Food & Nutrition
The Food and Nutrition stream was developed in 2002 when ACAORN was established and brings together a group of clinical and public health nutrition researchers from the Australasian region.
Food and Nutrition stream members have a strong commitment to inclusion of appropriate (fit for purpose), valid and reliable dietary assessment as part of child obesity research.
The collective experience of the group brings together a strong track record of research publications and experience and a set of skills which spans dietary methodology development and validation across the range of outcomes, settings and age ranges relevant to child obesity research.
The Food and nutrition stream goals are:
- To improve the quality of dietary methodologies and the reporting of dietary intake within research studies in infants, children and adolescents in Australia and Internationally
- To facilitate collaborations that increase high quality research that addresses nutrition and dietary intake in the context of obesity
- To provide opportunities for post-graduate and post-doctoral education and training in paediatric obesity research.
The specific objectives this stream has identified are:
- To develop research papers that guide dietary methodology selection
- To address nutrition methodology training needs of obesity researchers in Australia
- To encourage researchers to validate new instruments to measure nutrition and dietary intake
- To encourage researchers to validate new “brief tools” to measure nutrition and dietary intake in cost effective ways
- To meet regularly in order to facilitate effective collaborations within Australia and foster new collaboration and postdoctoral research opportunities.
Dietary intake assessment
Reporting what children eat and drink, how this changes in response to an intervention and examining factors that influence what children and adolescents eat and drink is crucial to understanding the energy imbalance associated with obesity. However, the challenges of this area of nutrition research, particularly relating to younger children and adolescents, means there is limited detailed dietary intake data arising from obesity prevention and treatment research in the published literature.
Despite the many difficulties and limitations, assessing dietary intake remains an important objective for researchers and practitioners working in the area of child obesity. It is acknowledged that there is a degree of uncertainty around the merits of different dietary assessment methods and in the selection of the best method for any particular circumstance. The Food and Nutrition Stream of the Australasian Child and Adolescent Obesity Research Network (ACAORN) aims to provide a simple guide for researchers and practitioners in selecting the most appropriate diet assessment method relevant to their objective.
In doing so, ACAORN is promoting
- Inclusion of dietary outcomes in publications arising from child obesity research
- Better quality diet assessment methodology in child obesity research (tools that are fit for purpose, valid and reliable)
- Collaboration between researchers and practitioners on the topic of dietary assessment, to utilise nutrition expertise and where practical, enhance the ability to compare outcomes through the use of standardised methodology.
The ACAORN Food and Nutrition Stream has developed a series of resources to help child obesity researchers and practitioners identify suitable outcomes of interest and determine an appropriate methodology for measuring this outcome in a variety of child and adolescent populations. The focus of these resources is to support research and practice in the area of child obesity.
- Diet Assessment Method Selection Guide - A series of matrices to guide selection of an appropriate outcome for the research question of interest and a quick reference point of considerations of choosing a particular tool when undertaking child obesity research. Where appropriate, the Medical Research Council (MRC) website (see side-bar) has been utilised for in-depth information around things to consider when choosing a dietary assessment method.
- Case scenarios - A number of case studies have been developed to reflect situations in which nutritional data may be collected as part of child obesity research. In each study, the intent is to illustrate a process for selecting a diet assessment method.
- Tools and validation studies - A database has been compiled of dietary assessment tools that have undergone some form of validation of their performance.
We would like to acknowledge the extensive work undertaken by the Population Health Sciences Research Network (PHSRN), the Medical Research Council (MRC) in the United Kingdom, using a similar approach, to facilitate researchers in selecting appropriate dietary intake and physical activity methodologies for populations.
The ACAORN project, established in 2004, aimed to
- Support researchers in making decisions about appropriate dietary methodology and
- Provide access to dietary intake assessment tools for children and adolescents
This project was undertaken in the context of child obesity, research and practice.
During the project ACAORN became aware of the PHSRN project being undertaken by the MRC. ACAORN consulted with researchers based at the MRC and would particularly like to acknowledge Dr Janet Warren.
In the spirit of collaboration and not wanting to re-invent the wheel, it was acknowledged that The Diet and Physical Activity Measurement Matrices and associated web pages in the MRC toolkit would be a valuable resource for Australian researchers.
The ACAORN Matrices provide practical information with a focus on special considerations of undertaking dietary assessment in the context of obesity research with children and adolescents.
