Epidemiological assessment of diet: a comparison of a 7-day diary with a food frequency questionnaire using urinary markers of nitrogen, potassium and sodium

Design of a instrumentation module for monitoring ingestive behavior in laboratory studies

The development of accurate and objective tools for monitoring of ingestive behavior (MIB) is one of the most important needs facing studies of obesity and eating disorders. This paper presents the design of an instrumentation module for non-invasive monitoring of food ingestion in laboratory studies. The system can capture signals from a variety of sensors that characterize ingestion process (such as acoustical and other swallowing sensors, strain sensor for chewing detection and self-report buttons). In addition to the sensors, the data collection system integrates time-synchronous video footage that can be used for annotation of subject's activity. Both data and video are simultaneously and synchronously acquired and stored by a LabVIEW-based interface specifically developed for this application. This instrumentation module improves a previously developed system by eliminating the post-processing stage of data synchronization and by reducing the risks of operator's error.

Meat and fish consumption and risk of pancreatic cancer: results from the European Prospective Investigation into Cancer and Nutrition

Pancreatic cancer is the fourth most common cause of cancer death worldwide with large geographical variation, which implies the contribution of diet and lifestyle in its etiology. We examined the association of meat and fish consumption with risk of pancreatic cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC). A total of 477,202 EPIC participants from 10 European countries recruited between 1992 and 2000 were included in our analysis. Until 2008, 865 nonendocrine pancreatic cancer cases have been observed. Calibrated relative risks (RRs) and 95% confidence intervals (CIs) were computed using multivariable-adjusted Cox hazard regression models. The consumption of red meat (RR per 50 g increase per day = 1.03, 95% CI = 0.93-1.14) and processed meat (RR per 50 g increase per day = 0.93, 95% CI = 0.71-1.23) were not associated with an increased pancreatic cancer risk. Poultry consumption tended to be associated with an increased pancreatic cancer risk (RR per 50 g increase per day = 1.72, 95% CI = 1.04-2.84); however, there was no association with fish consumption (RR per 50 g increase per day = 1.22, 95% CI = 0.92-1.62). Our results do not support the conclusion of the World Cancer Research Fund that red or processed meat consumption may possibly increase the risk of pancreatic cancer. The positive association of poultry consumption with pancreatic cancer might be a chance finding as it contradicts most previous findings.

Estimating the alcohol-breast cancer association: a comparison of diet diaries, FFQs and combined measurements

The alcohol-breast cancer association has been established using alcohol intake measurements from Food Frequency Questionnaires (FFQ). For some nutrients diet diary measurements are more highly correlated with true intake compared with FFQ measurements, but it is unknown whether this is true for alcohol. A case-control study (656 breast cancer cases, 1905 matched controls) was sampled from four cohorts in the UK Dietary Cohort Consortium. Alcohol intake was measured prospectively using FFQs and 4- or 7-day diet diaries. Both relied on fixed portion sizes allocated to given beverage types, but those used to obtain FFQ measurements were lower. FFQ measurements were therefore on average lower and to enable fair comparison the FFQ was "calibrated" using diet diary portion sizes. Diet diaries gave more zero measurements, demonstrating the challenge of distinguishing never-from episodic-consumers using short term instruments. To use all information, two combined measurements were calculated. The first is an average of the two measurements with special treatment of zeros. The second is the expected true intake given both measurements, calculated using a measurement error model. After confounder adjustment the odds ratio (OR) per 10 g/day of alcohol intake was 1.05 (95 % CI 0.98, 1.13) using diet diaries, and 1.13 (1.02, 1.24) using FFQs. The calibrated FFQ measurement and combined measurements 1 and 2 gave ORs 1.10 (1.03, 1.18), 1.09 (1.01, 1.18), 1.09 (0.99,1.20), respectively. The association was modified by HRT use, being stronger among users versus non-users. In summary, using an alcohol measurement from a diet diary at one time point gave attenuated associations compared with FFQ.

A new method for measuring meal intake in humans via automated wrist motion tracking

Measuring the energy intake (kcal) of a person in day-to-day life is difficult. The best laboratory tool achieves 95 % accuracy on average, while tools used in daily living typically achieve 60-80 % accuracy. This paper describes a new method for measuring intake via automated tracking of wrist motion. Our method uses a watch-like device with a micro-electro-mechanical gyroscope to detect and record when an individual has taken a bite of food. Two tests of the accuracy of our device in counting bites found that our method has 94 % sensitivity in a controlled meal setting and 86 % sensitivity in an uncontrolled meal setting, with one false positive per every 5 bites in both settings. Preliminary data from daily living indicates that bites measured by the device are positively related to caloric intake illustrating the potential of the device to monitor energy intake. Future research should seek to further explore the relationship between bites taken and kilocalories consumed to validate the device as an automated measure of energy intake.

Clustering of unhealthy behaviors in the aerobics center longitudinal study

BACKGROUND

Clustering of unhealthy behaviors has been reported in previous studies; however the link with all-cause mortality and differences between those with and without chronic disease requires further investigation.

OBJECTIVES

To observe the clustering effects of unhealthy diet, fitness, smoking, and excessive alcohol consumption in adults with and without chronic disease and to assess all-cause mortality risk according to the clustering of unhealthy behaviors.

METHODS

Participants were 13,621 adults (aged 20-84) from the Aerobics Center Longitudinal Study. Four health behaviors were observed (diet, fitness, smoking, and drinking). Baseline characteristics of the study population and bivariate relations between pairs of the health behaviors were evaluated separately for those with and without chronic disease using cross-tabulation and a chi-square test. The odds of partaking in unhealthy behaviors were also calculated. Latent class analysis (LCA) was used to assess clustering. Cox regression was used to assess the relationship between the behaviors and mortality.

RESULTS

The four health behaviors were related to each other. LCA results suggested that two classes existed. Participants in class 1 had a higher probability of partaking in each of the four unhealthy behaviors than participants in class 2. No differences in health behavior clustering were found between participants with and without chronic disease. Mortality risk increased relative to the number of unhealthy behaviors participants engaged in.

CONCLUSION

Unhealthy behaviors cluster together irrespective of chronic disease status. Such findings suggest that multi-behavioral intervention strategies can be similar in those with and without chronic disease.

Baby-led weaning and the family diet. A pilot study

Baby-led weaning (BLW) is a style of solid food introduction that emphasizes self-feeding rather than spoon-feeding. The purpose of this cross-sectional study was to determine whether parents using BLW change their dietary intake during weaning, and if their babies are offered family foods. Participants kept diet diaries at baseline and three months later, post-BLW implementation. Wilcoxon tests revealed no significant changes in dietary intake during the first three months of weaning, however, parents offered their children 57% of the same foods they were consuming. Results suggest that BLW does not lead to dietary changes among parents during the weaning process.

