Beyond weekdays ‒ Weekend dietary intake uncovers hidden micronutrient deficiencies in institutionalised children

Background/objectives: micronutrient deficiencies, or "hidden hunger," remain a persistent public health concern, particularly among institutionalised children. Accurate dietary assessment is essential to identify nutritional risks; however, many studies overlook weekend intake, when children return home and may face different dietary conditions than those provided in institutional settings. To evaluate diet quality and micronutrient adequacy in institutionalised children aged 6 to 12 years, comparing two assessment scenarios: 1) two weekday food records, and, 2) two weekday records plus a 24-hour dietary recall for Sunday. Methods: dietary data were collected from forty-two children using observational food records. A subsample of eighteen children with complete weekend data was selected for the scenario comparison. Diet quality was assessed using the Healthy Eating Index-2020 (HEI-2020), energy plausibility was evaluated with the Goldberg & Black method, and usual intake was estimated using the ISU model in PC-SIDE, adjusting for intra-individual variability. Nutrient adequacy was determined using Dietary Reference Intakes (DRIs). Results: including Sunday intake significantly reduced total HEI-2020 scores (56.4 vs. 52.6; p = 0.043), with lower intake of fruits and whole grains, increased consumption of saturated fats, and a lower contribution of added sugars to total energy intake. Nine out of twelve micronutrients showed significant changes in usual intake, with increased risk of inadequacy for folate, calcium, thiamine, zinc, and vitamin D. Conclusions: although weekday institutional meals provided a structured dietary pattern, excluding weekend intake underestimated the nutritional risk. Including this period is essential for comprehensive dietary assessment and designing more effective public health strategies in vulnerable populations.