Does vitamin D improve liver enzymes, oxidative stress, and inflammatory biomarkers in adults with non-alcoholic fatty liver disease? A randomized clinical trial

Calcium and Vitamin D in Obesity and Related Chronic Disease

There is a pandemic of lifestyle-related diseases. In both developed and lesser developed countries of the world, an inadequacy of calcium intake and low vitamin D status is common. In this chapter, we explore a mechanistic framework that links calcium and vitamin D status to chronic conditions including obesity, systemic inflammation, endothelial dysfunction, dyslipidemia and cardiovascular disease, and type 2 diabetes mellitus. We also update the available clinical evidence, mainly from randomized controlled trials, to provide a synthesis of evidence in favor or against these hypotheses. There is consistent data to support calcium increasing whole body fat oxidation and increasing fecal fat excretion, while there is good cellular evidence for vitamin D reducing inflammation. Clinical trials support a marginal reduction in circulating lipids and some meta-analysis support an increase in insulin sensitivity following vitamin D. However, these mechanistic pathways and intermediate biomarkers of disease do not consistently transcribe into measurable health outcomes. Cementing the benefits of calcium and vitamin D for extraskeletal health needs a reexamination of the target 25(OH)D level to be achieved and the minimum duration of future trials.

Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical Trial

BACKGROUND

Vitamin D may decrease depression symptoms through its beneficial effects on neurotransmitters, metabolic profiles, biomarkers of inflammation, and oxidative stress.

OBJECTIVE

This study was designed to assess whether vitamin D supplementation can reduce symptoms of depression, metabolic profiles, serum high-sensitivity C-reactive protein (hs-CRP), and biomarkers of oxidative stress in patients with major depressive disorder (MDD).

METHODS

This randomized, double-blind, placebo-controlled clinical trial was performed in 40 patients between 18 and 65 y of age with a diagnosis of MDD based on criteria from the Diagnostic and Statistical Manual of Mental Disorders. Patients were randomly assigned to receive either a single capsule of 50 kIU vitamin D/wk (n = 20) or placebo (n = 20) for 8 wk. Fasting blood samples were taken at baseline and postintervention to quantify relevant variables. The primary [Beck Depression Inventory (BDI), which examines depressive symptoms] and secondary (glucose homeostasis variables, lipid profiles, hs-CRP, and biomarkers of oxidative stress) outcomes were assessed.

RESULTS

Baseline concentrations of mean serum 25-hydroxyvitamin D were significantly different between the 2 groups (9.2 ± 6.0 and 13.6 ± 7.9 μg/L in the placebo and control groups, respectively, P = 0.02). After 8 wk of intervention, changes in serum 25-hydroxyvitamin D concentrations were significantly greater in the vitamin D group (+20.4 μg/L) than in the placebo group (-0.9 μg/L, P < 0.001). A trend toward a greater decrease in the BDI was observed in the vitamin D group than in the placebo group (-8.0 and -3.3, respectively, P = 0.06). Changes in serum insulin (-3.6 compared with +2.9 μIU/mL, P = 0.02), estimated homeostasis model assessment of insulin resistance (-1.0 compared with +0.6, P = 0.01), estimated homeostasis model assessment of β cell function (-13.9 compared with +10.3, P = 0.03), plasma total antioxidant capacity (+63.1 compared with -23.4 mmol/L, P = 0.04), and glutathione (+170 compared with -213 μmol/L, P = 0.04) in the vitamin D group were significantly different from those in the placebo group.

CONCLUSION

Overall, vitamin D supplementation of patients with MDD for 8 wk had beneficial effects on the BDI, indicators of glucose homeostasis, and oxidative stress. This trial was registered at www.irct.ir as IRCT201412065623N29.

