Janet E Cade

Development, validation and utilisation of food-frequency questionnaires – a review

OBJECTIVE The purpose of this review is to provide guidance on the development, validation and use of food-frequency questionnaires (FFQs) for different study designs. It does not include any recommendations about the most appropriate method for dietary assessment (e.g. food-frequency questionnaire versus weighed record). METHODS A comprehensive search of electronic databases was carried out for publications from 1980 to 1999. Findings from the review were then commented upon and added to by a group of international experts. RESULTS Recommendations have been developed to aid in the design, validation and use of FFQs. Specific details of each of these areas are discussed in the text. CONCLUSIONS FFQs are being used in a variety of ways and different study designs. There is no gold standard for directly assessing the validity of FFQs. Nevertheless, the outcome of this review should help those wishing to develop or adapt an FFQ to validate it for its intended use.

Randomised controlled trial of primary school based intervention to reduce risk factors for obesity

Abstract Objective: To assess if a school based intervention was effective in reducing risk factors for obesity. Design: Group randomised controlled trial. Setting: 10 primary schools in Leeds. Participants: 634 children aged 7-11 years. Intervention: Teacher training, modification of school meals, and the development of school action plans targeting the curriculum, physical education, tuck shops, and playground activities. Main outcome measures: Body mass index, diet, physical activity, and psychological state. Results: Vegetable consumption by 24 hour recall was higher in children in the intervention group than the control group (weighted mean difference 0.3 portions/day, 95% confidence interval 0.2 to 0.4), representing a difference equivalent to 50% of baseline consumption. Fruit consumption was lower in obese children in the intervention group (−1.0, −1.8 to −0.2) than those in the control group. The three day diary showed higher consumption of high sugar foods (0.8, 0.1 to 1.6)) among overweight children in the intervention group than the control group. Sedentary behaviour was higher in overweight children in the intervention group (0.3, 0.0 to 0.7). Global self worth was higher in obese children in the intervention group (0.3, 0.3 to 0.6). There was no difference in body mass index, other psychological measures, or dieting behaviour between the groups. Focus groups indicated higher levels of self reported behaviour change, understanding, and knowledge among children who had received the intervention. Conclusion: Although it was successful in producing changes at school level, the programme had little effect on childrens behaviour other than a modest increase in consumption of vegetables. What is already known on this topic Obesity is increasing among school children and demands preventive strategies Randomised controlled trials of school based primary prevention programmes have all used a prescriptive approach What this study adds Behavioural changes were disappointing with this programme based on the health promoting schools philosophy, despite changes at school level The only positive outcome was a modest increase in vegetable consumption The discrepancy between changes achieved at the individual and school level raises issues regarding the problems inherent in such trials

Adherence to a Smartphone Application for Weight Loss Compared to Website and Paper Diary: Pilot Randomized Controlled Trial

