The Effects of Vitamin E, Silymarin and Carnitine on the Metabolic Abnormalities Associated with Nonalcoholic Liver Disease

Vitamin E for people with non-alcoholic fatty liver disease

RATIONALE

Non-alcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD), is the most common liver disease worldwide, affecting an estimated 3 in 10 people. The available treatment is far from optimal. Diet and lifestyle changes to promote weight loss and weight loss maintenance are the basic management of NAFLD, but these are difficult to achieve and maintain. Vitamin E has shown beneficial effects on oxidative stress, which plays a major role in the pathogenesis of NAFLD. However, there is uncertainty about the effects of vitamin E for people with NAFLD.

OBJECTIVES

To evaluate the beneficial and harmful effects of vitamin E alone, or vitamin E in combination with other vitamins or minerals, versus placebo or no intervention in people with NAFLD.

SEARCH METHODS

We used recommended Cochrane search methods. The latest search was performed on 2 February 2024.

ELIGIBILITY CRITERIA

We included randomised clinical trials that compared vitamin E alone, or in combination with other vitamins or minerals, at any dose, duration, and route of administration, versus placebo or no intervention, in people with NAFLD of any age, sex, or ethnic origin. We included participants with imaging techniques or histology-proven NAFLD and minimal alcohol intake, and participants with steatohepatitis who had liver biopsies.

OUTCOMES

Our critical outcomes were all-cause mortality, liver-related mortality, and serious adverse events. Our important outcomes were liver-related morbidity, health-related quality of life, non-serious adverse events, biochemical response, and imaging assessment of the degree of fatty liver.

RISK OF BIAS

We used Cochrane's RoB 2 tool to assess risk of bias for each of the predefined outcomes.

SYNTHESIS METHODS

We used standard Cochrane methods. We used GRADE to assess the certainty of evidence.

INCLUDED STUDIES

We included 16 randomised clinical trials involving 1066 paediatric and adult participants with NAFLD. Experimental groups received vitamin E alone (14 trials) or vitamin E in combination with vitamin C (2 trials). Control groups received placebo in 13 trials and no intervention in three trials. Daily dosages of oral vitamin E ranged from 298 international units (IU) to 1000 IU. Co-interventions were lifestyle and low-calorie diet interventions in 13 trials, ursodeoxycholic acid in one trial, unchanged diet and physical activity in one trial, and baseline treatments for type 2 diabetes in one trial. Nine trials had more than two intervention groups, but we used only the groups in which vitamin E alone or vitamin E in combination with vitamin C were compared with placebo or no intervention. In total, 7.9% (84/1066) of participants dropped out. Follow-up ranged from 2 months to 24 months.

SYNTHESIS OF RESULTS

Vitamin E versus placebo or no intervention The effects of vitamin E versus placebo or no intervention on all-cause mortality (risk ratio (RR) 3.45, 95% confidence interval (CI) 0.57 to 20.86; 3 trials, 351 participants; very low certainty evidence) and serious adverse events (RR 1.91, 95% CI 0.30 to 12.01; 2 trials, 283 participants; very low certainty evidence) are very uncertain. There were no data on liver-related mortality or liver-related morbidity. The effects of vitamin E versus placebo or no intervention on physical health-related quality of life (mean difference (MD) 0.74, 95% CI -0.52 to 2.01; 2 trials, 251 participants; higher scores indicate better quality of life; very low certainty evidence); psychosocial health-related quality of life (MD -0.57, 95% CI -4.11 to 2.97; 2 trials, 251 participants; higher scores indicate better quality of life; very low certainty evidence); and non-serious adverse events (RR 0.86, 95% CI 0.64 to 1.17; 2 trials, 283 participants; very low certainty evidence) are also very uncertain. There were no data on proportion of participants without a decrease in liver enzymes. Vitamin E likely slightly reduces serum alanine transaminase (ALT) (MD -9.29, 95% CI -13.69 to -4.89; 11 trials, 708 participants; moderate certainty evidence) and aspartate aminotransferase (AST) (MD -4.90, 95% CI -7.24 to -2.57; 11 trials, 695 participants; moderate certainty evidence) levels compared with placebo or no intervention. Vitamin E may slightly reduce serum alkaline phosphatase (ALP) levels (MD -5.21, 95% CI -9.88 to -0.54; 5 trials, 416 participants; very low certainty evidence), but the evidence is very uncertain. Vitamin E plus vitamin C versus placebo There were no data on all-cause mortality, liver-related mortality, serious adverse events, liver-related morbidity, health-related quality of life, and non-serious adverse events. The effects of vitamin E plus vitamin C on reducing serum ALT (MD -0.50, 95% CI -4.58 to 3.58; 2 trials, 133 participants; very low certainty evidence), AST (MD 0.09, 95% CI -3.39 to 3.57; 1 trial, 88 participants; very low certainty evidence), and gamma-glutamyl transferase (GGT) levels (MD 1.58, 95% CI -3.22 to 6.38; 1 trial, 88 participants; very low certainty evidence) are very uncertain. We identified three ongoing trials, and six trials are awaiting classification.