Women may respond different from men to vitamin D supplementation regarding cardiometabolic biomarkers

Evidence has revealed that vitamin D status is associated with the cardiometabolic risk factors. Moreover, few gender-specific analyses have been performed in the clinical trials regarding vitamin D supplementation. As a result, assessing gender differences regarding the effects of vitamin D supplementation on some cardiometabolic biomarkers in patients with non-alcoholic fatty liver disease (NAFLD) was the aim of present study. We conducted a post hoc subgroup analysis of a double blind placebo controlled study. Patients with NAFLD randomly allocated to receive one oral pearl consisting of 50,000 IU vitamin D3 (n = 27, 13 men and 14 women) or a placebo (n = 26, 13 men and 13 women) every 14 days for four months. Serum lipid profiles, aminotransferases, high-sensitive C-reactive protein (hs-CRP), adiponectin as well as insulin resistance and dietary intakes were assessed pre- and post-study. In both genders, serum 25(OH) D3 increased significantly (P < 0.001). This increase was accompanied by significant decrease in serum total cholesterol (TC) (% of change: -7% in vitamin D vs. + 0.4% in placebo, P = 0.04) and LDL-C (%of change: -9.6% in vitamin D vs. -4% in placebo, P = 0.006) in women. However, in men, vitamin D supplementation increased the levels of serum TC (% of change: +9.2% in vitamin D vs. -10% in placebo, P = 0.02) with no significant effects on LDL-C. Moreover, vitamin D significantly reduced serum hs-CRP in women. The median daily calcium intake in both genders was well below the dietary reference intake for adults. In conclusion, improved vitamin D status might decrease serum TC and LDL-C levels as well as hs-CRP in women with NAFLD. However, it might increase serum TC in men who have low daily calcium intake. Further studies with larger sample sizes are needed to confirm these results.

Is Liver Enzyme Release Really Associated with Cell Necrosis Induced by Oxidant Stress?

Hepatic diseases are a major concern worldwide. Increased specific plasma enzyme activities are considered diagnostic features for liver diseases, since enzymes are released into the blood compartment following the deterioration of the organ. Release of liver mitochondrial enzymes is considered strong evidence for hepatic necrosis, which is associated with an increased production of ROS, often leading to greater hepatic lipid peroxidation. Lipotoxic mediators and intracellular signals activated Kupffer cells, which provides evidence strongly suggesting the participation of oxidant stress in acute liver damage, inducing the progression of liver injury to chronic liver damage. Elevated transaminase activities are considered as an index marker of hepatotoxicity, linked to oxidant stress. However, a drastic increase of serum activities of liver enzyme markers ought not necessarily to reflect liver cell death. In fact, increased serum levels of cytoplasmic enzymes have readily been observed after partial hepatectomy (PH) in the regenerating liver of rats. In this regard, we are now showing that in vitro modifications of the oxidant status affect differentially the release of liver enzymes, indicating that this release is a strictly controlled event and not directly related to the onset of oxidant stress of the liver.

The impact of vitamin D deficiency on patients undergoing kidney transplantation: focus on cardiovascular, metabolic, and endocrine outcomes

Vitamin D deficiency is common among kidney transplant (KT) recipients because of reduced sunlight exposure, low intake of vitamin D, the immunosuppressive drug regimen administered, and steroid therapy. Glucocorticoids regulate expression of genes coding for enzymes that catabolize vitamin D, further reducing its level in serum. Although vitamin D primarily regulates calcium homeostasis, vitamin D deficiency is associated with the risk of several diseases, such as diabetes mellitus and tuberculosis. Aim of this review is to highlight endocrine and metabolic alterations due to the vitamin D deficiency by evaluating the mechanisms involved in the development of KT-related disease (cardiovascular, bone mineral density, and new-onset diabetes after transplantation). Next, we review evidence to support a link between low vitamin D status and KT-related diseases. Finally, we briefly highlight strategies for restoring vitamin D status in KT patients.

