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

Abstract

An independent association between non-alcoholic fatty liver disease (NAFLD), a condition characterized by insulin-resistance, and low serum 25-hydroxyvitamin D [25(OH)D] levels has been reported. 25(OH)D concentrations are directly related with insulin sensitivity, whereas low [25(OH)D] predicts development of hypertension independent of glucose homeostasis alterations. We hypothesized that hypertensive patients with NAFLD have lower 25(OH)D than those without. Forty-four essential hypertensive (EH) patients with (n = 23) or without (n = 21) NAFLD were studied. No patient had diabetes mellitus, obesity, hyperlipidemia. The two hypertensive groups were compared with 24 healthy normotensive sex-, age-, body mass index (BMI)-matched subject, as controls. The two hypertensive groups had comparable age, sex, and blood pressure. BMI, glucose, insulin, homeostasis model assessment (HOMA) index and alanine aminotransferase were higher (P < 0.001 to <0.05) and plasma adiponectin was lower (P < 0.05) in EH patients with NAFLD than in those without NAFLD. Vitamin D deficiency, as defined by 25(OH)D levels <50 nmol/L, was similarly frequent in EH patients and controls (47.7 % vs. 45.8%, P NS). Prevalence of hypovitaminosis D was not different in EH patients with and without NAFLD (37.5% vs. 38.8%, P NS). In patients with EH and no additional cardiometabolic risk factors NAFLD is not associated with vitamin D deficiency.

Meta-analysis: vitamin D and non-alcoholic fatty liver disease

“…Of the 17 studies included, [18][19][20][21][22][23][25][26][27][28][29][30][31][32][33][34][35] six originated in North America, four from Asia and the rest in Europe or Israel (Table S3). Six studies were conducted in general population settings, five in out-patient settings, one included both inpatients and out-patients, one only inpatients and two studies did not report the clinical setting.…”

“…The reasons for exclusion were the presence of only NAFLD subjects in the study population in two studies 25,32 ; the evaluation of metabolic syndrome as the study outcome 30 ; the lack of detailed data on vitamin D levels, 18, 21, 23 the publication of duplicate data from another study from the same investigators 34 and the restriction to hypertensive NAFLD participants that could introduce heterogeneity in the analyses. 27 The meta-analysis for the continuous levels of vitamin D by NAFLD status included 12 794 participants (4855 NAFLD cases and 7939 controls). On average, NAFLD patients had 0.36 ng/mL lower levels of 25(OH)D levels compared to controls (SMD: 0.36 ng/mL, 95% CI: 0.32,0.40 ng/mL) (I 2 99%, P < 0.01).…”

Both high and low plasma levels of 25-hydroxy vitamin D increase blood pressure in a normal rat model

“…These data provide support for a U-shaped dose-response curve for the impact of vitamin D on this critical health outcome (systolic blood pressure) and confirms previous human epidemiological studies that suggest similar non-linear shapes for cardiovascular health (30)(31)(32)34) . It is possible that inconsistencies in previous studies in finding an association between vitamin D levels and blood pressure are explained by erroneous use of linear fits to data or assuming that higher vitamin D levels can only decrease blood pressure (19,43) . However, findings from this study show that time is also a factor in determining plasma vitamin D levels, taking up to 3 months for plasma vitamin D levels to fall, and thus may confound confirmation of this relationship.…”

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

“…Acta Pharmacologica Sinica npg lost [22] . It is also important to consider the various well-known influencing factors (such as ethnicity and geography) of serum vitamin D levels, which may have confounded the results from the various study populations.…”