The Athlete Diet Index: a valid and reliable dietary assessment e-tool for athletes

The Athlete Diet Index: a valid and reliable dietary assessment e-tool for athletes

Written by Dr Louise Capling (Accredited Sports Dietitian; Research Associate, The University of Sydney)

Assessing dietary intake in athletes is challenging for several reasons (1) including the time and resources needed to undertake dietary assessment and analysis, especially with large groups of athletes (2).  Athlete specific issues may include high volumes of food, differing energy intakes with changes in training loads and the use of sports foods and supplements (1).

In recent times, nutritional epidemiology has shifted from a focus on single nutrients toward evaluating the whole diet or diet quality (3). A diet quality index or score applies a scoring system that compares usual intake or overall dietary patterns to recommendations.  Diet quality indices are a practical, cost-effective method to evaluate dietary patterns, yet few have reported diet quality in athletes. While over 50 indices (or their variations exist) globally, no dietary index has been available which focuses on the unique needs of athletes (2).  Such an index would offer an efficient and practical way to assess the quality of athletes’ diets, guide nutrition interventions, and focus sport nutrition support (2). To respond to the needs of practitioners and athletes, the Athlete Diet Index (ADI) was developed.

Initial development and testing of the ADI took place in New Zealand (NZ) with a group of over 60 athletes (4).  The first version of the ADI was further refined to form the final ADI, which was also informed by reviewing existing diet indices, relevant literature and in-depth focus groups with 20 sports nutritionists from elite athlete sporting institutes in Australia and NZ (2). After further development of items in the ADI, a modified Delphi survey in a subgroup of sports nutritionists was undertaken to determine and confirm content validity. Pilot testing with 15 athletes to inform face validity suggested the ADI was easy (40%) or very easy (60% of participants) to use and was rated as relevant (37%) or very relevant (63%) to athletes (2).

The final ADI (n = 68 items) includes three sections. Section A (n = 45 items) evaluates usual intake, special diets or intolerances, dietary habits, and culinary skills. Section B (n = 15 items) assesses training load, nutrition supporting training, and sports supplement use. Section C (n = 8 items) captures the demographic details, sporting type, and caliber (2). The ADI evaluates usual dietary intake and compares responses to dietary guidelines and sports nutrition recommendations, intake of nutrients relevant to athletes (i.e., calcium, iron), and dietary habits that support training are assessed and summed to provide an overall ADI score.

Following development, 68 athletes completed the ADI on two occasions, 2 weeks apart, followed by a 4-d estimated food record (4-dFR) to assess validity and reliability. A range of statistical tests were used to assess 1) relative validity (by comparing mean scores of the two administrations of the ADI against scores from 4-dFR; 2) construct validity (by comparing scores from the ADI with 4-dFR-derived nutrient intakes); and 3) test–retest reliability (by comparing means scores from the two administrations of the ADI). The ADI showed good reliability (ICC = 0.80) and moderate relative validity (r_s=0.69).  Higher scores were associated with higher absolute nutrient intake consistent with a healthy dietary pattern (5).  Twelve accredited sports dietitians completed a survey, where most (75%) strongly agreed with the perceived utility of the ADI for screening athletes and identifying areas for nutrition support, confirming its suitability for use in practice (6).

The ADI offers a rapid, efficient method to assess diet quality in athletes. The ADI is visually appealing, can be completed online, takes approximately 15 minutes to complete and offers automated feedback sent to athletes upon completion. For sports nutritionists, the ADI offers a way to identify and prioritise athletes that may be at the greatest need for nutrition support, allows them to tailor education to target specific weaknesses and to track improvements in diet quality over time. From a research perspective, the availability of a valid and reliable tool allows researchers to investigate the diet quality of athletes and associated research questions.

Where is it now and can I use it with my athletes?

The ADI is currently free to use and is available at www.sportsnutritionassessment.com. Upon completion, respondents (by providing an email address) will receive their results and can choose to also send these results to a nominated sports dietitian of their choosing. The feedback reports sent to dietitians are designed in a way that allow for easy collation of results into a spreadsheet, which is useful for practitioners using the questionnaire with groups of athletes. Currently, the ADI has only been validated in Australia and New Zealand.

Can I use it for research?

The ADI is licensed by the University of Sydney. If you would like to use the ADI without modification as it appears on the www.sportsnutritionassessment.com for a research study, where you need access to collated group data, a data transfer agreement with the University of Sydney is needed.

If you would like to host your own version or modify and/or adapt the ADI for research, you will need to organise a licensing agreement with the University of Sydney for these purposes. For more information, contact the research team.

Figure 1. The ADI on www.sportsnutritionassessment.com/adi

References

1. Magkos F, Yannakoulia M. Methodology of dietary assessment in athletes: concepts and pitfalls. Current Opinion in Clinical Nutrition and Metabolic Care. 2003;6(5):539-49.
2. Capling L, Gifford JA, Beck KL, Flood VM, Slater GJ, Denyer GS, et al. Development of an Athlete Diet Index for rapid dietary assessment of athletes. International Journal of Sport Nutrition and Exercise Metabolism. 2019;29(6):643-50.
3. Hu FB. Dietary pattern analysis: a new direction in nutritional epidemiology. Current Opinion in Lipidology. 2002;13(1):3-9.
4. Blair R. The development, validity and reproducibility of a tool (the Athlete Diet Index Questionnaire) to assess the dietary intake of high performing athletes. Auckland, New Zealand: Massey University; 2016.
5. Capling L, Gifford JA, Beck KL, Flood VM, Halar F, Slater GJ, et al. Relative validity and reliability of a novel diet quality assessment tool for athletes: the Athlete Diet Index. British Journal of Nutrition. 2021;126(2):307-19.
6. Capling L, Tam R, Beck KL, Slater GJ, Flood VM, O’Connor HT, et al. Diet quality of elite Australian athletes evaluated using the Athlete Diet Index. Nutrients. 2021;13(1).