Nutrition and Physical Activity and Chronic Disease Prevention: Research Strategies and Recommendations

Cooking Methods and Their Relationship with Anthropometrics and Cardiovascular Risk Factors among Older Spanish Adults

Food consumption has a prominent role in the occurrence of cardiometabolic diseases, however, little is known about the specific influence of cooking methods. This study examined the association between cooking methods and anthropometrics, cardiovascular risk factors, and cardiac damage biomarkers in older adults. Data were taken from 2476 individuals aged ≥65 from the Seniors-ENRICA 2 cohort in Spain and recruited between 2015 and 2017. Eight cooking methods (raw, boiling, roasting, pan-frying, frying, toasting, sautéing, and stewing) were assessed using a face-to-face validated dietary history. Study associations were summarized as adjusted percentage differences (PDs) in anthropometrics, cardiovascular risk factors, and cardiac damage biomarkers between extreme sex-specific quintiles ((5th − 1st/1st) × 100) of food consumed with each cooking method, estimated using marginal effects from generalized linear models. After adjusting for potential confounders, including diet quality, PDs corresponding to raw food consumption were −13.4% (p-trend: <0.001) for weight, −12.9% (p-trend: <0.001) for body mass index (BMI), −14.8% (p-trend: <0.001) for triglycerides, and −13.6% (p-trend: <0.115) for insulin. PDs for boiled food consumption were −13.3% (p-trend: <0.001) for weight, −10.0% (p-trend: <0.001) for BMI, and −20.5% (p-trend: <0.001) for insulin. PDs for roasted food consumption were −11.1 (p-trend: <0.001) for weight and −23.3% (p-trend: <0.001) for insulin. PDs for pan-fried food consumption were −18.7% (p-trend: <0.019) for insulin, −15.3% (p-trend: <0.094) for pro-B-type natriuretic peptide amino-terminal, and −10.9% (p-trend: <0.295) for troponin T. No relevant differences were observed for blood pressure nor for other cooking methods. Raw food consumption along with boiling, roasting, and pan-frying were associated with healthier cardiovascular profiles, mainly due to lower weight and insulin levels. Future experimental research should test the effectiveness of these cooking methods for cardiovascular prevention in older adults.

Validation and Test of Measurement Invariance of the Adapted Health Consciousness Scale (HCS-G)

The objective of this study was the translation and validation of a health consciousness scale in order to provide an economically and empirically confirmed measurement of health consciousness, which is associated with health-related behavior. We evaluated this translation on the basis of psychometric testing in a German convenience sample. A cross-sectional online survey (n = 470) was carried out using a translated version of the health consciousness scale, oriented on the basis of international guidelines. As previous studies have not consistently confirmed the factorial structure of the health consciousness scale, we conducted a Confirmatory Factor Analysis to verify its factorial structure. Furthermore, we cross-validated the questionnaire with other scales in order to verify convergent and discriminant validity. The results indicated a two-factor solution for the Health Consciousness Scale-German (HCS-G). The criterion validity was confirmed on the basis of a significantly positive correlation between the HCS-G and health literacy. Furthermore, strict measurement invariance was able to be verified, indicating that the HCS-G is an applicable measurement, regardless of gender. In practical research, this questionnaire can help to assess health consciousness and its influence on health-related constructs. Future studies should consider possible mediating variables between health consciousness and health outcomes.

Evaluation of potential metabolomic-based biomarkers of protein, carbohydrate and fat intakes using a controlled feeding study

PURPOSE

Objective biomarkers of dietary exposure are needed to establish reliable diet-disease associations. Unfortunately, robust biomarkers of macronutrient intakes are scarce. We aimed to assess the utility of serum, 24-h urine and spot urine high-dimensional metabolites for the development of biomarkers of daily intake of total energy, protein, carbohydrate and fat, and the percent of energy from these macronutrients (%E).

METHODS

A 2-week controlled feeding study mimicking the participants' habitual diets was conducted among 153 postmenopausal women from the Women's Health Initiative (WHI). Fasting serum metabolomic profiles were analyzed using a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for aqueous metabolites and a direct-injection-based quantitative lipidomics platform. Urinary metabolites were analyzed using ¹H nuclear magnetic resonance (NMR) spectroscopy at 800 MHz and by untargeted gas chromatography-mass spectrometry (GC-MS). Variable selection was performed to build prediction models for each dietary variable.

RESULTS

The highest cross-validated multiple correlation coefficients (CV-R²) for protein intake (%E) and carbohydrate intake (%E) using metabolites only were 36.3 and 37.1%, respectively. With the addition of established dietary biomarkers (doubly labeled water for energy and urinary nitrogen for protein), the CV-R² reached 55.5% for energy (kcal/d), 52.0 and 45.0% for protein (g/d, %E), 55.9 and 37.0% for carbohydrate (g/d, %E).

CONCLUSION

Selected panels of serum and urine metabolites, without the inclusion of doubly labeled water and urinary nitrogen biomarkers, give a reliable and robust prediction of daily intake of energy from protein and carbohydrate.

Reproducibility of Accelerometer and Posture-derived Measures of Physical Activity

PURPOSE

The present study estimated the long-term reproducibility of accelerometer-based measures over 6 months in adults and the implications for statistical power, and attenuation in regression coefficients for future activity-disease studies.

METHODS

We used data from 914 adults in the Interactive Diet and Activity Tracking in AARP study. Participants wore an activPAL 3 (AP) and an ActiGraph GT3X (AG) twice, 6 months apart. AP measures included time spent sitting or lying, standing, and stepping, whereas AG measures included time spent in sedentary, light, and moderate-to-vigorous physical activity (PA). Reproducibility of each metric and implications for epidemiological studies were determined based on intraclass correlation coefficients (ICC; 95% confidence interval).

RESULTS

The ICC values for AP estimates were 0.58 (95% confidence interval, 0.53-0.63) for sitting, 0.62 (0.57-0.67) for standing, and 0.57 (0.51-0.62) for stepping. The ICC values for AG were 0.56 (0.50-0.61) for sedentary, 0.54 (0.49-0.60) for light PA, and 0.58 (0.52-0.63) for moderate-to-vigorous PA. Modeling showed that increasing the number of replicate administrations to two or three resulted in the most noticeable increases in ICC values, statistical power, and reductions in attenuation coefficients. For example, administering the AP twice reduced within-subject variability by half and resulted in an increase in the ICC associated with sitting time from 0.58 to 0.74. Similar comparisons for AG and measure of sedentary time resulted in an increase in ICC values from 0.56 to 0.72. Increasing the number of replicate administrations from one to two reduced the attenuation in activity-outcome associations from 40% to 25%.

CONCLUSION

Accelerometer-based classifications of activity are moderately stable over time, but there is considerable within-subject variability that needs to be considered when estimating usual activity in future studies.

Test-Retest Reliability of a Food Frequency Questionnaire to Assess Seafood Intake Dynamics for High-End Consumers in Coastal Gulf of Mexico Communities

Background

Estimates for fish and shellfish intake are used to inform communities and healthcare systems about potential health risks and benefits for individuals, communities, and vulnerable populations. A dietary assessment instrument was designed for use in populations of high-end consumers of seafood to examine intake of finfish, shrimp, oysters, and blue crab in coastal communities across the Gulf of Mexico.

Objective

To validate the reliability of a novel food frequency questionnaire (FFQ) for seafood intake.

