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

Urinary Sugars--A Biomarker of Total Sugars Intake

Measurement error in self-reported sugars intake may explain the lack of consistency in the epidemiologic evidence on the association between sugars and disease risk. This review describes the development and applications of a biomarker of sugars intake, informs its future use and recommends directions for future research. Recently, 24 h urinary sucrose and fructose were suggested as a predictive biomarker for total sugars intake, based on findings from three highly controlled feeding studies conducted in the United Kingdom. From this work, a calibration equation for the biomarker that provides an unbiased measure of sugars intake was generated that has since been used in two US-based studies with free-living individuals to assess measurement error in dietary self-reports and to develop regression calibration equations that could be used in future diet-disease analyses. Further applications of the biomarker include its use as a surrogate measure of intake in diet-disease association studies. Although this biomarker has great potential and exhibits favorable characteristics, available data come from a few controlled studies with limited sample sizes conducted in the UK. Larger feeding studies conducted in different populations are needed to further explore biomarker characteristics and stability of its biases, compare its performance, and generate a unique, or population-specific biomarker calibration equations to be applied in future studies. A validated sugars biomarker is critical for informed interpretation of sugars-disease association studies.

Evaluation of Salt Intake, Urinary Sodium Excretion and Their Relationship to Overhydration in Chronic Kidney Disease Patients

The purpose of this study was to estimate sodium intake in a group of patients with chronic kidney disease (CKD) and to correlate the results with the urinary excretion values of sodium and signs of fluid overload. We included patients with CKD in different stages. Urinary sodium was measured in 24 h urine samples. Body composition monitor (BCM) was used to estimate the hydration status. Sixty patients (38 ± 15 ml/min of GFR) presented 4.14 ± 1.71 g/24 h of urinary sodium excretion. Overhydration was detected in 50% of the patients by the BCM. There was a positive correlation between the measured sodium excretion values and BCM, ICW, ECW and TBW. In conclusion, markers of overhydration evaluated by BCM were positively correlated with urinary sodium excretion.

Comparison of a Web-Based Dietary Assessment Tool with Software for the Evaluation of Dietary Records

Background

Dietary assessment in clinical practice is performed by means of computer support, either in the form of a web-based tool or software. The aim of the paper is to present the results of the comparison of a Slovenian web-based tool with German software for the evaluation of four-day weighted paper-and-pencil-based dietary records (paper-DRs) in pregnant women.

Methods

A volunteer group of pregnant women (n=63) completed paper-DRs. These records were entered by an experienced research dietitian into a web-based application (Open Platform for Clinical Nutrition, OPEN, http://opkp.si/en, Ljubljana, Slovenia) and software application (Prodi 5.7 Expert plus, Nutri-Science, Stuttgart, Germany, 2011). The results for calculated energy intake, as well as 45 macro- and micronutrient intakes, were statistically compared by using the non-parametric Spearman’s rank correlation coefficient. The cut-off for Spearman’s rho was set at >0.600.

Results

12 nutritional parameters (energy, carbohydrates, fat, protein, water, potassium, calcium, phosphorus, dietary fiber, vitamin C, folic acid, and stearic acid) were in high correlation (>0.800), 18 in moderate (0.600–0.799), 11 in weak correlation (0.400–0.599), while 5 (arachidonic acid, niacin, alpha-linolenic acid, fluoride, total sugars) did not show any statistical correlation.

Conclusion

Comparison of the results of the evaluation of dietary records using a web-based dietary assessment tool with those using software shows that there is a high correlation for energy and macronutrient content.

Factors influencing the frequency of children's consumption of soft drinks

Among other focus areas, interventions designed to improve children's diets need to address key factors contributing to children's consumption of sugar-sweetened beverages. The present study employed structural equation modelling to investigate the relationship between a broad range of predictor variables and the frequency with which Australian children consume soft drinks. In total, 1302 parents of children aged 8 to 14 years responded to an online survey about their children's food consumption behaviours. Soft drink consumption frequency was primarily influenced by parents' attitudes to soft drinks, children's pestering behaviours, and perceived social norms relating to children's consumption of these products. Importantly, pestering and social norms had significant direct effects on consumption frequency in addition to indirect effects via their impact on parents' attitudes to soft drink.

Prospective study of breast cancer in relation to coffee, tea and caffeine in Sweden

Studies of coffee and tea consumption and caffeine intake as risk factors for breast cancer are inconclusive. We assessed coffee and tea consumption, caffeine intake, and possible confounding factors among 42,099 women from the Swedish Women's Lifestyle and Health study, the participants of which were aged 30-49 years at enrollment in 1991-1992. Complete follow-up for breast cancer incidence was performed through 2012 via linkage to national registries. Poisson regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer. During follow-up 1,395 breast cancers were diagnosed. The RR was 0.97 (95% CI 0.94-0.99) for a 1-unit increase in cups of coffee/day, 1.14 (95% CI 1.05-1.24) for a 1-unit increase in cups of tea/day, and 0.97 (95% CI 0.95-1.00) for a 100 mg/day increase in caffeine intake. Although the RR for no consumption (RR = 0.86, 95% CI 0.69-1.08), a group with a relatively small number of women, was not statistically significant, women with higher consumption had a decreased breast cancer risk (3-4 cups/day: RR = 0.87, 95% CI 0.76-1.00; ≥5 cups/day: RR = 0.81, 95% CI 0.70-0.94) compared to women consuming 1-2 cups of coffee/day. Compared to no consumption, women consuming >1 cups tea/day showed an increased breast cancer risk (RR = 1.19, 95% CI 1.00-1.42). Similar patterns of estimates were observed for breast cancer risk overall, during pre- and postmenopausal years, and for ER+ or PR+ breast cancer, but not for ER- and PR- breast cancer. Our findings suggest that coffee consumption and caffeine intake is negatively associated with the risk of overall and ER+/PR- breast cancer, and tea consumption is positively associated with the risk of overall and ER+/PR+ breast cancer.

Prediction of fruit and vegetable intake from biomarkers using individual participant data of diet-controlled intervention studies

Fruit and vegetable consumption produces changes in several biomarkers in blood. The present study aimed to examine the dose–response curve between fruit and vegetable consumption and carotenoid (α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin), folate and vitamin C concentrations. Furthermore, a prediction model of fruit and vegetable intake based on these biomarkers and subject characteristics (i.e. age, sex, BMI and smoking status) was established. Data from twelve diet-controlled intervention studies were obtained to develop a prediction model for fruit and vegetable intake (including and excluding fruit and vegetable juices). The study population in the present individual participant data meta-analysis consisted of 526 men and women. Carotenoid, folate and vitamin C concentrations showed a positive relationship with fruit and vegetable intake. Measures of performance for the prediction model were calculated using cross-validation. For the prediction model of fruit, vegetable and juice intake, the root mean squared error (RMSE) was 258·0 g, the correlation between observed and predicted intake was 0·78 and the mean difference between observed and predicted intake was − 1·7 g (limits of agreement: − 466·3, 462·8 g). For the prediction of fruit and vegetable intake (excluding juices), the RMSE was 201·1 g, the correlation was 0·65 and the mean bias was 2·4 g (limits of agreement: − 368·2, 373·0 g). The prediction models which include the biomarkers and subject characteristics may be used to estimate average intake at the group level and to investigate the ranking of individuals with regard to their intake of fruit and vegetables when validating questionnaires that measure intake.

