Suspected Nonalcoholic Fatty Liver Disease Is Not Associated with Vitamin D Status in Adolescents after Adjustment for Obesity

Abstract

This study investigated a potential independent association between hypovitaminosis D and suspected nonalcoholic fatty liver disease (NAFLD) in a nationally representative sample of the US adolescents. Data from 1630 subjects 12–19 years of age were examined using the National Health and Nutrition Examination Survey, 2001–2004. The vitamin D status of subjects was categorized into quartiles of serum 25-hydroxyvitamin D. Subjects with serum ALT > 30 U/L were classified as having suspected NAFLD. Data regarding age, sex, race, BMI, and poverty level were also analyzed in bivariate and multivariate analyses using SAS and SUDAAN software. Suspected NAFLD was identified in 12.1% of adolescents in the lowest quartile compared to 6.9% of adolescents in the second quartile, 8.0% in the third quartile, and 13.17% in the highest quartile of serum 25(OH)D concentrations (P = .05). In analyses utilizing vitamin D as a continuous variable, no independent association was found between Vitamin D levels and rates of elevated ALT levels. In multivariate analyses, higher risks for suspected NAFLD were observed in males and overweight adolescents; however, vitamin D status was not found to be independently associated with suspected NAFLD after adjusting for obesity.

Non-Alcoholic Fatty Liver Disease is Not Associated with Vitamin D Deficiency in Essential Hypertension

“…An association between NAFLD and low 25(OH)D levels, independent from that between NAFLD and altered glucose homeostasis parameters, has been observed in a general population [5]. This finding was not confirmed in adolescents, in whom vitamin D status was not independently associated with NAFLD after adjusting for obesity [17]. Targher et al reported that among NAFLD patients with chronically elevated liver enzymes who underwent liver biopsy, significantly lower 25(OH)D concentrations were closely associated with histologic severity of hepatic steatosis, independent of age, insulin resistance or body mass index [18].…”

Serum vitamin D is associated with non-alcoholic fatty liver disease in Chinese males with normal weight and liver enzymes

“…Furthermore, in two studies using B-mode ultrasound NAFLD diagnosis (again from Italy and the USA), serum vitamin D was also found to be an independent predictor of NAFLD [19,20] . However, the inverse relationship that was shown to exist between serum levels of vitamin D and an unexplained elevation in ALT [9] was found to disappear in an adolescent population study after adjustment for obesity [21] . Moreover, when an Italian study of essential hypertension performed an analysis of NAFLD, the association with vitamin D deficiency was Data are presented as mean±SD or median (interquartile range).…”

High serum vitamin D levels reduce the risk for nonalcoholic fatty liver disease in healthy men independent of metabolic syndrome

“…Another study performed with a small number (162) of participants with NAFLD also reported an association of low 25(OH) D levels with the presence of NAFLD, independent of metabolic syndrome, diabetes or insulin resistance [22]. In contrast, a very recent study conducted using the National Health and Nutrition Examination Survey database of 1,630 American adolescents found that, after adjustment for obesity, vitamin D levels were not associated with suspected NAFLD assessed only by elevated ALT levels [20]. The authors commented that their study population was larger than those in previous studies, and that adult results might not be applicable in the adolescent population, as adults may have other confounding factors that cannot be considered in these kinds of analyses.…”

“…Because inflammation and oxidative stress might act as the common pathogenic mechanisms of NAFLD and vitamin D deficiency, and as both diseases are associated with insulin resistance, type 2 diabetes and cardiovascular disease, studies have been recently performed to examine the relationship of vitamin D levels with the development of NAFLD [17][18][19][20][21][22]. Previous studies showed that low vitamin D levels were associated with the development of NAFLD, although the numbers of subjects included in the studies were small [17,18,22].…”