Vitamins D, A and E, and Beta-Carotene in Adherent and Non-Adherent Individuals with Phenylketonuria: Cross-Sectional Study, Systematic Review and Meta-Analysis

Bokayeva K. Jamka M. Kałużny Ł. Duś-Żuchowska M. Wichłacz-Trojanowska N. Mozrzymas R. Chrobot A. Walkowiak D. Ļubina O. Rabkevich I. Kurek S. Miśkiewicz-Chotnicka A. Sultanova G. Herzig K.-H. Auzenbaha M. Walkowiak J.
December 2025 Multidisciplinary Digital Publishing Institute (MDPI)

Nutrients
2025 #17 Issue 24

Background/Objectives: The impact of dietary adherence and formula intake regularity on fat-soluble vitamin status in phenylketonuria (PKU) is uncertain. This study assessed whether vitamin A, D, E, and beta-carotene levels differ by dietary adherence and regularity of Phe-free formula intake. Methods: A cross-sectional study included 98 individuals (age 6–41 years) with vitamin D measurements. In a subgroup of 68 patients, vitamin A, vitamin E, and beta-carotene levels were determined. Vitamin levels were compared between adherent and non-adherent groups and between participants with regular vs. irregular formula intake. A subsequent systematic review and meta-analysis of six studies (from PubMed, Scopus, Web of Science, and Cochrane; searched in August 2025) pooled standardised mean differences (SMDs) using fixed-effects and random-effects models. Results: The cross-sectional results showed higher vitamin D in adherent (35.60 [30.39–41.65] vs. 32.90 [26.50–40.00] ng/mL, p = 0.034) and regular formula consumers (35.97 [30.03–42.28] vs. 30.20 [26.08–35.06] ng/mL, p = 0.002). Beta-carotene was elevated with regular intake (74.40 [56.70–98.45] vs. 53.20 [34.10–68.60] ng/mL, p = 0.003). Meta-analysis confirmed higher vitamin D in adherent individuals (fixed-effects model, SMD = 0.290, 95% CI: 0.004, 0.576, p = 0.047) and regular consumers (fixed-effects model, SMD = 0.750, 95% CI: 0.382, 1.118, p < 0.0001). No differences were observed for vitamin E or beta-carotene. Conclusions: Adherence to diet and regular formula intake is associated with improved vitamin D status, underscoring the critical role of fortified formulas in PKU management. The very low certainty of evidence necessitates further research, especially for the other fat-soluble vitamins. Nonetheless, clinical practice should emphasise support for adherence and ongoing nutritional monitoring.

adherence , diet therapy , inborn errors of metabolism , metabolism , nutrition , PKU , vitamins

Text of the article Перейти на текст статьи

Poznan University of Medical Sciences, Department of Pediatric Gastroenterology and Metabolic Diseases, Szpitalna Str. 27/33, Poznań, 60-572, Poland
Poznan University of Medical Sciences, Doctoral School, Bukowska Str. 70, Poznań, 60-812, Poland
Research and Development Center, Department of Pediatrics, Regional Specialist Hospital, Kamienskiego Str. 73a, Wrocław, 51-124, Poland
Metabolic Outpatient Clinic, Voievodship Children Hospital, Chodkiewicza Str. 44, Bydgoszcz, 85-667, Poland
Poznan University of Medical Sciences, Department of Organization and Management in Health Care, Marii Magdaleny Str. 14, Poznań, 61-786, Poland
Clinic of Medical Genetics and Prenatal Diagnostics, Children’s Clinical University Hospital, Vienības Gatve Str. 45, Riga, 1004, Latvia
School of Dentistry, Pharmacy, Nursing, Public Health and Preventive Medicine, West Kazakhstan Marat Ospanov Medical University, Maresyev Str. 68, Aktobe, 030019, Kazakhstan
Research Unit of Biomedicine and Internal Medicine, Faculty of Medicine, University of Oulu, Aapistie Str. 5, Oulu, 90220, Finland
Biocenter Oulu, University of Oulu, Aapistie Str. 5, Oulu, 90220, Finland
Medical Research Center, Oulu University Hospital, Aapistie Str. 5, Oulu, 90220, Finland

Poznan University of Medical Sciences
Poznan University of Medical Sciences
Research and Development Center
Metabolic Outpatient Clinic
Poznan University of Medical Sciences
Clinic of Medical Genetics and Prenatal Diagnostics
School of Dentistry
Research Unit of Biomedicine and Internal Medicine
Biocenter Oulu
Medical Research Center

10 лет помогаем публиковать статьи Международный издатель

Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026