Meat and fish consumption and the risk of renal cell carcinoma in the European prospective investigation into cancer and nutrition

Renal cell cancer (RCC) incidence varies worldwide with a higher incidence in developed countries and lifestyle is likely to contribute to the development of this disease. We examined whether meat and fish consumption were related to the risk of RCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). The analysis included 493,179 EPIC participants, recruited between 1992 and 2000. Until December 2008, 691 RCC cases have been identified. Meat and fish consumption was assessed at baseline using country-specific dietary assessment instruments; 24-hour recalls were applied in an 8% subsample for calibration purposes. Cox proportional hazards regression was used to calculate multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI). Women with a high consumption of red meat (HR = 1.36, 95% CI 1.14-1.62; calibrated, per 50 g/day) and processed meat (HR = 1.78, 95% CI 1.05-3.03; calibrated, per 50 g/day) had a higher risk of RCC, while no association existed in men. For processed meat, the association with RCC incidence was prominent in premenopausal women and was lacking in postmenopausal women (p interaction = 0.02). Neither poultry nor fish consumption were statistically significantly associated with the risk of RCC. The results show a distinct association of red and processed meat consumption with incident RCC in women but not in men. A biological explanation for these findings remains unclear.

Difference between 24-h diet recall and urine excretion for assessing population sodium and potassium intake in adults aged 18-39 y

BACKGROUND

Limited data are available on the accuracy of 24-h dietary recalls used to monitor US sodium and potassium intakes.

OBJECTIVE

We examined the difference in usual sodium and potassium intakes estimated from 24-h dietary recalls and urine collections.

DESIGN

We used data from a cross-sectional study in 402 participants aged 18-39 y (∼50% African American) in the Washington, DC, metropolitan area in 2011. We estimated means and percentiles of usual intakes of daily dietary sodium (dNa) and potassium (dK) and 24-h urine excretion of sodium (uNa) and potassium (uK). We examined Spearman's correlations and differences between estimates from dietary and urine measures. Multiple linear regressions were used to evaluate the factors associated with the difference between dietary and urine measures.

RESULTS

Mean differences between diet and urine estimates were higher in men [dNa - uNa (95% CI) = 936.8 (787.1, 1086.5) mg/d and dK - uK = 571.3 (448.3, 694.3) mg/d] than in women [dNa - uNa (95% CI) = 108.3 (11.1, 205.4) mg/d and dK - uK = 163.4 (85.3, 241.5 mg/d)]. Percentile distributions of diet and urine estimates for sodium and potassium differed for men. Spearman's correlations between measures were 0.16 for men and 0.25 for women for sodium and 0.39 for men and 0.29 for women for potassium. Urinary creatinine, total caloric intake, and percentages of nutrient intake from mixed dishes were independently and consistently associated with the differences between diet and urine estimates of sodium and potassium intake. For men, body mass index was also associated. Race was associated with differences in estimates of potassium intake.

CONCLUSIONS

Low correlations and differences between dietary and urinary sodium or potassium may be due to measurement error in one or both estimates. Future analyses using these methods to assess sodium and potassium intake in relation to health outcomes may consider stratifying by factors associated with the differences in estimates from these methods. This trial was registered at clinicaltrials.gov as NCT01631240.

The interaction between epigenetics, nutrition and the development of cancer

Unlike the genome, the epigenome can be modified and hence some epigenetic risk markers have the potential to be reversed. Such modifications take place by means of drugs, diet or environmental exposures. It is widely accepted that epigenetic modifications take place during early embryonic and primordial cell development, but it is also important that we gain an understanding of the potential for such changes later in life. These “later life” epigenetic modifications in response to dietary intervention are the focus of this paper. The epigenetic modifications investigated include DNA methylation, histone modifications and the influence of microRNAs. The epigenotype could be used not only to predict susceptibility to certain cancers but also to assess the effectiveness of dietary modifications to reduce such risk. The influence of diet or dietary components on epigenetic modifications and the impact on cancer initiation or progression has been assessed herein.

Socio-economic dietary inequalities in UK adults: an updated picture of key food groups and nutrients from national surveillance data

Socio-economic differences in diet are a potential contributor to health inequalities. The present study provides an up-to-date picture of socio-economic differences in diet in the UK, focusing on the consumption of three food groups and two nutrients of public health concern: fruit and vegetables; red and processed meat; oily fish; saturated fats; non-milk extrinsic sugars (NMES). We analysed data for 1491 adults (age ≥ 19 years) from the National Diet and Nutrition Survey 2008-2011. Socio-economic indicators were household income, occupational social class and highest educational qualification. Covariate-adjusted estimates for intakes of fruit and vegetables, red and processed meat, and both nutrients were estimated using general linear models. Covariate-adjusted OR for oily fish consumption were derived with logistic regression models. We observed consistent socio-economic gradients in the consumption of the three food groups as estimated by all the three indicators. Contrasting highest and lowest levels of each socio-economic indicator, we observed significant differences in intakes for the three food groups and NMES. Depending on the socio-economic indicator, highest socio-economic groups consumed up to 128 g/d more fruit and vegetables, 26 g/d less red and processed meat, and 2·6% points less NMES (P< 0·05 for all). Relative to lowest socio-economic groups, highest socio-economic groups were 2·4 to 4·0 times more likely to eat oily fish. No significant patterns in saturated fat consumption were apparent. In conclusion, socio-economic differences were identified in the consumption of food groups and one nutrient of public health importance. Aligning dietary intakes with public health guidance may require interventions specifically designed to reduce health inequalities.

Using growth mixture modeling to identify classes of sodium adherence in adults with heart failure

BACKGROUND

The prevention of fluid retention is important to reduce hospitalizations in patients with heart failure (HF). Following a low-sodium diet helps to reduce fluid retention.

OBJECTIVE

The primary objective of this study was to use growth mixture modeling to identify distinct classes of sodium adherence-characterized by shared growth trajectories of objectively measured dietary sodium. The secondary objective was to identify patient-level determinants of the nonadherent trajectory.

