Reference
Ebrahimpour-Koujan S, Sohrabpour AA, Giovannucci E, Vatannejad A, Esmaillzadeh A. Effects of vitamin D supplementation on liver fibrogenic factors, vitamin D receptor and liver fibrogenic microRNAs in metabolic dysfunction-associated steatotic liver disease (MASLD) patients: an exploratory randomized clinical trial. Nutr J. 2024;23(1):24.
Study Objective
The objective of this study was to determine if vitamin D supplementation impacts serum levels of vitamin D receptor (VDR), fibrogenic factors, and fibrogenic microRNAs in patients with metabolic dysfunction–associated steatotic liver disease (MASLD).
Key Takeaway
Vitamin D supplementation may play a role in reducing fibrogenic factors and fibrosis-related microRNAs that contribute to the development of MASLD.
Design
Parallel, randomized, double-blind, placebo-controlled clinical trial
Participants
Forty-two subjects completed the clinical trial, with 20 subjects in the placebo group and 22 in the vitamin D group. All subjects had MASLD with nonalcoholic steatohepatitis (NASH) and were aged 20 to 60 years.
Investigators used block randomization method to randomly assign participants to intervention and placebo groups. Each block assignment consisted of a pair of participants sharing the same sex and similar body mass index (BMI).
Exclusion criteria included the following: smokers; those consuming alcohol; pregnant or lactating women or those who planned to get pregnant during the next 12 weeks; and those taking vitamin D supplements and antioxidants during the last 12 weeks.
Intervention
Investigators instructed subjects in the intervention group to take 4,000 IU of vitamin D, in the form of tablets with food, daily for 12 weeks. They advised subjects in the placebo group to take lactose-containing placebo tablets during the same timeframe.
Study Parameters Assessed
Investigators collected anthropometric measurements at the study’s baseline; these included weight, height, waist circumference, and BMI calculations. They also collected socioeconomic status, medication use, demographic characteristics, and medical history at baseline also.
Investigators collected the following biochemical and molecular measurements at baseline and at the end of the 12-week study: serum 25 hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), serum VDR, laminin, collagen type IV, hyaluronic acid, microRNA-122 (miR-122), miR-21, miR-34a, liver enzymes, lipid profile, and glycemic indices.
Primary Outcome
The primary outcomes included changes in of the following:
- Serum VDR
- Laminin
- Collagen type IV
- Hyaluronic acid
- MicroRNAs MiR-122, MiR-21, and MiR-34a
The secondary outcomes of the study included changes in the following:
- Liver enzymes
- Lipid profile
- Glycemic indices
Key Findings
At the 12-week point, there was a clinically significant increase in serum 25(OH)D (changes from baseline in vitamin D group: 15.2 ng/mL vs –3.9 ng/mL in placebo group, P<0.001) and in serum VDR (4.1 ng/mL vs –2.8 ng/mL, P=0.008).
Following vitamin D supplementation, there was a significant decrease in serum laminin concentrations (changes from baseline in vitamin D group: –10.6 ng/mL vs 4.9 ng/mL in placebo group, P=0.01) and in hyaluronic acid (–28.7 ng/mL vs –3.5 ng/mL, P=0.04) compared to placebo.
Serum levels of collagen type IV were not significantly different between the 2 groups at the end point (–26.5 ng/mL vs –8.5 ng/mL, P=0.09).
There was significantly lower miR-21 gene expression compared to the placebo group at week 12 (changes from baseline in vitamin D group: 0.16 relative fold change [RFC] vs 1.49 RFC in placebo group, P=0.01). MiR-122 gene expression significantly decreased following vitamin D supplementation (–0.77 RFC vs 0.93 RFC, P<0.001) compared with placebo.
Gene expression of MiR-34a was not significantly different between the 2 groups following vitamin D supplementation (0.05 RFC vs 0.05 RFC, P=0.22).