Fruit intake associated with urinary estrogen metabolites in healthy premenopausal women

Urinary concentrations of 2:16-hydroxyestrone (2:16-OHE₁) approximate concentrations of 2-OHE₁ and 16α -OHE₁ in breast tissue. As estrogens are purported to be involved in breast cancer development, the 2:16-OHE₁ ratio can provide an indication of estrogen metabolite exposure in the breast. With prior studies observing associations between urinary estrogen metabolites and dietary intake of fruits, vegetables, and fiber ascertained from food questionnaires, we examined associations between dietary factors ascertained through 3-day food records and urinary 2:16-OHE₁ in 191 pre-menopausal healthy women. Fruit consumption was positively associated with 2:16-OHE₁ after adjustment for total energy, ethnicity, body mass index, parity, smoking history, and serum estradiol (p= 0.003). Fruit consumption was positively associated with 2- OHE₁ concentrations (p=0.006), but was not associated with 16α-OHE₁ (p=0.92). The Musaceae botanical grouping (comprised primarily of bananas) was positively associated with the 2:16-OHE₁ ratio, and Rosaceae (comprised of citrus fruits) and Musaceae botanical groupings were positively associated with 2-OHE₁ (but not 16α-OHE₁) concentrations, after adjustment for confounders. Our data suggest that dietary fruit intake is associated with urinary 2- OHE₁ and the 2:16-OHE₁ ratio and that breast tissue exposure to estrogen metabolites may thus be influenced by diet.

Assessment of the effect of high or low protein diet on the human urine metabolome as measured by NMR

The objective of this study was to identify urinary metabolite profiles that discriminate between high and low intake of dietary protein during a dietary intervention. Seventy-seven overweight, non-diabetic subjects followed an 8-week low-calorie diet (LCD) and were then randomly assigned to a high (HP) or low (LP) protein diet for 6 months. Twenty-four hours urine samples were collected at baseline (prior to the 8-week LCD) and after dietary intervention; at months 1, 3 and 6, respectively. Metabolite profiling was performed by ¹H NMR and chemometrics. Using partial least squares regression (PLS), it was possible to develop excellent prediction models for urinary nitrogen (root mean square error of cross validation (RMSECV) = 1.63 mmol/L; r = 0.89) and urinary creatinine (RMSECV = 0.66 mmol/L; r = 0.98). The obtained high correlations firmly establish the validity of the metabolomic approach since urinary nitrogen is a well established biomarker for daily protein consumption. The models showed that trimethylamine-N-oxide (TMAO) is correlated to urinary nitrogen. Furthermore, urinary creatine was found to be increased by the HP diet whereas citric acid was increased by the LP diet. Despite large variations in individual dietary intake, differentiated metabolite profiles were observed at the dietary group-level.

Strength of the relationships between three self-reported dietary intake instruments and serum carotenoids: the Observing Energy and Protein Nutrition (OPEN) Study

Objective

To assess the strength of the relationships between serum carotenoids and three self-reported dietary intake instruments often used to characterize carotenoid intake in studies of diet and disease.

Design

Participants completed a Diet History Questionnaire (DHQ), two 24 h dietary recalls (24HR), a fruit and vegetable screener and a fasting blood draw. We derived dietary intake estimates of α-carotene, β-carotene, cryptoxanthin, lutein, zeaxanthin and lycopene from each diet instrument and calculated sex-specific multivariate correlations between dietary intake estimates and their corresponding serum values.

Setting

Montgomery County, Maryland, USA.

Subjects

Four hundred and seventy women and men aged 40–69 years in the National Cancer Institute's Observing Protein and Energy Nutrition (OPEN) Study.

Results

Serum carotenoids correlated more strongly with the DHQ (r = 0·34–0·54 for women; r = 0·38–0·56 for men) than with the average of two recalls (r = 0·26–0·47 for women; r = 0·26–0·40 for men) with the exception of zeaxanthin, for which the correlations using recalls were higher. With adjustment for within-person variation, correlations between serum carotenoids and recalls were greatly improved (r = 0·38–0·83 for women; r = 0·42–0·74 for men). In most cases, correlations between serum carotenoids and the fruit and vegetable screener resembled serum–DHQ correlations.

Conclusions

Evidence from the study provides support for the use of the DHQ, a fruit and vegetable screener and deattenuated recalls for estimating carotenoid status in studies without serum measures, and draws attention to the importance of adjusting for intra-individual variability when using recalls to estimate carotenoid values.

A Sensor System for Automatic Detection of Food Intake Through Non-Invasive Monitoring of Chewing

Objective and automatic sensor systems to monitor ingestive behavior of individuals arise as a potential solution to replace inaccurate method of self-report. This paper presents a simple sensor system and related signal processing and pattern recognition methodologies to detect periods of food intake based on non-invasive monitoring of chewing. A piezoelectric strain gauge sensor was used to capture movement of the lower jaw from 20 volunteers during periods of quiet sitting, talking and food consumption. These signals were segmented into non-overlapping epochs of fixed length and processed to extract a set of 250 time and frequency domain features for each epoch. A forward feature selection procedure was implemented to choose the most relevant features, identifying from 4 to 11 features most critical for food intake detection. Support vector machine classifiers were trained to create food intake detection models. Twenty-fold cross-validation demonstrated per-epoch classification accuracy of 80.98% and a fine time resolution of 30 s. The simplicity of the chewing strain sensor may result in a less intrusive and simpler way to detect food intake. The proposed methodology could lead to the development of a wearable sensor system to assess eating behaviors of individuals.

Association of dietary sodium and potassium intakes with albuminuria in normal-weight, overweight, and obese participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND

Among obese adults, sodium intake has been associated with cardiovascular disease. Few data are available on sodium intake and albuminuria, a marker of kidney damage and risk factor for cardiovascular disease.

OBJECTIVE

We examined the relation between dietary sodium and potassium intakes and the ratio of sodium to potassium (Na/K) with albuminuria by BMI in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study (n = 30,239 adults aged ≥45 y).

DESIGN

A modified Block 98 food-frequency questionnaire was used for dietary assessment in 21,636 participants, and nutritional variables were categorized by sex-specific quintiles. Normal weight, overweight, and obese were defined as BMI (in kg/m(2)) categories of 18.5-24.9, 25-29.9, and ≥30, respectively. Albuminuria was defined as a ratio (mg/g) of urinary albumin to creatinine of ≥30.

RESULTS

The prevalences of albuminuria were 11.5%, 11.6%, and 16.0% in normal-weight, overweight, and obese participants, respectively. The multivariable-adjusted ORs for albuminuria in a comparison of the highest with the lowest quintile of Na/K intake (≥1.12 to <0.70 for men and ≥1.07 to <0.62 for women) were 0.89 (95% CI: 0.65, 1.22), 1.08 (95% CI: 0.85, 1.36), and 1.28 (95% CI: 1.02, 1.61) in normal-weight, overweight, and obese participants, respectively. The highest quintile of dietary sodium was associated with an increased OR for albuminuria in obese participants (OR: 1.44; 95% CI: 1.00, 2.07) but not in normal-weight or overweight participants. Dietary potassium was not associated with albuminuria.