METHODS

This was a secondary analysis of data collected from a prospective longitudinal study of 279 community-dwelling adults with previously or currently symptomatic HF. Growth mixture modeling was used to identify distinct trajectories of change in 24-hour urinary sodium excretion measured at 3 time points over 6 months. Logistic modeling was used to predict membership in observed trajectories.

RESULTS

The sample was predominantly male (64%), had a mean age of 62 years, was functionally compromised (59% New York Heart Association class III), and had nonischemic HF etiology. Two distinct trajectories of sodium intake were identified and labeled adherent (66%) and nonadherent (34%) to low-sodium diet recommendations. Three predictors of the nonadherent trajectory were identified, confirming our previous mixed-effect analysis. Compared with being normal weight (body mass index <25 kg/m2), being overweight and obese was associated with a 4-fold incremental increase in the likelihood of being in the nonadherent trajectory (odds ratio [OR], 4.63; 95% confidence interval [CI], 1.66-12.91; P < .002). Being younger than 65 years (OR, 4.66; 95% CI, 1.04-20.81; P = .044) or having diabetes (OR, 4.15; 95% CI, 1.29-13.40; P = .016) were both associated with more than 4 times the odds of being in the nonadherent urine sodium trajectory compared with being older than 65 years or not having diabetes, respectively.

CONCLUSIONS

Two distinct trajectories of sodium intake were identified in patients with HF. The nonadherent trajectory was characterized by an elevated pattern of dietary sodium intake shown by others to be associated with adverse outcomes in HF. Predictors of the nonadherent trajectory included higher body mass index, younger age, and diabetes.

Identifying predictors of high sodium excretion in patients with heart failure: a mixed effect analysis of longitudinal data

BACKGROUND

A low-sodium diet is a core component of heart failure self-care but patients have difficulty following the diet.

AIM

The aim of this study was to identify predictors of higher than recommended sodium excretion among patients with heart failure.

METHODS

The World Health Organization Five Dimensions of Adherence model was used to guide analysis of existing data collected from a prospective, longitudinal study of 280 community-dwelling adults with previously or currently symptomatic heart failure. Sodium excretion was measured objectively using 24-hour urine sodium measured at three time points over six months. A mixed effect logistic model identified predictors of higher than recommended sodium excretion.

RESULTS

The adjusted odds of higher sodium excretion were 2.90, (95% confidence interval (CI): 1.15-4.25, p<0.001) for patients who were obese; 2.80 (95% CI: 1.33-5.89, p=0.007) for patients with diabetes; and 2.22 (95% CI: 1.09-4.53, p=0.028) for patients who were cognitively intact.

CONCLUSION

Three factors were associated with excess sodium excretion and two factors, obesity and diabetes, are modifiable by changing dietary food patterns.

Use of a urinary sugars biomarker to assess measurement error in self-reported sugars intake in the nutrition and physical activity assessment study (NPAAS)

BACKGROUND

Measurement error in self-reported sugars intake may be obscuring the association between sugars and cancer risk in nutritional epidemiologic studies.

METHODS

We used 24-hour urinary sucrose and fructose as a predictive biomarker for total sugars, to assess measurement error in self-reported sugars intake. The Nutrition and Physical Activity Assessment Study (NPAAS) is a biomarker study within the Women's Health Initiative (WHI) Observational Study that includes 450 postmenopausal women ages 60 to 91 years. Food Frequency Questionnaires (FFQ), four-day food records (4DFR), and three 24-hour dietary recalls (24HRs) were collected along with sugars and energy dietary biomarkers.

RESULTS

Using the biomarker, we found self-reported sugars to be substantially and roughly equally misreported across the FFQ, 4DFR, and 24HR. All instruments were associated with considerable intake- and person-specific bias. Three 24HRs would provide the least attenuated risk estimate for sugars (attenuation factor, AF = 0.57), followed by FFQ (AF = 0.48) and 4DFR (AF = 0.32), in studies of energy-adjusted sugars and disease risk. In calibration models, self-reports explained little variation in true intake (5%-6% for absolute sugars and 7%-18% for sugars density). Adding participants' characteristics somewhat improved the percentage variation explained (16%-18% for absolute sugars and 29%-40% for sugars density).

CONCLUSIONS

None of the self-report instruments provided a good estimate of sugars intake, although overall 24HRs seemed to perform the best.

IMPACT

Assuming the calibrated sugars biomarker is unbiased, this analysis suggests that measuring the biomarker in a subsample of the study population for calibration purposes may be necessary for obtaining unbiased risk estimates in cancer association studies.

Use of two-part regression calibration model to correct for measurement error in episodically consumed foods in a single-replicate study design: EPIC case study

In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference measurements are required. Short-term reference measurements for foods that are not consumed daily contain excess zeroes that pose challenges in the calibration model. We adapted two-part regression calibration model, initially developed for multiple replicates of reference measurements per individual to a single-replicate setting. We showed how to handle excess zero reference measurements by two-step modeling approach, how to explore heteroscedasticity in the consumed amount with variance-mean graph, how to explore nonlinearity with the generalized additive modeling (GAM) and the empirical logit approaches, and how to select covariates in the calibration model. The performance of two-part calibration model was compared with the one-part counterpart. We used vegetable intake and mortality data from European Prospective Investigation on Cancer and Nutrition (EPIC) study. In the EPIC, reference measurements were taken with 24-hour recalls. For each of the three vegetable subgroups assessed separately, correcting for error with an appropriately specified two-part calibration model resulted in about three fold increase in the strength of association with all-cause mortality, as measured by the log hazard ratio. Further found is that the standard way of including covariates in the calibration model can lead to over fitting the two-part calibration model. Moreover, the extent of adjusting for error is influenced by the number and forms of covariates in the calibration model. For episodically consumed foods, we advise researchers to pay special attention to response distribution, nonlinearity, and covariate inclusion in specifying the calibration model.

Measuring population sodium intake: a review of methods

Reduction of population sodium intake has been identified as a key initiative for reduction of Non-Communicable Disease. Monitoring of population sodium intake must accompany public health initiatives aimed at sodium reduction. A number of different methods for estimating dietary sodium intake are currently in use. Dietary assessment is time consuming and often under-estimates intake due to under-reporting and difficulties quantifying sodium concentration in recipes, and discretionary salt. Twenty-four hour urinary collection (widely considered to be the most accurate method) is also burdensome and is limited by under-collection and lack of suitable methodology to accurately identify incomplete samples. Spot urine sampling has recently been identified as a convenient and affordable alternative, but remains highly controversial as a means of monitoring population intake. Studies suggest that while spot urinary sodium is a poor predictor of 24-h excretion in individuals, it may provide population estimates adequate for monitoring. Further research is needed into the accuracy and suitability of spot urine collection in different populations as a means of monitoring sodium intake.

