Dietary intake from birth through adolescence in relation to risk of benign breast disease in young women.

PURPOSE: Nutritional factors during different periods in life impact breast cancer risk. Because benign breast disease (BBD) is a well-established risk factor for breast cancer, we investigated childhood nutrition from birth through age 14 year and subsequent BBD. METHODS: A prospective cohort study of 9031 females, 9-15 year at baseline, completed questionnaires (including heights, weights) annually from 1996 to 2001, in 2003, 2005, 2007, 2010, 2013 and 2014. In 1996, mothers reported infant feeding practices during their daughters first year of life. Beginning in 1996, participants completed annual food frequency questionnaires. In 2005, participants (18 year +) began reporting whether they had ever been diagnosed with biopsy-confirmed BBD (N = 173 cases). Multivariable logistic regression models estimated associations between childhood nutrition and BBD, adjusted for maternal breast disease and childhood body size factors. RESULTS: Although no infant nutrition factors were associated with biopsy-confirmed BBD, certain adolescent dietary factors were. A multivariable model simultaneously included the most important diet and body size factors from different age periods: higher BBD risk was associated with greater age 10 year consumption of animal (non-dairy, energy-adjusted) fat (OR 2.27, p < .02, top vs. bottom quartiles) and with lower 14 year consumption of nuts/peanut butter (OR 0.60, p = .033, top vs. bottom quartiles). CONCLUSION: Greater intake of animal (non-dairy) fat at 10 year and lower intake of nuts/peanut butter at 14 year were independently associated with higher BBD risk. These dietary factors appeared to operate on BBD risk independent of childhood growth (gestational weight gain, childhood BMI and height, adolescent height growth velocity), young adult height and BMI, and family history.

Childhood diet and growth in boys in relation to timing of puberty and adult height: the Longitudinal Studies of Child Health and Development.

PURPOSE: To begin to explore the possible roles of childhood diet and growth in prostate cancer (PCa) development, we investigated these exposures in relation to two known/suspected PCa risk factors, earlier pubertal timing and greater attained height, in the Longitudinal Studies of Child Health and Development. METHODS: We used biannual/annual height, weight, and dietary history data to investigate childhood diet, body mass index (BMI), birth length, and childhood height in relation to PCa risk factors (age at peak height velocity (APHV), height at age 13, and adult height) for 64 Caucasian American boys. RESULTS: In adjusted models, childhood fat and animal protein intake was positively associated with height at age 13 and adult height (P < 0.05). A childhood diet high in fat and animal protein and low in vegetable protein was also associated with earlier APHV (P < 0.05), whereas no associations were observed for childhood energy intake or BMI. Birth length and childhood height were positively associated with height at age 13 and adult height, and childhood height was inversely associated with APHV (P < 0.05). CONCLUSION: Our findings suggest that both childhood diet and growth potential/growth contribute to earlier pubertal timing and taller attained height in males, supporting roles of these factors in PCa development.

Weight and weight changes in early adulthood and later breast cancer risk.

Obesity is a well-established cause of postmenopausal breast cancer. However, early life adiposity is inversely associated with breast cancer incidence. To understand these conflicting relations, we use validated measures to assess adiposity in childhood and late adolescence, as well as weight change, in relation to total invasive breast cancer incidence and receptor subtypes. We conducted a prospective observational study among 74,177 women from the Nurses' Health Study from 1980-2012, with updated risk factors every 2 years during which 4,965 incident invasive breast cancers occurred. Overall, weight at age 18 was inversely associated with both premenopausal (HR per 30 kg = 0.52, 95% CI = 0.39-0.71) and postmenopausal (HR per 30 kg = 0.81, 95% CI = 0.72-0.92) breast cancer which was largely explained by adiposity at age 10. Long-term weight gain from age 18 both during premenopause and postmenopause were positively associated with postmenopausal breast cancer risk. However, premenopausal weight gain was not related to premenopausal breast cancer risk. Furthermore, weight gain since age 18 was positively associated with ER+/PR+ postmenopausal breast cancer (HR per 30 kg = 1.50, 95% CI = 1.36-1.65) but not ER+/PR- (HR per 30 kg = 0.96, 95% CI = 0.78-1.19) or ER-/PR- (HR per 30 kg = 1.16, 95% CI = 0.95-1.42) postmenopausal breast cancer. Overall, 17% of ER+/PR+ postmenopausal breast cancer and 14% of total postmenopausal breast cancer are attributable to weight gain of > 5 kg since age 18.