CONCLUSION

In obese adults, higher dietary Na/K and sodium intakes were associated with albuminuria.

The contribution of β-carotene to vitamin A supply of humans

Populations that administer highly restrictive diets using a strong dietary regime, excluding certain types of food, might be at risk of vitamin A insufficiency, even in developed countries. Thus, provitamin A carotenoids from plants represent an additional major dietary source of vitamin A for most of the world's population. Our aim was to estimate the contribution of β-carotene to vitamin A supply in industrialized countries using available data from the literature. A total of 11 studies from 8 countries were used, representing data of 121,256 participants. Intakes of total vitamin A, provitamin A carotenoids, including β-carotene were retrieved and used to calculate the retinol activity equivalents (RAE) utilizing current conversion factors. Mean total daily dietary intake of RAE was 1083±175. The mean β-carotene intake was 3.9 mg/day. Preformed vitamin A accounts for nearly 65% of total vitamin A intake, carotenoids make up 35%. No statistical differences between men and women in total intake of retinol were observed. We conclude that a safe vitamin A intake in general cannot be reached by consuming only one component (vitamin A or β-carotene) alone, even in Western countries where animal products are commonly available.

Evaluation and comparison of food records, recalls, and frequencies for energy and protein assessment by using recovery biomarkers

The food frequency questionnaire approach to dietary assessment is ubiquitous in nutritional epidemiology research. Food records and recalls provide approaches that may also be adaptable for use in large epidemiologic cohorts, if warranted by better measurement properties. The authors collected (2007-2009) a 4-day food record, three 24-hour dietary recalls, and a food frequency questionnaire from 450 postmenopausal women in the Women's Health Initiative prospective cohort study (enrollment, 1994-1998), along with biomarkers of energy and protein consumption. Through comparison with biomarkers, the food record is shown to provide a stronger estimate of energy and protein than does the food frequency questionnaire, with 24-hour recalls mostly intermediate. Differences were smaller and nonsignificant for protein density. Food frequencies, records, and recalls were, respectively, able to "explain" 3.8%, 7.8%, and 2.8% of biomarker variation for energy; 8.4%, 22.6%, and 16.2% of biomarker variation for protein; and 6.5%, 11.0%, and 7.0% of biomarker variation for protein density. However, calibration equations that include body mass index, age, and ethnicity substantially improve these numbers to 41.7%, 44.7%, and 42.1% for energy; 20.3%, 32.7%, and 28.4% for protein; and 8.7%, 14.4%, and 10.4% for protein density. Calibration equations using any of the assessment procedures may yield suitable consumption estimates for epidemiologic study purposes.

National Diet and Nutrition Survey: fat and fatty acid intake from the first year of the rolling programme and comparison with previous surveys

High saturated fat intake is an established risk factor for several chronic diseases. The objective of the present study is to report dietary intakes and main food sources of fat and fatty acids (FA) from the first year of the National Diet and Nutrition Survey (NDNS) rolling programme in the UK. Dietary data were collected using 4 d estimated food diaries (n 896) and compared with dietary reference values (DRV) and previous NDNS results. Total fat provided 34-36 % food energy (FE) across all age groups, which was similar to previous surveys for adults. Men (19-64 years) and older girls (11-18 years) had mean intakes just above the DRV, while all other groups had mean total fat intakes of < 35 % FE. SFA intakes were lower compared with previous surveys, ranging from 13 to 15 % FE, but still above the DRV. Mean MUFA intakes were 12·5 % FE for adults and children aged 4-18 years and all were below the DRV. Mean n-3 PUFA intake represented 0·7-1·1 % FE. Compared with previous survey data, the direction of change for n-3 PUFA was upwards for all age groups, although the differences in absolute terms were very small. Trans-FA intakes were lower than in previous NDNS and were less than 2 g/d for all age groups, representing 0·8 % FE and lower than the DRV in all age groups. In conclusion, dietary intake of fat and FA is moving towards recommended levels for the UK population. However, there remains room for considerable further improvement.

Consumption of meat and fish and risk of lung cancer: results from the European Prospective Investigation into Cancer and Nutrition

Evidence from case-control studies, but less so from cohort studies, suggests a positive association between meat intake and risk of lung cancer. Therefore, this association was evaluated in the frame of the European Prospective Investigation into Cancer and Nutrition, EPIC. Data from 478,021 participants, recruited from 10 European countries, who completed a dietary questionnaire in 1992-2000 were evaluated; 1,822 incident primary lung cancer cases were included in the present evaluation. Relative risk estimates were calculated for categories of meat intake using multi-variably adjusted Cox proportional hazard models. In addition, the continuous intake variables were calibrated by means of 24-h diet recall data to account for part of the measurement error. There were no consistent associations between meat consumption and the risk of lung cancer. Neither red meat (RR = 1.06, 95% CI 0.89-1.27 per 50 g intake/day; calibrated model) nor processed meat (RR = 1.13, 95% CI 0.95-1.34 per 50 g/day; calibrated model) was significantly related to an increased risk of lung cancer. Also, consumption of white meat and fish was not associated with the risk of lung cancer. These findings do not support the hypothesis that a high intake of red and processed meat is a risk factor for lung cancer.

Alterations in PTEN and PIK3CA in colorectal cancers in the EPIC Norfolk study: associations with clinicopathological and dietary factors

Background

The PTEN tumour suppressor gene and PIK3CA proto-oncogene encode proteins which contribute to regulation and propagation of signal transduction through the PI3K/AKT signalling pathway. This study investigates the prevalence of loss of PTEN expression and mutations in both PTEN and PIK3CA in colorectal cancers (CRC) and their associations with tumour clinicopathological features, lifestyle factors and dietary consumptions.

Methods

186 adenocarcinomas and 16 adenomas from the EPIC Norfolk study were tested for PTEN and PIK3CA mutations by DNA sequencing and PTEN expression changes by immunohistochemistry. Dietary and lifestyle data were collected prospectively using seven day food diaries and lifestyle questionnaires.

Results

Mutations in exons 7 and 8 of PTEN were observed in 2.2% of CRC and PTEN loss of expression was identified in 34.9% CRC. Negative PTEN expression was associated with lower blood low-density lipoprotein concentrations (p = 0.05). PIK3CA mutations were observed in 7% of cancers and were more frequent in CRCs in females (p = 0.04). Analysis of dietary intakes demonstrated no link between PTEN expression status and any specific dietary factor. PTEN expression negative, proximal CRC were of more advanced Dukes' stage (p = 0.02) and poor differentiation (p < 0.01). Testing of the prevalence of PIK3CA mutations and loss of PTEN expression demonstrated that these two events were independent (p = 0.55).