Endometrial cancer in relation to coffee, tea, and caffeine consumption: a prospective cohort study among middle-aged women in Sweden

This study aimed to add to prospective data on the possible inverse association between coffee consumption and endometrial cancer risk, already supported by several case-control studies. Coffee and tea consumption and possible confounding factors were assessed among 42,270 women aged 30-49 years at enrollment in 1991-1992 in the Swedish Women's Lifestyle and Health cohort study, with complete follow-up through 2009. We calculated caffeine intake per day; Cox proportional hazard models were used to estimate multivariable relative risks (mRR) for endometrial cancer with 95% confidence intervals (CIs). One hundred forty-four endometrial cancers were diagnosed during follow-up. Women with and without endometrial cancer had a similar mean daily coffee consumption (549 vs. 547 g), tea consumption (104 vs. 115 g), and caffeine intake (405 vs. 406 mg). Compared to those consuming <2 cups of coffee per day, women consuming >3 cups had a mRR of 1.56 (95% CI: 0.94-2.59; P for trend = 0.17). Compared with the lowest tertile of caffeine intake, the highest tertile had a mRR of 1.32 (95% CI: 0.87-1.99; P for trend = 0.27). Our study provides no convincing evidence of an association between coffee consumption, tea consumption, or caffeine intake and endometrial cancer risk among middle-aged women.

"Vitamin D supplementation and bone health in adults with diabetic nephropathy: the protocol for a randomized controlled trial"

BACKGROUND

Suboptimal vitamin D status is highly prevalent in Northern communities, particularly in those patients with chronic diseases such as diabetes and chronic renal disease. Emerging literature suggests that adherence to daily vitamin D supplementation may be an important factor influencing vitamin D status and overall bone health, but compliance with therapies for bone health is a major challenge. It is unknown what level of vitamin D supplementation will ameliorate or improve suboptimal vitamin D status in patients with diabetic nephropathy or contribute to improved bone health, particularly for those living in northern climates.

METHODS/DESIGN

The study purpose was to examine two different strategies of vitamin D3 supplementation; daily dosing of 2000 IU per day verses monthly dosing of 40,000 IU per month on markers of vitamin D status, bone health and to examine whether adherence, quality of life and patient satisfaction with the supplementation strategy differs between the two vitamin D strategies in adults diagnosed with diabetic nephropathy.

DISCUSSION

The need for RCTs assessing higher doses of vitamin D3 supplementation at varying frequencies of administration and its impact on bone health in adults with diabetes and chronic kidney disease are needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01476501.

Dietary protein's and dietary acid load's influence on bone health

A variety of genetic, mechano-response-related, endocrine-metabolic, and nutritional determinants impact bone health. Among the nutritional influences, protein intake and dietary acid load are two of the factors most controversially discussed. Although in the past high protein intake was often assumed to exert a primarily detrimental impact on bone mass and skeletal health, the majority of recent studies indicates the opposite and suggests a bone-anabolic influence. Studies examining the influence of alkalizing diets or alkalizing supplement provision on skeletal outcomes are less consistent, which raises doubts about the role of acid-base status in bone health. The present review critically evaluates relevant key issues such as acid-base terminology, influencing factors of intestinal calcium absorption, calcium balance, the endocrine-metabolic milieu related to metabolic acidosis, and some methodological aspects of dietary exposure and bone outcome examinations. It becomes apparent that for an adequate identification and characterization of either dietary acid load's or protein's impact on bone, the combined assessment of both nutritional influences is necessary.

Urinary potassium excretion and risk of developing hypertension: the prevention of renal and vascular end-stage disease study

Previous prospective cohort studies on the association between potassium intake and risk of hypertension have almost exclusively relied on self-reported dietary data, whereas repeated 24-hour urine excretions, as estimate of dietary uptake, may provide a more objective and quantitative estimate of this association. Risk of hypertension (defined as blood pressure ≥140/90 mm Hg or initiation of blood pressure-lowering drugs) was prospectively studied in 5511 normotensive subjects aged 28 to 75 years not using blood pressure-lowering drugs at baseline of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study. Potassium excretion was measured in two 24-hour urine specimens at baseline (1997-1998) and midway during follow-up (2001-2003). Baseline median potassium excretion was 70 mmol/24 h (interquartile range, 57-85 mmol/24 h), which corresponds to a dietary potassium intake of ≈91 mmol/24 h. During a median follow-up of 7.6 years (interquartile range, 5.0-9.3 years), 1172 subjects developed hypertension. The lowest sex-specific tertile of potassium excretion (men: <68 mmol/24 h; women: <58 mmol/24 h) had an increased risk of hypertension after multivariable adjustment (hazard ratio, 1.20; 95% confidence interval, 1.05-1.37), compared with the upper 2 tertiles (Pnonlinearity=0.008). The proportion of hypertension attributable to low potassium excretion was 6.2% (95% confidence interval, 1.7%-10.9%). No association was found between the sodium to potassium excretion ratio and risk of hypertension after multivariable adjustment. Low urinary potassium excretion was associated with an increased risk of developing hypertension. Dietary strategies to increase potassium intake to the recommended level of 90 mmol/d may have the potential to reduce the incidence of hypertension.

The effect of bushmeat consumption on migratory wildlife in the Serengeti ecosystem, Tanzania

Bushmeat hunting is a threat to wildlife populations in many parts of sub-Saharan Africa, including to migratory wildebeest Connochaetes taurinus and other wildlife populations in the Serengeti ecosystem. Accurate assessments of offtake through bushmeat hunting are necessary to determine whether hunting pressure on the wildebeest population is unsustainable. We used a panel dataset of local bushmeat consumption to measure offtake of wildlife and examine the long-term threat to the Serengeti wildebeest population. Based on these data we estimate an annual offtake of 97,796–140,615 wildebeest (6–10% of the current population), suggesting that previous estimates based on ecological models underestimated the effect of poaching on these populations.

The proof is in the eating: subjective peer norms are associated with adolescents’ eating behaviour

Objective

To investigate associations of self-perceived eating-related peer norms (called ‘subjective peer norms’) with adolescents’ healthy eating intentions and intake of healthy and unhealthy food.

Design

Cross-sectional data were collected in a large international survey.

Setting

Two types of subjective peer norms were assessed: perceived peer encouragement of healthy eating and perceived peer discouragement of unhealthy eating. Outcome variables were healthy eating intentions, intake of healthy food (fruits and vegetables) and intake of unhealthy food (snacks and soft drinks).

Subjects

Over 2500 European (pre-)adolescents aged between 10 and 17 years participated.