To expand the level of information on the relevant ACAORN Food and Nutrition web pages, please visit http://www.dapa-toolkit.mrc.ac.uk/dietary-assessment/. We have provided links to similar pages on the MRC web site in the features column on the right side of each applicable ACAORN web page
The MRC web pages will open in a new browser window enabling you to view both the data on the MRC and ACAORN web sites simultaneously.
For information on the MRC Diet and physical activity measurement toolkit, click here
Dietary intake assessment - Case scenarios
Choosing a dietary assessment tool
The following case studies have been developed to reflect situations in which nutritional data may be collected as part of child obesity research. In each study, the intent is to illustrate a process for selecting a diet assessment method. The information provided in each study is only sufficient to illustrate key considerations for various dietary assessment approaches and recommend the adoption of one or more methodology approaches (e.g. direct observation or food frequency questionnaire). Details of specific instruments are not provided, but suitable tools may be found in the database of dietary assessment tools.
- Study 1: Nutrition intervention among pre-schoolers
- Study 2: Clinical weight management program for adolescents
- Study 3: Population based obesity prevention program among school aged children
Researchers plan to evaluate a 12-week program in pre-schools targeting fruit and vegetable consumption in 3-5 year olds. All pre-schools with children 3-5 years in a given area will randomly be assigned to either an intervention group or control group in the study. The intervention group will be provided with parental education, targeting the provision of availability of fruit and vegetables in the pre-schooler's home environment. The control group will be provided with information about availability of fruit and vegetables at the pre-school.
The aims of the study are to determine:
- Does an intervention which aims to increase the availability of fruit and vegetables in pre-schooler's homes through parental education increase childrens consumption of fruit and vegetables beyond that achieved through increasing availability at the pre-school level
- The availability of fruit and vegetables in the pre-schooler's home in each group in comparison to the availability in the pre-school.
In this case study situation, funding is limited, and so the intervention is assessed in a random sample of 110 children in each arm of the study (allowing for a 10% drop out following initial consent to participate). It has been determined that this number should be an adequate sample size to detect a change of 0.5 serves/day of fruit and vegetable intake, providing a reasonably robust dietary assessment method could be conducted.
Consideration is also given to whether the impact of fruit and vegetables intake on total diet and nutrient could be investigated, but it was decided this would beoutside the study scope and resources. Focus is to be on robust, quantitative measure of single foods (fruit and vegetables) and their availability.
Dietary methods selection process
The following factors were considered in selecting study dietary assessment tools:
- Resources were available for (objective) in home and in pre-school data collection
- Children were too young to report intake so there was a reliance on parent report, however children also spent time at pre-school so parent report only was limiting
- Multiple instances of fruit and vegetable intake across a day (limits direct observation for primary outcome)
- Limited pre-school or parent time for data collection (need low participant burden)
- Usual intake at group level considered acceptable
- Need to detect change over 12 weeks (recall period important).
Seven methods were considered as they would provide information on intake of whole food/s. Four were eliminated based on participant burden and excess information collected (ie more suited to total diet).
A combination of diet assessment methods was selected:
- Childrens fruit and vegetable intake (primary outcome) will be assessed using a parent-reported FFQ previously validated in a similar population
- Complemented with an objective measure of fruit and vegetable availability in the home and pre-school using direct observation. An alternative measure to direct observation was considered, in relation to collection of purchasing receipts of fruit and vegetable items, but this was considered potentially intrusive for the parents
- In order to assess availability at the pre-school, a review of menus and direct observation was undertaken at baseline and 12 weeks.
A community health centre run a 6-month group weight management program for adolescents four times a year. Approximately 12 adolescents attend a 60 minute session once a month (n=48 per year). Feedback on progress is incorporated as a behaviour change technique into the group sessions. Currently this is only based on weight results. Facilitators would like to expand this focus to provide feedbacks on the lifestyle behaviours the adolescents are changing during the program in order to facilitate gradual weight loss.
The aims of the study are to determine if a weight management program for adolescents can:
- Reduce intake of intake of non-core foods, portion size, water consumption andfruit and vegetable intake
- Reduce entertainment sedentary activity and increase opportunities to be active.
Dietary methods selection process
The following factors were considered in selecting the diet assessment methodology;
- High risk of under-reporting given an overweight and adolescent population
- The need for low participant and facilitator burden (limited time in sessions, need to utilise to provide on the spot feedback)
- Low research budget.