Design

Test-retest reliability of the FFQ, which included a species-specific photographic portion guide, was evaluated by the inperson administration and readministration of the instrument with each participant by the same interviewer. Responses from coastal and noncoastal participants were compared to discern FFQ reliability in heterogeneous samples. Participants/setting. A convenience sample of 27 coastal participants from Cedar Key, Steinhatchee, and Apalachicola, Florida, reported data for 101 household members; and 15 noncoastal participants from Gainesville, Florida, reported for 42 household members. Analysis. Repeated measures from the FFQ were evaluated using correlation concordance for continuous variables (age, weight, and height) and kappa coefficient for categorical variables (type, amount, and frequency of seafood consumed).

Results

Concordance correlation coefficient (1.00) and kappa coefficient (r = 0.73 to 1.00) for yearly and seasonal seafood consumption indicated substantial to almost perfect reproducibility, i.e., participants provided responses that were reproducible. Test-retest agreement was highest for coastal participants who consumed more seafood, as compared to occasional, noncoastal consumers, based on the intergroup comparison of kappa coefficients for yearly and seasonal seafood consumption (r = 0.69 to 0.99).

Conclusions

The seafood FFQ instrument evaluated in this study, included as a supplement to this report, used in tandem with a photographic portion guide, provides a utilitarian tool for assessing fish, shrimp, oyster, and blue crab intake dynamics in adult and youth populations drawn from coastal communities.

Perspective: Dietary Biomarkers of Intake and Exposure-Exploration with Omics Approaches

While conventional nutrition research has yielded biomarkers such as doubly labeled water for energy metabolism and 24-h urinary nitrogen for protein intake, a critical need exists for additional, equally robust biomarkers that allow for objective assessment of specific food intake and dietary exposure. Recent advances in high-throughput MS combined with improved metabolomics techniques and bioinformatic tools provide new opportunities for dietary biomarker development. In September 2018, the NIH organized a 2-d workshop to engage nutrition and omics researchers and explore the potential of multiomics approaches in nutritional biomarker research. The current Perspective summarizes key gaps and challenges identified, as well as the recommendations from the workshop that could serve as a guide for scientists interested in dietary biomarkers research. Topics addressed included study designs for biomarker development, analytical and bioinformatic considerations, and integration of dietary biomarkers with other omics techniques. Several clear needs were identified, including larger controlled feeding studies, testing a variety of foods and dietary patterns across diverse populations, improved reporting standards to support study replication, more chemical standards covering a broader range of food constituents and human metabolites, standardized approaches for biomarker validation, comprehensive and accessible food composition databases, a common ontology for dietary biomarker literature, and methodologic work on statistical procedures for intake biomarker discovery. Multidisciplinary research teams with appropriate expertise are critical to moving forward the field of dietary biomarkers and producing robust, reproducible biomarkers that can be used in public health and clinical research.

Effect of home-based strength training program on IGF-I, IGFBP-1 and IGFBP-3 in obese Latino boys participating in a 16-week randomized controlled trial

Introduction Growing evidence indicates that circulating concentrations of insulin-like growth factor 1 (IGF-I), along with IGF-I relative to IGF-binding proteins (IGFBP), are associated with an increased risk of cancer. In accord, regular exercise is linked with a lower risk of cancer. Purpose To assess the effects of a 16-week home-based strength training (HBST) program on serum IGF-I, IGFBP-1 and IGFBP-3. Methods A total of 32 obese Latino adolescent males (aged 14-18 years) were randomized into a twice-weekly HBST (n = 16) or a control group (C, n = 16) for 16 weeks. The following were measured at pre- and post-intervention: IGF-I, IGFBP-1 and IGFBP-3, glucose/insulin indices by oral and/or intravenous (IV) glucose tolerance tests, strength by one-repetition maximum (1RM), dietary intake by 3-d records, body composition by DEXA and physical activity using the Actigraph GT1X. The generalized linear model (GLM) was used to assess differences in changes among outcome measures between the HBST and C groups. Results Exercise adherence in the HBST group was 89%. IGF-1 showed a trend for significant within-subject improvements (p = 0.078) but no significant within-subject or between-subject differences for IGFBP-1, IGFBP-3 two-glucose, fasting glucose or 2-h glucose (p > 0.05). There was a significant decrease (p > 0.05) in fasting glucose in the C group (p = 0.02) and also in the intervention group (p = 0.03) between baseline and follow-up testing. A significant difference was also found in the C group for 2-h glucose with an increase at follow-up testing (p = 0.04). Conclusions Though not statistically significant (p < 0.05), the results indicated that a 16-week HBST program decreased IGF-I and increased IGFBP-1, along with IGFBP-3, concentrations among overweight/obese Latino boys. However, further studies should consider increasing either the dose or the duration of the intervention to elicit greater improvements in this at-risk pediatric population.

Domain-specific physical activity and sedentary behaviour in relation to colon and rectal cancer risk: a systematic review and meta-analysis

Background

Physical activity is associated with reduced risk of colorectal cancer, but most epidemiological studies have focused on occupational and recreational physical activity. The evidence for other domains of activity, and for sedentary behaviour, is limited.

Methods

Medline, Embase and Web of Science were searched from inception to December 2015 for studies examining domain-specific physical activity or sedentary behaviour and the risk of colon and/or rectal cancer. We extracted maximally adjusted relative risks (RRs) except when RRs not adjusted for body mass index, were also presented. We used random-effects meta-analysis to compute pooled RRs comparing the highest versus the lowest level of exposure. We used meta-regression to assess sources of heterogeneity in estimates.

Results

We identified 17 cohort and 21 case-control studies, of which 17 had occupational data, 23 had recreational data, three each had data on transport and household physical activity domains, and 6 studies had data on occupational sedentary behaviour. The pooled relative risks (RRs) for colon cancer were 0.74 (95% confidence interval (CI): 0.67, 0.82) for occupational activity, 0.80 (95% CI: 0.71, 0.89) for recreational activity, 0.66 (95% CI: 0.45, 0.98) for transport-related physical activity, 0.85 (95% CI: 0.71, 1.02) for household physical activity, and 1.44 (95% CI: 1.28, 1.62) for occupational sedentary behaviour. For rectal cancer, the pooled RRs were 0.88 (95% CI: 0.79, 0.98) for occupational activity, 0.87 (95% CI: 0.75, 1.01) for recreational activity, 0.88 (95% CI: 0.70, 1.12) for transport-related physical activity, 1.01 (95% CI: 0.80, 1.27) for household physical activity, and 1.02 (95% CI: 0.82, 1.28) for occupational sedentary behaviour.

Conclusions

In addition to increasing occupational and recreational physical activity, promoting physical activity during transport and reducing sedentary behaviour in the workplace may also be useful colorectal cancer prevention strategies.

Serum untargeted metabolomic profile of the Dietary Approaches to Stop Hypertension (DASH) dietary pattern

Background

The Dietary Approaches to Stop Hypertension (DASH) dietary pattern is recommended for cardiovascular disease risk reduction. Assessment of dietary intake has been limited to subjective measures and a few biomarkers from 24-h urine collections.

Objective

The aim of the study was to use metabolomics to identify serum compounds that are associated with adherence to the DASH dietary pattern.

Design

We conducted untargeted metabolomic profiling in serum specimens collected at the end of 8 wk following the DASH diet (n = 110), the fruit and vegetables diet (n = 111), or a control diet (n = 108) in a multicenter, randomized clinical feeding study (n = 329). Multivariable linear regression was used to determine the associations between the randomized diets and individual log-transformed metabolites after adjustment for age, sex, race, education, body mass index, and hypertension. Partial least-squares discriminant analysis (PLS-DA) was used to identify a panel of compounds that discriminated between the dietary patterns. The area under the curve (C statistic) was calculated as the cumulative ability to distinguish between dietary patterns. We accounted for multiple comparisons with the use of the Bonferroni method (0.05 of 818 metabolites = 6.11 × 10-5).