Profile of oxidative stress markers is dependent on vitamin D levels in patients with chronic hepatitis C

OBJECTIVES

Although vitamin D deficiency can change liver injury progression in patients with hepatitis C virus (HCV), the main molecular mechanisms involved are largely unknown. The first aim of this study was to evaluate the association between oxidative stress and hypovitaminosis D in patients with HCV. The second aim was to verify whether oxidative stress is involved in the molecular mechanisms related to liver injury.

METHODS

The study included 147 participants: 89 controls and 58 patients with HCV (vitamin D < 30, n = 32; vitamin D > 30, n = 26).

RESULTS

Patients with HCV and hypovitaminosis D presented significantly higher aminotransferase-to-platelet ratio index (APRI; P = 0.0464) and viral load (P = 0.0426) levels than patients with HCV without hypovitaminosis D. Regarding oxidative stress, HCV patients with hypovitaminosis D had higher advanced oxidation protein products (P = 0.0409), nitric oxide metabolites (P = 0.0206) levels, and oxidative stress index (P = 0.0196), whereas total radical-trapping antioxidant parameter (P = 0.0446) levels were significantly lower than HCV patients without hypovitaminosis D. Vitamin D in patients with HCV showed inverse correlations with levels of iron (r = -0.407, P = 0.0285), ferritin (r = -0.383, P = 0.0444), APRI (r = -0.453, P = 0.0154) and plasma lipid hydroperoxides levels (r = -0.426, P = 0.0189).

CONCLUSION

Vitamin D insufficiency contributes to the inflammatory process and oxidative stress imbalance in patients with HCV. The profile of oxidative stress markers in these patients depends on vitamin D levels, which probably change intracellular signalling pathways and increase inflammation and liver injury.

Vitamin D deficiency in non-alcoholic fatty liver disease: The chicken or the egg?

BACKGROUND & AIMS

Serum vitamin D concentration is reduced in patients with non-alcoholic fatty liver disease (NAFLD). Although the mechanism of vitamin D deficiency in liver disease is not fully understood, a few reports have suggested the beneficial effects of vitamin D supplements. The present study investigated changes in serum 25-hydroxy vitamin D level and clinical parameters after total calorie restriction with vitamin D intake reduction in NAFLD patients.

METHODS

Newly diagnosed NAFLD patients with elevated aminotransferase levels were chosen for a calorie restriction and weight-reduction program. A total of 82 patients received nutritional education from nutritionists every 2 weeks for 2 months. Serum 25-hydroxy vitamin D level, amount of vitamin D intake, and physical activity were thoroughly investigated.

RESULTS

The mean serum 25-hydroxy vitamin D concentration was 13.0 ng/ml. Twenty-nine patients (35.4%) had severe vitamin D deficiency. Patients with a 25-hydroxy vitamin D concentration <10 ng/ml had an increased risk of abdominal obesity (72.4% vs. 47.2%, P = 0.023) and a higher prevalence of metabolic syndrome (69% vs. 42.2%, P = 0.015) compared with patients with 25-hydroxy vitamin D levels >10 ng/ml. Although total energy and vitamin D intake were reduced during the program, serum 25-hydroxy vitamin D levels increased in patients with NAFLD (P < 0.001). Liver enzymes and metabolic parameters also improved, even as vitamin D intake decreased. Serum vitamin D concentration increased with body weight and intrahepatic fat reduction, independent of decreases in vitamin D intake.

CONCLUSIONS

Weight loss per increased serum vitamin D level without vitamin D supplementation and improved metabolic parameters in NAFLD.

Dietary supplements and pediatric non-alcoholic fatty liver disease: Present and the future

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children. High prevalence of pediatric obesity and sedentary lifestyle has augmented the incidence of NAFLD in children. Obesity is associated with an increased risk of NAFLD through various mechanisms such as intensification of insulin resistance and increased levels of inflammatory markers. There is no approved medical intervention for treatment of pediatric NAFLD; the only proven strategy in management of pediatric NAFLD is lifestyle modification. Recently, the effects of nutritional supplements have been examined in the management of pediatric NAFLD. The purpose of this review is to summarize the studies evaluating the effects of nutritional supplements on pediatric NAFLD and explain the future direction in this field.

