of visual resolution acuity differences within seven age categories. RESULTS OF RANDOMIZED COMPARISONS: The combined visual resolution acuity difference measured with behaviorally based methods between DHA-supplemented formula fed groups and DHA-free formula fed groups is 0.32+/-0.09 octaves (combined difference+/-S.E.M., P=0.0003) at 2 months of age. The direction of this value indicates higher acuity in DHA-fed groups. RESULTS OF NON-RANDOMIZED STUDY DESIGNS: The combined visual resolution acuity difference measured with behaviorally based methods between human milk fed groups and DHA-free formula fed groups is 0.49+/-0.09 octaves (P< or =0.000001) at 2 months of age and 0.18+/-0.08 octaves (P=0.04) at 4 months of age. Acuity differences for electrophysiologic-based measures are also greater than zero at 4 months (0.37+/-0.16 octaves, P=0.02). CONCLUSION: Some aspect of dietary n-3 intake is associated with performance on visual resolution acuity tasks at 2, and possibly, 4 months of age in healthy fullterm infants. Whether n-3 intake confers lasting advantage in the development of visually based processes is still in question.

Family dinner and diet quality among older children and adolescents.

CONTEXT: The proportion of children eating dinner with their families declines with age and has decreased over time. Few data exist concerning the nutritional effect of eating family dinner. OBJECTIVE: To examine the associations between frequency of eating dinner with family and measures of diet quality. DESIGN: Cross-sectional. SETTING: A national convenience sample. PARTICIPANTS: There were 8677 girls and 7525 boys in the study, aged 9 to 14 years, who were children of the participants in the ongoing Nurses' Health Study II. MAIN OUTCOME MEASURES: We collected data from a self-administered mailed survey, including food and nutrient intakes from a validated semiquantitative food frequency questionnaire. Main outcome measures included servings per day of selected foods and food groups, daily intakes of selected macronutrients and micronutrients, and frequency of multivitamin use. RESULTS: Approximately 17% of participants ate dinner with members of their family never or some days, 40% on most days, and 43% every day. More than half of the 9-year-olds ate family dinner every day, whereas only about one third of 14-year-olds did so. In age- and sex-adjusted logistic regression models, the odds ratios associated with a frequency of family dinner of most days compared with never or some days, or every day compared with most days, were as follows: for eating at least 5 servings per day of fruits and vegetables, 1.45 (95% confidence interval [CI], 1.37-1.53); for eating any fried foods away from home, 0.67 (95% CI, 0.64-0.70); and for drinking any soda, 0.73 (95% CI, 0.66-0.80). Multiple linear regression showed that an increased frequency of family dinner was also associated with substantially higher intake of several nutrients, including fiber, calcium, folate, iron, vitamins B6, B12, C, and E; lower glycemic load; and lower intake of saturated and trans fat as a percentage of energy. We observed little or no effect on intakes of whole dairy products, red meat, or snack foods. Patterns were similar for boys and girls. CONCLUSIONS: Eating family dinner was associated with healthful dietary intake patterns, including more fruits and vegetables, less fried food and soda, less saturated and trans fat, lower glycemic load, more fiber and micronutrients from food, and no material differences in red meat or snack foods.

Relation of peer and media influences to the development of purging behaviors among preadolescent and adolescent girls.

OBJECTIVE: To assess prospectively the relation of peer and media influences on the risk of development of purging behaviors. DESIGN: Prospective cohort study. SETTING: One year follow-up of 6982 girls aged 9 to 14 years in 1996 who completed questionnaires in 1996 and 1997 and reported in 1996 that they did not use vomiting or laxatives to control weight. MAIN OUTCOME MEASURE: Self-report of using vomiting or laxatives at least monthly to control weight. RESULTS: During 1 year of follow-up, 74 girls began using vomiting or laxatives at least monthly to control weight. Tanner stage of pubic hair development was predictive of beginning to purge (odds ratio [OR] = 1.8; 95% confidence interval [CI], 1.3-2.4). Independent of age and Tanner stage of pubic hair development, importance of thinness to peers (OR = 2.3; 95% CI, 1.8-3.0) and trying to look like females on television, in movies, or in magazines (OR= 1.9; 95% CI, 1.6-2.3) were predictive of beginning to purge at least monthly. Regardless of the covariates included in the logistic regression model, the risk of beginning to purge increased approximately 30% to 40% per 1-category increase in frequency of trying to look like females on television, in movies, or in magazines. CONCLUSIONS: Both peers and popular culture, independent of each other, exert influence on girls' weight control beliefs and behaviors. Therefore, to make eating disorder prevention programs more effective, efforts should be made to persuade the television, movie, and magazine industries to employ more models and actresses whose weight could be described as healthy, not underweight.

Weight concerns, weight control behaviors, and smoking initiation.