Results

Serum concentrations of 44 known metabolites differed significantly between participants randomly assigned to the DASH diet compared with both the control diet and the fruit and vegetables diet, which included an amino acid, 2 cofactors and vitamins (n = 2), and lipids (n = 41). With the use of PLS-DA, component 1 explained 29.4% of the variance and component 2 explained 12.6% of the variance. The 10 most influential metabolites for discriminating between the DASH and control dietary patterns were N-methylproline, stachydrine, tryptophan betaine, theobromine, 7-methylurate, chiro-inositol, 3-methylxanthine, methyl glucopyranoside, β-cryptoxanthin, and 7-methylxanthine (C statistic = 0.986).

Conclusions

An untargeted metabolomic platform identified a broad array of serum metabolites that differed between the DASH diet and 2 other dietary patterns. This newly identified metabolite panel may be used to assess adherence to the DASH dietary pattern. This trial was registered at http://www.clinicaltrials.gov as NCT03403166.

Lifestyle Interventions for Breast Cancer Prevention

One-in-eight women in the United States will develop breast cancer in her lifetime. Despite the established efficacy of selective estrogen receptor modulators and aromatase inhibitors in reducing the risk of developing hormone receptor positive breast cancer, use of these therapies in clinical practice is often limited by concerns over toxicities that may negatively influence quality of life. There is emerging interest in the oncology community to understand how modifiable risk factors related to energy balance-such as obesity, physical inactivity, and poor dietary patterns-may relate to breast cancer risk. Over the past three decades, observational studies have reported that obesity, physical inactivity, sedentary behavior, and dietary patterns are associated with increased breast cancer risk. However, uncertainty exists about whether the observed associations are attributable to confounding from other factors. Randomized controlled trials are necessary to provide unbiased efficacy estimates of lifestyle changes on breast cancer risk. However, such trials would typically require a large sample size, long-term follow up, and substantial financial investment. One approach to manage these barriers is to leverage recent advances in precision prevention to select high-risk study participants to reduce sample size or shorten length of follow up. This approach may accelerate the translation of epidemiologic discoveries into proven population-based breast cancer prevention interventions.

The Physical Activity-Related Barriers and Facilitators Perceived by Men Living in Rural Communities

Men, especially those living in rural areas, experience chronic disease at higher rates than the general population. Physical activity is a well-established protective factor against many chronic diseases; however, only a small fraction of men are meeting national guidelines for physical activity. The purpose of this study was to examine the perceived physical activity-related barriers and facilitators experienced by men living in rural areas in Canada. Participants completed a paper-and-pencil or online survey and asked to select personally relevant physical activity-related barriers and facilitators from a list of 9 and 10 choices, respectively. A total of 149 men completed the survey (50.3% between the ages of 18 and 55 years; 43.0% older than 55 years). Participants were predominantly from rural areas and smaller communities. Overall, the response options "I'm too tired," "I don't have enough time," and "I think I get enough exercise as work" were the three most frequently cited barriers to regular physical activity. The response options "Personal motivation to be healthy," "I enjoy it," and "Support from family and/or friends" were the three most often cited facilitators to physical activity. Results are similar to those shown in other populations. Results can be used to inform the development of policies and programs that aim to increase the physical activity levels of men living in rural areas and small communities.

Differences in physical activity, eating habits and risk of obesity among Kuwaiti adolescent boys and girls: a population-based study

The study aimed to assess gender differences among Kuwaiti adolescents in healthy living choices that impact the risk of obesity. A cross-sectional multistage cluster design was employed with a representative sample of 2672 students aged 13-15 years who completed a self-administered Global School-based Student Health (GSHS) survey. The study found that around 48.0% of adolescents were overweight and obese. More boys than girls were obese (28.2% vs. 22.3%, p < 0.0001). However, boys were more likely than girls to report healthy food choices regarding fruit (38.1% vs. 33.2%), and vegetables (21.8% vs. 16.7%). Only 20.7% of adolescents reported physical activity for more than 60 min/day, predominately by boys rather than girls (30.8% vs. 10.5%, respectively, p < 0.0001). Multivariate analysis revealed that male gender, skipping breakfast and physical inactivity were significantly correlated with the risk of overweight and obesity among adolescents. These results suggest that lifestyle education for promoting healthy body masses targeting adolescents should take gender into account.

Reliability and concurrent and construct validity of the Strategies for Weight Management measure for adults

INTRODUCTION

This study evaluates the reliability and validity of the strategies for weight management (SWM) measure, a questionnaire that assesses weight management strategies for adults. The SWM includes 20 items that are categorized within the following subscales: (1) energy intake, (2) energy expenditure, (3) self-monitoring, and (4) self-regulation.

METHODS

Baseline and 6-month data were collected from 404 overweight/obese adults (mean age=22±3.8 years, 68% ethnic minority) enrolled in a randomized controlled trial aiming to reduce weight by improving diet and physical activity behaviours. Reliability and validity were assessed for each subscale separately. Cronbach alpha was conducted to assess reliability. Concurrent, construct I (sensitivity to the study treatment condition), and construct II (relationship to the outcomes) validity were assessed using linear regressions with the following outcome measures: weight, self-reported diet, and weekly energy expenditure.

RESULTS

All subscales showed strong internal consistency. The strength of the validity evidence depended on subscale and validity type. The strongest validity evidence was concurrent validity of the energy intake and energy expenditure subscales; construct I validity of the energy intake and self-monitoring subscales; and construct II validity of the energy intake, energy expenditure, and self-regulation subscales.

CONCLUSIONS

Results indicate that the SWM can be used to assess weight management strategies among an ethnically diverse sample of adults as each subscale showed evidence of reliability and select types of validity. As validity is an accumulation of evidence over multiple studies, this study provides initial reliability and validity evidence in one population segment.

Dietary patterns and breast cancer risk: a study in 2 cohorts

BACKGROUND

Evidence for a role of dietary risk factors in the cause of breast cancer has been inconsistent. The evaluation of overall dietary patterns instead of foods in isolation may better reflect the nature of true dietary exposure in a population.

OBJECTIVE

We used 2 cohort studies to identify and confirm associations between dietary patterns and breast cancer risk.

DESIGN

Dietary patterns were derived by using a principal components factor analysis in 1097 breast cancer cases and an age-stratified subcohort of 3320 women sampled from 39,532 female participants in the Canadian Study of Diet, Lifestyle and Health (CSDLH). We conducted a confirmatory factor analysis in 49,410 subjects in the National Breast Screening Study (NBSS) in whom 3659 cases of incident breast cancer developed. Cox regression models were used to estimate HRs for the association between derived dietary factors and risk of breast cancer in both cohorts.

RESULTS

The following 3 dietary factors were identified from the CSDLH: healthy, ethnic, and meat and potatoes. In the CSDLH, the healthy dietary pattern was associated with reduced risk of breast cancer (HR for high compared with low quintiles: 0.73; 95% CI: 0.58, 0.91; P-trend = 0.001), and the meat and potatoes dietary pattern was associated with increased risk in postmenopausal women only (HR for high compared with low quintiles: 1.26; 95% CI: 0.92, 1.73; P-trend = 0.043). In the NBSS, the association between the meat and potatoes pattern and postmenopausal breast cancer risk was confirmed (HR: 1.31; 95% CI: 0.98, 1.76; P-trend = 0.043), but there was no association between the healthy pattern and risk of breast cancer.

CONCLUSION

Adherence to a plant-based diet that limits red meat intake may be associated with reduced risk of breast cancer, particularly in postmenopausal women.

Factors affecting fruit and vegetable school lunch waste in Wisconsin elementary schools participating in Farm to School programmes

OBJECTIVE

To examine characteristics potentially associated with school lunch fruit and vegetable waste, both overall and pre/post implementation of the Healthy, Hunger-Free Kids Act.