Results

Subjective peer norms were associated with all three outcome variables. While both perceived encouragement of healthy eating and perceived discouragement of unhealthy eating were related to intentions, only peer encouragement of healthy eating was related to intakes of both healthy and unhealthy food.

Conclusions

Subjective peer norms play a role in adolescent eating behaviour and as such are an important target for health promotion. Addressing norms that encourage healthy eating may be more promising in changing behaviour than norms that discourage unhealthy eating.

Serum carbon isotope values change in adults in response to changes in sugar-sweetened beverage intake

Serum carbon isotope values [13C-to-12C serum carbon isotope ratio (δ(13)C)], which reflect consumption of corn- and cane-based foods, differ between persons consuming high and low amounts of sugar-sweetened beverages (SSBs). In this study, we determined whether serum δ(13)C changes in response to change in SSB intake during an 18-mo behavioral intervention trial. Data were from a subset of 144 participants from the PREMIER trial, a completed behavioral intervention (Maryland, 1998-2004). SSB intake was assessed using 2 24-h dietary recall interviews. Blinded serum samples were assayed for δ(13)C by natural abundance stable isotope mass spectroscopy. Multiple linear regression models with generalized estimating equations and robust variance estimation were used. At baseline, mean SSB intake was 13.8 ± 14.2 fl oz/d, and mean δ(13)C serum value was -19.3 ± 0.6 units per mil (designated ‰). A reduction of 12 oz (355 mL)/d SSB (equivalent to 1 can of soda per day) was associated with 0.17‰ (95% CI: 0.08‰, 0.25‰ P < 0.0001) reduction in serum δ(13)C values over 18 mo (equivalent to a 1% reduction in δ(13)C from baseline). After adjusting for potential confounders, a reduction of 12 oz/d SSB (equivalent to 1 can of soda per day), over an 18-mo period, was associated with 0.12‰ (95% CI: 0.01‰, 0.22‰ P = 0.025) reduction in serum δ(13)C. These findings suggest that serum δ(13)C can be used as a measure of dietary changes in SSB intake.

Methodological Issues in Cohort Studies That Relate Sodium Intake to Cardiovascular Disease Outcomes

Background—

The results of cohort studies relating sodium (Na) intake to blood pressure–related cardiovascular disease (CVD) are inconsistent. To understand whether methodological issues account for the inconsistency, we reviewed the quality of these studies.

Methods and Results—

We reviewed cohort studies that examined the association between Na and CVD. We then identified methodological issues with greatest potential to alter the direction of association (reverse causality, systematic error in Na assessment), some potential to alter the direction of association (residual confounding, inadequate follow-up), and the potential to yield false null results (random error in Na assessment, insufficient power). We included 26 studies with 31 independent analyses. Of these, 13 found direct associations between Na and CVD, 8 found inverse associations, 2 found J-shaped associations, and 8 found null associations only. On average there were 3 to 4 methodological issues per study. Issues with greater potential to alter the direction of association were present in all but 1 of the 26 studies (systematic error, 22; reverse causality, 16). Issues with lesser potential to alter the direction of association were present in 18 studies, whereas those with potential to yield false null results were present in 23.

Conclusions—

Methodological issues may account for the inconsistent findings in currently available observational studies relating Na to CVD. Until well-designed cohort studies in the general population are available, it remains appropriate to base Na guidelines on the robust body of evidence linking Na with elevated blood pressure and the few existing general population trials of the effects of Na reduction on CVD.

Inadequate nutrient intake in patients with celiac disease: results from a German dietary survey

BACKGROUND

Currently, the only treatment for celiac disease (CD) is a lifelong gluten-free diet (GFD). Research has been carried out in various countries into the nutritional adequacy of the GFD in terms of macro- and micronutrients, mostly presenting conflicting results. However, no data for Germany are available to date.

AIM

To elucidate the nutritional composition of a GFD and to compare it with non-GFD in a representative German non-CD population.

METHODS AND PATIENTS

A total of 1,000 patients who were members of the German Celiac Society (DZG) were invited to fill out a prospective 7-day food diary and a questionnaire. Data from 88 patients aged 14-80 years were analyzed and compared to the DACH reference values and to data from the German National Diet and Nutrition Survey (NVS II).

RESULTS

No significant difference was observed for the intake of energy and macronutrients in male celiac patients compared to the NVS II. Only the fiber intake of male patients was significantly lower than that of the general population. Female patients, however, showed a significantly higher fat intake, but lower carbohydrate consumption. The average daily micronutrient intake of male and female patients, specifically of vitamin B1, B2, B6, folic acid, magnesium and iron, was significantly lower in celiac patients compared to the NVS II.

CONCLUSION

This study reveals inadequate nutrient intake by male and female celiac patients in Germany. Based on our findings, regular (laboratory) monitoring of celiac patients should be recommended.

A toolkit for measurement error correction, with a focus on nutritional epidemiology

Exposure measurement error is a problem in many epidemiological studies, including those using biomarkers and measures of dietary intake. Measurement error typically results in biased estimates of exposure-disease associations, the severity and nature of the bias depending on the form of the error. To correct for the effects of measurement error, information additional to the main study data is required. Ideally, this is a validation sample in which the true exposure is observed. However, in many situations, it is not feasible to observe the true exposure, but there may be available one or more repeated exposure measurements, for example, blood pressure or dietary intake recorded at two time points. The aim of this paper is to provide a toolkit for measurement error correction using repeated measurements. We bring together methods covering classical measurement error and several departures from classical error: systematic, heteroscedastic and differential error. The correction methods considered are regression calibration, which is already widely used in the classical error setting, and moment reconstruction and multiple imputation, which are newer approaches with the ability to handle differential error. We emphasize practical application of the methods in nutritional epidemiology and other fields. We primarily consider continuous exposures in the exposure-outcome model, but we also outline methods for use when continuous exposures are categorized. The methods are illustrated using the data from a study of the association between fibre intake and colorectal cancer, where fibre intake is measured using a diet diary and repeated measures are available for a subset.

Global, regional and national sodium intakes in 1990 and 2010: a systematic analysis of 24 h urinary sodium excretion and dietary surveys worldwide

OBJECTIVES

To estimate global, regional (21 regions) and national (187 countries) sodium intakes in adults in 1990 and 2010.

DESIGN

Bayesian hierarchical modelling using all identifiable primary sources.

DATA SOURCES AND ELIGIBILITY

We searched and obtained published and unpublished data from 142 surveys of 24 h urinary sodium and 103 of dietary sodium conducted between 1980 and 2010 across 66 countries. Dietary estimates were converted to urine equivalents based on 79 pairs of dual measurements.