Background There is growing interest in the use of information communication technologies to treat obesity. An intervention delivered by smartphone could be a convenient, potentially cost-effective, and wide-reaching weight management strategy. Although there have been studies of texting-based interventions and smartphone applications (apps) used as adjuncts to other treatments, there are currently no randomized controlled trials (RCT) of a stand-alone smartphone application for weight loss that focuses primarily on self-monitoring of diet and physical activity. Objective The aim of this pilot study was to collect acceptability and feasibility outcomes of a self-monitoring weight management intervention delivered by a smartphone app, compared to a website and paper diary. Methods A sample of 128 overweight volunteers were randomized to receive a weight management intervention delivered by smartphone app, website, or paper diary. The smartphone app intervention, My Meal Mate (MMM), was developed by the research team using an evidence-based behavioral approach. The app incorporates goal setting, self-monitoring of diet and activity, and feedback via weekly text message. The website group used an existing commercially available slimming website from a company called Weight Loss Resources who also provided the paper diaries. The comparator groups delivered a similar self-monitoring intervention to the app, but by different modes of delivery. Participants were recruited by email, intranet, newsletters, and posters from large local employers. Trial duration was 6 months. The intervention and comparator groups were self-directed with no ongoing human input from the research team. The only face-to-face components were at baseline enrollment and brief follow-up sessions at 6 weeks and 6 months to take anthropometric measures and administer questionnaires. Results Trial retention was 40/43 (93%) in the smartphone group, 19/42 (55%) in the website group, and 20/43 (53%) in the diary group at 6 months. Adherence was statistically significantly higher in the smartphone group with a mean of 92 days (SD 67) of dietary recording compared with 35 days (SD 44) in the website group and 29 days (SD 39) in the diary group (P<.001). Self-monitoring declined over time in all groups. In an intention-to-treat analysis using baseline observation carried forward for missing data, mean weight change at 6 months was -4.6 kg (95% CI –6.2 to –3.0) in the smartphone app group, –2.9 kg (95% CI –4.7 to –1.1) in the diary group, and –1.3 kg (95% CI –2.7 to 0.1) in the website group. BMI change at 6 months was –1.6 kg/m2 (95% CI –2.2 to –1.1) in the smartphone group, –1.0 kg/m2 (95% CI –1.6 to –0.4) in the diary group, and –0.5 kg/m2 (95% CI –0.9 to 0.0) in the website group. Change in body fat was –1.3% (95% CI –1.7 to –0.8) in the smartphone group, –0.9% (95% CI –1.5 to –0.4) in the diary group, and –0.5% (95% CI –0.9 to 0.0) in the website group. Conclusions The MMM app is an acceptable and feasible weight loss intervention and a full RCT of this approach is warranted. Trial Registration ClinicalTrials.gov NCT01744535; http://clinicaltrials.gov/ct2/show/NCT01744535 (Archived by WebCite at http://www.webcitation.org/6FEtc3PVB)

Structured patient education: the Diabetes X-PERT Programme makes a difference

Aims  To develop a patient‐centred, group‐based self‐management programme (X‐PERT), based on theories of empowerment and discovery learning, and to assess the effectiveness of the programme on clinical, lifestyle and psychosocial outcomes.

Factors affecting food choice in relation to fruit and vegetable intake: a review.

The present review provides an investigation into the food choice decisions made by individuals in relation to fruit and vegetable consumption. A comprehensive body of evidence now exists concerning the protective effect of fruit and vegetables against a number of diseases, particularly cardiovascular disease and certain forms of cancer. Current UK recommendations are to increase intakes of fruit and vegetables to 400 g/person per d. In the main body of the review the factors that affect food choice decisions of adults in relation to fruit and vegetable consumption are studied, following a suggested framework of food choice. Factors covered include sensory appeal, familiarity and habit, social interactions, cost, availability, time constraints, personal ideology, media and advertising and health. The content of the review shows just how complex the food choice process can be. Health promotion techniques can be better targeted towards certain groups of individuals, all holding similar sets of values, when making food choice decisions. Food choice, in relation to fruit and vegetable intake, needs to be studied in more depth, in order to provide effective nutrition education programmes, in particular the sets of priorities that different sub-groups of the population consider when making food choice decisions.

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 fibre intake and risk of cardiovascular disease: systematic review and meta-analysis

Objective To investigate dietary fibre intake and any potential dose-response association with coronary heart disease and cardiovascular disease. Design Systematic review of available literature and dose-response meta-analysis of cohort studies using random effects models. Data sources The Cochrane Library, Medline, Medline in-process, Embase, CAB Abstracts, ISI Web of Science, BIOSIS, and hand searching. Eligibility criteria for studies Prospective studies reporting associations between fibre intake and coronary heart disease or cardiovascular disease, with a minimum follow-up of three years and published in English between 1 January 1990 and 6 August 2013. Results 22 cohort study publications met inclusion criteria and reported total dietary fibre intake, fibre subtypes, or fibre from food sources and primary events of cardiovascular disease or coronary heart disease. Total dietary fibre intake was inversely associated with risk of cardiovascular disease (risk ratio 0.91 per 7 g/day (95% confidence intervals 0.88 to 0.94)) and coronary heart disease (0.91 (0.87 to 0.94)). There was evidence of some heterogeneity between pooled studies for cardiovascular disease (I2=45% (0% to 74%)) and coronary heart disease (I2=33% (0% to 66%)). Insoluble fibre and fibre from cereal and vegetable sources were inversely associated with risk of coronary heart disease and cardiovascular disease. Fruit fibre intake was inversely associated with risk of cardiovascular disease. Conclusions Greater dietary fibre intake is associated with a lower risk of both cardiovascular disease and coronary heart disease. Findings are aligned with general recommendations to increase fibre intake. The differing strengths of association by fibre type or source highlight the need for a better understanding of the mode of action of fibre components.