Conclusion

These data demonstrated the frequent occurrence (34.9%) of PTEN loss of expression in colorectal cancers, for which gene mutations do not appear to be the main cause. Furthermore, dietary factors are not associated with loss of PTEN expression. PTEN expression negative CRC were not homogenous, as proximal cancers were associated with a more advanced Dukes' stage and poor differentiation, whereas distal cancers were associated with earlier Dukes' stage.

Detection of periods of food intake using Support Vector Machines

Studies of obesity and eating disorders need objective tools of Monitoring of Ingestive Behavior (MIB) that can detect and characterize food intake. In this paper we describe detection of food intake by a Support Vector Machine classifier trained on time history of chews and swallows. The training was performed on data collected from 18 subjects in 72 experiments involving eating and other activities (for example, talking). The highest accuracy of detecting food intake (94%) was achieved in configuration where both chews and swallows were used as predictors. Using only swallowing as a predictor resulted in 80% accuracy. Experimental results suggest that these two predictors may be used for differentiation between periods of resting and food intake with a resolution of 30 seconds. Proposed methods may be utilized for development of an accurate, inexpensive, and non-intrusive methodology to objectively monitor food intake in free living conditions.

Allowing for never and episodic consumers when correcting for error in food record measurements of dietary intake

Food records, including 24-hour recalls and diet diaries, are considered to provide generally superior measures of long-term dietary intake relative to questionnaire-based methods. Despite the expense of processing food records, they are increasingly used as the main dietary measurement in nutritional epidemiology, in particular in sub-studies nested within prospective cohorts. Food records are, however, subject to excess reports of zero intake. Measurement error is a serious problem in nutritional epidemiology because of the lack of gold standard measurements and results in biased estimated diet-disease associations. In this paper, a 3-part measurement error model, which we call the never and episodic consumers (NEC) model, is outlined for food records. It allows for both real zeros, due to never consumers, and excess zeros, due to episodic consumers (EC). Repeated measurements are required for some study participants to fit the model. Simulation studies are used to compare the results from using the proposed model to correct for measurement error with the results from 3 alternative approaches: a crude approach using the mean of repeated food record measurements as the exposure, a linear regression calibration (RC) approach, and an EC model which does not allow real zeros. The crude approach results in badly attenuated odds ratio estimates, except in the unlikely situation in which a large number of repeat measurements is available for all participants. Where repeat measurements are available for all participants, the 3 correction methods perform equally well. However, when only a subset of the study population has repeat measurements, the NEC model appears to provide the best method for correcting for measurement error, with the 2 alternative correction methods, in particular the linear RC approach, resulting in greater bias and loss of coverage. The NEC model is extended to include adjustment for measurements from food frequency questionnaires, enabling better estimation of the proportion of never consumers when the number of repeat measurements is small. The methods are applied to 7-day diary measurements of alcohol intake in the EPIC-Norfolk study.

Race and region are associated with nutrient intakes among black and white men in the United States

Stroke mortality rates and prevalence of several chronic diseases are higher in Southern populations and blacks in the US. This study examined the relationships of race (black, white) and region (Stroke Belt, Stroke Buckle, other) with selected nutrient intakes among black and white American men (n = 9229). The Block 98 FFQ assessed dietary intakes and multivariable linear regression analysis was used to examine whether race and region were associated with intakes of fiber, saturated fat, trans fat, sodium, potassium, magnesium, calcium, and cholesterol. Race and region were significant predictors of most nutrient intakes. Black men consumed 1.00% lower energy from saturated fat compared with white men [multivariable-adjusted β: 1.00% (95% CI = -0.88, -1.13)]. A significant interaction between race and region was detected for trans fat (P < 0.0001), where intake was significantly lower among black men compared with white men only in the Stroke Belt [multivariable-adjusted β: -0.21 (95% CI = -0.11, -0.31)]. Among black men, intakes of sodium, potassium, magnesium, and calcium were lower, whereas cholesterol was higher, compared with white men (P < 0.05 for all). Comparing regions, men in the Stroke Buckle had the lowest intakes of fiber, potassium, magnesium, and calcium compared with those in the Stroke Belt and other regions; men in both the Stroke Buckle and Stroke Belt had higher intakes of cholesterol compared with those in other regions (P < 0.005 for all). Given these observed differences in dietary intakes, more research is needed to understand if and how they play a role in the health disparities and chronic disease risks observed among racial groups and regions in the US.

Use of the predictive sugars biomarker to evaluate self-reported total sugars intake in the Observing Protein and Energy Nutrition (OPEN) study

BACKGROUND

A predictive biomarker for intake of total sugars was recently developed under controlled conditions. We used this biomarker to assess measurement error (ME) structure in self-reported intake of total sugars in free-living individuals.

METHODS

The Observing Protein and Energy Nutrition (OPEN) study involved 484 participants aged 40 to 69 years. Diet was assessed using two administrations of a food frequency questionnaire (FFQ) and two nonconsecutive 24-hour dietary recalls (24HDR). Two 24-hour urine samples checked for completeness were analyzed on sucrose and fructose. We applied the biomarker calibrated in a feeding study to OPEN data to assess the ME structure and the attenuation factors (AF) for intakes of absolute total sugars and sugars density for the FFQ and 24HDR.

RESULTS

The AFs for absolute sugars were similar for a single FFQ and 24HDR, but attenuation decreased with repeated 24HDRs. For sugars density, the AFs for FFQ (men: 0.39; women: 0.33) were greater than for single 24HDR (men: 0.30; women: 0.24), and similar to two 24HDRs (men: 0.41; women: 0.35). The attenuation associated with both instruments was greater in women than in men.

CONCLUSIONS

Both the FFQ and 24HDR were found to be biased; hence, incorporation of the sugars biomarker in calibration studies within the cohorts may be necessary to more reliably estimate associations of sugars and disease.

IMPACT

In this article, we propose a new dietary reference instrument based on the recently defined class of predictive biomarkers. Using sugars biomarker, we quantify ME in the FFQ- and 24HDR-reported absolute total sugars and total sugars density.

Web-based nutrition education intervention improves self-efficacy and self-regulation related to increased dairy intake in college students

Dairy consumption declines substantially during young adulthood. Interventions that incorporate theory-based nutrition education can provide insight into factors associated with dietary choices. The aim of this experimental study was to improve outcome expectations, self-efficacy, self-regulation, and behavior related to dairy intake in college students using social cognitive theory. Students (n=294) enrolled in a personal health class were randomized to intervention (n=148) or comparison group (n=146). The 5-week intervention (March 2006 to April 2006) was conducted using an online course system; components included e-mail messages, posted information, and behavior checklists with tailored feedback. Multivariate analysis of covariance with age and sex as covariates (P<0.05) was conducted to measure change related to dairy intake and social cognitive theory variables. Ninety-two percent of participants (n=135 intervention, n=136 control) completed the study. Dairy intake from food records did not differ between groups at baseline; baseline intake for all participants (mean ± standard error) was 0.45 ± 0.05 servings/day for low-fat dairy products and 1.44 ± 0.06 servings/day for total dairy products. Participants in the intervention group made greater increases in use of self-regulatory strategies (P=0.038) and self-efficacy for consuming three servings/day of dairy products (P=0.049), but not in outcome expectations or consumption of dairy products. A Web-based intervention designed to change dairy intake in college students was effective in modifying some social cognitive theory constructs; strategies that positively impact outcome expectations and social support through online interventions require further development.