AUTHORS' CONCLUSIONS

Given the very low certainty evidence, we do not know if long-term treatment (18 months to 24 months) with vitamin E administered alone affects all-cause mortality, serious adverse events, quality of life, or non-serious adverse events in people with NAFLD when compared with placebo or no intervention. We found no data on liver-related mortality, liver-related morbidity, or proportion of participants without a decrease in liver enzymes. Vitamin E likely reduces ALT and AST slightly when compared with placebo, but whether this has any impact on the clinical course in people with NAFLD is unknown. The trials on vitamin E plus vitamin C did not report on all-cause mortality, liver-related mortality, serious adverse events, liver-related morbidity, health-related quality of life, or non-serious adverse events. Given the very low certainty evidence, we do not know the effects of vitamin E plus vitamin C on liver enzymes in people with NAFLD when compared with placebo.

FUNDING

Three trials disclosed no external funding. Five trials were industry funded. Five trials were funded by organisations with no vested interests. Three trials did not provide any information on clinical trial support or sponsorship.

REGISTRATION

Protocol: doi.org/10.1002/14651858.CD015033.

Natural compounds proposed for the management of non-alcoholic fatty liver disease

Although non-alcoholic fatty liver disease (NAFLD) presents as an intricate condition characterized by a growing prevalence, the often-recommended lifestyle interventions mostly lack high-level evidence of efficacy and there are currently no effective drugs proposed for this indication. The present review delves into NAFLD pathology, its diverse underlying physiopathological mechanisms and the available in vitro, in vivo, and clinical evidence regarding the use of natural compounds for its management, through three pivotal targets (oxidative stress, cellular inflammation, and insulin resistance). The promising perspectives that natural compounds offer for NAFLD management underscore the need for additional clinical and lifestyle intervention trials. Encouraging further research will contribute to establishing more robust evidence and practical recommendations tailored to patients with varying NAFLD grades.

Preventive and Therapeutic Effects of Silybum marianum Seed Extract Rich in Silydianin and Silychristin in a Rat Model of Metabolic Syndrome

Metabolic syndrome (MetS) has become an increasing global health problem, which leads to cardiovascular diseases and type 2 diabetes. Silybum marianum extracts have been reported to possess several biological activities. In this study, an ethyl acetate extract prepared from S. marianum seeds of the Iraqi Kurdistan region was analyzed to identify its chemical constituents. Subsequently, its potential for the prevention and treatment of MetS was studied in a rat model induced by a high-fat/high-fructose diet (HFD/F). Silydianin and silychristin were the most abundant flavonolignan constituents (39.4%) identified in the S. marianum extract (SMEE). HFD/F-induced rats treated with SMEE exhibited preventive effects including reduced serum triglyceride levels (TG), decreased glucose levels in an oral glucose tolerance test (p < 0.001), attenuated weight gain, and reduced blood pressure compared to the untreated control group. Therapeutic application of SMEE after inducing MetS led to lowering of TG (p < 0.001) and glucose levels, in addition to reducing weight gain and normalizing blood pressure (p < 0.005). Thus, S. marianum extract rich in silydianin and silychristin may be useful for preventing and attenuating MetS, and further research and clinical trials are warranted.