MODELLING METHODS

Bayesian hierarchical modelling used survey data and their characteristics to estimate mean sodium intake, by sex, 5 years age group and associated uncertainty for persons aged 20+ in 187 countries in 1990 and 2010. Country-level covariates were national income/person and composition of food supplies.

MAIN OUTCOME MEASURES

Mean sodium intake (g/day) as estimable by 24 h urine collections, without adjustment for non-urinary losses.

RESULTS

In 2010, global mean sodium intake was 3.95 g/day (95% uncertainty interval: 3.89 to 4.01). This was nearly twice the WHO recommended limit of 2 g/day and equivalent to 10.06 (9.88-10.21) g/day of salt. Intake in men was ∼10% higher than in women; differences by age were small. Intakes were highest in East Asia, Central Asia and Eastern Europe (mean >4.2 g/day) and in Central Europe and Middle East/North Africa (3.9-4.2 g/day). Regional mean intakes in North America, Western Europe and Australia/New Zealand ranged from 3.4 to 3.8 g/day. Intakes were lower (<3.3 g/day), but more uncertain, in sub-Saharan Africa and Latin America. Between 1990 and 2010, modest, but uncertain, increases in sodium intakes were identified.

CONCLUSIONS

Sodium intakes exceed the recommended levels in almost all countries with small differences by age and sex. Virtually all populations would benefit from sodium reduction, supported by enhanced surveillance.

Differential association between adherence to nutritional recommendations and body weight status across educational levels: a cross-sectional study

OBJECTIVE

The impact of diet quality and physical activity (PA) on weight might be different according to socioeconomic status. Our aim was to estimate associations between adherence to nutritional guidelines and BMI and the interaction with socioeconomic characteristics.

METHODS

A total of 11,931 men and 39,737 women from the NutriNet-Santé cohort (France, 2009-2012) were included in this cross-sectional analysis. The association between PNNS-GS (a score estimating adherence to French nutritional guidelines) and BMI was assessed by multivariate linear regression. A modified score (mPNNS-GS) separating diet quality from PA was also used.

RESULTS

BMI, overweight and obesity displayed an inverse gradient from less to more educated groups, whereas PNNS-GS increased. A higher PNNS-GS was associated with a lower BMI, more importantly in the less educated: BMI decrease ranged from -1.1% in less educated to -0.7% in more educated men and from -0.6% to -0.3% in women. The effect of mPNNS-GS and PA in particular was also stronger among less educated subjects.

CONCLUSION

Overall, better adherence to nutritional recommendations was inversely associated with BMI, and this association was stronger in the less educated groups. This suggests that nutritional policies should still concentrate on promoting access to a healthier diet and PA, especially among less educated individuals.

Association between adherence to nutritional guidelines, the metabolic syndrome and adiposity markers in a French adult general population

INTRODUCTION

Few studies have focused on the association between diet quality scores and the Metabolic Syndrome (MetS), a multi-component condition predictive of cardiovascular diseases (CVD) and death. The present study aims at investigating, in a cross-sectional design, the association between adherence to the French dietary guidelines through an a priori score - the French Nutrition and Health Program-Guideline Score (PNNS-GS) - and cardiovascular risk factors (CVRF) including the MetS and adiposity markers.

METHODS

7902 French adults participating in the NutriNet-Santé study (an on-going web-based cohort study) attended a clinical and biological examination between January 2011 and November 2012: a fasting blood sample was drawn, blood pressure and body composition (bio-impedance) were measured. Multivariate linear and logistic regression models were used to assess the association between PNNS-GS and CVRF or the MetS.

RESULTS

An increase of PNNS-GS was significantly negatively associated with waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP) and serum triglycerides concentrations. From bottom to top quartile of PNNS-GS, SBP decreased from 129.9 to 128.8 mm Hg, DBP from 76.7 to 75.9 mm Hg, serum triglycerides concentrations from 110.8 to 104.6 mg/dL and WC from 94.8 to 90.1 cm for men and 81.3 to 78.9 cm for women. All adiposity markers (waist and hip circumference, % body fat, % trunk fat, % leg fat) were markedly reduced across quartiles of PNNS-GS and linearly. Individuals with a better PNNS-GS (quartile 4 vs quartile 1) were less likely to have the MetS (OR=0.71, 95% CI: 0.56-0.89).

CONCLUSION

The negative association between a higher adherence to the French dietary guidelines and a number of CVRF, the MetS prevalence and regional adiposity supports the importance of promoting the PNNS dietary guidelines in the population for the prevention of cardiometabolic abnormalities and hence, cardiovascular diseases.

Positive effect of mushrooms substituted for meat on body weight, body composition, and health parameters. A 1-year randomized clinical trial

Reducing energy density (ED) of the diet is an important strategy for controlling obesity. This 1-year, randomized clinical trial examined the effect of substituting mushrooms for red meat ('mushroom diet'), compared to a standard diet ('meat diet'), on weight loss and maintenance among 73 obese adults (64 women, 9 men). The subjects completed anthropometric measurements and 7-day food records four times during a standardized weight loss and maintenance regimen. At the end of the 1-year trial, compared to participants on the standard diet, participants on the mushroom diet (n=36) reported lower intakes of energy (mean ± [SE]=-123 ± 113 kcals) and fat (-4.25 ± 6.88 g), lost more pounds and percentage body weight (-7.03 ± 3.34 lbs, 3.6%), achieved lower body mass index (-1.53 ± 0.36), waist circumference (-2.6 ± 3.5 in.) and percent total body fat (-0.85 ± 0.53), and had lower systolic and diastolic pressure (-7.9 and -2.5 mmHg); their lipid profile and inflammatory markers also improved. After initial weight loss, subjects following the mushroom diet maintained that loss well. Those who completed the full 12-month trial still weighed a mean of 7 lbs less than baseline. Thus, encouraging adults to substitute mushrooms for red meat was a useful strategy for enhancing weight loss, weight maintenance, and health parameters.

Social relationships and healthful dietary behaviour: evidence from over-50s in the EPIC cohort, UK

Social relationships are an important aspect of a person's social environment that can protect against a wide range of chronic conditions and facilitate recovery from disease. Social relationships have also been linked to dietary behaviour which may be an important pathway through which social circumstances exert their influence on health. Yet, questions remain about which structural aspects of social relationships most affect healthful dietary behaviours and whether different structural components interact to produce a combined effect. Using data from adults (≥50 years) in the European Prospective Investigation of Cancer-Norfolk study (1996-2002), we examined marital status, living arrangement and social isolation in relation to scores for variety of fruit and vegetable intake as a marker of diet quality associated with adverse health outcomes. Data were analysed with multivariable linear regression models for gender-specific and interaction associations. We found that being single or widowed was associated with a lower variety score, particularly vegetable variety, and associations were enhanced when combined with male gender, living alone or infrequent friend contact. Lower variety scores for lone-living were also observed, especially for men. Infrequent friend contact interacted with living arrangement to amplify negative associations of lone-living with variety, with statistically significant differences in contact frequency for vegetable variety. Lower levels of friend contact were associated with reduced variety of fruits and vegetables in a graded trend for both genders; the trend was more pronounced among men. Family contact appeared to have limited association with vegetable variety in men; among women, weekly contact was significantly and positively associated with vegetable variety compared to daily family contact. Results highlight the importance of considering living arrangement and/or frequency of social contact when assessing whether widowed, single or lone-living older adults are at risk of lower fruit and vegetable variety.