DESIGN

Multi-year (2010-2013) cross-sectional study using pre- and post-meal digital photographs of students' school lunch trays to estimate fruit and vegetable availability and consumption. Fruit and vegetable items were categorized for factors suspected to impact waste: prior farm to school years, placement (main menu, salad bar), procurement (local, conventional), preparation (cooked, raw) and meal component (entrée, side, topping). Analyses to assess within-category differences in waste volume were performed using a Tobit model.

SETTING

Wisconsin elementary schools participating in farm to school programmes, USA.

SUBJECTS

Children in third to fifth grade.

RESULTS

Many within-factor differences were detected overall and/or across time. Cooked fruits were wasted less than raw, while cooked vegetables were wasted more than raw. Where identified, locally sourced items were wasted more than conventionally sourced (+0·1 cups, P<0·0001) and salad bar items more than main menu items (+0·01 cups, P<0·0001). Increasing prior farm to school years decreased waste (-0·02 cups, P<0·0001). Items previously tried were wasted at the same volume whether reported as liked or not. New school lunch meal pattern requirement implementation did not uniformly impact fruit and vegetable waste across all categories and there was no change in waste for seven of fifteen assessed categories.

CONCLUSIONS

Many factors impact elementary students' school lunch waste. These factors may be helpful for school food-service authorities to consider when planning school menus.

A vision for chronic disease prevention intervention research: report from a workshop

The Population Studies Research Network of Cancer Care Ontario hosted a strategic planning workshop to establish an agenda for a prevention intervention research program in Ontario, including priority topics for investigation and design considerations. The two-day workshop included: presentations on background papers developed to facilitate participants' preparation for and discussions in the workshop; keynote presentations on intervention research concerning primary prevention of chronic diseases, design and study implementation considerations; a dedicated session on critical and creative thinking to stimulate participation and discussion topics; break out groups to identify, discuss and present study ideas, designs, implementation considerations; and a consensus process to discuss and identify recommendations for research priorities and next steps. The retreat yielded the following recommendations: 1) develop an intervention research agenda that includes working with existing large-scale cohorts; 2) develop an intervention research agenda that includes novel research designs that could target individuals or groups; and 3) develop an intervention research agenda in which studies collect data on costs, define stakeholders, and ensure clear strategies for stakeholder engagement and knowledge transfer. The Population Studies Research Network will develop options from these recommendations and release a call for proposals in 2014 for intervention research pilot projects that reflect these recommendations. Pilot projects will be evaluated based on their fit with the retreat's recommendations, and their potential to scale up to full studies and application in practice.

Applying the Health Belief Model to college students' health behavior

The purpose of this research was to investigate how university students' nutrition beliefs influence their health behavioral intention. This study used an online survey engine (Qulatrics.com) to collect data from college students. Out of 253 questionnaires collected, 251 questionnaires (99.2%) were used for the statistical analysis. Confirmatory Factor Analysis (CFA) revealed that six dimensions, "Nutrition Confidence," "Susceptibility," "Severity," "Barrier," "Benefit," "Behavioral Intention to Eat Healthy Food," and "Behavioral Intention to do Physical Activity," had construct validity; Cronbach's alpha coefficient and composite reliabilities were tested for item reliability. The results validate that objective nutrition knowledge was a good predictor of college students' nutrition confidence. The results also clearly showed that two direct measures were significant predictors of behavioral intentions as hypothesized. Perceived benefit of eating healthy food and perceived barrier for eat healthy food to had significant effects on Behavioral Intentions and was a valid measurement to use to determine Behavioral Intentions. These findings can enhance the extant literature on the universal applicability of the model and serve as useful references for further investigations of the validity of the model within other health care or foodservice settings and for other health behavioral categories.

Reliability and validity of child/adolescent food frequency questionnaires that assess foods and/or food groups

OBJECTIVE

Summarize the validity and reliability of child/adolescent food frequency questionnaires (FFQs) that assess food and/or food groups.

METHODS

We performed a systematic review of child/adolescent (6-18 years) FFQ studies published between January 2001 and December 2010 using MEDLINE, Cochrane Library, PsycINFO, and Google Scholar. Main inclusion criteria were peer reviewed, written in English, and reported reliability or validity of questionnaires that assessed intake of food/food groups. Studies were excluded that focused on diseased people or used a combined dietary assessment method. Two authors independently selected the articles and extracted questionnaire characteristics such as number of items, portion size information, time span, category intake frequencies, and method of administration. Validity and reliability coefficients were extracted and reported for food categories and averaged across food categories for each study.

RESULTS

Twenty-one studies were selected from 873, 18 included validity data, and 14 included test-retest reliability data. Publications were from the United States, Europe, Africa, Brazil, and the south Pacific. Validity correlations ranged from 0.01 to 0.80, and reliability correlations ranged from 0.05 to 0.88. The highest average validity correlations were obtained when the questionnaire did not assess portion size, measured a shorter time span (ie, previous day/week), was of medium length (ie, ≈ 20-60 items), and was not administered to the child's parents.

CONCLUSIONS

There are design and administration features of child/adolescent FFQs that should be considered to obtain reliable and valid estimates of dietary intake in this population.

Prevalence of the equol-producer phenotype and its relationship with dietary isoflavone and serum lipids in healthy Chinese adults

BACKGROUND

Studies have suggested that daidzein-metabolizing phenotypes have beneficial effects on a range of health outcomes. We investigated the prevalence of equol producers and the relationship of equol phenotype with habitual isoflavone consumption and serum lipid concentrations in 200 Chinese adults in Beijing.

METHODS

After the baseline survey and dietary records, 200 healthy adults in Beijing were challenged with a soy-isoflavone supplement for 3 days; 24-hour urine samples were collected before and after the challenge. Isoflavones and their metabolites in urine were measured to determine equol phenotype. Serum lipids, uric acid, and other biochemical markers were also measured.

RESULTS

Only 26.8% of the participants excreted equol when on a regular diet, as compared with 60.4% after the challenge. After the challenge, urinary isoflavonoid excretion increased in all participants, while equol excretion increased only in equol producers. Isoflavone intake was correlated with urinary isoflavone (range r = 0.49-0.58, P < 0.01). As compared with nonproducers, equol producers were less likely to consume cereals (P < 0.001). There was no significant correlation between serum lipids and isoflavone intake. Serum lipids were not significantly affected by equol phenotype.

CONCLUSIONS

Urinary equol excretion was detected in about 25% of participants under their usual dietary conditions. Their potential to produce equol was increased after the challenge. Urinary isoflavone levels may serve as a useful biomarker for isoflavone intake in populations. We observed an association between equol phenotype and cereal intake. Our findings also suggest that dietary isoflavone intake has no significant effect on serum lipids in healthy participants, regardless of equol phenotype.

The National Cancer Institute of Canada Clinical Trials Group MAP.3 trial: an international breast cancer prevention trial

Several large phase iii trials have demonstrated that tamoxifen—and more recently, raloxifene—can effectively reduce the incidence of invasive breast cancer by 50%. However, these selective estrogen receptor modulators can also be associated with several rare, but serious, adverse events. Recently, the third-generation aromatase inhibitors (ais) have demonstrated excellent efficacy in adjuvant breast cancer trials, and they show particular promise in the breast cancer prevention setting. The National Cancer Institute of Canada Clinical Trials Group (ncic ctg) has developed a randomized phase iii study to determine the efficacy of an ai (exemestane) to reduce the incidence of invasive breast cancer in postmenopausal women at an increased risk for developing breast cancer. The ncic ctg map.3 (ExCel) trial is a double-blind placebo-controlled multicentre, multinational trial. Based on the known preclinical and clinical profile of the ais, a greater reduction in breast cancer incidence with fewer side effects is hypothesized with this class of agents than with tamoxifen or raloxifene.