Body size from birth through adolescence in relation to risk of benign breast disease in young women.

PURPOSE: Body size, from birth throughout adulthood, is associated with breast cancer risk, but few studies have investigated early-life body size and benign breast disease (BBD), a well-established breast cancer risk factor. We consider whether prenatal factors and size at birth, 10, 18 year, and intervening growth, are related to BBD risk. METHODS: The Growing Up Today Study includes 9032 females who completed questionnaires annually from 1996 to 2001, then 2003, 2005, 2007, 2010, and 2013. In 1996, their mothers provided pregnancy-related data. From 2005 to 2013, participants (18 year+) reported whether they had ever been diagnosed with biopsy-confirmed BBD (N = 142 cases). RESULTS: Girls had greater adiposity (BMI; kg/m2) at 10 year if they were larger at birth, if mother's pre-pregnancy BMI was higher, or if gestational weight gain was greater (all p < .01). Maternal height was (positively) associated (p < .05) with adolescent peak height growth velocity (PHV; in./year). Greater 10 year adiposity was associated with lower PHV and less height growth 10-18 year (both p < .01). Adiposity at 10 year was inversely associated with BBD (OR 0.83/(kg/m2), p < .01) as was increasing adiposity 10-18 year (OR 0.85/(kg/m2), p = .01). In a separate model, 10 year height (OR 1.13/in., p = .02) and height growth 10-18 year (OR 1.19/in.; p < .01) were positively associated. PHV was similarly positively associated (OR 2.58, p = .01, fastest versus slowest growth quartiles). In a multivariable model of BBD risk, gestational weight gain (daughters at highest risk if <20 lb gained), PHV (slowest growing girls at lowest risk), age 10 year height (positive), and BMI (inverse) were the most critical childhood risk factors (each p < .05). CONCLUSIONS: Body size factors from pregnancy through adolescence were independently associated with BBD risk in young women.

Prenatal factors and infant feeding in relation to risk of benign breast disease in young women.

Benign breast disease (BBD) is a well-established risk factor for breast cancer, but little work has considered a girl's early life and her risk for BBD in adulthood. We investigated factors, from pre-conception through infant feeding practices, in relation to subsequent BBD risk in young women. The Growing Up Today Study (GUTS) includes 9032 females, born 1980-1987, who completed questionnaires annually from 1996 through 2001, then 2003, 2005, 2007, 2010, and 2013. In 1996, their mothers provided each participant's birth weight and length, gestational age, biological father's height, and infant feeding factors (e.g., breast-fed, type of formula). In 1999, their mothers reported maternal pre-pregnancy weight and weight gain during index pregnancy. Beginning in 2005, daughters (18 years+) reported whether they had ever been diagnosed with biopsy-confirmed BBD (n = 142 cases, through 2013). Logistic regression estimated associations between early life factors and biopsy-confirmed BBD. Girls whose mother's BMI prior to pregnancy was 20-25 kg/m(2) were at lower risk of BBD as young women (OR = 0.66, p = 0.04, vs. maternal pre-pregnancy BMI < 20). Girls whose mothers gained 20 + pounds (vs. <20 pounds) during pregnancy were at lower risk (among full-term singleton births: OR = 0.48, p = 0.007, if mother gained 20-35 pounds). However, neither birth weight nor BMI at birth were associated with subsequent BBD risk. We found no evidence that infant feeding practices were linked to BBD. A healthy maternal BMI before pregnancy and sufficient weight gain during pregnancy may produce daughters at lower risk for BBD as young women. Further examination of these findings is needed.