Effects of High-Dose Vitamin D Supplementation on Metabolic Status and Pregnancy Outcomes in Pregnant Women at Risk for Pre-Eclampsia

This study was designed to assess the beneficial effects of high-dose (cholecalciferol) vitamin D supplementation on metabolic profiles and pregnancy outcomes among pregnant women at risk for pre-eclampsia. This randomized double-blind placebo-controlled clinical trial was performed among 60 pregnant women at risk for pre-eclampsia according to abnormal uterine artery Doppler waveform. Subjects were randomly divided into 2 groups to receive 50 000 IU vitamin D supplements (n=30) or receive placebo (n=30) every 2 weeks from 20 to 32 weeks of gestation. Fasting blood samples were taken at baseline study and 12 weeks after the intervention to quantify relevant variables. Newborn's anthropometric measurements were determined. Pregnant women who received cholecalciferol supplements had significantly increased serum 25-hydroxyvitamin D concentrations (+17.92±2.28 vs. +0.27±3.19 ng/ml, p<0.001) compared with the placebo. The administration of cholecalciferol supplements, compared with the placebo, resulted in significant differences in serum insulin concentrations (+1.08±6.80 vs. +9.57±10.32 μIU/ml, p<0.001), homeostasis model of assessment-insulin resistance (HOMA-IR) (+0.19±1.47 vs. +2.10±2.67, p<0.001), homeostatic model assessment-beta cell function (HOMA-B) (+5.82±29.58 vs. +39.81±38.00, p<0.001) and quantitative insulin sensitivity check index (QUICKI) score (-0.009±0.03 vs. -0.04±0.03, p=0.004). Furthermore, cholecalciferol-supplemented pregnant women had increased HDL-cholesterol concentrations (+2.67 ± 8.83 vs. -3.23±7.76 mg/dl, p=0.008) compared with the placebo. Finally, cholecalciferol supplementation led to a significant rise in plasma total antioxidant capacity (TAC) concentrations (+79.00±136.69 vs. -66.91±176.02 mmol/l, p=0.001) compared with the placebo. Totally, the administration of cholecalciferol supplements among pregnant women at risk for pre-eclampsia for 12 weeks had favorable effects on insulin metabolism parameters, serum HDL-cholesterol, and plasma TAC concentrations.

Endocrine causes of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the industrialized world. The prevalence of NAFLD is increasing, becoming a substantial public health burden. NAFLD includes a broad spectrum of disorders, from simple conditions such as steatosis to severe manifestations such as fibrosis and cirrhosis. The relationship of NAFLD with metabolic alterations such as type 2 diabetes is well described and related to insulin resistance, with NAFLD being recognized as the hepatic manifestation of metabolic syndrome. However, NAFLD may also coincide with endocrine diseases such as polycystic ovary syndrome, hypothyroidism, growth hormone deficiency or hypercortisolism. It is therefore essential to remember, when discovering altered liver enzymes or hepatic steatosis on radiological exams, that endocrine diseases can cause NAFLD. Indeed, the overall prognosis of NAFLD may be modified by treatment of the underlying endocrine pathology. In this review, we will discuss endocrine diseases that can cause NALFD. Underlying pathophysiological mechanisms will be presented and specific treatments will be reviewed.

1,25(OH)2D3 downregulates the Toll-like receptor 4-mediated inflammatory pathway and ameliorates liver injury in diabetic rats

BACKGROUND

Fatty acid deposition in the liver can activate a number of pro-inflammatory signaling pathways such as the Toll-like receptor 4 (TLR4) pathway, which may be important in the pathogenesis of nonalcoholic steatohepatitis. 1,25(OH)2D3 downregulates the expression of TLR4 and may represent a novel treatment strategy for reducing hepatocyte injury. Therefore, in this study, we investigated the protective effects of 1,25(OH)2D3 on diabetic liver injury in vivo.