A questionnaire or diet/activity checklist approach was considered. A 5-minute questionnaire approach was chosen so that facilitators and barriers to lifestyle change could also be explored. Where possible questionnaire items were adapted from validated questionnaires. As part of a dietetic student placement, the questionnaire will be validated against a measure of total diet.
In a large scale, population based program, practitioners are working in partnership with primary schools across a regional area to encourage healthy and active lifestyles. Strategies target food behaviours associated with childhood obesity including increasing fruit and vegetable consumption, water intake and decreasing energy-dense nutrient-poor snacks, sweetened drinks and meals eaten in front of television. While all schools in the region are included in the program, a representative random sample is to be selected for a pre and post evaluation. This evaluation will occur at both the school environment and individual level and examine whether the program strategies led to changes in both the selected behaviours and the school environments that support healthy lifestyles.
The aims of the study are to determine:
- If an in-school intervention can change food related behaviours
- Is an in-school environment more supportive of a healthy lifestyle.
Dietary intake assessment - Tools and validation studies
In 2004, 2009 and more recently in 2012, the ACAORN Food and Nutrition Stream conducted surveys to identify current Australasian research activities that include assessment of the dietary intakes of children and adolescents. From the survey results, a database has been compiled of dietary assessment tools that have undergone some form of validation of their performance.
The ACAORN Food and Nutrition Stream does not see this database as endorsement of any particular dietary assessment tools. The intent of the database is to highlight existing tools for consideration by researchers and practitioners planning research to include a dietary outcome.
Please note that the table summarises information as reported by responders to the ACAORN surveys. It is recommended that before using a particular tool, that you cross-check the information with the published paper or tool contact. The database should also be used in conjunction with an understanding of interpreting validation studies of dietary assessment tools. Consultation with a nutrition researcher with expertise in diet assessment methodology is also encouraged to ensure selection of an appropriate tool for a given research context.
This is measured in kilojoules (kJ) or Calories (cal/kcal) and forms the basis of many dietary studies as one side of the energy balance equation. If more energy is taken in than is required, excess weight gain ensues. If more energy is expended than is taken in, sub-optimal weight gain, weight loss or poor growth can occur. This may be desirable (eg during obesity treatment) or may indicate risk of malnutrition. During childhood, energy needs vary widely depending on the stage of growth, gender and physical activity level. A sub-variable can be created in dietary studies known as kJ/kg, which is total energy intake adjusted for a child's body weight which will allow for better comparisons to be made between children and/or over time.
Total energy intake could also be reported relative to lean body mass or fat free mass to adjust for body composition. Another approach is to report total energy intake relative to multiples of resting energy expenditure, if it has been measured, or to compare the reported intake to a standardised value. This approach may allow for comparisons to be made between studies over time.
Energy density is a measure of the amount of caloric energy from a given volume of a food or beverage.
Food / foods groups
The basic food groups include: breads and cereals, fruit, vegetables, meat and alternatives, dairy and extras (energy-dense nutrient-poor) or sometimes referred to as non-core foods. Intakes of specific foods can be assessed directly depending on the nature of the research question and may include items such as sweetened drinks (soft drinks, cordials and fruit juice) or dairy foods (milk, yoghurt, cheese).
Assessment and reporting of actual food intake is essential for continual development and refinement of food-based guidelines used for effective prevention of childhood obesity. People eat food and not nutrients.
This includes the assessment of whole diet, or quality and variety not just specific components. The study of eating patterns is similar conceptually, to the more traditional dietary approach used in intervention trials which assesses foods and nutrient intakes. However rather than creating or prescribing a specific diet, this approach uses statistical methods such as factor or cluster analysis, usually within a large data set from observational studies, to derive eating patterns or demographic characteristics that are located together. For dietary intake, this ideally leads to the reporting of a meaningful set of eating patterns to describe the way groups of people actually eat.
Understanding how people actually eat in natural settings through the use of eating pattern methods provides an advantage over single nutrient approaches in nutritional epidemiology. This includes the assessment of eating patterns such as breakfast consumption, the inclusion of snacks, skipping meals, timing of eating, size of meals.