Why do women use dietary supplements? The use of the theory of planned behaviour to explore beliefs about their use

Dietary supplements use is increasing, despite the lack of evidence to suggest they are needed to meet dietary deficiency in the majority of people. Reasons for consuming dietary supplements are likely to be complex, combining social, psychological, knowledge and economic factors. The Theory of Planned Behaviour (TPB) is a widely used model of social cognition, which has recently been applied to the nutrition field. It was used in a questionnaire, along with a number of additional measures, to explore dietary supplement use in a cohort of women. Data from 303 questionnaires were included in the analysis. The results showed that intentions were the major predictor of dietary supplement use. Health value and susceptibility to illness were also significant predictors of dietary supplement use (total of 82.9% of respondents correctly classified as users or non-users). Intentions themselves were most strongly predicted by attitude, with 70% of variance explained by attitude, subjective norms and perceived behavioural control. Other significant predictors of intentions were control beliefs, normative beliefs and health value. Beliefs underlying dietary supplement use revealed differences between supplement users and non-users in relation to the notion that taking dietary supplements acts as an insurance against possible ill-health, with supplement users believing more strongly than non-users that taking dietary supplements would stop them getting ill and help them to be healthy. Both users and non-users of supplements also perceived the media, in the form of books and magazines, to be a powerful influence on a persons decision to use supplements. The findings of this study highlight the potential of the TPB in exploring supplement-taking behaviour, while throwing light on the factors influencing an individuals motivations to use dietary supplements.

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.

The sugar–fat relationship revisited: differences in consumption between men and women of varying BMI

OBJECTIVE: To assess the relationship of dietary fat and sugar consumption in men and women with different body mass indices (BMI). To determine the actual food sources for sugar intake, comparing differences between men and women across BMI groups. The effect of excluding individuals with low energy intakes (that is, invalid data) on these relationships was also incorporated in the analysis.SUBJECTS: Subjects for this analysis were those individuals who participated in the 1986–1987 Dietary and Nutrition Survey of British Adults (DNSBA).METHOD: In the DNSBA, dietary intake was assessed using seven-day weighed food records, providing estimates of dietary fat and sugar intake. From the DNSBA database food records, sources of sugar intake were classified into five sugar containing food groups (high fat sweet products, fruits, dairy products, sugar products (excluding soft drinks) and sugar products (including soft drinks)). BMI was calculated from the measurement of height and body weight.RESULT: A positive relationship between BMI and dietary fat intake was found for men, both when fat was expressed as a percentage of energy and in absolute terms (g/d). This relationship was only replicated for women when intake was expressed in absolute terms. A negative relationship was found between sugar intake (as a percentage of energy) and BMI in men, but not women. Expressing sugar consumption in absolute terms did not produce a statistically significant relationship with BMI for either men or women. In women the only sugar source associated with BMI was high fat sweet products (for example, cakes, biscuits, chocolate), where higher intakes were related to higher BMIs. The reverse relationship was found for men. In men, BMI was also negatively related to the intake of sugar products (for example, table sugar, preserves, sugar confectionery), both when soft drinks were included and excluded. The inclusion of low energy reporters (LER) in the analysis altered the relationships between nutrients and BMI, particularly among women. The association between overall fat intake (g/d) and BMI was weakened, while the negative relationship with sugar intake was strengthened. In the case of women, the inclusion of LER completely reversed the relationship between consumption of high fat sweet foods (cakes, biscuits, chocolate) and BMI (due to the reduced reporting of these products by obese women). Fewer alterations in the relationships between BMI and the sources of sugar consumed were observed in men than in women when LER were included in the analysis.CONCLUSION: The relationships between dietary fat, sugar and BMI are different in men and women, and are dependent on the inclusion of LER, particularly in women. The results suggest that among women the consumption of high fat sweet products may be a factor in understanding obesity. Furthermore, the observation of high consumption of these foods among obese women is consistent with measured preferences for these high fat sweet foods. The altered representation of the data created by LER appears to distort the relationship between sugar, fat and the degree of obesity in men and women.