METHODS

Streptozotocin (STZ)-induced diabetic rats were randomly divided into five groups and treated with low-dose 1,25(OH)2D3 (0.025 μg/kg/day), medium-dose 1,25(OH)2D3 (0.15 μg/kg/day), high-dose 1,25(OH)2D3 (0.3 μg/kg/day), insulin (protamine zinc insulin 16 U/kg/day, subcutaneous injection), or no intervention (the control group). Sixteen weeks later, the rats were killed, and blood samples were obtained to test lipid profiles and hepatic function. The infiltration of inflammatory cells, the level of fibrosis, and the expression levels of TLR4, nuclear factor-kappa B (NF-κB), and tumor necrosis factor-α (TNF-α) in the liver were analyzed. The hepatocytes were treated with vehicle control, LPS (100 ng), high fat [DMEM + FFA (0.1 mM: palmitic acid, oleic acid, 1:2)], LPS + high fat, vehicle + 1,25(OH)2D3 (10(-7) M), LPS + 1,25(OH)2D3, high fat + 1,25(OH)2D3, or LPS + high fat + 1,25(OH)2D3. RNA and protein were extracted to detect the expression of TLR4 and downstream inflammatory factors such as NF-ΚB, TNF-α, and IL-6. Groups of data were compared by single factor variance analysis.

RESULTS

High-dose 1,25(OH)2D3 administration for 16 weeks downregulated the expression of TLR4, NF-κB, and TNF-α in the liver tissue of diabetic rats and attenuated hepatic inflammation and fibrosis, as shown by immunohistochemical staining, hematoxylin and eosin staining, Masson's trichrome staining, reverse transcription polymerase chain reaction (RT-PCR), and western blotting. In vitro, hepatocytes treated with high fat or LPS exhibited significantly increased expression of TLR4, NF-κB, and downstream inflammatory factors (P < 0.05). Intervention with 1,25(OH)2D3 decreased the expression of TLR4, NF-κB, and inflammatory factors (P < 0.05).

CONCLUSIONS

1,25(OH)2D3 exhibited protective effects against diabetes-related liver injury, possibly through downregulation of components of the TLR4 signaling pathway.

Serum vitamin D levels are inversely related with non-alcoholic fatty liver disease independent of visceral obesity in Chinese postmenopausal women

The aim of the present study was to investigate the association between serum vitamin D levels and both visceral adipose and with non-alcoholic fatty liver disease (NAFLD) in Chinese postmenopausal women. Four hundred and fifty-one postmenopausal women between 45 and 74 years of age (mean (± SD) age 57.3 ± 4.6 years) were enrolled in the study. All subjects participated in the Shanghai Obesity Study between June and August 2011 and underwent abdominal magnetic resonance imaging and an abdominal ultrasonography. Patients with a visceral fat area (VFA) ≥ 80 cm(2) were classified as abdominally obese. Serum 25-hydroxyvitamin D3 (25(OH)D3 ) levels were measured with an electrochemiluminescence immunoassay. The prevalence of NAFLD in the study population was 34.8% (n = 157). Women with abdominal obesity had significantly lower serum 25(OH)D3 levels than those without abdominal obesity (median (interquartile range) 11.23 (8.64-14.12) vs 12.56 (9.41-15.98) ng/mL, respectively; P < 0.01). Regardless of abdominal obesity status, serum 25(OH)D3 levels in patients with NAFLD were lower than those without non-NAFLD (11.14 (8.63-13.81) vs 12.92 (9.48-16.37) ng/mL (P < 0.05) for those without abdominal obesity; 10.86 (8.61-13.56) vs 11.55 (8.82-16.38) ng/mL (P < 0.05) for those with abdominal obesity). Partial correlation analyses demonstrated a negative correlation between serum 25(OH)D3 levels and VFA (P < 0.05). Logistic regression analysis revealed that high serum 25(OH)D3 levels were a protective factor against NAFLD after adjusting for risk factors such as VFA. In conclusion, independent of visceral obesity, vitamin D is inversely correlated with NAFLD in Chinese postmenopausal women.