This category includes the energy yielding nutrients of protein, fat and carbohydrates. These macronutrients are the basis of most foods and beverages in the diet and contribute to an individual’s energy intake. These are often reported as mean daily intakes (g/ day) and/or their individual percentage contribution to total energy intake. This provides direct comparison with national food selection advice, including The Australian Guide to Healthy Eating, National Dietary Guidelines for Australian Children and Adolescents and the Nutrient Reference Values (NRV).
Due to the smaller molecular size and contribution to dietary intake when compared to macronutrients, they are usually measured in smaller units such as milli (mg) or micrograms (μg) per day. If trying to determine usual or habitual consumption of micronutrients, longer reporting periods of dietary intake, often greater than 8 days are required due to the large daily variation in intake. To estimate intakes of micronutrients a food database that reports the nutrient profile for a nationally representative range of foods consumed is required. Therefore it is important to select the most accurate and current database available for the nutrient or nutrients of interest.
Food / eating behaviours
It is becoming more common to try and assess food behaviours as part of dietary intake and obesity related studies. Food behaviours influence food intake and preferences and may include behaviours such as eating in front of television, pace of eating, picky or fussy eating, eating as a family or at a dinner table.
There is a need to consider other influences on food intake and eating behaviours, including neighbourhood, school, social and home settings. This is particularly for children and adolescents who will have less control over these environments compared to adults. Examples include the number and variety of fast food restaurants in the local area, food availability in the home and school, price of food, peer/social pressures, purchasing practices, food marketing and advertising.
This captures the time and effort required to complete the dietary assessment method. Two aspects need to be considered:
How much time do researchers need to dedicate to conducting the dietary assessment method within the study. A researcher needs to consider standardisation and training of personnel (if required), implementation of the method, data entry and analysis, time, analysis method and cost.
- How and what is the participant being asked to do?
- How long is the survey?
- How literate is the participant?
- How much time do they have to commit to complete the method?
- Do they have to travel to a venue?
- Do they need to have any special equipment such as food scales or standard household measures to complete the method? Do they require access to a computer?
How many people are going to be part of the study and how many are going to have dietary intake assessed? It is highly recommended before the study commences that a power calculation is conducted. The estimation of sample size from the outset will help in planning the study timetable and articulate the number of participants required to detect a change or difference in the dietary variable that is considered to be important within the study. Freely available software can assist with this or a statistician can be consulted. It is not recommended to simply select a number of participants that can be recruited. If a change in fruit and vegetable intake by 0.5 serve/day over a three week period is to be detected, there is a need to determine how many participants are required before study commencement to detect a change so that a study is not conducted with inadequate numbers to conduct the statistical test with sufficient power.
Do participants report accurately? There is always a need to consider key potential biases influencing estimates of dietary intake. This may include:-
Recall bias: Can people accurately remember what they ate?
Responder bias: Are the people participating in the study different from the general population? Are they more motivated or different in some way?
Reporting bias: Are people reporting what they think is important in relation to the research study they have consented to participate in?
Social desirability: Are people reporting what they think other people do, i.e. the ‘norm’, or what they think the researchers want to hear?
How reflective is the dietary data collected? Does it capture one day, many days or the average over three or 12 months?
Does the research require data such as how the consumer feels about foods available in their environment or the way foods are cooked. This type of information can be obtained by individual interviews or from focus groups with analysis identifying key themes, or some data could be collected as part of a diet history. Does the research require quantitative data such as the daily intake of specific foods e.g. breads, macronutrients (grams of protein) or micronutrients (mg of calcium). These quantitative methods will require access to a National specific food and nutrient database for the analysis.
How much finance is available to undertake assessment of diet? How much time needs to be allocated by researchers for the data collection, entry and analysis? Do researchers need to have pre-requisite skills to conduct the dietary assessment such as being an Accredited Practising Dietitian (APD)? Do they need to be trained in order to standardise the dietary data collection technique? Is there a cost to use the dietary tool? Is there a cost associated with analysis? Are participants going to need to be provided with equipment such as food scales or standard household measures in order to complete a weighed food record? Will they be out of pocket for any items related to assessment of their dietary intake and if so will they be reimbursed?
The age of children needs to be considered as their attention span, cognitive abilities, literacy skills will influence the selection of the dietary methods and the quality of the dietary information that is to be collected. It is generally accepted that children under the age of 9 yrs cannot accurately report their own diet intake and a parent should be used as a proxy. With increasing age, children become more accurate when reporting over shorter periods of time such as the previous days or week. However, accuracy declines as the time period over which the child is asked to recall intake increases. Parents and/or carers can be used to supplement the child's information. The Populations of Interest Matrix provides details of who can be used as the reporter for each diet method.