Measurement error of dietary self-report in intervention trials

Dietary intervention trials aim to change dietary patterns of individuals. Participating in such trials could impact dietary self-report in divergent ways: Dietary counseling and training on portion-size estimation could improve self-report accuracy; participant burden could increase systematic error. Such intervention-associated biases could complicate interpretation of trial results. The authors investigated intervention-associated biases in reported total carotenoid intake using data on 3,088 breast cancer survivors recruited between 1995 and 2000 and followed through 2006 in the Women's Healthy Eating and Living Study, a randomized intervention trial. Longitudinal data from 2 self-report methods (24-hour recalls and food frequency questionnaires) and a plasma carotenoid biomarker were collected. A flexible measurement error model was postulated. Parameters were estimated in a Bayesian framework by using Markov chain Monte Carlo methods. Results indicated that the validity (i.e., correlation with "true" intake) of both self-report methods was significantly higher during follow-up for intervention versus nonintervention participants (4-year validity estimates: intervention = 0.57 for food frequency questionnaires and 0.58 for 24-hour recalls; nonintervention = 0.42 for food frequency questionnaires and 0.48 for 24-hour recalls). However, within- and between-instrument error correlations during follow-up were higher among intervention participants, indicating an increase in systematic error. Diet interventions can impact measurement errors of dietary self-report. Appropriate statistical methods should be applied to examine intervention-associated biases when interpreting results of diet trials.

A randomised controlled trial to evaluate the efficacy of a 6 month dietary and physical activity intervention for prostate cancer patients receiving androgen deprivation therapy

Background

Treatment with Androgen Deprivation Therapy (ADT) for prostate cancer is associated with changes in body composition including increased fat and decreased lean mass; increased fatigue, and a reduction in quality of life. No study to date has evaluated the effect of dietary and physical activity modification on the side-effects related to ADT. The aim of this study is to evaluate the efficacy of a 6-month dietary and physical activity intervention for prostate cancer survivors receiving ADT to minimise the changes in body composition, fatigue and quality of life, typically associated with ADT.

Methods

Men are recruited to this study if their treatment plan is to receive ADT for at least 6 months. Men who are randomised to the intervention arm receive a home-based tailored intervention to meet the following guidelines a) ≥ 5 servings vegetables and fruits/day; b) 30%-35% of total energy from fat, and < 10% energy from saturated fat/day; c) 10% of energy from polyunsaturated fat/day; d) limited consumption of processed meats; e) 25-35 gm of fibre/day; f) alcoholic drinks ≤ 28 units/week; g) limited intake of foods high in salt and/or sugar. They are also encouraged to include at least 30 minutes of brisk walking, 5 or more days per week. The primary outcomes are change in body composition, fatigue and quality of life scores. Secondary outcomes include dietary intake, physical activity and perceived stress. Baseline information collected includes: socio-economic status, treatment duration, perceived social support and health status, family history of cancer, co-morbidities, medication and supplement use, barriers to change, and readiness to change their health behaviour. Data for the primary and secondary outcomes will be collected at baseline, 3 and 6 months from 47 intervention and 47 control patients.

Discussion

The results of this study will provide detailed information on diet and physical activity levels in prostate cancer patients treated with ADT and will test the feasibility and efficacy of a diet and physical activity intervention which could provide essential information to develop guidelines for prostate cancer patients to minimise the side effects related to ADT.

Trial registration

ISRCTN trial number ISCRTN75282423

Intake of dietary fats and colorectal cancer risk: prospective findings from the UK Dietary Cohort Consortium

INTRODUCTION

Epidemiologic evidence for an association between colorectal cancer (CRC) risk and total dietary fat, saturated fat (SF), monounsaturated fat (MUFA) and polyunsaturated fat (PUFA) is inconsistent. Previous studies have used food frequency questionnaires (FFQ) to assess diet, but data from food diaries may be less prone to severe measurement error than data from FFQ.

METHODS

We conducted a case-control study nested within seven prospective UK cohort studies, comprising 579 cases of incident CRC and 1996 matched controls. Standardized dietary data from 4- to 7-day food diaries and from FFQ were used to estimate odds ratios for CRC risk associated with intake of fat and subtypes of fat using conditional logistic regression. We also calculated multivariate measurement error corrected odds ratios for CRC using repeated food diary measurements.

RESULTS

We observed no associations between intakes of total dietary fat or types of fat and CRC risk, irrespective of whether dietary data were obtained using food diaries or FFQ.

CONCLUSION

Our results do not support the hypothesis that intakes of total dietary fat, SF, MUFA or PUFA are linked to risk of CRC.

Detection of food intake from swallowing sequences by supervised and unsupervised methods

Studies of food intake and ingestive behavior in free-living conditions most often rely on self-reporting-based methods that can be highly inaccurate. Methods of Monitoring of Ingestive Behavior (MIB) rely on objective measures derived from chewing and swallowing sequences and thus can be used for unbiased study of food intake with free-living conditions. Our previous study demonstrated accurate detection of food intake in simple models relying on observation of both chewing and swallowing. This article investigates methods that achieve comparable accuracy of food intake detection using only the time series of swallows and thus eliminating the need for the chewing sensor. The classification is performed for each individual swallow rather than for previously used time slices and thus will lead to higher accuracy in mass prediction models relying on counts of swallows. Performance of a group model based on a supervised method (SVM) is compared to performance of individual models based on an unsupervised method (K-means) with results indicating better performance of the unsupervised, self-adapting method. Overall, the results demonstrate that highly accurate detection of intake of foods with substantially different physical properties is possible by an unsupervised system that relies on the information provided by the swallowing alone.

Alcohol intake and risk of colorectal cancer: results from the UK Dietary Cohort Consortium

Background:

Epidemiological studies have suggested that excessive alcohol intake increases colorectal cancer (CRC) risk. However, findings regarding tumour subsites and sex differences have been inconsistent.

Methods:

We investigated the prospective associations between alcohol intake on overall and site- and sex-specific CRC risk. Analyses were conducted on 579 CRC cases and 1996 matched controls nested within the UK Dietary Cohort Consortium using standardised data obtained from food diaries as a main nutritional method and repeated using data from food frequency questionnaire (FFQ).