Supplementation with vitamin D also resulted in a clinically significant increase in serum high-density lipoprotein cholesterol (HDL-C) concentrations (3.9 mg/dL vs –2.0 mg/dL, P<0.001) compared to placebo. There were reductions in serum levels of alanine transaminase (ALT; changes from baseline in vitamin D group: –11.8 mg/dL vs 5.9 mg/dL in placebo group, P<0.001), aspartate transaminase (AST; –4.3 mg/dL vs 1.2 mg/dL, P=0.001), fasting blood glucose (–5.2 mg/dL vs 6.9 mg/dL, P<0.001), low-density lipoprotein cholesterol (LDL-C) concentrations (–9.0 mg/dL vs 5.7 mg/dL, P=0.01), and total cholesterol (–10.5 mg/dL vs 10.0 mg/dL, P=0.03) compared with placebo.
Transparency
This study was funded by Tehran University of Medical Sciences.
Practice Implications & Limitations
To the best of their knowledge, the authors report that this is the first study that has investigated the effectiveness of vitamin D supplementation on liver fibrogenic factors and liver fibrosis–related microRNAs in MASLD patients.
It is well-known that vitamin D plays an important role in affecting the biological activity in the skeleton, acting as an anti-inflammatory agent, regulating cell differentiation and apoptosis, impacting immune-system maturation, and reducing mortality risk in cancer, cardiovascular disease, and immunological diseases.1
MASLD, formerly known as nonalcoholic fatty liver disease (NAFLD), is a chronic, progressive condition affecting about 38% of the global population and is strongly associated with features of metabolic syndrome, including type 2 diabetes mellitus.2 In 2022, the World Health Organization reported that obesity and being overweight were strong independent risk factors for MASLD.3
Progression of steatosis, as part of the disease process, can lead to liver cirrhosis, liver failure, and hepatocellular carcinoma. Implementing healthy lifestyle habits through nutrition and exercise plays an important role in addressing this condition. This study suggests that vitamin D supplementation may also play a role in improving this condition.
Having elevated lipids, especially triglycerides and LDL, has been associated with increased risk of MASLD. Glucose dysregulation in the form of prediabetes and type-2 diabetes has also been associated with an increased risk of MASLD. Over the 12-week study period, vitamin D supplementation decreased LDL levels, increased HDL levels, and decreased serum concentrations of fasting glucose.
MASLD, formerly known as nonalcoholic fatty liver disease (NAFLD), is a chronic, progressive condition affecting about 38% of the global population and is strongly associated with features of the metabolic syndrome, including type 2 diabetes mellitus.
Although vitamin D has been shown to modulate gene expression involving insulin homeostasis, end-point results showed no influence on the serum concentration of insulin and homeostatic model assessment for insulin resistance (HOMA-IR). It remains to be investigated whether an improved insulin response would have been observed if vitamin D were dosed over a longer period.
The reduced levels of the fibrogenic factors, laminin, and hyaluronic acid displayed in the study results suggest that vitamin D impacted the TGF-β/SMAD (transforming growth factor beta/“small worm phenotype” mothers again decapentaplegic) signaling pathway in hepatic stellate cells (HSCs). This has also been observed in animal studies.
Limitations of this study certainly include the small sample size. The authors shared that they did not use liver histopathology for the evaluation of NASH, which is considered the gold-standard method. Imaging evaluation was used instead as a noninvasive method.
The most important signaling pathway in the hepatic stellate cells that contributes to liver fibrosis is the TGF-β/SMAD signaling pathway.4 Unfortunately, the authors were unable to measure the gene expression of TGF-β due to lack of funding. Funding limitations also prevented the measurement of other fibrogenic factors. Some studies have shown that vitamin D decreases the production and activation of other fibrogenic factors, including plasminogen activator inhibitor-1.5 The authors also report that the lack of imaging re-evaluation with liver fibroscan at the 12-week end point was another limitation. Lastly, the authors do not specify if the intervention group received vitamin D2 or vitamin D3 in supplement form.
Vitamin D supplementation should be considered in patients with MASLD based on the findings of this study. Vitamin D is a relatively safe supplement that can have a favorable impact on metabolic factors impacting MASLD and other health conditions as well.
Conflict of Interest Disclosure
The author disclosed no conflict of interest.