Estimating trajectories of energy intake through childhood and adolescence using linear-spline multilevel models

BACKGROUND

Methods for the assessment of changes in dietary intake across the life course are underdeveloped.

METHODS

We demonstrate the use of linear-spline multilevel models to summarize energy-intake trajectories through childhood and adolescence and their application as exposures, outcomes, or mediators. The Avon Longitudinal Study of Parents and Children assessed children's dietary intake several times between ages 3 and 13 years, using both food frequency questionnaires (FFQs) and 3-day food diaries. We estimated energy-intake trajectories for 12,032 children using linear-spline multilevel models. We then assessed the associations of these trajectories with maternal body mass index (BMI), and later offspring BMI, and also their role in mediating the relation between maternal and offspring BMIs.

RESULTS

Models estimated average and individual energy intake at 3 years, and linear changes in energy intake from age 3 to 7 years and from age 7 to 13 years. By including the exposure (in this example, maternal BMI) in the multilevel model, we were able to estimate the average energy-intake trajectories across levels of the exposure. When energy-intake trajectories are the exposure for a later outcome (in this case offspring BMI) or a mediator (between maternal and offspring BMI), results were similar, whether using a two-step process (exporting individual-level intercepts and slopes from multilevel models and using these in linear regression/path analysis), or a single-step process (multivariate multilevel models). Trajectories were similar when FFQs and food diaries were assessed either separately, or when combined into one model.

CONCLUSIONS

Linear-spline multilevel models provide useful summaries of trajectories of dietary intake that can be used as an exposure, outcome, or mediator.

Quantifying diet for nutrigenomic studies

The field of nutrigenomics shows tremendous promise for improved understanding of the effects of dietary intake on health. The knowledge that metabolic pathways may be altered in individuals with genetic variants in the presence of certain dietary exposures offers great potential for personalized nutrition advice. However, although considerable resources have gone into improving technology for measurement of the genome and biological systems, dietary intake assessment remains inadequate. Each of the methods currently used has limitations that may be exaggerated in the context of gene × nutrient interaction in large multiethnic studies. Because of the specificity of most gene × nutrient interactions, valid data are needed for nutrient intakes at the individual level. Most statistical adjustment efforts are designed to improve estimates of nutrient intake distributions in populations and are unlikely to solve this problem. An improved method of direct measurement of individual usual dietary intake that is unbiased across populations is urgently needed.

Using surrogate biomarkers to improve measurement error models in nutritional epidemiology

Nutritional epidemiology relies largely on self-reported measures of dietary intake, errors in which give biased estimated diet–disease associations. Self-reported measurements come from questionnaires and food records. Unbiased biomarkers are scarce; however, surrogate biomarkers, which are correlated with intake but not unbiased, can also be useful. It is important to quantify and correct for the effects of measurement error on diet–disease associations. Challenges arise because there is no gold standard, and errors in self-reported measurements are correlated with true intake and each other. We describe an extended model for error in questionnaire, food record, and surrogate biomarker measurements. The focus is on estimating the degree of bias in estimated diet–disease associations due to measurement error. In particular, we propose using sensitivity analyses to assess the impact of changes in values of model parameters which are usually assumed fixed. The methods are motivated by and applied to measures of fruit and vegetable intake from questionnaires, 7-day diet diaries, and surrogate biomarker (plasma vitamin C) from over 25000 participants in the Norfolk cohort of the European Prospective Investigation into Cancer and Nutrition. Our results show that the estimated effects of error in self-reported measurements are highly sensitive to model assumptions, resulting in anything from a large attenuation to a small amplification in the diet–disease association. Commonly made assumptions could result in a large overcorrection for the effects of measurement error. Increased understanding of relationships between potential surrogate biomarkers and true dietary intake is essential for obtaining good estimates of the effects of measurement error in self-reported measurements on observed diet–disease associations. Copyright © 2013 John Wiley & Sons, Ltd.

Meat consumption and mortality--results from the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Recently, some US cohorts have shown a moderate association between red and processed meat consumption and mortality supporting the results of previous studies among vegetarians. The aim of this study was to examine the association of red meat, processed meat, and poultry consumption with the risk of early death in the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

Included in the analysis were 448,568 men and women without prevalent cancer, stroke, or myocardial infarction, and with complete information on diet, smoking, physical activity and body mass index, who were between 35 and 69 years old at baseline. Cox proportional hazards regression was used to examine the association of meat consumption with all-cause and cause-specific mortality.

RESULTS

As of June 2009, 26,344 deaths were observed. After multivariate adjustment, a high consumption of red meat was related to higher all-cause mortality (hazard ratio (HR) = 1.14, 95% confidence interval (CI) 1.01 to 1.28, 160+ versus 10 to 19.9 g/day), and the association was stronger for processed meat (HR = 1.44, 95% CI 1.24 to 1.66, 160+ versus 10 to 19.9 g/day). After correction for measurement error, higher all-cause mortality remained significant only for processed meat (HR = 1.18, 95% CI 1.11 to 1.25, per 50 g/d). We estimated that 3.3% (95% CI 1.5% to 5.0%) of deaths could be prevented if all participants had a processed meat consumption of less than 20 g/day. Significant associations with processed meat intake were observed for cardiovascular diseases, cancer, and 'other causes of death'. The consumption of poultry was not related to all-cause mortality.

CONCLUSIONS

The results of our analysis support a moderate positive association between processed meat consumption and mortality, in particular due to cardiovascular diseases, but also to cancer.

Achieving salt restriction in chronic kidney disease

There is consistent evidence linking excessive dietary sodium intake to risk factors for cardiovascular disease and chronic kidney disease (CKD) progression in CKD patients; however, additional research is needed. In research trials and clinical practice, implementing and monitoring sodium intake present significant challenges. Epidemiological studies have shown that sodium intake remains high, and intervention studies have reported varied success with participant adherence to a sodium-restricted diet. Examining barriers to sodium restriction, as well as factors that predict adherence to a low sodium diet, can aid researchers and clinicians in implementing a sodium-restricted diet. In this paper, we critically review methods for measuring sodium intake with a specific focus on CKD patients, appraise dietary adherence, and factors that have optimized sodium restriction in key research trials and discuss barriers to sodium restriction and factors that must be considered when recommending a sodium-restricted diet.