Statistical Aspects of the Use of Biomarkers in Nutritional Epidemiology Research

Few strong and consistent associations have arisen from observational studies of dietary consumption in relation to chronic disease risk. Measurement error in self-reported dietary assessment may be obscuring many such associations. Attempts to correct for measurement error have mostly used a second self-report assessment in a subset of a study cohort to calibrate the self-report assessment used throughout the cohort, under the dubious assumption of uncorrelated measurement errors between the two assessments. The use, instead, of objective biomarkers of nutrient consumption to produce calibrated consumption estimates provides a promising approach to enhance study reliability. As summarized here, we have recently applied this nutrient biomarker approach to examine energy, protein, and percent of energy from protein, in relation to disease incidence in Women's Health Initiative cohorts, and find strong associations that are not evident without biomarker calibration. A major bottleneck for the broader use of a biomarker-calibration approach is the rather few nutrients for which a suitable biomarker has been developed. Some methodologic approaches to the development of additional pertinent biomarkers, including the possible use of a respiratory quotient from indirect calorimetry for macronutrient biomarker development, and the potential of human feeding studies for the evaluation of a range of urine- and blood-based potential biomarkers, will briefly be described.

Should implementation intentions interventions be implemented in obesity prevention: the impact of if-then plans on daily physical activity in Dutch adults

BACKGROUND

Forming implementation intentions (specifying when, where and how to act) has been proposed as a potentially effective and inexpensive intervention, but has mainly been studied in controlled settings for straightforward behaviors.

PURPOSE

To examine if forming implementation intentions (II) could be used in large-scale, population-based interventions that aim to promote more complex and clinically relevant behavior change, we tested the impact of different II on increasing daily physical activity (PA) aimed at weight maintenance among 709 Dutch adults.

METHODS

At T0, participants were randomly allocated to a control group or to form II for 1) a prescribed action (walking), 2) self-selected activities, 3) self-selected activities and repeat making these II two times. All participants were asked to increase PA by at least two hours a week (15-20 minutes per day). Post-tests took place two weeks (response 85%), three months (response 78%) and six months (response 79%) post-intervention.

RESULTS

No main effects of II formation on BMI or physical activity were found. Intention to increase physical activity moderated the effects of repeated II, but not of the other II conditions. Forming repeated II had a positive effect on total PA and number of active days for respondents with strong intentions.

CONCLUSION

Implementation intention interventions may not yet be ready for implementation on its own for large-scale obesity prevention in the general public. Future research should test strategies for optimal II formation in both initiating and maintaining behavioral change.

TRIAL REGISTRATION

ISRCTN81041724.

Mendelian randomization: how it can--and cannot--help confirm causal relations between nutrition and cancer

Observational epidemiologic studies of nutrition and cancer have faced formidable methodologic obstacles, including dietary measurement error and confounding. We consider whether Mendelian randomization can help surmount these obstacles. The Mendelian randomization strategy, building on both the accuracy of genotyping and the random assortment of alleles at meiosis, involves searching for an association between a nutritional exposure-mimicking gene variant (a type of "instrumental variable") and cancer outcome. Necessary assumptions are that the gene is independent of cancer, given the exposure, and also independent of potential confounders. An allelic variant can serve as a proxy for diet and other nutritional factors through its effects on either metabolic processes or consumption behavior. Such a genetic proxy is measured with little error and usually is not confounded by nongenetic characteristics. Examples of potentially informative genes include LCT (lactase), ALDH2 (aldehyde dehydrogenase), and HFE (hemochromatosis), proxies, respectively, for dairy product intake, alcoholic beverage drinking, and serum iron levels. We show that use of these and other genes in Mendelian randomization studies of nutrition and cancer may be more complicated than previously recognized and discuss factors that can invalidate the instrumental variable assumptions or cloud the interpretation of these studies. Sample size requirements for Mendelian randomization studies of nutrition and cancer are shown to be potentially daunting; strong genetic proxies for exposure are necessary to make such studies feasible. We conclude that Mendelian randomization is not universally applicable, but, under the right conditions, can complement evidence for causal associations from conventional epidemiologic studies.

Lifestyle and Successful Aging: An Overview

Since the 1950s, the phrase successful aging has been used increasingly to represent the factors and conditions underlying healthy aging and is often attributed to the healthy elderly. In this short review, the authors discuss the transformation in the social theories of aging that allowed for the evolution of successful aging as a construct and ultimately a theoretical basis for investigation. Because of the multifactorial nature of the psychosocial and biomedical domains, there is no clear consensus on the definition of successful aging or its determinants. What is clear, however, is that successful aging is related to the human health span, or healthy life expectancy. Moreover, the accumulating information from multidimensional studies suggests that many age-associated changes in physiological and cognitive functioning can be explained by such modifiable lifestyle factors as smoking, physical activity, and nutrition choice. The evidence presented supports the promotion of a healthy lifestyle as an effective strategy for successful aging.

Dietary intake and different types of physical activity: full-day energy expenditure, occupational and leisure-time

Objective

To describe the relationship between dietary intake and different levels and types of physical activity (PA).

Design

Cross-sectional evaluation of the EPIPorto study. Energy expenditure (metabolic energy equivalent tasks) and dietary intake during the past year were assessed using a PA questionnaire and a semi-quantitative food-frequency questionnaire, respectively.

Setting

Representative sample of adults in Porto, Portugal.

Subjects

Data were analysed for 2404 Portuguese Caucasian adults, aged between 18 and 92 years.

Results

For total PA, males who were active had significantly higher mean intake of energy (10·76 (2570·7) vs. 9·78 (2336·9) MJ/d (kcal/d), P < 0·001) and lower level of protein consumption (16·9 vs. 17·6 % of energy, P < 0·001) compared with sedentary males. In males, the association between total PA and energy intake remained after adjustment for age, education and body mass index. Similar results were observed when occupational activity was analysed. Concerning the energy expended in leisure time, in both genders, after adjustment for the previously described variables, a significant positive association was found between PA and intake of vitamin C (g/d): β = 0·12, 99 % confidence interval (CI) 0·02, 0·21 for females and β = 0·13, 99 % CI 0·03, 0·22 for males. Leisure-time activity in females was also positively associated with intakes of fibre, vitamin E, folate, calcium and magnesium, and negatively associated with saturated fat.

Conclusions

Higher levels of PA in leisure time were associated with higher intakes of micronutrients and lower intakes of saturated fat, particularly in females. For total and occupational PA, similar nutrient intake was observed between active and sedentary individuals.

Integrating anticipated nutrigenomics bioscience applications with ethical aspects

Nutrigenomics is a subspecialty of nutrition science which aims to understand how gene-diet interactions influence individuals' response to food, disease susceptibility, and population health. Yet ethical enquiry into this field is being outpaced by nutrigenomics bioscience. The ethical issues surrounding nutrigenomics face the challenges of a rapidly evolving field which bring forward the additional dimension of crossdisciplinary integrative research between social and biomedical sciences. This article outlines the emerging nutrigenomics definitions and concepts and analyzes the existing ethics literature concerning personalized nutrition and presents "points to consider" over ethical issues regarding future nutrigenomics applications. The interest in nutrigenomics coincides with a shift in emphasis in medicine and biosciences toward prevention of future disease susceptibilities rather than treatment of already established disease. Hence, unique ethical issues emerge concerning the extent to which nutrigenomics can alter our relation to food, boundaries between health and disease, and the folklore of medical practice. Nutrigenomics can result in new social values, norms, and responsibilities for both individuals and societies. Nutrigenomics is not only another new application of "-omics" technologies in the context of gene-diet interactions. Nutrigenomics may fundamentally change the way we perceive human illness while shifting the focus and broadening the scope of health interventions from patients to healthy individuals. In resource- and time-limited healthcare settings, this creates unique ethical dilemmas and distributive justice issues. Ethical aspects of nutrigenomics applications should be addressed proactively, as this new science develops and increasingly coalesces with other applications of genomics in medicine and public health.