Adolescent dietary vitamin D and sun exposure in relation to benign breast disease.

PURPOSE: Vitamin D may reduce cell proliferation and tumor growth in breast tissue, and exposure may be most important during adolescence when breast tissue is developing. In the Nurses' Health Study II, higher recalled adolescent vitamin D intake was associated with a lower risk of benign breast disease (BBD). Our study aimed to assess adolescent vitamin D exposure in relation to BBD in young women. METHODS: Vitamin D was assessed in 6,593 adolescent girls (9-15 years of age at baseline) in the prospective Growing Up Today Study cohort using the mean energy-adjusted intakes from food frequency questionnaires in 1996, 1997, and 1998. In 1999, 5,286 girls reported skin color, sunscreen use, tanning bed use, and number of sunburns in the past year, and we used state of residence to assess low versus high ultraviolet index. Biopsy-confirmed BBD was reported on questionnaires in 2005, 2007, and 2010 (n = 122). RESULTS: Dietary vitamin D, tanning behaviors, and other sun exposure variables were not significantly associated with BBD in logistic regression models adjusted for age, family history of breast cancer or BBD, age at menarche, nulliparity, alcohol intake, body mass index, and physical activity. The relative risk for the top (>467 IU/day) versus bottom (<243 IU/day) quartile of vitamin D intake was 0.76 (95 % CI 0.47, 1.23). CONCLUSIONS: Sun exposure was not significantly associated with BBD in this prospective cohort. However, a suggestive inverse association between dietary vitamin D and BBD was observed that merits further study.

Breast cancer risk accumulation starts early: prevention must also.

Nearly one in four breast cancers is diagnosed before the age of 50, and many early-stage premalignant lesions are present but not yet diagnosed. Therefore, we review evidence to support the strategy that breast cancer prevention efforts must begin early in life. This study follows the literature review methods and format. Exposures during childhood and adolescence affect a woman's long-term risk of breast cancer, but have received far less research attention than exposures that occur later in life. Breast tissue undergoes rapid cellular proliferation between menarche and first full-term pregnancy, and risk accumulates rapidly until the terminal differentiation that accompanies first pregnancy. Evidence on childhood diet and growth in height, and adolescent alcohol intake, among other adolescent factors is related to breast cancer risk and risk of premalignant proliferative benign lesions. Breast cancer prevention efforts will have the greatest effect when initiated at an early age and continued over a lifetime. Gaps in knowledge are identified and deserve increase attention to inform prevention.

Adolescent physical activity and inactivity: a prospective study of risk of benign breast disease in young women.

In previous investigations of adolescent activity recalled in adulthood, modest reductions in risk of benign breast disease (BBD) and premenopausal breast cancer were seen with moderate-strenuous activity during high school. We therefore investigated physical activity, walking, and recreational inactivity (watching TV-videos, playing computer-videogames) reported by adolescent girls in relation to their subsequent risk for BBD as young women. The Growing Up Today Study includes 9,039 females, 9-15 years at study initiation (1996), who completed questionnaires annually through 2001, then in 2003, 2005, 2007, 2010 and 2013. Annual surveys (1996-2001) obtained data on physical and sedentary activities during the past year. Beginning in 2005, women (≥18 years) reported whether they had ever been diagnosed with BBD confirmed by breast biopsy (n = 133 cases, to 11/01/2013). Logistic regression (adjusted for baseline adiposity and age; additional factors in multivariable-adjusted models) estimated associations between adolescent activities (moderate-vigorous, walking, METS, inactivity) and biopsy-confirmed BBD in young women. Girls who walked the most had significantly lower risk of BBD (multivariable-adjusted OR = 0.61, ≥30 vs ≤15 min/day; p = .049). We observed no evidence that inactivity (≥3 vs <2 h/day OR = 1.02, p = .92) or METS (top vs bottom tertile OR = 1.19, p = .42) were associated with BBD. Accounting for factors including family history, childhood adiposity, and other activities and inactivities, adolescent girls who walked the most were at lower risk for BBD. We found no evidence that high moderate-vigorous activity might reduce risk, nor did we observe any association with inactivity. Continued follow-up will re-evaluate these findings as more BBD cases, and ultimately breast cancer, are diagnosed.