Mitochondrial carnitine palmitoyltransferase-II dysfunction: A possible novel mechanism for nonalcoholic fatty liver disease in hepatocarcinogenesis

Nonalcoholic fatty liver disease (NAFLD) or metabolic-associated fatty liver disease has been characterized by the lipid accumulation with injury of hepatocytes and has become one of the most common chronic liver diseases in the world. The complex mechanisms of NAFLD formation are still under identification. Carnitine palmitoyltransferase-II (CPT-II) on inner mitochondrial membrane (IMM) regulates long chain fatty acid β-oxidation, and its abnormality has had more and more attention paid to it by basic and clinical research in NAFLD. The sequences of its peptide chain and DNA nucleotides have been identified, and the catalytic activity of CPT-II is affected on its gene mutations, deficiency, enzymatic thermal instability, circulating carnitine level and so on. Recently, the CPT-II dysfunction has been discovered in models of liver lipid accumulation. Meanwhile, the malignant transformation of hepatocyte-related CD44⁺ stem T cell activation, high levels of tumor-related biomarkers (AFP, GPC3) and abnormal activation of Wnt3a expression as a key signal molecule of the Wnt/β-catenin pathway run parallel to the alterations of hepatocyte pathology. This review focuses on some of the progress of CPT-II inactivity on IMM with liver fatty accumulation as a possible novel pathogenesis for NAFLD in hepatocarcinogenesis.

Lessons on Drug Development: A Literature Review of Challenges Faced in Nonalcoholic Fatty Liver Disease (NAFLD) Clinical Trials

NAFLD is the most common chronic liver disease worldwide, occurring in both obese and lean patients. It can lead to life-threatening liver diseases and nonhepatic complications, such as cirrhosis and cardiovascular diseases, that burden public health and the health care system. Current care is weight loss through diet and exercise, which is a challenging goal to achieve. However, there are no FDA-approved pharmacotherapies for NAFLD. This review thoroughly examines the clinical trial findings from 22 drugs (Phase 2 and above) and evaluates the future direction that trials should take for further drug development. These trialed drugs can broadly be categorized into five groups-hypoglycemic, lipid-lowering, bile-pathway, anti-inflammatory, and others, which include nutraceuticals. The multitude of challenges faced in these yet-to-be-approved NAFLD drug trials provided insight into a few areas of improvement worth considering. These include drug repurposing, combinations, noninvasive outcomes, standardization, adverse event alleviation, and the need for precision medicine with more extensive consideration of NAFLD heterogenicity in drug trials. Understandably, every evolution of the drug development landscape lies with its own set of challenges. However, this paper believes in the importance of always learning from lessons of the past, with each potential improvement pushing clinical trials an additional step forward toward discovering appropriate drugs for effective NAFLD management.

Nutritional supplementation for nonalcohol-related fatty liver disease: a network meta-analysis

BACKGROUND

The prevalence of non-alcohol-related fatty liver disease (NAFLD) varies between 19% and 33% in different populations. NAFLD decreases life expectancy and increases risks of liver cirrhosis, hepatocellular carcinoma, and the requirement for liver transplantation. Uncertainty surrounds relative benefits and harms of various nutritional supplements in NAFLD. Currently no nutritional supplement is recommended for people with NAFLD.