The implications of genetic susceptibility for the prevention of colorectal cancer: a qualitative study of older adults' understanding

OBJECTIVE

To assess whether public understandings of inherited predisposition to colorectal cancer may undermine preparedness to respond to preventive messages.

METHODS

Structured in-depth interviews with 31 women and men, aged 50 years and over.

RESULTS

Most participants viewed genetic factors as prompts for taking preventive measures rather than as reasons for fatalism and inaction. They were optimistic about the potential benefits of new developments in cancer prevention and treatment.

CONCLUSIONS

There was little evidence of perceived genetic determinism in relation to colorectal cancer, but there were some significant misunderstandings about causes, prevention and treatment. These findings have important implications for public health communications about the contribution of genetics to cancer causation.

Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in the Age-Related Eye Disease Study, an Ancillary Study of the Women's Health Initiative

OBJECTIVE

To evaluate associations between nuclear cataract (determined from slitlamp photographs between May 2001 and January 2004) and lutein and zeaxanthin in the diet and serum in patients between 1994 and 1998 and macula between 2001 and 2004.

DESIGN

A total of 1802 women aged 50 to 79 years in Iowa, Wisconsin, and Oregon with intakes of lutein and zeaxanthin above the 78th (high) and below the 28th (low) percentiles in the Women's Health Initiative Observational Study (1994-1998) were recruited 4 to 7 years later (2001-2004) into the Carotenoids in Age-Related Eye Disease Study.

RESULTS

Women in the group with high dietary levels of lutein and zeaxanthin had a 23% lower prevalence of nuclear cataract (age-adjusted odds ratio, 0.77; 95% confidence interval, 0.62-0.96) compared with those with low levels. Multivariable adjustment slightly attenuated the association (odds ratio, 0.81; 95% confidence interval, 0.65-1.01). Women in the highest quintile category of diet or serum levels of lutein and zeaxanthin as compared with those in the lowest quintile category were 32% less likely to have nuclear cataract (multivariable-adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.97; P for trend = .04; and multivariable-adjusted odds ratio, 0.68; 95% confidence interval, 0.47-0.98; P for trend = .01, respectively). Cross-sectional associations with macular pigment density were inverse but not statistically significant.

CONCLUSIONS

Diets rich in lutein and zeaxanthin are moderately associated with decreased prevalence of nuclear cataract in older women. However, other protective aspects of such diets may in part explain these relationships.

Influence of diet on metastasis and tumor dormancy

Tumor metastasis is responsible for most cancer deaths, and can occur after long periods of tumor dormancy. Information learned from experimental studies on tumor metastasis and dormancy is shedding light on mechanisms responsible and possible therapeutic approaches. 'Seed' (the cancer cell) and 'soil' (the microenvironment of the secondary organ) factors contribute to metastatic outcome. This review considers the possibility that various dietary components may affect both 'seed' and 'soil' compartments, thereby influencing the growth of metastases, and discusses an experimental study on dietary genistein that illustrates this concept. While studies on human diet are complex, the possibility that relatively non-toxic dietary intervention strategies could impact on metastasis and patient survival is attractive and worthy of further study in appropriate experimental models of metastasis and tumor dormancy.

Demographic, anthropometric, and lifestyle factors and dietary intakes in relation to daidzein-metabolizing phenotypes among premenopausal women in the United States

BACKGROUND

The soy isoflavone daidzein is metabolized to equol and O-desmethylangolensin (ODMA) by intestinal bacteria in approximately 30-50% and 80-90% of persons, respectively. Studies suggest beneficial health effects associated with daidzein-metabolizing phenotypes; thus, assessing their determinants is an important goal.

OBJECTIVE

We evaluated relations between daidzein-metabolizing phenotypes and demographic, anthropometric, lifestyle, and dietary factors among premenopausal women in the United States.

DESIGN

Two hundred women provided a first-void urine sample after a 3-d soy challenge and completed a health and demographics questionnaire, physical activity questionnaire, food-frequency questionnaire, and 3-d food record. Urine samples were measured for isoflavones by gas chromatography-mass spectrometry to determine daidzein-metabolizing phenotypes.

RESULTS

Fifty-five (27.5%) and 182 (91%) women had detectable concentrations of urinary equol and ODMA (>87.5 ng/mL), respectively, and were classed as producers of these metabolites. Compared with nonproducers, equol producers were more likely (P < or = 0.05) to be Hispanic or Latino, to be highly educated, and to have frequent constipation, and ODMA producers were taller and less likely to be Asian than white. Equol and ODMA producers reported higher overall physical activity than did nonproducers.

CONCLUSIONS

We observed associations between equol production and ethnicity, education, constipation, and physical activity and between ODMA production and race, height, and physical activity. Associations with race and ethnicity were based on small numbers of Asian and Hispanic or Latino women, and confirmation of these findings is needed. Few dietary factors, assessed with the use of either a food-frequency questionnaire or food record, were associated with daidzein-metabolizing phenotypes.

Biological variability dominates and influences analytical variance in HPLC-ECD studies of the human plasma metabolome

Background

Biomarker-based assessments of biological samples are widespread in clinical, pre-clinical, and epidemiological investigations. We previously developed serum metabolomic profiles assessed by HPLC-separations coupled with coulometric array detection that can accurately identify ad libitum fed and caloric-restricted rats. These profiles are being adapted for human epidemiology studies, given the importance of energy balance in human disease.

Methods

Human plasma samples were biochemically analyzed using HPLC separations coupled with coulometric electrode array detection.

Results

We identified these markers/metabolites in human plasma, and then used them to determine which human samples represent blinded duplicates with 100% accuracy (N = 30 of 30). At least 47 of 61 metabolites tested were sufficiently stable for use even after 48 hours of exposure to shipping conditions. Stability of some metabolites differed between individuals (N = 10 at 0, 24, and 48 hours), suggesting the influence of some biological factors on parameters normally considered as analytical.

Conclusion

Overall analytical precision (mean median CV, ~9%) and total between-person variation (median CV, ~50–70%) appear well suited to enable use of metabolomics markers in human clinical trials and epidemiological studies, including studies of the effect of caloric intake and balance on long-term cancer risk.

The lifestyle of our kids (LOOK) project: outline of methods

This methods paper outlines the overall design of a community-based multidisciplinary longitudinal study with the intent to stimulate interest and communication from scientists and practitioners studying the role of physical activity in preventive medicine. In adults, lack of regular exercise is a major risk factor in the development of chronic degenerative diseases and is a major contributor to obesity, and now we have evidence that many of our children are not sufficiently active to prevent early symptoms of chronic disease. The lifestyle of our kids (LOOK) study investigates how early physical activity contributes to health and development, utilizing a longitudinal design and a cohort of eight hundred and thirty 7-8-year-old (grade 2) school children followed to age 11-12 years (grade 6), their average family income being very close to that of Australia. We will test two hypotheses, that (a) the quantity and quality of physical activity undertaken by primary school children will influence their psychological and physical health and development; (b) compared with existing practices in primary schools, a physical education program administered by visiting specialists will enhance health and development, and lead to a more positive perception of physical activity. To test the first hypothesis we will monitor all children longitudinally over the 4 years. To test the second we will involve an intervention group of 430 children who receive two 50min physical education classes every week from visiting specialists and a control group of 400 who continue with their usual primary school physical education with their class-room teachers. At the end of grades 2, 4, and 6 we will measure several areas of health and development including blood risk factors for chronic disease, cardiovascular structure and function, physical fitness, psychological characteristics and perceptions of physical activity, bone structure and strength, motor control, body composition, nutritional intake, influence of teachers and family, and academic performance.

