National Dietary Guidelines for children and adolescents recommend that children enjoy a wide variety of nutritious foods . The ACARFS was designed to capture eating habits and food behaviours recommended within these guidelines. Therefore, like the adult Recommended Food Score [33, 34] it only considers intake of foods that align with dietary guidelines. Although the median score was not high at 25, the ACARFS correlated with nutrient intakes in the direction expected and applying Kappa statistics to quartiles of score, generally agreed with estimated nutrient intakes assessed from the ACAES FFQ. Importantly, children with higher ACARFS scores were more likely to meet the NRVs. The ACARFS therefore implies one or both of the following; firstly that a child who scores well on the ACARFS consumes a wide variety of healthy foods and has an adequate nutrient intake, or secondly that a child who scores well on the ACARFS consumes a wide variety of healthy and unhealthy foods, but still has an adequate nutrient intake. It is important to note that the dietary guidelines are not disease specific. Therefore adherence to the guidelines may have a varied effect on chronic disease risk and no assumptions can be made about higher ACARFS scores and decreased risk of chronic diseases without research to specifically evaluate this.
Strategies to enhance diet quality should potentially focus on promotion of a greater variety of sources of lean protein food, high fibre and wholegrains, vegetables and reduced fat dairy foods. Our results indicate that the majority of individuals were categorised within one quartile for both the ACARFS and the majority of nutrients evaluated, and rated as having moderate to substantial agreement. This is encouraging in terms of using a diet quality tool to potentially evaluate the impact of a broad public health campaign aimed at promoting adherence to national dietary guidelines or improving overall diet quality.
When applied to the quartiles of ACARFS and nutrient intakes, the weighted κ statistics showed slight to substantial agreement overall, though most nutrients showed moderate agreement . This indicates that the ACARFS is moderately strong in correctly classifying an individual or populations as having either good diet quality or poor diet quality. However the ability to correctly classify those in middle quartiles is slight. This could be partly explained by the non-normal data with skews to lower values for the ACARFS and nutrient intakes. Furthermore, the ACARFS correctly classified a third to almost half of individuals into the same quartile for nutrient intakes, with the exception of percent energy from SFA. The strongest agreement between ACARFS and nutrient intake was for vitamin C, fibre, β-carotene and magnesium, where the majority of individuals were classified into the same or adjacent quartile. The poorest agreement was for percent energy from SFA where the weighted κ statistic was slight but two thirds of individuals were classified into the same or adjacent quartile. For SFA the correlation with ACARFS produced a similar result with a slightly negative and statistically significant correlation with percent energy from SFA. The modest results regarding SFA may be due to the dairy and/or meat/flesh components of the ACARFS as many of these foods may contain large amounts of SFA, such as cheese or red meats . While correlation with all of the vitamins and minerals was moderately strong and statistically significant, correlation with fibre, vitamin C, β-carotene and magnesium were strongest. The ACARFS was also positively correlated with energy intake, a common finding in variety indices such as the ACARFS or dietary diversity scores, as the more food consumed the more variety in the diet and the higher the nutrient intakes [44–46]. Although this relationship with energy exists and diet quality and variety scores have been known to be positively associated with BMI [21, 47], the ACARFS was not correlated with BMI, and BMI z-scores had minimal influence on variation in the ACARFS.
Although participants, with the lowest ACARFS scores, indicating the poorest diet quality had the lowest nutrient intakes of the sample population, they still met most of the RDIs and AIs. However, the NRVs for fibre, folate and calcium were not met by about half of the participants in quartile one or two. This indicates that the ACARFS is sensitive enough to identify participants not eating a sufficient variety of nutrient rich foods. Even those participants not eating a wide variety of nutritious foods are unlikely to be deficient in the other vitamins and minerals considered as these nutrients are plentiful in the Australian food supply [37, 40]. It is important to note that the ACARFS is determined by the number of foods from each food group usually consumed at least weekly. This means that although an individual may consume the recommended servings of each food group, such as one fruit and three vegetables each day , which would provide a sufficient intake of most nutrients, consumption of a wide variety from each food group every week is required to gain a high score.
The sample population were aged nine to 12 years only and had a lower SES than the NSW average which may reduce how generalisable it is to other populations. While parents can fill in the ACARFS on behalf of their child, this may introduce bias as parents have been reported to overestimate child diet quality . The relative contribution of each component to the final score was dependent on the questions in the ACAES FFQ and is not necessarily representative of the Australian Guide to Healthy Eating . However, this may be viewed as a strength and a more realistic representation of the food group proportions available in the food supply. As the dietary guidelines for children in Australia do not provide specific recommendations for amounts to be consumed within food groups, the scoring contains an additional degree of subjectivity. This potentially means the ACARFS could overestimate usual diet quality. Further, given that biomarkers to objectively verify components of dietary intake were not measured, the results should be interpreted with caution.
In the ACAES validation study the FFQ demonstrated higher nutrient intakes compared to food records which may explain why the median intakes of niacin, vitamin A and magnesium were above the corresponding upper limit. However, the ACAES FFQ validation study demonstrated the ability of the ACAES FFQ to correctly classify participants into quintiles of nutrient intake and therefore not affect the assessment of agreement and correlations . This also suggests that participants in the first and second ACARFS quartiles may be at risk of inadequate intakes of nutrients other than fibre, folate and calcium.
Implications for research and practice
As the ACARFS is derived from a validated FFQ for children it offers the opportunity for researchers to use it independently or to derive it secondarily from the FFQ as a measure of overall dietary quality as a single continuous variable. The calculation of the ACARFS from the full ACAES FFQ is less onerous than indices that include nutrient based sub-scales. Its use as a brief tool to assess diet quality using only the FFQ questions and relevant responses could extend its use by allowing the ACARFS to be used along with the provision of timely feedback.
To extend its usability further research should examine use of the ACARFS method applied to other FFQs, in other populations, age groups, as well as other settings such as a self-monitoring tool or within clinical practice. In order for the ACARFS to be of use clinically or for self-assessment, then cut points may need to be derived. However, the agreement between quartiles suggests that those with an ACARFS score of 32 and above have a good diet quality and consume a reasonably wide variety of nutritious foods and that they have the highest nutrient intakes. Those with an ACARFS score of 19 to 31 (quartiles two and three) have a moderate diet quality, and consume a moderate variety of nutritious foods, but are at risk of sub-optimal intakes of fibre, folate and calcium. Finally, those with an ACARFS score of 18 or less have a poorer diet quality, do not consume a wide variety of nutritious foods and have the lowest intakes of a range of nutrients.