There is a need to consider where the research is going to be conducted, how many people are going to be involved and how much space, how the location may need to be set out for an interview versus completion of a questionnaire and the time needed to complete the tasks.
Often research studies are conducted in clinical environments such as hospitals or clinics. Hospitals can be a convenient location for participants, particularly if they already have scheduled medical appointments. They are often centrally located and there may be facilities for a range of measurements to be collected such as height, weight or blood testing facilities and able to cater for a number of participants (individual or group) and have appropriate public transport services.
Issues to consider for data collection at an individual's home include the usual Ethics Committee requirements as well as Occupational Health & Safety issues. An allowance for time for researchers to travel to and from participant homes as well as provision of all equipment needed for assessment will need to be addressed. Access to a vehicle to allow researchers to travel will be necessary. Organisation of suitable times for both researchers and participants can timely, along with having a high researcher burden if visits are needed on more than one occasion.
This type of study involves recruitment of a moderate number of free living community participants (20-200?). The aim of undertaking a study in this setting is to reduce the recruitment bias in order to establish ‘true’ or real diet relationships.
Large scale population surveys with participants greater than 1000 require detailed planning.
Issues which should be considered:-
What is the procedure and method of recruitment? How will data be collected and analysed for such large numbers? What data quality checks will need to be made? Is there appropriate funding, time and expertise available for this to occur?
There are a number of benefits to this type of study including large numbers, potential for the detection of diet disease relationships over long periods of time and population consumption patterns.
A key consideration if participants are going to be followed up at a later time will relate to repeated use of the same dietary intake assessment tool and ensuring the participant can be tracked in the future. If so, secondary contact details of other family members may be crucial to establish.
Dietary information can be collected and obtained from participants in different ways, some of which may help to reduce participant and researcher burden.
This is a common dietary collection method and involves the participant reporting their own dietary intake. This is commonly done via a face-to-face interview, but can also be performed by a mailed survey, telephone interview or via newer electronic methods. For children of younger ages, it is recommended that a parent or main carer act as a proxy for the child. Older children and adolescents are able to self-report.
If using a mail survey then it is recommended that the surveys are pre-coded with a participant ID number to avoid confusion when surveys are returned and to avoid lost data if the survey comes back with no name. To increase the likelihood of participants returning surveys, it is also useful to send a reply paid pre-addressed envelope with the possibility of an incentive or reward, to improve the response rate or ease the burden on the participants or compensate them for their time.
Dietary information is collected at an in-person interview or over a telephone which may or not be assisted by CATI*. To ensure that data is collected effectively and efficiently, research personnel conducting the interview should be trained and quality checking of the process throughout the collection period. This will help to eliminate errors and reduce biases (see bias above). Due to the high costs involved in face-to-face interviews and the time needed to collect information from participants, there has been a trend away from this method. Travel costs to participant’s homes and personnel costs involved in face-to-face methods are typically higher than they are for mail, telephone, or web surveys.
*CATI - Computer Assisted Telephone Interviewing allows a dietary interview to be conducted with a computer assisted prompting system. This system increases the efficiency and cost effectiveness of conducting large scale surveys. It reduces coding and data entry errors and also improves data management and processing capabilities since these tasks are automated, avoiding the necessity for separate coding and data entry steps.
This method is resource intensive and should involve trained researchers directly observing a participant’s food intake and behaviours for defined periods to ascertain foods, brands and portions consumed. This may or may not be within a research environment and it is often preferable if a participant is not able to identify who the observer is so as to not alter their dietary intake.
This is a newer means of collecting dietary information but becoming more popular due to the benefits that it can provide and the increasing computer literacy of the population.
Study websites can be set up that rely on passwords and/or PIN numbers to ensure survey responses are confidential, that only respondents selected for the study have access to the survey and that there is no duplication of survey respondents.
It is useful for studies where there is no central location for data collection or where it is difficult for participants to meet for a face-to-face interview. Through liaison with a web development team, basic online surveys for food intake or behaviors can be set up. Food diaries or weighed food records can be entered with information supplemented from food scales or standard household measures but little is known on the validity of these methods currently.