Development and validation of a quantitative food frequency questionnaire among rural- and urban-dwelling adults in Colombia

OBJECTIVE

To validate a food frequency questionnaire (FFQ) against multiple 24-hour dietary recalls (DRs) that could be used for Colombian adults.

METHODS

A convenience sample of 219 individuals participated in the study. The validity of the FFQ was evaluated against multiple DRs. Four dietary recalls were collected during the year, and an FFQ was administered at the end of the study along with the fourth DR.

RESULTS

Deattenuated correlation coefficient for FFQ against mean intake of 4 DRs varied from 0.77 for carbohydrate, 0.55 for energy, and 0.51 for protein. In rural areas, lower correlations were observed. The overall extent of agreement in each quartile of estimated nutrient intake varied from 61% to 83%.

CONCLUSIONS AND IMPLICATIONS

The FFQ provides moderate to high estimates for energy and nutrient intake and can be employed to rank individuals based on their habitual intake.

No evidence that the skeletal non-response to potassium alkali supplements in healthy postmenopausal women depends on blood pressure or sodium chloride intake

BACKGROUND/OBJECTIVES

In vitro studies demonstrate that bone is degraded in an acidic environment due to chemical reactions and through effects on bone cells. Clinical evidence is insufficient to unequivocally resolve whether the diet net acid or base load bone affects breakdown in humans. Increasing dietary salt (sodium chloride, NaCl) mildly increases blood acidity in humans and in rats with increased sensitivity to the blood pressure effects of salt, whereas increased potassium (K) intake can decrease blood pressure. Blood pressure responses to NaCl or K may potentially be a marker for increased bone turnover or lower bone mineral density (BMD) in women at higher risk for osteoporosis and fracture.

SUBJECTS/METHODS

We retrospectively analysed data from two data sets (California and NE Scotland) of postmenopausal women (n=266) enrolled in long-term randomized, placebo-controlled studies of the effects of administration of low- or high-dose dietary K alkali supplementation on bone turnover in relation to sodium or chloride excretion (a marker of dietary salt intake). Mean arterial pressure (MAP) was calculated from blood pressure measures, MAP was divided into tertiles and its influence on the effect of dietary NaCl and K alkali supplementation on deoxypyridinoline markers of bone resorption and BMD by DEXA was tested. Data was analysed for each data set separately and then combined.

RESULTS

Percentage change in BMD after 24 months was less for California compared with North East Scotland (hip: -0.6 ± 2.8% and -1.5 ± 2.4%, respectively (P=0.027); spine: -0.5 ± 3.4% and -2.6 ± 3.5%, (P<0.001). We found no effect of dietary alkali treatment on BMD change or bone resorption for either centre. Adjusting for the possible calcium- or potassium-lowering effects on blood pressure did not alter the results.

CONCLUSIONS

Blood pressure responses to Na, Cl or K intake did not help predict a BMD response to diet alkali therapy.

Fruit and vegetable intake and type 2 diabetes: EPIC-InterAct prospective study and meta-analysis

Fruit and vegetable intake (FVI) may reduce the risk of type 2 diabetes (T2D), but the epidemiological evidence is inconclusive. The aim of this study is to examine the prospective association of FVI with T2D and conduct an updated meta-analysis. In the European Prospective Investigation into Cancer-InterAct (EPIC-InterAct) prospective case-cohort study nested within eight European countries, a representative sample of 16,154 participants and 12,403 incident cases of T2D were identified from 340,234 individuals with 3.99 million person-years of follow-up. For the meta-analysis we identified prospective studies on FVI and T2D risk by systematic searches of MEDLINE and EMBASE until April 2011. In EPIC-InterAct, estimated FVI by dietary questionnaires varied more than twofold between countries. In adjusted analyses the hazard ratio (95% confidence interval) comparing the highest with lowest quartile of reported intake was 0.90 (0.80-1.01) for FVI; 0.89 (0.76-1.04) for fruit and 0.94 (0.84-1.05) for vegetables. Among FV subtypes, only root vegetables were inversely associated with diabetes 0.87 (0.77-0.99). In meta-analysis using pooled data from five studies including EPIC-InterAct, comparing the highest with lowest category for FVI was associated with a lower relative risk of diabetes (0.93 (0.87-1.00)). Fruit or vegetables separately were not associated with diabetes. Among FV subtypes, only green leafy vegetable (GLV) intake (relative risk: 0.84 (0.74-0.94)) was inversely associated with diabetes. Subtypes of vegetables, such as root vegetables or GLVs may be beneficial for the prevention of diabetes, while total FVI may exert a weaker overall effect.

Automatic identification of the number of food items in a meal using clustering techniques based on the monitoring of swallowing and chewing

The number of distinct foods consumed in a meal is of significant clinical concern in the study of obesity and other eating disorders. This paper proposes the use of information contained in chewing and swallowing sequences for meal segmentation by food types. Data collected from experiments of 17 volunteers were analyzed using two different clustering techniques. First, an unsupervised clustering technique, Affinity Propagation (AP), was used to automatically identify the number of segments within a meal. Second, performance of the unsupervised AP method was compared to a supervised learning approach based on Agglomerative Hierarchical Clustering (AHC). While the AP method was able to obtain 90% accuracy in predicting the number of food items, the AHC achieved an accuracy >95%. Experimental results suggest that the proposed models of automatic meal segmentation may be utilized as part of an integral application for objective Monitoring of Ingestive Behavior in free living conditions.

Regression calibration for dichotomized mismeasured predictors

Epidemiologic research focuses on estimating exposure-disease associations. In some applications the exposure may be dichotomized, for instance when threshold levels of the exposure are of primary public health interest (e.g., consuming 5 or more fruits and vegetables per day may reduce cancer risk). Errors in exposure variables are known to yield biased regression coefficients in exposure-disease models. Methods for bias-correction with continuous mismeasured exposures have been extensively discussed, and are often based on validation substudies, where the "true" and imprecise exposures are observed on a small subsample. In this paper, we focus on biases associated with dichotomization of a mismeasured continuous exposure. The amount of bias, in relation to measurement error in the imprecise continuous predictor, and choice of dichotomization cut point are discussed. Measurement error correction via regression calibration is developed for this scenario, and compared to naïvely using the dichotomized mismeasured predictor in linear exposure-disease models. Properties of the measurement error correction method (i.e., bias, mean-squared error) are assessed via simulations.

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.