A recent clinical trial found that vitamin D supplementation reduced liver fat infiltration among patients with non-alcoholic fatty liver disease.
Non-alcoholic fatty liver disease (NAFLD) is the accumulation of fat in the liver unrelated to excessive alcohol consumption. The cause of NALFD is multifactorial, resulting from both genetic and environmental factors.
NAFLD is common, with a prevalence of 25-45% in Western countries. The majority of individuals with NAFLD do not experience signs, symptoms or complications. However, in some, NAFLD can progress to liver cancer or liver failure.
Researchers became interested in the role that vitamin D plays in NAFLD due to the presence of vitamin D receptors in the liver. Furthermore, research shows that vitamin D deficiency is linked to greater severity of NAFLD.
Recently, researchers aimed to determine the effects of vitamin D supplementation in NAFLD patients who were considered vitamin D deficient (< 20 ng/ml). A total of 40 patients from an outpatient liver clinic fit the criteria, and thus, were included in the study. The researchers quantified the severity of NAFLD by measuring controlled attenuation parameter (CAP), a marker used to assess liver fat content. Higher values signify greater liver fat content.
The study lasted six months. During the first week, all patients were instructed to supplement with 20,000 IU vitamin D3 daily. This dosage was followed by 20,000 IU vitamin D taken on a weekly basis for the remainder of the six months. The researchers performed follow ups after four weeks, and at three and six months. Here is what they found:
- Average vitamin D status at baseline was 11.8 ng/ml.
- Following six months of supplementation, average vitamin D levels significantly increased to 34.7 ng/ml (p < 0.0001).
- CAP decreased significantly from baseline (330 vs 307 dB/m) during supplementation (P = 0.007).
- An average CAP reduction relative to baseline was observed at four weeks, three and six months.
The researchers concluded,
“The degree of hepatic steatosis significantly improved after only four weeks of vitamin D replacement therapy in the absence of concomitant weight loss in this six-month supplementation study. Hepatic steatosis, as assessed by CAP, is a dynamic process, which appears to be modulated by interventions such as vitamin D substitution.”
The study suggests that patients who are affected with NAFLD should supplement with vitamin D to reduce liver fat content. As a clinical trial, the study design was relatively strong. However, the study lacked a control group, leaving room for placebo effect to possibly skew the results. The researchers called for controlled trials to further assess the possibility of managing NAFLD with vitamin D.
Tovey, A. Recent clinical trial discovers vitamin D supplementation may improve non-alcoholic fatty liver disease. The Vitamin D Council Blog & Newsletter, 2016.
Ifigeneia P, Lammert F & Stokes C. Effect of Short-Term Vitamin D Correction on Hepatic Steatosis as Quantified by Controlled Attenuation Parameter (CAP). Journal of Gastrointestinal Liver Disease, 2016.