New Vitamin and Mineral Supplements: Acceptability, Tolerability, and Short-Term Adherence in a Paediatric Cohort with IMDs

Background/Objectives: Dietary therapy for inherited metabolic disorders (IMDs) can restrict nutrient-dense foods and increase reliance on vitamin and mineral supplementation. However, formulation-related barriers may limit supplement acceptability and adherence, particularly in children with feeding difficulties and complex dietary regimens. We evaluated the acceptability, gastrointestinal (GI) tolerability, and short-term adherence of two novel low-carbohydrate, low-volume vitamin and mineral formulations in children and adolescents with IMDs. Methods: This prospective, single-centre, open-label, non-randomised interventional study enrolled children and adolescents with IMDs aged ≥1 year who were either taking vitamin and mineral supplements already or were clinically identified as requiring micronutrient supplementation. Participants replaced their usual vitamin and mineral supplement with one of two age-appropriate study formulations (product A or B) for 7 consecutive days under usual home conditions. Acceptability was assessed using structured questionnaires, GI symptoms were assessed at baseline and on day 7 and monitored using daily diaries, and adherence was recorded daily by caregivers. Clinical characteristics and anthropometric measurements were assessed at baseline. Results: Thirty-one participants (median age, 7.2 years; range, 2.1–16.6) were enrolled; 15 were allocated to study product A and 16 to study product B, with 14 and 15 participants, respectively, completing the 7-day intervention. Full-dose intake (always or mostly) during the 7-day study period was reported in 27/30 (90.0%) participants. Among evaluable participants, GI symptoms improved or remained unchanged in 12/13 (92.3%) receiving product A and in 12/14 (85.7%) receiving product B. Mean acceptability scores improved for both product A (from 2.4 to 1) and product B (from 2.2 to 0.4), with lower scores indicating greater acceptability. Overall preference for the study product was reported by 10/14 (71.4%) participants receiving product A and 15/15 (100%) receiving product B. At the end of the study, 6/14 (42.9%) participants receiving product A and 7/15 (46.7%) receiving product B elected to continue to use the study product. Conclusions: In this exploratory study, two low-carbohydrate, low-volume vitamin and mineral formulations demonstrated favourable short-term acceptability, GI tolerability, and adherence in children and adolescents with IMDs. These findings suggest that formulation characteristics and ease of administration may influence the practical feasibility of micronutrient supplementation in this population. However, the short seven-day study duration and absence of a control group limit interpretation of these findings. Larger, longer-term studies are warranted to determine whether these benefits are sustained and whether improved acceptability and adherence translate into improved micronutrient status and clinical outcomes.