Vegetable protein and vegetable fat intakes in pre-adolescent and adolescent girls, and risk for benign breast disease in young women.

Previous investigations, of adolescent diet recalled in adulthood, found lower risk for benign breast disease (BBD) with higher intakes of vegetable fat and nuts during high school. We investigate whether vegetable protein and fat, derived from diets reported during pre-adolescence and adolescence, are associated with subsequent risk for BBD in young women. The Growing Up Today Study includes 9,039 females, 9-15 years in 1996, who completed questionnaires annually through 2001, and then in 2003, 2005, 2007, and 2010. Food frequency questionnaires (1996-2001) obtained intake data on a variety of foods. Beginning in 2005, women (18-30 years) reported whether they had ever been diagnosed with BBD that was confirmed by breast biopsy (n = 112 cases). Logistic regression estimated associations between intakes of vegetable protein and fat and biopsy-confirmed BBD. Those individual foods that were the largest contributors of protein and fat in this cohort were also investigated. In analyses of intakes from 1996 through 1998, when our cohort was youngest, vegetable fat (OR = 0.72/(10 gm/day), 95 % CI 0.53-0.98; p = 0.04) was inversely associated with BBD risk. The greatest sources of vegetable fat and protein in these girls were peanut butter, peanuts, nuts, beans (beans, lentils, and soybeans), and corn. A daily serving of any one of these was associated with lower risk (OR = 0.32/(serv/day), 95 % CI 0.13-0.79; p = 0.01). Peanut butter (and nuts) at age 11 years was inversely associated with risk (p = 0.01). In analyses of intakes at age 14 years, vegetable protein was associated with lower BBD risk (OR = 0.64/(10 gm/day), 95 % CI 0.43-0.95; p = 0.03). A daily serving at 14 years of any one of the foods was associated with lower risk (OR = 0.34, 95 % CI 0.16-0.75; p = 0.01), as was peanut butter (and nuts) (p = 0.02). Girls with a family history of breast cancer had significantly lower risk if they consumed these foods or vegetable fat. In conclusion, consumption of vegetable protein, fat, peanut butter, or nuts by older girls may help reduce their risk of BBD as young women.

Young women with family history of breast cancer and their risk factors for benign breast disease.

BACKGROUND: Breast cancer (BC) patients wonder how their daughters might reduce their risk. The authors investigated childhood/adolescent risk factors for benign breast disease (BBD), a well-documented risk factor for BC, among girls with a family history. METHODS: GUTS (the Growing Up Today Study) includes females, aged 9 to 15 years in 1996, who completed annual questionnaires during 1996 to 2001, then in 2003, 2005, and 2007. Participants provided information regarding alcohol, menarche, height, and body mass index (BMI; kg/m(2)). Peak height growth velocity (PHV; in./y) was estimated from longitudinal heights. On 2005-2007 surveys, 6888 women (18-27 years old) reported whether they were diagnosed with biopsy-confirmed BBD (n = 67 cases); 6741 women (noncases) reported no BBD. Participants' mothers reported their own biopsy-confirmed BBD and BC, and BC in their sisters and mothers. Stratified by family history, logistic models investigated BBD risk factors. RESULTS: Young women whose mothers or aunts had BC were more likely to be diagnosed with BBD (odds ratio [OR], 2.34; P = .01), as were those with maternal BBD (OR, 1.59; P = .095). Adolescents with BC family history (mother, aunt, grandmother) who consumed alcohol (7 drinks/wk) doubled their BBD risk (OR, 2.28; P = .01), similar to those with maternal BBD (OR, 1.96; P = .02). Girls whose mother or aunt had BC saw their BBD risk elevated with higher PHV (OR, 1.82 [inch/yr]; P = .05). Among girls with no family history, BBD risk appeared to be related to other factors: childhood BMI, adolescent waist circumference, and adult height. CONCLUSIONS: Adolescents with family history may reduce their risk by avoiding alcohol. Separate risk factors were observed among girls with family history versus girls with no family history, possibly reflecting different causes of BC.