A role of 1,25(OH)2D3 supplementation in rats with nonalcoholic steatohepatitis induced by choline-deficient diet

BACKGROUND AND AIMS

It has been reported that 1,25(OH)2D3 (1,25-VD3) ameliorates the progression of nonalcoholic steatohepatitis (NASH). However, it is unclear whether 1,25-VD3 plays a role in NASH induced by a choline-deficient (CD) diet. In this study, we investigated the roles of 1,25-VD3 in the development and progression of NASH in rats induced by a CD diet.

METHODS AND RESULTS

Wistar rats with NASH induced by a CD diet were subjected to intraperitoneal injections of 1, 5, or 10 μg/kg of 1,25-VD3 twice weekly for 12 weeks. The administration of 1,25-VD3 decreased free fatty acids (FFAs), triglycerides (TGs), thiobarbituric acid-reactive substances (TBARS), the number of apoptotic cells, and the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) in the liver, and it improved liver histology, but it did not change the total antioxidant capacity (TAOC) in the liver. Interestingly, the level of CK18-M30 was decreased in the liver of model animals. Treatment with 1,25-VD3 may restrain the downregulation of CK18-M30 in the liver and its release into the bloodstream, thus decreasing the level of serum CK18-M30. 1,25-VD3 supplementation elevated the serum level of 25(OH)D3 and the expression of VDR in the liver. The dose-effect relationship of 1,25-VD3 indicated that 1,25-VD3 slows down the development and progression of NASH induced by a CD diet, but higher doses of 1,25-VD3 may lead to adverse effects.

CONCLUSION

The results suggest the presence of both antagonistic and adverse dose-dependent effects of the long-term supplementation of 1,25-VD3 on NASH induced by a CD diet.

Can skin exposure to sunlight prevent liver inflammation?

Liver inflammation contributes towards the pathology of non-alcoholic fatty liver disease (NAFLD). Here we discuss how skin exposure to sunlight may suppress liver inflammation and the severity of NAFLD. Following exposure to sunlight-derived ultraviolet radiation (UVR), the skin releases anti-inflammatory mediators such as vitamin D and nitric oxide. Animal modeling studies suggest that exposure to UVR can prevent the development of NAFLD. Association studies also support a negative link between circulating 25-hydroxyvitamin D and NAFLD incidence or severity. Clinical trials are in their infancy and are yet to demonstrate a clear beneficial effect of vitamin D supplementation. There are a number of potentially interdependent mechanisms whereby vitamin D could dampen liver inflammation, by inhibiting hepatocyte apoptosis and liver fibrosis, modulating the gut microbiome and through altered production and transport of bile acids. While there has been a focus on vitamin D, other mediators induced by sun exposure, such as nitric oxide may also play important roles in curtailing liver inflammation.

Vitamin D: A new player in non-alcoholic fatty liver disease?

Vitamin D through its active form 1a-25-dihydroxyvtamin D [1,25(OH)₂D] is a secosteroid hormone that plays a key role in mineral metabolism. Recent years have witnessed a significant scientific interest on vitamin D and expanded its actions to include immune modulation, cell differentiation and proliferation and inflammation regulation. As our understanding of the many functions of vitamin D has grown, the presence of vitamin D deficiency has become one of the most prevalent micronutrient deficiencies worldwide. Concomitantly, non-alcoholic fatty liver disease (NAFLD) has become the most common form of chronic liver disease in western countries. NAFLD and vitamin D deficiency often coexist and epidemiologic evidence has shown that both of these conditions share several cardiometabolic risk factors. In this article we provide an overview of the epidemiology and pathophysiology linking NAFLD and vitamin D deficiency, as well as the available evidence on the clinical utility of vitamin D supplementation in NAFLD.