OBJECTIVE: To examine the cross-sectional relationships between weight concerns, weight control behaviors, and initiation of tobacco use among youths. STUDY DESIGN: Smoking status, weight concerns, and weight control behaviors were assessed in a cross-sectional sample of 16 862 children, 9 to 14 years of age, in 1996. Logistic regression was used to examine the relationship between weight concerns, weight control behaviors, and early stages of smoking initiation (precontemplation, contemplation, and experimentation). All analyses were adjusted for age, body mass index, and known predictors of initiation. RESULTS: Approximately 9% of participants had experimented with cigarettes, and 6% were contemplating cigarette smoking. Contemplation of tobacco use was associated with misperception of being overweight (boys: odds ratio [OR], 1.65; 95% confidence interval [CI], 1.10-2.48), unhappiness with appearance (girls: OR, 2.05; 95% CI, 1.48-2.84; boys: OR, 1.60; 95% CI, 1.05-2. 42), and a tendency to change eating patterns around peers (girls: OR, 2.87; 95% CI, 2.28-3.62; boys: OR, 1.83; 95% CI, 1.25-2.66). Experimentation with cigarettes was associated with daily exercise to control weight among boys (OR, 1.92; 95% CI, 1.07-3.43) and with monthly purging (OR, 2.54; 95% CI, 1.27-5.07) and daily dieting among girls (OR, 1.79; 95% CI, 1.09-2.96). CONCLUSIONS: Our findings suggest that, among both girls and boys, contemplation of smoking is positively related to weight concerns. Experimentation seems to be positively related to weight control behaviors. It is important for both pediatricians and comprehensive school health programs to address healthy methods of weight maintenance and to dispel the notion of tobacco use as a method of weight control.

Reproducibility and validity of maternal recall of pregnancy-related events.

We assessed the reproducibility and validity of a questionnaire that asks mothers to recall pregnancy-related events from thirty or more years ago. Among 146 women who completed the questionnaire twice, responses were highly reproducible for pre-pregnancy height and weight (r = 0.95), pregnancy complications (r = 0.74), substance use (r = 0.80), preterm delivery (r = 0.82), birthweight (r = 0.94), and breastfeeding (r = 0.89). Among 154 women whose questionnaire responses were compared to data collected during their pregnancies, recall was highly accurate for height (r = 0.90), pre-pregnancy weight (r = 0.86), birthweight (r = 0.91), and smoking (sensitivity = 0.86, specificity = 0.94). These findings suggest that long-term maternal recall is both reproducible and accurate for many factors related to pregnancy and delivery.

Overweight, weight concerns, and bulimic behaviors among girls and boys.

OBJECTIVE: To assess the prevalence rates and correlates of overweight, concern with weight, and bulimic behaviors. METHOD: A survey was completed by a population-based sample of 16,114 boys and girls aged 9 to 14 years. RESULTS: Although fewer girls (19%) than boys (26%) were overweight, more girls (25% versus 22%) perceived themselves as overweight (p < .001). The proportion of girls reporting trying to lose weight increased with age (p < .001). The prevalence of binge eating at least monthly increased with age among the girls, but remained stable among the boys. The prevalence of purging was low (< or = 1%) and comparable between genders until age 13. Among the 13- and 14-year-olds, girls were significantly more likely than boys to report using laxatives or vomiting to control weight (p < or = .001). Purging was independently positively associated with stage of pubertal development (girls: odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.6-2.7; boys: OR = 1.5, 95% CI 1.0-2.2) and overweight (girls: OR = 1.9, 95% CI 1.2-3.0; boys: OR = 2.7, 95% CI 1.4-5.1). CONCLUSIONS: Misperception of being overweight and concern with weight were common. Purging was a very rare behavior, but increased with pubertal development. Among the girls, the prevalence increased sharply around the onset of adolescence.

Adolescence and breast carcinoma risk.

BACKGROUND: Breast carcinoma risk may be modified by early life factors, including physical growth and development, diet, and life-style factors of preadolescence and adolescence, as well as genetic factors. METHODS: The authors tested their hypothesis that adolescent growth and development are related to breast carcinoma incidence by evaluating 65,140 women who participated in the Nurses' Health Study. During 16 years of follow-up, 806 women were diagnosed with breast carcinoma prior to menopause, and another 1485 were diagnosed after menopause. Because adolescent growth was not directly observed in this cohort, the peak height growth velocity for each participant was estimated by using a model from another longitudinal study. Finally, Cox proportional hazards regression models were used to study associations between breast carcinoma incidence and adolescent factors in the Nurses' Health Study. RESULTS: Later menarche (relative risk [RR] = 0.52 for > or =15 vs. < or =11 years) and more body fatness at age 10 years (RR = 0.60 for fattest vs. leanest) were associated with a decreased risk of premenopausal breast carcinoma. The risk of postmenopausal breast carcinoma was lower for girls with later menarche (RR = 0.80), more body fat at age 10 years (RR = 0.72), and shorter adult height (RR = 1.29 for > or =67 vs. < or =62 inches). Higher peak height growth velocity, derived from these 3 variables, was associated with increased risk of both premenopausal (RR = 1.31 for highest vs. lowest quintile) and postmenopausal (RR = 1.40) breast carcinoma. These analyses controlled for birth cohort, other possible risk factors from the adolescent period, and family history. These associations persisted after controlling for age at the birth of a first child, parity, adult adiposity, and age at menopause. Post-hoc analyses suggested that, although childhood body fatness was associated with lower risk, increasing body fatness between ages 10 and 20 years was not protective against either premenopausal or postmenopausal breast carcinoma. CONCLUSIONS: Earlier menarche, extremely lean body mass at age 10 years, and taller adult height were predictive of elevated breast carcinoma risk. The same three factors were also predictive of higher peak growth velocities during adolescence, lending credence to the hypothesis that more rapid adolescent growth may increase the risk of breast carcinoma development.