Are you struggling to decide on the best method to use to assess food and nutrient intake?
look no further, below we summarise the strengths and weaknesses of different methods to help make the decision that’s right for you and your needs.
Accurately measuring diet is not an easy task, not only because you’re relying on the individuals being truthful about what they ate, how much of it they ate and whether any food was left over, but consideration also needs to be taken about the context the food has been eaten in. Does this represent a typical day? Is the individual following any particular dietary pattern? How much of the diet is due to food availability and accessibility rather than preference?
Another level of complexity is choosing the right method to measure diet and this largely depends on what it is you want to measure and find out.
Here we summarise some, but not all, of the methods that could be used to measure food and nutrient intake.
24-hr recalls
This is a retrospective method measuring food and drink items that have been consumed the previous day (midnight to midnight) or over the last 24 hours. These can be conducted by an interviewer or self-completed. In order to capture habitual intake and individual variation, multiple recalls need to be taken. Typically aids are required to help gauge portion size for example images of defined portion sizes and household measures.
Strengths:
– Enhanced accuracy due to more detailed descriptions of foods and portion sizes
– When used on multiple occasions they can estimate usual intake
– Contextual information can be gathered e.g. whether foods have been eaten outside of the home
– Low participant burden
– If interviewer completed, participants do not need to be literate
– Reasonably quick to administer (20-30 mins)
Weaknesses:
– Relies on accurate recall of dietary intake
– ‘Coding’ diaries to calculate the nutritional value of the foods can be costly and time consuming
– If an interviewer is required it can be expensive as it requires a trained professional
– Could be subject to participants selectively recalling items to appear more healthy
– Repeating recalls increases the time and cost of analysis
Resources required:
– Trained interviewer
– Checklist and materials to record responses
– Trained coder
– Nutrient analysis software
– Portion aids
Check out our article to learn more about 24hr recalls.
Food Frequency Questionnaires
Food Frequency Questionnaires (FFQs) are retrospective methods to assess dietary intake typically over longer periods of time for example weeks, months and years. FFQs can be flexible in regards to the information they require and therefore can be long or short in nature e.g. frequency of foods only, assigned portion sizes and asking participants to define portion sizes. They may also be self-administered or completed by an interviewer.
Strengths:
– Assesses long term and habitual intake
– Low researcher and participant burden
– Potentially have higher response rates as often quick to complete
– Coding FFQs tends to be less laborious than food diaries and 24hr recalls
Limitations:
– Relies on accurate recall of dietary intake over a long period of time
– Only assesses intake for the food items that are listed on the FFQ therefore must be tailored
– Short FFQs aren’t reliable for measuring total diet and nutrient intakes
– Foods that are listed together in the FFQ can’t be separated for analysis
– Prone to misreporting
Resources required:
– Trained interviewer maybe be required
– Portion aids
– Trained coder
– Nutrient analysis software
– Standardised procedures for conducting
Want to learn more about food frequency questionnaires? Find out more about FFQs here.
Diet history
This is a retrospective method, the interviewer typically asks the participants open ended questions about their dietary behaviours like dieting and skipping breakfast and also about their typical intake of foods from core food groups e.g. cereals, fruits and vegetables, dairy etc.
Strengths:
– Usual diet and nutrient intake can be assessed
– Obtains information about meal patterns, food preparation and foods eaten less regularly
– Participants don’t need to be literate
Limitations:
– Accuracy of the data relies on the skill of the interviewer
– Relies on accurate recall of dietary intake
– Burdensome for both participant and researcher to complete
– Requires a trained interviewer to conduct interview and ‘code’ the data, which is costly
Resources required:
– Trained interviewer
– Checklist and material to record responses
– Trained coder
– Nutrient analysis software
Food diaries
Also known as a diet diary or food record. A food diary is a prospective method to measure food and drink intake as they are being eaten, therefore doesn’t rely on memory to recall what was consumed that day. There are two types of food diary: weighed and estimated.
Although weighed food diaries provide a more accurate method to estimate dietary intake it is less convenient for participants as exact measures of all items need to be known. Estimated food diaries do not require food items to be weighed, instead participants give an approximate measure for food and drink items.
Strengths:
– Does not rely on memory if completed prospectively
– Enhanced accuracy due to more detailed descriptions of foods and portion sizes
– When used on multiple occasions can be used to estimate usual intake
– Contextual information such as whether foods have been consumed outside of the home, timings of food consumption and whether foods have been eaten with others etc. can be captured
– Prompts within the diary can help gather more comprehensive and accurate data e.g. items often forgotten like condiments, portion images can also be used to help with portion size estimation
Limitations:
– Burdensome for participants to complete, more so if using a weighed food diary
– ‘Coding’ diaries to calculate the nutritional value of the diary can be costly and time consuming
– Could be subject to biases for example the participant altering their eating habits or selectively recalling items to appear more healthy
– Participants need to be literate or have a proxy to complete on their behalf
Resources required:
– Food diary to log food and drink items
– Instructions on how to complete the diary
– Trained coder
– Nutrient analysis software
Read our article to find out more about food diaries.
myfood24 takes a novel approach to assessing dietary intake
myfood24 offers an alternative solution to handwritten food diaries and interviewer administered recalls, in fact the only resource you will need is myfood24!
Participants are able to self complete their myfood24 food diary using their smartphone, tablet or computer, the diary itself contains instructions on how to complete the diary and is simple and easy to use. myfood24 does not require a trained coder to input the information, it automatically calculates the nutritional value of the food diary that has been entered by the participant!
Click # to try a free demonstration of the myfood24 food diary
For more information on how to choose the most appropriate dietary assessment tool, head over to Nutritools which offers Best Practice Guidelines and a library of validated tools.
Or read our articles looking at various dietary assessment methods in more detail: food diaries, FFQs and 24-hr recalls.