Micronutrient status in nursing home residents: associations with dietary supplementation and health characteristics in the cross-sectional multicentre Nutricare study

Micronutrient deficiencies are common in institutionalised older adults due to chronic diseases, functional decline and age-related changes, increasing their risk of poor health outcomes. The study aim was to assess the usual daily intakes and status of selected micronutrients in nursing home (NH) residents, and to examine the relationship between dietary supplementation, micronutrient status and health characteristics. Additionally, we aimed to identify factors associated with serum 25-hydroxy-vitamin D (25(OH)D) and haemoglobin levels. The Nutricare study included 387 NH residents with low to moderate care needs from 20 NH. Collected data included resident characteristics, usual dietary intake (two 24-hour recalls, food frequency questionnaire), blood/serum biomarkers (25(OH)D, folate, vitamin B12, haemoglobin, ferritin), hand grip strength and body composition, estimated by bioelectrical impedance spectroscopy. Over 90% of study participants had inadequate intakes of vitamin D, magnesium and potassium. Despite 63% of participants reported use of supplements, suboptimal micronutrient status was common, with those aged 80+ and with higher care needs being more at risk. Most of participants who did not supplement vitamin D had insufficient 25(OH)D levels-both during winter (98%) and summer (71%). Low haemoglobin (<130 g/L) was found in 43% and ferritin <30 μg/L in 9%. These findings highlight the need for optimised NH menus and personalised supplementation strategies. Year-round vitamin D supplementation is essential, as diet and sun exposure are insufficient. Priority should be given to prevention over treatment, supported by clear guidelines for micronutrient management in this vulnerable population.