Nutritional Deficits and Vitamin D Insufficiency Common in Primary Ciliary Dyskinesia, Study Finds

A recent study published in the European Respiratory Review reported substantial evidence of nutritional deficiencies and growth abnormalities among patients with primary ciliary dyskinesia (PCD), a rare autosomal recessive ciliopathy, while simultaneously exposing a critical gap in standardized nutritional monitoring across clinical practice. The findings carry direct implications for the multidisciplinary teams including neurologists and geneticists who participate in the care of rare multisystem genetic disorders who manage these patients across the lifespan.¹

The review, led by Nena Karavasiloglou, PhD, RD, a postdoctoral research fellow at the University of Bern in Switzerland, represents the first systematic synthesis of growth and nutrition data in PCD, a disease long overshadowed by its pulmonary phenotype despite well-established systemic manifestations. At the conclusion of the research article, the authors argued that nutritional assessment must be elevated to a standard-of-care practice and that the current evidence base, although alarming in its findings, remains too sparse to permit definitive clinical guidance.

Study Overview

Investigators searched Medline, Embase, Scopus, and PubMed for observational studies published over the prior 20 years, applying a 20-year limit to account for diagnostic evolution in PCD. Eligible studies included cross-sectional, case-control, prospective designs, and case series with more than 5 patients reporting on growth, nutritional status, or intake in individuals with PCD. After duplicate removal and exclusion of overlapping populations, 50 publications were included in qualitative synthesis.

Studies ranged widely in size from 6 to 1609 participants and geographic origin, with most data from Europe and North America. Since substantial heterogeneity in outcome definitions, reference standards, and reporting methods, meta-analysis was not feasible, and findings were synthesized qualitatively. Risk of bias was assessed using a modified Agency for Healthcare Research and Quality tool; 84% of included studies were judged to be at moderate risk of bias.

Key Findings

Across the 50 included studies, considerable variability in height, weight, and body mass index (BMI) z-scores was observed. Some studies reported significantly reduced anthropometric measures compared with population reference standards, while others found no meaningful differences, a pattern the authors attributed in part to heterogeneity in diagnostic certainty, age at diagnosis, geographic reference standards, and inconsistent z-score reporting.

Regarding malnutrition specifically, undernutrition (defined as BMI z-score ≤−2) was identified in 4% to 11% of pediatric patients across 6 European studies. Underweight prevalence ranged from 0% to 50% across studies combining pediatric and adult populations, and overweight and obesity estimates ranged from 3% to 25%, with some obesity estimates exceeding global age-standardized prevalence figures.

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Vitamin D insufficiency, which is defined as serum 25-hydroxyvitamin D between 20 and 30 ng/mL, was identified in 54% of participants across 2 studies, whereas frank vitamin D deficiency (levels below 20 ng/mL) was reported in 18% to 26% of patients. These findings persisted despite seasonal variation in assessment timing. Only 3 studies reported on macronutrient and micronutrient intake, all of which found vitamin D dietary intake consistently below recommended levels.

Clinical Context

PCD affects approximately 1 in 7500 individuals globally and is caused by pathogenic variants across more than 50 genes encoding structural or functional ciliary proteins.² The disease manifests most prominently as chronic rhinosinusitis, bronchiectasis, and otitis media, but systemic features, including situs inversus, congenital heart defects, hydrocephalus, and fertility impairment, underscore its classification as a multiorgan ciliopathy. The relationship between chronic pulmonary disease, systemic inflammation, and nutritional status is well established in conditions such as cystic fibrosis (CF), where malnutrition is formally recognized and closely monitored.³ PCD, though sharing several overlapping features with CF, lacks equivalent nutritional surveillance infrastructure or consensus guidelines directing dietary assessment.¹

Interpretation

The authors interpreted the nutritional findings, particularly the undernutrition prevalence and the near-universal vitamin D insufficiency, as clinically meaningful signals warranting prompt integration of nutritional monitoring into PCD care pathways. They noted that delayed diagnosis may deprive patients of nutritional intervention during developmentally critical windows, potentially compounding long-term respiratory outcomes. Importantly, an international consensus statement on routine blood testing in PCD published in 2025 already endorses vitamin D status assessment as part of standard clinical evaluation, providing a framework into which supplementation protocols could be incorporated.⁴

Future Research

The authors called for multicenter, prospective studies dedicated to nutritional assessment as a primary endpoint in PCD, with standardized intake methodologies and consistent reference standards across age groups. Research exploring whole-diet patterns, nutritional behavior, and supplementation outcomes, particularly in populations beyond Europe, is identified as a priority. Longitudinal data in patients with advanced disease or those undergoing lung transplantation are also notably absent.

REFERENCES
1. Karavasiloglou N, Gkatzou V, Fernandez-Rodriguez A, Schwartz V, Goutaki M. Nutrition and growth of primary ciliary dyskinesia patients: a systematic review. Eur Respir Rev. 2026;35(180):260024. Published 2026 May 27. doi:10.1183/16000617.0024-2026
2. Hannah WB, Seifert BA, Truty R, et al. The global prevalence and ethnic heterogeneity of primary ciliary dyskinesia gene variants: a genetic database analysis. Lancet Respir Med. 2022;10(5):459-468. doi:10.1016/S2213-2600(21)00453-7
3. Mielus M, Sands D, Woynarowski M. Improving nutrition in cystic fibrosis: A systematic literature review. Nutrition. 2022;102:111725. doi:10.1016/j.nut.2022.111725
4. Altaraihi S, Marthin JK, Anagnostopoulou P, et al. International consensus statement on routine blood testing in primary ciliary dyskinesia. ERJ Open Res. 2025;11(3):01071-2024. Published 2025 Jun 23. doi:10.1183/23120541.01071-2024