Primary dietary prevention: is the fiber story over?

Colorectal cancer is a major cause of morbidity in developed countries, and epidemiological and experimental research suggests that environmental factors, particularly diet, may play a key etiologic role. Among the various dietary factors that have been proposed to affect the risk and progression of colon cancer, dietary fiber has been of greatest interest, due to the effects of fiber on the function of the large bowel. Dietary fiber is a heterogeneous group of compounds, consisting of the remnants of plant cells resistant to hydrolysis by human alimentary enzymes. Several case-control studies and a few cohort studies have linked higher fiber intake to reduced risk for colorectal cancer, although the results of these observational studies have been inconsistent. In the large European Prospective Investigation into Cancer and Nutrition observational study, higher dietary fiber from foods was associated with an estimated 25% reduction in risk for large bowel cancer. However, no significant relationship between fiber intake (or major food sources of fiber) and risk for colorectal cancer was observed in a recently reported large pooled analysis of several cohort studies. Well-known limitations of observational studies, particularly relating to the collection and interpretation of dietary data, constrain conclusions from these studies. To date, intervention studies testing the relationship between dietary fiber and colon cancer have focused on whether fiber supplementation or diet modification can affect the risk for adenoma recurrence and growth in individuals with a history of adenomatous polyps. In four of these intervention studies, subjects in the intervention arm were prescribed dietary fiber supplements, and beneficial effects on adenoma recurrence were not observed over 3-5 years of follow-up. In a large randomized U.S. study, the Polyp Prevention Trial, the effect of prescribing diet modification (increased fiber and reduced fat intakes) was tested, and no effects on adenoma recurrence were observed, although dietary biomarker data suggest that the change in dietary intakes in the intervention arm was not substantial. The effect of increased dietary fiber intake on risk for colorectal cancer has not been adequately addressed in studies conducted to date. Longer-term trials and higher levels of fiber intake are strategies that have been suggested to increase knowledge in this area. Also, laboratory and clinical studies that continue to provide insight into biological mechanisms may help to better target intervention efforts.

Position of the American Dietetic Association: the roles of registered dietitians and dietetic technicians, registered in health promotion and disease prevention

It is the position of the American Dietetic Association (ADA) that primary prevention is the most effective, affordable course of action for preventing and reducing risk for chronic disease. Registered dietitians and dietetic technicians, registered, are leaders in delivering preventive services in both clinical and community settings, including advocating for funding and inclusion of these services in programs and policy initiatives at local, state, and federal levels. In addition, registered dietitians are leaders in facilitating and participating in research in chronic disease prevention and health promotion. Diet, nutrition, and physical activity are important factors in the promotion and maintenance of good health throughout the life cycle. Cost-effective interventions that produce a change in personal health practices are likely to lead to substantial reductions in the incidence and severity of the leading causes of disease in the United States. In an era of increasing health care expenditures and relative decreases in availability of federal funds, there is increasing demand on health promotion and disease prevention to be economically viable. Through clinical involvement and rigorous participation in research on chronic disease prevention and health promotion, the field of dietetics can lead the way to effectively translate the impact of nutrition on all ages.

Increases in Plasma Carotenoid Concentrations in Response to a Major Dietary Change in the Women's Healthy Eating and Living Study

BACKGROUND

Cohort studies suggest that higher circulating carotenoid concentrations through food sources may reduce breast cancer events. Other intervention studies have not achieved the level of change in circulating carotenoids required to properly test this hypothesis.

METHODS

In a randomized trial of 2,922 breast cancer survivors, we examined blood and self-reported diet at baseline and 1 year. Intensive telephone counseling encouraged a plant-based diet in the intervention group. Diet was measured via 24-hour recalls, and a panel of plasma carotenoid concentrations was assessed at both time points.

RESULTS

The study intervention was associated with a 51% increase in total carotenoid concentration, from 2.272 +/- 1.294 to 3.440 +/- 2.320 micromol/L, achieved mainly by marked increases in targeted carotenoids: alpha-carotene, beta-carotene, and lutein. For each of these targeted carotenoids, the proportion of the intervention sample remaining below the cutpoint for the lowest baseline quartile decreased by one third to one half. After 1 year of study, half of the intervention group was in the highest baseline quartile. No change in distribution was observed in comparison group. Intervention participants achieved this change by both dietary pattern and vegetable juice consumption. Participants who chose to change dietary pattern without consuming significant quantities of vegetable juice achieved 75% of the level of change observed in other intervention participants.

CONCLUSIONS

Innovative telephone counseling intervention and dietary targets in the Women's Healthy Eating and Living study were associated with the level of change in circulating carotenoid concentration necessary to test the diet and breast cancer hypothesis suggested by cohort studies.

Lignan and isoflavone excretion in relation to uterine fibroids: a case-control study of young to middle-aged women in the United States

BACKGROUND

Uterine fibroids are hormonally responsive; estradiol and progesterone stimulate their growth, and gonadotrophin-releasing hormone agonists shrink them. Phytoestrogens, including isoflavones and lignans, can act as weak estrogens or antiestrogens.

OBJECTIVE

The objective of this case-control study was to evaluate the relation between uterine fibroid risk and phytoestrogen exposure.

DESIGN

Two overnight urine collections (48 h apart) from 170 uterine fibroid cases and 173 controls were analyzed for isoflavonoids (ie, daidzein, genistein, equol, and O-desmethylangolensin) and lignans (enterodiol and enterolactone). Logistic regression was used to determine associations between the mean excretion of the 2 collections and the risk of uterine fibroids.

RESULTS

Unadjusted isoflavone excretion did not differ significantly between cases and controls (2.33 +/- 5.82 and 2.60 +/- 5.90 nmol/mg Cr, respectively; P = 0.68), but cases excreted significantly less lignans than did controls (2.86 +/- 3.45 and 4.57 +/- 6.67 nmol/mg Cr, respectively; P < 0.01). The trend for a reduced risk of uterine fibroids with increasing quartiles of lignan excretion was significant (odds ratio for highest versus lowest quartile = 0.31; 95% CI: 0.17, 0.58; P for trend < 0.01). When adjusted for age, BMI, race, family history of uterine fibroids, and isoflavone excretion, this trend remained but was attenuated (P = 0.07).

CONCLUSIONS

Our findings suggest a modest inverse association between lignan excretion and uterine fibroid risk. Whether this relation represents an effect of lignans per se or of other constituents of lignan-containing foods on the development of uterine fibroids remains to be determined. No association was found between isoflavone excretion and uterine fibroids; however, the intake of soy foods, the primary source of isoflavones, was low in this population.

Statistical issues arising in the Women's Health Initiative

A brief overview of the design of the Women's Health Initiative (WHI) clinical trial and observational study is provided along with a summary of results from the postmenopausal hormone therapy clinical trial components. Since its inception in 1992, the WHI has encountered a number of statistical issues where further methodology developments are needed. These include measurement error modeling and analysis procedures for dietary and physical activity assessment; clinical trial monitoring methods when treatments may affect multiple clinical outcomes, either beneficially or adversely; study design and analysis procedures for high-dimensional genomic and proteomic data; and failure time data analysis procedures when treatment group hazard ratios are time dependent. This final topic seems important in resolving the discrepancy between WHI clinical trial and observational study results on postmenopausal hormone therapy and cardiovascular disease.