Adolescent intakes of vitamin D and calcium and incidence of proliferative benign breast disease.

Vitamin D and calcium have been shown to have protective effects against breast cancer development in animal studies. Vitamin D and calcium play important anticarcinogenic roles in animal studies. Exposures between menarche and first birth may be important in breast development and future breast cancer risk. However, the relations between adolescent vitamin D and calcium intake and the risk of proliferative benign breast disease (BBD), a marker of increased breast cancer risk, have not yet been evaluated. We examined these associations in the Nurses' Health Study II. Among the 29,480 women who completed an adolescent diet questionnaire in 1998, 682 proliferative BBD cases were identified and confirmed by centralized pathology review between 1991 and 2001. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated by Cox proportional hazards regression and adjusted for potential confounders. A suggestive inverse association was observed between adolescent total vitamin D intake and proliferative BBD. Women in the highest quintile of vitamin D intake during adolescence had a 21 % lower risk (multivariate HR (95 % CI): 0.79 (0.61, 1.01), p-trend = 0.07) of proliferative BBD than women in the lowest quintile. Results were essentially the same when the analysis was restricted to prospective cases (n = 142) diagnosed after return of the adolescent diet questionnaire and independent of adult vitamin D intake. Adolescent total milk intake was positively associated with proliferative BBD (≥3 servings/day vs. <1 serving/day HR (95 % CI): 1.41 (0.91, 2.17), p-trend = 0.03), after additional adjustment for total vitamin D. Calcium intake during adolescence was not associated with proliferative BBD (p-trend = 0.91). Vitamin D intake during adolescence may be important in the earlier stage of breast carcinogenesis. These findings, if corroborated, may suggest new pathways and strategies for breast cancer prevention.

Adiposity Change Over the Life Course and Mammographic Breast Density in Postmenopausal Women.

Mammographic breast density is a strong risk factor for breast cancer. We comprehensively investigated the associations of body mass index (BMI) change from ages 10, 18, and 30 to age at mammogram with mammographic breast density in postmenopausal women. We used multivariable linear regression models, adjusted for confounders, to investigate the associations of BMI change with volumetric percent density, dense volume, and nondense volume, assessed using Volpara in 367 women. At the time of mammogram, the mean age was 57.9 years. Compared with women who had a BMI gain of 0.1-5 kg/m2 from age 10, women who had a BMI gain of 5.1-10 kg/m2 had a 24.4% decrease [95% confidence interval (CI), 6.0%-39.2%] in volumetric percent density; women who had a BMI gain of 10.1-15 kg/m2 had a 46.1% decrease (95% CI, 33.0%-56.7%) in volumetric percent density; and women who had a BMI gain of >15 kg/m2 had a 56.5% decrease (95% CI, 46.0%-65.0%) in volumetric percent density. Similar, but slightly attenuated associations were observed for BMI gain from ages 18 and 30 to age at mammogram and volumetric percent density. BMI gain over the life course was positively associated with nondense volume, but not dense volume. We observed strong associations between BMI change over the life course and mammographic breast density. The inverse associations between early-life adiposity change and volumetric percent density suggest that childhood adiposity may confer long-term protection against postmenopausal breast cancer via its effect of mammographic breast density.

Adolescent alcohol, nuts, and fiber: combined effects on benign breast disease risk in young women.

