Dietary under-reporting: what foods and which meals are typically under-reported?

Introduction 

- Dietary under-reporting is a widely acknowledged limitation of dietary assessment.
- Social desirability biases, participant burden and recall errors are key contributors to the overall reporting bias, but little objective evidence exists regarding what foods, and at which meals, participants are likely to under-report.

Method
- Healthy volunteers N=40 (20 males, 20 females, mean age 28-35, mean BMI 22-27)
- Total energy expenditure was assessed during a 15-day doubly labelled water protocol
- A wearable camera was wore on the days before three image-assisted 24-h dietary recalls during the study period

Results
- Under-reporting occurred throughout the day, but afternoon snacks (75/265 foods, 28%) and dinner (54/265 foods, 20%) contributed almost half of all unreported foods (including alcohol and ‘other’ foods)
- Beverages and snack foods (for example, biscuits, muesli bars and chips) were the foods most likely to be under-reported during afternoon snacks
- A wider variety of foods breads/cereals/rice, fruits and vegetables, condiments and dairy foods were commonly under-reported during dinner (eating episodes defined by the participant).
- Condiments were the food group most frequently under-reported at breakfast
- Snack foods (n = 64), condiments (n = 50) and beverages (n = 40) together contributed to 154/265 (57%) of all unreported foods, providing 58% of the additional energy

Limitations
- Small sample size
- Low generalizability
- Limitation of wearable camera: wear time, rate of imaging frequency and lighting conditions – may not capture all unreported food

Conclusion
- The most commonly under-reported food that have substantial impact on energy intake are snack foods, condiments and beverages
- Meals at which foods are most likely to be unreported are afternoon snacks and dinner.

Gemming & Mhurchu. Eur J Clin Nutr 2015; 70:640-41. DOI:10.1038/ejcn.2015.204