Results:

Compared with individuals in the lightest category of drinkers (>0–<5 g per day), the multivariable odds ratios of CRC were 1.16 (95% confidence interval (95% CI): 0.88, 1.53) for non-drinkers, 0.91 (95% CI: 0.67, 1.24) for drinkers with 5–<15 g per day, 0.90 (95% CI: 0.65, 1.25) for drinkers with 15–<30 g per day, 1.02 (95% CI: 0.66, 1.58) for drinkers with 30–<45 g per day and 1.19 (95% CI: 0.75, 1.91) for drinkers with ⩾45 g per day. No clear associations were observed between site-specific CRC risk and alcohol intake in either sex. Analyses using FFQ showed similar results.

Conclusion:

We found no significantly increased risk of CRC up to 30 g per day of alcohol intake within the UK Dietary Cohort Consortium.

Dietary potassium intake and mortality in long-term hemodialysis patients

BACKGROUND

Hyperkalemia has been associated with higher mortality in long-term hemodialysis (HD) patients. There are few data concerning the relationship between dietary potassium intake and outcome.

STUDY DESIGN

The mortality predictability of dietary potassium intake from reported food items estimated using the Block Food Frequency Questionnaire (FFQ) at the start of the cohort was examined in a 5-year (2001-2006) cohort of 224 HD patients in Southern California using Cox proportional hazards regression.

SETTING & PARTICIPANTS

224 long-term HD patients from 8 DaVita dialysis clinics.

PREDICTORS

Dietary potassium intake ranking using the Block FFQ.

OUTCOMES

5-year survival.

RESULTS

HD patients with higher potassium intake had greater dietary energy, protein, and phosphorus intakes and higher predialysis serum potassium and phosphorus levels. Greater dietary potassium intake was associated with significantly increased death HRs in unadjusted models and after incremental adjustments for case-mix, nutritional factors (including 3-month averaged predialysis serum creatinine, potassium, and phosphorus levels; body mass index; normalized protein nitrogen appearance; and energy, protein, and phosphorus intake) and inflammatory marker levels. HRs for death across the 3 higher quartiles of dietary potassium intake in the fully adjusted model (compared with the lowest quartile) were 1.4 (95% CI, 0.6-3.0), 2.2 (95% CI, 0.9-5.4), and 2.4 (95% CI, 1.1-7.5), respectively (P for trend = 0.03). Restricted cubic spline analyses confirmed the incremental mortality predictability of higher potassium intake.

LIMITATIONS

FFQs may underestimate individual potassium intake and should be used to rank dietary intake across the population.

CONCLUSIONS

Higher dietary potassium intake is associated with increased death risk in long-term HD patients, even after adjustments for serum potassium level; dietary protein; energy, and phosphorus intake; and nutritional and inflammatory marker levels. The potential role of dietary potassium in the high mortality rate of HD patients warrants clinical trials.

Meat, poultry and fish and risk of colorectal cancer: pooled analysis of data from the UK dietary cohort consortium

OBJECTIVE

Some but not all epidemiological studies have reported that high intakes of red and processed meat are associated with an increased risk of colorectal cancer. In the UK Dietary Cohort Consortium, we examined associations of meat, poultry and fish intakes with colorectal cancer risk using standardised individual dietary data pooled from seven UK prospective studies.

METHODS

Four- to seven-day food diaries were analysed, disaggregating the weights of meat, poultry and fish from composite foods to investigate dose-response relationships. We identified 579 cases of colorectal cancer and matched with 1,996 controls on age, sex and recruitment date. Conditional logistic regression models were used to estimate odds ratios for colorectal cancer associated with meat, poultry and fish intakes, adjusting for relevant covariables.

RESULTS

Disaggregated intakes were moderately low, e.g. mean red meat intakes were 38.2 g/day among male and 28.7 g/day among female controls. There was little evidence of association between the food groups examined and risk for colorectal cancer: Odds ratios (95% confidence intervals) for a 50 g/day increase were 1.01 (0.84-1.22) for red meat, 0.88 (0.68-1.15) for processed meat, 0.97 (0.84-1.12) for red and processed meat combined, 0.80 (0.65-1.00) for poultry, 0.92 (0.70-1.21) for white fish and 0.89 (0.70-1.13) for fatty fish.

CONCLUSIONS

This study using pooled data from prospective food diaries, among cohorts with low to moderate meat intakes, shows little evidence of association between consumption of red and processed meat and colorectal cancer risk.

Validity and reproducibility of a food frequency questionnaire to assess dietary nutrients for prevention and management of metabolic syndrome in Korea

Little data exists on metabolic syndrome (MetS) related with intake, especially for the South Korean. The purpose of this study was to develop and evaluate a food frequency questionnaire (FFQ) for nutritional assessment in the population with MetS in South Korea. Randomly selected female participants, mean age 21.9 years (n = 38) were invited to answer the FFQ twice (FFQ1 and FFQ2) over a nine-month interval and to complete twelve-day diet records (DR) during the months between in South Korea. The correlation coefficients for nutrient intake between FFQ1 and FFQ2 varied from 0.253 (niacin) to 0.573 (cholesterol), and the energy intake-adjusted correlation coefficients ranged from 0.187 for protein to 0.662 for iron. The energy intake-adjusted and de-attenuated correlation coefficients for comparison of FFQ1 and the DRs ranged between 0.277 (vitamin B1) and 0.768 (fiber), and between 0.229 (zinc) and 0.859 (fat) for comparison of DRs with FFQ2. The percentages of study subjects classified into the same quartiles in both the DRs and FFQ1 ranged from 15.8% (vitamin B₆) to 47.4% (calcium), and for the same quartiles in DRs and FFQ2 from 13.2% (vitamin B₁) to 44.7% (potassium). The FFQ has reasonably good validity and reproducibility. Further research is needed for an assessment of reproducibility and validation of present FFQ in the subjects with MetS.

Relative validities of 3-day food records and the food frequency questionnaire

The food frequency questionnaire (FFQ) has been used as an important dietary assessment tool in epidemiologic studies, but the usefulness of the FFQ has been debated in recent years. This study was performed to evaluate the relative validities of 3-day food records and the semi-quantitative FFQ. A total of 124 subjects finished 3-day food records (FRs) during each of the four seasons, as well as the FFQ from December 2002 to May 2004. The FFQ was a food based semi-quantitative FFQ including 103 items. Three-day FRs from each season and a randomly selected season were compared with the remaining 9-day FRs. The remaining 9-day FRs, as a reference measurement, were also compared with the FFQ. Pearson's correlation coefficients between the 3-day FRs and the 9-day FRs were between 0.14 and 0.56. Pearson's correlation coefficients between the FFQ and the 9-day FRs ranged between 0.07 and 0.41. Average proportions of classification into the same quartiles, adjacent quartiles, and distant quartiles between the 3-day FRs and the 9-day FRs were 35.8%, 40.5%, and 5.2%, respectively. On average, the proportions of classification into the same quartiles, adjacent quartiles, and distant quartiles between the FFQ and the 9-day FRs were 31.1%, 39.4%, and 6.9%, respectively. Three-day FRs showed higher correlations and higher agreement proportions of quartile classification with the 9-day FRs than did the FFQ, but both relative validities of 3-day FRs and the FFQ appear to be acceptable as dietary assessment tools. Further studies for validating food intake by reliable biomarkers are necessary.