Impact of physical activity on intestinal cancer development in mice

Observational epidemiology supports the hypothesis that variation in diet and other lifestyle exposures accounts for a large part of the variation in incidence of colorectal cancer (CRC). Physical inactivity is associated strongly with enhanced CRC risk, but no human intervention studies have shown causality. This paper reviews data from all available studies of the effects of exercise interventions on intestinal neoplasia using rat and mouse models. All 5 published studies of effects of increased physical activity (both forced and voluntary) using carcinogen-treated rat models show strong protection against CRC by greater physical activity. In contrast, there is little convincing evidence of reduced intestinal neoplasia after increased physical activity in the 3 published studies using Apc(Min) mice (which develop multiple intestinal polyps spontaneously) although the nature and amounts of physical activity imposed in rats and mice were similar. Major differences in protocol between the 2 groups of studies are that the rat studies were much longer (at least 20 wk and in most cases 38 wk compared with < or =9 wk for the mouse studies) and the primary endpoint was colorectal carcinoma (rats) rather than small bowel adenomas (mice). The epidemiological evidence for protection against adenoma formation by increased physical activity is weaker than that for carcinoma. The limited evidence available suggests that, compared with rats, mice may show a greater compensation for energy expenditure in exercise through reduction in nonexercise physical activity, thus ameliorating effects. The resulting smaller effects on body weight and body fatness may limit changes in intestinal neoplasia in Apc(Min) mice.

Prática de esportes durante a adolescência e atividade física de lazer na vida adulta

FUNDAMENTOS E OBJETIVOS: Inatividade física é importante fator de risco para as doenças crônicas. Os resultados da literatura são controvertidos em relação à prática de atividades esportivas na infância e adolescência e atividade física na vida adulta. O objetivo deste estudo foi verificar em adultos jovens a freqüência de atividade física de lazer (AFL) e determinar se a prática de esportes durante a adolescência influenciou esta atividade. MÉTODOS: Foi realizado um estudo transversal, tipo inquérito, no período de novembro de 2003 a abril de 2004, em 170 alunos do curso médico que realizaram o estágio de internato em pediatria e tocoginecologia no Instituto Materno Infantil de Pernambuco (IMIP). Foram considerados como atletas aqueles que afirmaram terem praticado algum tipo de esporte durante pelo menos dois anos consecutivos, entre a faixa etária dos 10 aos 19 anos. Atividade física desenvolvida atualmente foi aferida através da informação sobre AFL, na última semana que antecedeu a aplicação do questionário, para a prática de algum tipo de atividade física que provocasse sudorese e respiração acelerada. Foram considerados como fisicamente ativos aqueles que despenderam um mínimo de 150 minutos de atividade física por semana. RESULTADOS: Apenas 22,5% (35/155) dos internos desenvolviam AFL. Entre aqueles que foram atletas durante a adolescência, a prática de AFL na vida adulta foi maior; 26,8% (33/123), do que aqueles não atletas, 6,2% (2/32); p < 0,03 (tabela 1). Entretanto, a presença de excesso de peso ou obesidade, hipertensão arterial, tabagismo e antecedentes familiares de doença aterosclerótica precoce não diferiu entre os grupos com maior e menor AFL. CONCLUSÃO: Práticas de atividades esportivas durante a adolescência contribuem para AFL na vida adulta.

Diet and cancer: the disconnect between epidemiology and randomized clinical trials

Dietary epidemiology has been highly successful in identifying the responsible agent in many diseases, including scurvy, pellagra, blindness, and spinal bifida. Case-control, cohort, and ecologic observational studies have consistently associated increased consumption of fruits and vegetables with a decreased risk for a wide variety of epithelial cancers and, in many cases, specific dietary components seem to decrease the risk for a wide array of epithelial cancers. Over time, there has been enthusiasm for one or another compounds, such as beta-carotene in the past and folate currently. Despite the success of translating similar epidemiologic observations to clinical benefit in other areas of medicine via the crucible of the randomized clinical trial, this strategy has not been nearly as successful for cancer. We propose that the inability of nutritional epidemiology to identify effective chemopreventive strategies is not just a problem of quantitation, but rather that the discipline is usually qualitatively incapable of identifying a dietary compound(s) that will be efficacious. One needs to consider the following basic questions in trying to understand why nutritional epidemiology has not been translated into progress in cancer prevention: Why do fruits and vegetable show a consistent protective effect against many epithelial cancers in epidemiologic studies? Once a specific dietary compound is identified as protective in observational studies, why do most subsequent observational studies confirm the effect? Why are dietary epidemiology observations frequently not confirmed by the randomized clinical trial? We call the identified problems "fishing with only one bait" and the "four-legged stool problem." The considerations identified in this analysis offer a number of possible solutions to puzzling findings: (a) Fruits and vegetables consistently show a protective effect against cancer in observational studies because they represent the entire "biological action package." (b) Dietary compounds show a protective effect in observational studies, but not in clinical trials, because this is an inevitable consequence of one compound being falsely identified as the active agent in a system in which multiple agents or multiple interacting regulatory molecules underlie the biological effect. The consequences are serious for trying to use epidemiology to identify effective nutritional compounds. The major conclusion has to be as follows: Supplementation with single dietary compounds is rarely going to be as effective as epidemiologic studies suggest; it is the biological action package that determines efficacy. Options for how we should move forward will be discussed. Dietary observational epidemiology is complex and involves many biases and confounders. We need to be more critical in the design of large randomized trials based on observational epidemiology or analysis. Rules of evidence are frequently ignored or misunderstood although the limitations of observational epidemiology are analogous to the problems associated with discovery-based research and biomarker identification. We need to be much more self-critical in the important and critical assessment of dietary compounds and their role in cancer prevention given the very high appeal for this approach both within the lay and scientific communities.

Sustained rise in triacylglycerol synthesis and increased epididymal fat mass when rats cease voluntary wheel running

Four-week-old, Fischer-Brown Norway F1-generation male rats were given access to voluntary running wheels for 21 days, and then the wheels were locked for 5 (WL5), 10 (WL10), 29 (WL29), or 53 (WL53) hours. Two other groups (SED5 and SED10) had no access to voluntary running wheels and were killed at the same time as WL5 and WL10, respectively. Absolute and relative epididymal fat mass, mean cell volume, and amount of lipid per cell increased in WL53 relative to all other groups, with no change in cell number. C/EBPalpha protein levels in epididymal fat were 30% greater in SED5 than in WL5. The rate of triacylglycerol synthesis in epididymal fat was 4.2-fold greater in SED5 than in WL5, increased 14-fold between WLS and WL10, and was 79% lower in SED10 than in WL10. Triacylglycerol synthesis remained at this elevated level (at least 3.5-fold greater than SED5) through WL53. Thus, the rapid increase in epididymal fat mass with the cessation of voluntary wheel running is associated with a prolonged overshoot in epididymal fat triacylglycerol synthesis. Moreover, rats without running wheels had a 9.4% lower body mass after 21 days than those with running wheels. The individual mass of seven different muscles from the hindlimb, upper forelimb, and back were each lower in animals without running wheels, suggesting that physical activity in rapidly growing rats may be requisite for optimal muscle development.

Chronic disease prevention: public health potential and research needs

This paper, arising out of an event to honour the statistical and scientific contributions of Professor Peter Armitage, is concerned with research strategies and needs for chronic disease prevention. A few highlights from recent intervention trials for the prevention of cancer, cardiovascular disease, fractures and diabetes is provided, along with a discussion of some settings where intervention trial results seem discrepant with a body of preceding observational data. This background is used to identify research strategies and infrastructure needs for moving this vitally important research area forward, for both chemoprevention and lifestyle modification interventions.