Adolescent drinking is associated with higher risks of proliferative benign breast disease (BBD) and invasive breast cancer (BC). Furthermore, adolescent nut and fiber consumptions are associated with lower risks of benign lesions and premenopausal BC. We hypothesize that diet (nuts, fiber) may mitigate the elevated BBD risk associated with alcohol. A prospective cohort of 9031 females, 9-15 years at baseline, completed questionnaires in 1996-2001, 2003, 2005, 2007, 2010, 2013, and 2014. Participants completed food frequency questionnaires in 1996-2001. In 2005, participants (>=18 years) began reporting biopsy-confirmed BBD (N = 173 cases). Multivariable logistic regression estimated associations between BBD and cross-classified intakes (14-17 years) of alcohol and peanut butter/nuts (separately, total dietary fiber). Only 19% of participants drank in high school; drinking was associated with elevated BBD risk (OR = 1.75, 95% CI: 1.20-2.56; p = 0.004) compared to nondrinkers. Participants consuming any nuts/butter had lower BBD risk (OR = 0.64, 95% CI: 0.45-0.90; p = 0.01) compared to those consuming none. Participants in top 75% fiber intake had lower risk (OR = 0.57, 95% CI: 0.40-0.81; p = 0.002) compared to bottom quartile. Testing our hypothesis that consuming nuts/butter mitigates the elevated alcohol risk, analyzing alcohol and nuts combined found that those who consumed both had lower risk (RR = 0.47, 95% CI: 0.24-0.89; p = 0.02) compared to drinkers eating no nuts. Our analysis of alcohol and fiber together did not demonstrate risk mitigation by fiber. For high school females who drink, their BBD risk may be attenuated by consuming nuts. Due to modest numbers, future studies need to replicate our findings in adolescent/adult females. However, high school students may be encouraged to eat nuts and fiber, and to avoid alcohol, to reduce risk of BBD and for general health benefits.

Weight gain in older adolescent females: the internet, sleep, coffee, and alcohol.

OBJECTIVES: To examine whether excessive recreational Internet time, insufficient sleep, regular coffee consumption, or alcoholic beverages promote weight gain. STUDY DESIGN: A longitudinal cohort of >5000 girls (Growing Up Today Study), from all over the United States and aged 14 to 21 years, returned surveys in 2001 reporting typical past-year recreational Internet time, sleep, coffee (with caffeine), and alcohol consumption. We estimated correlations among these 4 exposures. Each girl also reported her height and weight in 2000 and again in 2001. Multivariate models investigated associations between 1-year change in body mass index and same-year exposures, adjusted for adolescent growth/development, activity, and inactivity. RESULTS: The exposures were highly (P < .0001) correlated with each other, except for coffee with Internet time (P > .50). More Internet time, more alcohol, and less sleep were all associated (P < .05) with same-year increases in body mass index. Females, aged 18+ years, who slept

Milk consumption and acne in teenaged boys.

OBJECTIVE: We sought to examine the association between dietary dairy intake and teenaged acne among boys. METHODS: This was a prospective cohort study. We studied 4273 boys, members of a prospective cohort study of youths and of lifestyle factors, who reported dietary intake on up to 3 food frequency questionnaires from 1996 to 1998 and teenaged acne in 1999. We computed multivariate prevalence ratios and 95% confidence intervals for acne. RESULTS: After adjusting for age at baseline, height, and energy intake, the multivariate prevalence ratios (95% confidence interval; P value for test of trend) for acne comparing highest (>2 servings/d) with lowest (<1/wk) intake categories in 1996 were 1.16 (1.01, 1.34; 0.77) for total milk, 1.10 (0.94, 1.28; 0.83) for whole/2% milk, 1.17 (0.99, 1.39; 0.08) for low-fat (1%) milk, and 1.19 (1.01, 1.40; 0.02) for skim milk. LIMITATIONS: Not all members of the cohort responded to the questionnaire. Acne assessment was by self-report and boys whose symptoms might have been part of an underlying disorder were not excluded. We did not adjust for steroid use and other lifestyle factors that may affect occurrence of acne. CONCLUSION: We found a positive association between intake of skim milk and acne. This finding suggests that skim milk contains hormonal constituents, or factors that influence endogenous hormones, in sufficient quantities to have biological effects in consumers.