Dietary fiber and colorectal cancer risk: a nested case-control study using food diaries

BACKGROUND

Results of epidemiological studies of dietary fiber and colorectal cancer risk have not been consistent, possibly because of attenuation of associations due to measurement error in dietary exposure ascertainment.

METHODS

To examine the association between dietary fiber intake and colorectal cancer risk, we conducted a prospective case-control study nested within seven UK cohort studies, which included 579 case patients who developed incident colorectal cancer and 1996 matched control subjects. We used standardized dietary data obtained from 4- to 7-day food diaries that were completed by all participants to calculate the odds ratios for colorectal, colon, and rectal cancers with the use of conditional logistic regression models that adjusted for relevant covariates. We also calculated odds ratios for colorectal cancer by using dietary data obtained from food-frequency questionnaires that were completed by most participants. All statistical tests were two-sided.

RESULTS

Intakes of absolute fiber and of fiber intake density, ascertained by food diaries, were statistically significantly inversely associated with the risks of colorectal and colon cancers in both age-adjusted models and multivariable models that adjusted for age; anthropomorphic and socioeconomic factors; and dietary intakes of folate, alcohol, and energy. For example, the multivariable-adjusted odds ratio of colorectal cancer for highest vs the lowest quintile of fiber intake density was 0.66 (95% confidence interval = 0.45 to 0.96). However, no statistically significant association was observed when the same analysis was conducted using dietary data obtained by food-frequency questionnaire (multivariable odds ratio = 0.88, 95% confidence interval = 0.57 to 1.36).

CONCLUSIONS

Intake of dietary fiber is inversely associated with colorectal cancer risk. Methodological differences (ie, study design, dietary assessment instruments, definition of fiber) may account for the lack of convincing evidence for the inverse association between fiber intake and colorectal cancer risk in some previous studies.

Association of dietary phosphorus intake and phosphorus to protein ratio with mortality in hemodialysis patients

BACKGROUND AND OBJECTIVES

Epidemiologic studies show an association between higher predialysis serum phosphorus and increased death risk in maintenance hemodialysis (MHD) patients. The hypothesis that higher dietary phosphorus intake and higher phosphorus content per gram of dietary protein intake are each associated with increased mortality in MHD patients was examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Food frequency questionnaires were used to conduct a cohort study to examine the survival predictability of dietary phosphorus and the ratio of phosphorus to protein intake. At the start of the cohort, Cox proportional hazard regression was used in 224 MHD patients, who were followed for up to 5 years (2001 to 2006).

RESULTS

Both higher dietary phosphorus intake and a higher dietary phosphorus to protein ratio were associated with significantly increased death hazard ratios (HR) in the unadjusted models and after incremental adjustments for case-mix, diet, serum phosphorus, malnutrition-inflammation complex syndrome, and inflammatory markers. The HR of the highest (compared with lowest) dietary phosphorus intake tertile in the fully adjusted model was 2.37. Across categories of dietary phosphorus to protein ratios of <12, 12 to <14, 14 to <16, and > or =16 mg/g, death HRs were 1.13, 1.00 (reference value), 1.80, and 1.99, respectively. Cubic spline models of the survival analyses showed similar incremental associations.

CONCLUSIONS

Higher dietary phosphorus intake and higher dietary phosphorus to protein ratios are each associated with increased death risk in MHD patients, even after adjustments for serum phosphorus, phosphate binders and their types, and dietary protein, energy, and potassium intakes.

Dietary, lifestyle and clinicopathological factors associated with BRAF and K-ras mutations arising in distinct subsets of colorectal cancers in the EPIC Norfolk study

Background

BRAF and K-ras proto-oncogenes encode components of the ERK signalling pathway and are frequently mutated in colorectal cancer. This study investigates the associations between BRAF and K-ras mutations and clinicopathological, lifestyle and dietary factors in colorectal cancers.

Methods

186 adenocarcinomas and 16 adenomas from the EPIC Norfolk study were tested for BRAF and K-ras mutations. Diet and lifestyle data were collected prospectively using seven day food diaries.

Results

BRAF V600E mutation was found in 15.6% of colorectal cancers but at higher frequencies in cancers with proximal location, poor differentiation and microsatellite instability (MSI) (all p < 0.001). K-ras mutation (mostly in codons 12 and 13) was found in 22.0% of colorectal cancers but at higher frequencies in cancers of more advanced Dukes' stage (p = 0.001), microsatellite stable (MSS) status (p = 0.002) and in individuals with lower blood high-density lipoprotein concentrations (p = 0.04). Analysis of dietary factors demonstrated no link between BRAF mutation and any specific dietary constituent, however, K-ras mutation was found at higher frequencies in individuals with higher white meat consumption (p < 0.001). Further analysis of specific mutation type demonstrated that G to A transitions in K-ras were observed at higher frequencies in individuals consuming lower amounts of fruit (p = 0.02).

Conclusion

These data support the model of BRAF and K-ras mutations arising in distinct colorectal cancer subsets associated with different clinicopathological and dietary factors, acting as mutually exclusive mechanisms of activation of the same signalling pathway.

Comparative analysis of two FFQ

OBJECTIVE

To examine the utility of a shorter FFQ compared with a longer FFQ, both of which are commonly used in Australia.

DESIGN

Comparative study.

SETTING

Community setting.

SUBJECTS

One hundred and fifty-nine men (mean 55 (sem 7) years) screened for participation in an intervention study completed both the Commonwealth Scientific and Industrial Research Organisation FFQ and the Cancer Council of Victoria FFQ. Agreement between both questionnaires was assessed according to Bland-Altman plots and limits of agreement (LOA) and ordinary least products regression to test for the presence of fixed and proportional bias.

RESULTS

There was good relative agreement between the methods for energy and macronutrients (Pearson's correlation coefficients: energy r = 0.7, protein r = 0.6, fat r = 0.8, carbohydrate r = 0.7, alcohol r = 0.8; P < 0.01). Mean group-level agreement for the majority of nutrients (70 %) fell between 80 % and 110 %. According to the criteria used (maximum LOA was 50-200 % and no significant proportional bias), there was acceptable agreement between the FFQ for energy and total saturated and monounsaturated fat, but not for protein, carbohydrate and fibre. Micronutrients that did not meet the agreement criteria including calcium, iron, thiamin, niacin, riboflavin and folate. When the data were analysed according to quintiles, the majority of subjects were either in exactly the same quintile or within one quintile for most nutrients, and 1-2 % were grossly misclassified by three or four quintiles.

CONCLUSIONS

We conclude that there is sufficient agreement between the instruments for group-level comparisons in men, but they are not interchangeable for estimation of individual intakes.

