Author information
1
Department of Nutritional Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.
2
Pediatric Liver, GI and Nutrition Centre, King's College London School of Medicine at King's College Hospital, London, UK.
3
Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, London, UK.
4
School of Food Science and Nutrition, University of Leeds, Leeds, UK.
Abstract
BACKGROUND:
Vitamin D deficiency has been associated with non-alcoholic fatty liver disease (NAFLD). However, the role of polymorphisms determining vitamin D status remains unknown.
OBJECTIVES:
The objectives of this study were to determine in UK children with biopsy-proven NAFLD (i) their vitamin D status throughout a 12-month period and (ii) interactions between key vitamin D-related genetic variants (nicotinamide adenine dinucleotide synthase-1/dehydrocholesterol reductase-7, vitamin D receptor, group-specific component, CYP2R1) and disease severity.
METHODS:
In 103 paediatric patients with NAFLD, serum 25-hydroxyvitamin D (25OHD) levels and genotypes were determined contemporaneously to liver biopsy and examined in relation to NAFLD activity score and fibrosis stage.
RESULTS:
Only 19.2% of children had adequate vitamin D status; most had mean 25OHD levels considered deficient (<25 nmol·L-1 , 25.5%) or insufficient (<50 nmol·L-1 , 55.3%). Patients had significantly lower 25OHD levels in winter months (95% CI: 22.7-31.2 nmol·L-1 ) when compared with spring (30.5-42.1 nmol·L-1 ; P = 0.0089), summer (36.3-47.2 nmol·L-1 ; P < 0.0001) and autumn (34.2-47.5 nmol·L-1 ; P = 0.0003). Polymorphisms in the nicotinamide adenine dinucleotide synthase-1/dehydrocholesterol reductase-7 (rs3829251, rs12785878) and vitamin D receptor (rs2228570) genes were independently associated with increased steatosis; while a group-specific component variant (rs4588) was associated with increased inflammation in liver biopsies.
CONCLUSIONS:
Children with NAFLD in the UK have particularly low winter vitamin D status, with vitamin D insufficiency prevalent throughout the year. Polymorphisms in the vitamin D metabolic pathway are associated with histological severity of paediatric NAFLD.