Adiposity at Age 10 and Mammographic Density among Premenopausal Women.

Although childhood adiposity is inversely associated with breast cancer risk, the association of childhood adiposity with mammographic density in premenopausal women has not been adequately studied. We analyzed data from 365 premenopausal women who came in for screening mammography at Washington University (St. Louis, MO) from 2015 to 2016. Body size at age 10 was self-reported using somatotype pictogram. Body mass index (BMI) at age 10 was imputed using data from Growing Up Today Study. Volpara software was used to evaluate volumetric percent density (VPD), dense volume (DV), and nondense volume (NDV). Adjusted multivariable linear regression models were used to evaluate the associations between adiposity at age 10 and mammographic density measures. Adiposity at age 10 was inversely associated with VPD and positively associated with NDV. A 1 kg/m2 increase in BMI at age 10 was associated with a 6.4% decrease in VPD, and a 6.9% increase in NDV (P < 0.001). Compared with women whose age 10 body size was 1 or 2, women with body size 3 or 4 had a 16.8% decrease in VPD and a 26.6% increase in NDV, women with body size 5 had a 32.2% decrease in VPD and a 58.5% increase in NDV, and women with body sizes ≥6 had a 47.8% decrease in VPD and a 80.9% increase in NDV (P < 0.05). The associations were attenuated, but still significant after adjusting for current BMI. Mechanistic studies to understand how childhood adiposity influences breast development, mammographic density, and breast cancer in premenopausal women are needed. Cancer Prev Res; 11(5); 287-94. ©2018 AACR.

Adiposity in adolescents: change in actual BMI works better than change in BMI z score for longitudinal studies.

PURPOSE: Longitudinal epidemiologic studies often relate adiposity changes to suspected causal factors. In growing adolescents, this becomes complicated. Many investigators use within-child change in body mass index (BMI) z scores (Delta z) from sex- and age-specific BMI charts developed by the Centers for Disease Control and Prevention (CDC). These charts, derived from cross-sectional data, may not represent BMI growth patterns of real children. Furthermore, because cross-sectional BMIs are not Gaussian, these z scores are from month-specific transformed distributions, with possible unintended consequences when used longitudinally. Alternatively, we can directly analyze BMI change (Delta BMI). We compare these two widely used measures of change in adiposity. METHODS AND RESULTS: With real adolescent data, we show that annual Delta BMIs have nonlinear peaks that are inconsistent with the CDC curves. We also show that a specified Delta z represents a broad range of adiposity changes for children measured at the same two ages. To see how this affects power, we performed simulation studies confirming that analyzing Delta BMIs in models with hypothesized factors is more powerful than analyzing Delta zs. CONCLUSIONS: In longitudinal studies of adolescent adiposity, investigators should be encouraged to analyze Delta BMI rather than Delta z because analyses using BMI are more powerful and findings presented in BMI units are more interpretable.

Milk consumption and acne in adolescent girls.

There has been a remarkable paucity of evidence for an association between diet and acne. Our previous studies suggest that there is an association between milk intake and teenage acne. This is a prospective cohort study to evaluate that relationship. We studied 6,094 girls, aged 9-15 years in 1996, who reported dietary intake on up to three food frequency questionnaires from 1996 to 1998. Presence and severity of acne was assessed by questionnaire in 1999. We computed multivariate prevalence ratios (PR) and 95 percent confidence intervals for acne. After accounting for age at baseline, height and energy intake, the multivariate PRs (95 % CI; p-value for test of trend) for acne comparing highest (2 or more servings per day) to lowest (<1 per week) intake categories in 1996, were 1.20 (1.09, 1.31; <0.001) for total milk, 1.19 (1.06, 1.32; <0.001) for whole milk, 1.17 (1.04, 1.31; 0.002) for low fat milk and 1.19 (1.08, 1.31; <0.001) for skim milk. This result did not change appreciably when we excluded girls who reported use of contraceptives and when we restricted our analysis to those younger than 11 years of age at baseline. We found a positive association between intake of milk and acne. This finding supports earlier studies and suggests that the metabolic effects of milk are sufficient to elicit biological responses in consumers.