OBJECTIVES

• To assess the benefits and harms of different nutritional supplements for treatment of NAFLD through a network meta-analysis • To generate rankings of different nutritional supplements according to their safety and efficacy SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Science Citation Index Expanded, Conference Proceedings Citation Index-Science, the World Health Organization International Clinical Trials Registry Platform, and trials registers until February 2021 to identify randomised clinical trials in people with NAFLD.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or status) for people with NAFLD, irrespective of method of diagnosis, age and diabetic status of participants, or presence of non-alcoholic steatohepatitis (NASH). We excluded randomised clinical trials in which participants had previously undergone liver transplantation.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS using Bayesian methods whenever possible and calculated differences in treatments using hazard ratios (HRs), odds ratios (ORs), and rate ratios with 95% credible intervals (CrIs) based on an available-case analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance.

MAIN RESULTS

We included in the review a total of 202 randomised clinical trials (14,200 participants). Nineteen trials were at low risk of bias. A total of 32 different interventions were compared in these trials. A total of 115 trials (7732 participants) were included in one or more comparisons. The remaining trials did not report any of the outcomes of interest for this review. Follow-up ranged from 1 month to 28 months. The follow-up period in trials that reported clinical outcomes was 2 months to 28 months. During this follow-up period, clinical events related to NAFLD such as mortality, liver cirrhosis, liver decompensation, liver transplantation, hepatocellular carcinoma, and liver-related mortality were sparse. We did not calculate effect estimates for mortality because of sparse data (zero events for at least one of the groups in the trial). None of the trials reported that they measured overall health-related quality of life using a validated scale. The evidence is very uncertain about effects of interventions on serious adverse events (number of people or number of events). We are very uncertain about effects on adverse events of most of the supplements that we investigated, as the evidence is of very low certainty. However, people taking PUFA (polyunsaturated fatty acid) may be more likely to experience an adverse event than those not receiving an active intervention (network meta-analysis results: OR 4.44, 95% CrI 2.40 to 8.48; low-certainty evidence; 4 trials, 203 participants; direct evidence: OR 4.43, 95% CrI 2.43 to 8.42). People who take other supplements (a category that includes nutritional supplements other than vitamins, fatty acids, phospholipids, and antioxidants) had higher numbers of adverse events than those not receiving an active intervention (network meta-analysis: rate ratio 1.73, 95% CrI 1.26 to 2.41; 6 trials, 291 participants; direct evidence: rate ratio 1.72, 95% CrI 1.25 to 2.40; low-certainty evidence). Data were sparse (zero events in all groups in the trial) for liver transplantation, liver decompensation, and hepatocellular carcinoma. So, we did not perform formal analysis for these outcomes. The evidence is very uncertain about effects of other antioxidants (antioxidants other than vitamins) compared to no active intervention on liver cirrhosis (HR 1.68, 95% CrI 0.23 to 15.10; 1 trial, 99 participants; very low-certainty evidence). The evidence is very uncertain about effects of interventions in any of the remaining comparisons, or data were sparse (with zero events in at least one of the groups), precluding formal calculations of effect estimates. Data were probably because of the very short follow-up period (2 months to 28 months). It takes follow-up of 8 to 28 years to detect differences in mortality between people with NAFLD and the general population. Therefore, it is unlikely that differences in clinical outcomes are noted in trials providing less than 5 to 10 years of follow-up.

AUTHORS' CONCLUSIONS

The evidence indicates considerable uncertainty about effects of nutritional supplementation compared to no additional intervention on all clinical outcomes for people with non-alcohol-related fatty liver disease. Accordingly, high-quality randomised comparative clinical trials with adequate follow-up are needed. We propose registry-based randomised clinical trials or cohort multiple randomised clinical trials (study design in which multiple interventions are trialed within large longitudinal cohorts of patients to gain efficiencies and align trials more closely to standard clinical practice) comparing interventions such as vitamin E, prebiotics/probiotics/synbiotics, PUFAs, and no nutritional supplementation. The reason for the choice of interventions is the impact of these interventions on indirect outcomes, which may translate to clinical benefit. Outcomes in such trials should be mortality, health-related quality of life, decompensated liver cirrhosis, liver transplantation, and resource utilisation measures including costs of intervention and decreased healthcare utilisation after minimum follow-up of 8 years (to find meaningful differences in clinically important outcomes).