Playing with food. A novel approach to understanding nutritional behaviour development

This study explored the use of a novel method of collecting data on nutritional behaviour development in young children: videos posted on the Internet site YouTube. YouTube videos (n=115) of children alone and interacting with parents in toy kitchen settings were analyzed using constant comparison analysis. Results revealed that in the videos of play nutritional behaviours, children showed influences of their real social environments, and that this medium enabled the observation of parent-child interactions in a more natural context without the researcher's presence. These findings encourage further research in the development and validity of alternative methods of data collection.

MGMT Ile143Val polymorphism, dietary factors and the risk of breast, colorectal and prostate cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk study

O(6)-Methylguanine-DNA methyltransferase (MGMT) repairs DNA damage caused by alkylating agents including N-nitroso compounds from diet. MGMT Ile143Val polymorphism may lead to less DNA damage repair and increased cancer risk depending on the environmental exposures. We investigated interactions between dietary factors and the MGMT Ile143Val polymorphism in relation to breast, colorectal and prostate cancer risk. There were 276/1498, 273/2984 and 312/1486 cases/controls for the breast, colorectal and prostate cancer studies respectively; all nested within the EPIC-Norfolk study, a prospective cohort of approximately 25,000 men and women aged 40-79. Baseline 7-day food diary data were collected for dietary assessment. MGMT Ile143Val polymorphism was not overall associated with breast, colorectal and prostate cancer risk. There was a significant interaction between this polymorphism and intake of red and processed meat on colorectal cancer risk (P(interaction)=0.04) suggesting an increased risk among carriers of the variant genotype compared to the MGMT Ile143Ile common genotype. A lower colorectal cancer risk was seen with higher intake of vitamin E and carotene among the variant genotype group but not in the common genotype group (P(interaction)=0.009 and P(interaction)=0.005 for vitamin E and carotene, respectively). A higher prostate cancer risk was seen with higher alcohol intake among the variant genotype (OR=2.08, 95% CI=1.21-3.57, P(interaction)=0.0009) compared to the common genotype with lower alcohol intake. In this UK population, the MGMT Ile143Val polymorphism was not overall associated with breast, colorectal and prostate cancer risk. There was evidence for this polymorphism playing a role in modulating the risk of prostate cancer in presence of alcohol. For colorectal cancer, the MGMT Ile143Val polymorphism may confer increased or decreased risk depending on the dietary exposure.

Food-frequency questionnaires: a review of their design, validation and utilisation

A review of the literature concerning the design, utilisation and validation of food-frequency questionnaires (FFQ) has been carried out using a semi-systematic approach to obtaining, reviewing and extracting data from articles. Databases were searched from 1980 to 1999. The present review identified 227 validation (from 1980 to September 1999) and 164 utilisation (for 1998 only) studies. A number of design issues have been evaluated through the present review. These include: the need to consider how portion sizes have been described, self-defined giving higher mean correlations; how an FFQ was administered, interviewer-administered giving higher mean correlations for some nutrients; how many items to include on an FFQ, those with the largest number of items having higher correlations. Validation techniques were described. Most validation studies involved comparing an FFQ against another dietary assessment method; only 19 % compared an FFQ to a biomarker. Measurement differences were most commonly assessed by correlation coefficients as opposed to other more appropriate methods. Mean correlation coefficients were highest for Ca and fat, and lowest for vitamin A and vegetables. The utilisation studies showed that FFQ were most commonly used in cross-sectional surveys, with ninety-three of the FFQ being designed to be disease-specific. The present review results were presented to a group of experts and a consensus arrived at concerning the development, validation and use of FFQ. Recommendations derived from the consensus arising from the literature review are presented as an appendix to the present paper.

Dietary patterns and risk of asthma: results from three countries in European Community Respiratory Health Survey-II

Dietary patterns offer an alternative to the analysis of individual foods or nutrients in nutritional epidemiological studies. The aim of the present study was to identify dietary patterns common to different European countries and examine their associations with asthma. In five study centres (two in Germany, two in the UK and one in Norway), 1174 adults aged 29-55 years completed a FFQ and respiratory symptoms questionnaire. A meta-analytic approach was used to identify the dietary patterns and analyse them in relation to current asthma, asthma symptoms and bronchial responsiveness (BHR). Two patterns emerged, generally correlating with the same foods at different centres: one associated with intake of meats and potatoes; the other with fish, fruits and vegetables. There was no evidence that the fish, fruits and vegetables pattern was associated with asthma (OR 1.11 (95 % CI 0.93, 1.33)), symptom score (ratio of means 1.07 (0.98, 1.17)) or BHR (regression coefficient - 0.01 ( - 0.12, 0.10)), though these CI appeared to rule out large protective effects of consuming these foods. There was no overall evidence that the meat and potato pattern was associated with asthma (OR 1.02 (0.79, 1.31)), symptom score (ratio of means 1.07 (0.84, 1.36)) or BHR (regression coefficient - 0.08 ( - 0.27, 0.10)), but there was heterogeneity between centres in the association with symptom score: a negative association at the two German centres; a positive association at the others. Heterogeneity in a multi-centre observational study of diet could suggest alternative explanations for apparent effects of diet, such as uncontrolled confounding.

Low dietary sodium intake is associated with enhanced vascular endothelial function in middle-aged and older adults with elevated systolic blood pressure

BACKGROUND

Age and increasing systolic blood pressure (BP) are associated with vascular endothelial dysfunction, but the factors involved are incompletely understood. We tested the hypothesis that vascular endothelial function is related to dietary sodium intake among middle-aged and older adults (MA and O) with elevated systolic BP.

METHODS

Data were analyzed on 25 otherwise healthy adults aged 48-73 years with high normal systolic BP or stage I systolic hypertension (130-159 mmHg). Self-reported sodium intake was <100 mmol/d in 12 (7 M) subjects (low sodium, 73+/-6 mmol/d) and between 100 and 200 mmol/d in 13 (9 M) subjects (normal sodium, 144+/-6 mmol/d).

RESULTS

Groups did not differ in other dietary factors, age, body weight and composition, BP, metabolic risk factors, physical activity and maximal aerobic capacity. Plasma concentrations of norepinephrine, endothelin-1, oxidized low-density lipoproteins (LDL), antioxidant status and inflammatory markers did not differ between groups. Brachial artery flow-mediated dilation (FMD) was 42% (mm Delta) to 52% (% Delta) higher in the low versus normal sodium group (p < 0.05). In all subjects, brachial artery FMD was inversely related to dietary sodium intake (FMD mm Delta r =-0.40, p < 0.05; %Delta r =-0.53, p < 0.01). Brachial artery FMD was not related to any other variable. In contrast, endothelium-independent dilation did not differ between groups (p >or= 0.24) and was not related to sodium intake in the overall group (p >or= 0.29).

CONCLUSIONS

Low sodium intake is associated with enhanced brachial artery FMD in MA and O with elevated systolic BP. These results suggest that dietary sodium restriction may be an effective intervention for improving vascular endothelial function in this high-risk group.