Milk, dairy fat, dietary calcium, and weight gain: a longitudinal study of adolescents.

BACKGROUND: Milk is promoted as a healthy beverage for children, but some researchers believe that estrone and whey protein in dairy products may cause weight gain. Others claim that dairy calcium promotes weight loss. OBJECTIVE: To assess the associations between milk, calcium from foods and beverages, dairy fat, and weight change over time.Design, Subjects, and Outcome Measure We followed a cohort of 12 829 US children, aged 9 to 14 years in 1996, who returned questionnaires by mail through 1999. Children annually reported their height and weight and completed food frequency questionnaires regarding typical past-year intakes. We estimated associations between annual change in body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) and our dietary factors, adjusted for adolescent growth and development, race, physical activity, inactivity, and (in some models) total energy intake. RESULTS: Children who drank more than 3 servings a day of milk gained more in BMI than those who drank smaller amounts (boys: beta +/- SE, 0.076 +/- 0.038 [P = .04] more than those who drank 1 to 2 glasses a day; girls: beta +/- SE, 0.093 +/- 0.034 [P = .007] more than those who drank 0 to 0.5 glass a day). For boys, milk intake was associated with small BMI increases during the year (beta +/- SE, 0.019 +/- 0.009 per serving a day; P = .03); results were similar for girls (beta +/- SE, 0.015 +/- 0.007 per serving a day; P = .04). Quantities of 1% milk (boys) and skim milk (girls) were significantly associated with BMI gain, as was total dietary calcium intake. Multivariate analyses of milk, dairy fat, calcium, and total energy intake suggested that energy was the most important predictor of weight gain. Analyses of year-to-year changes in milk, calcium, dairy fat, and total energy intakes provided generally similar conclusions; an increase in energy intake from the prior year predicted BMI gain in boys (P = .003) and girls (P = .03). CONCLUSIONS: Children who drank the most milk gained more weight, but the added calories appeared responsible. Contrary to our hypotheses, dietary calcium and skim and 1% milk were associated with weight gain, but dairy fat was not. Drinking large amounts of milk may provide excess energy to some children.

Dietary composition and weight change among low-income preschool children.

OBJECTIVE: To examine the relation between dietary composition and weight change among children. We tested several hypotheses considering intake of nutrients (total fat and fiber) and predefined food groups (breads and grains, "fat foods," fruits, and vegetables) used in the North Dakota Special Supplemental Nutrition Program for Women, Infants, and Children (WIC Program). DESIGN: Prospective study. Subjects We collected dietary, anthropometric, and sociodemographic data from 1379 children aged 2 to 5 years participating in the North Dakota WIC Program on 2 visits ranging from 6 to 12 months apart. Main Outcome Measure Annual change in weight. RESULTS: In multiple regression analyses, no significant relations were found between total intake of fat, fiber, fruits, or vegetables and weight change. There was a 0.16-kg lower weight change per year (95% confidence interval [CI], -0.20 to -0.12 kg; P<.01) with each additional daily serving of breads and grains, and a 0.05-kg greater weight change per year (95% CI, 0.1-0.09 kg; P<.05) for each additional serving of fat foods in a model adjusting for sex, age, baseline weight, change in height, and sociodemographic variables. CONCLUSIONS: Intake of North Dakota WIC Program-defined fat foods, but not dietary fat per se, significantly predicted weight gain, whereas intake of North Dakota WIC Program-defined breads and grains, but not fiber per se, significantly predicted weight loss in preschool children.