Serum, liver and bile sitosterol and sitostanol in obese patients with and without NAFLD

The Effects of Olive Oil Consumption on Biochemical Parameters and Body Mass Index of People with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disorder, is closely associated with insulin resistance, obesity, and metabolic syndromes. A body of research has proposed that olive oil, a basic component of the Mediterranean diet with antioxidant and anti-inflammatory properties, may alleviate metabolic disturbances and retard the progression of NAFLD. We conducted a systematic review and meta-analysis to assess the effectiveness of olive oil intake in people with NAFLD. We systematically searched the major electronic databases (PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials), as well as grey literature sources, to identify randomized controlled trials (RCTs) investigating the effects of olive oil consumption on biochemical and anthropometric parameters of individuals with NAFLD. The quality of the studies was evaluated using the risk-of-bias tool 2.0 (RoB 2). The mean difference (MD) and the 95% confidence interval (CI) were calculated using fixed-effects and random-effects models. Seven RCTs involving 515 subjects were included in the analysis. In the random-effects model, no statistically significant differences were identified with respect to alanine transaminase (MD = -1.83 IU/L, 95% CI: -5.85, 2.19 IU/L, p = 0.37, I2 = 69%) and aspartate transaminase (MD = -1.65 IU/L, 95% CI: -4.48, 1.17 IU/L, p = 0.25, I2 = 72%) levels or waist circumference values (MD = -0.23 cm, 95% CI: -1.23, 0.76 cm, p = 0.65, I2 = 0%). However, a significant effect on body mass index was observed (MD = -0.57 kg/m2, 95% CI: -1.08, -0.06 kg/m2, p = 0.03, I2 = 51%) for subjects who received olive oil compared to those who received an alternative diet or placebo. The findings of the present meta-analysis suggest a modestly positive impact of olive oil intake on body weight in people with NAFLD.

The Role of Phytosterols in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease is now recognized as the most common cause of chronic liver disease with an increasing prevalence in both adults and children. Although the symptoms are absent or poorly expressed in most cases, some patients may progress to end-stage liver disease. The pathogenesis of NAFLD is known to be multifactorial. Current therapeutic recommendations focus on lifestyle changes in order to reduce the incidence of risk factors and drugs targeting major molecular pathways potentially involved in the development of this disease. Given that a pharmacological treatment, completely safe and effective, is not currently known in recent years more research has been done on the effects that some bio-active natural compounds, derived from plants, have in preventing the onset and progression of NAFLD. Numerous studies, in animals and humans, have shown that phytosterols (PSs) play an important role in this pathology. Phytosterols are natural products that are found naturally in plant. More than 250 phytosterols have been identified, but the most common in the diet are stigmasterol, β-sitosterol, and campesterol. Consumption of dietary PSs can reduce serum cholesterol levels. Due to these properties, most studies have focused on their action on lipid metabolism and the evolution of NAFLD. PSs may reduce steatosis, cytotoxicity oxidative stress, inflammation, and apoptosis. The purpose of this review is to provide an overview of the importance of dietary phytosterols, which are a window of opportunity in the therapeutic management of NAFLD.

Therapeutic Properties and Use of Extra Virgin Olive Oil in Clinical Nutrition: A Narrative Review and Literature Update

Extra virgin olive oil (EVOO) is a cornerstone of the Mediterranean diet (MedD). In this narrative review, we synthesize and illustrate the various characteristics and clinical applications of EVOO and its components—such as oleic acid, hydroxytyrosol, and oleuropein—in the field of clinical nutrition and dietetics. The evidence is split into diet therapy, oleic acid-based enteral nutrition formulations and oral supplementation formulations, oleic acid-based parenteral nutrition, and nutraceutical supplementation of minor components of EVOO. EVOO has diverse beneficial health properties, and current evidence supports the use of whole EVOO in diet therapy and the supplementation of its minor components to improve cardiovascular health, lipoprotein metabolism, and diabetes mellitus in clinical nutrition. Nevertheless, more intervention studies in humans are needed to chisel specific recommendations for its therapeutic use through different formulations in other specific diseases and clinical populations.

Plant Sterol Ester of α-Linolenic Acid Attenuates Nonalcoholic Fatty Liver Disease by Rescuing the Adaption to Endoplasmic Reticulum Stress and Enhancing Mitochondrial Biogenesis

Nonalcoholic fatty liver disease (NAFLD) is becoming more common in the world and is presenting a great challenge concerning prevention and treatment. Plant sterol ester of α-linolenic acid (PS-ALA) has a potential benefit to NAFLD. To examine the effect of PS-ALA on NAFLD, C57BL/6J mice were given a control diet, high fat and high cholesterol diet (HFD), and HFD plus 2% PS, 1.3% ALA, or 3.3% PS-ALA for 16 weeks. Our results showed that PS-ALA treatment suppressed hepatic steatosis, ameliorated lipid disorder, attenuated inflammatory response, and inhibited oxidative stress. In the molecular level, PS-ALA downregulated high transcriptional and translational levels of endoplasmic reticulum (ER) stress markers (Grp78 and Chop) leading to decreased protein expression of transcription factor and key enzymes involved in de novo lipogenesis (Srebp-1c and Fas) and cholesterol synthesis (Srebp-2 and Hmgcr). In parallel, PS-ALA blocked Nlrp3 activation and reduced release of IL-1β and IL-18 via inhibiting ER stress-induced sensitization of unfolded protein response sensors (Ire1α and Xbp1s). Finally, PS-ALA improved HFD-induced mitochondrial damage and fatty acid accumulation as exhibited by higher protein and mRNA expression of key genes administering mitochondrial biogenesis (Pgc-1α, Nrf1, and Tfam) and fatty acid β-oxidation (Pparα and Cpt1a). In conclusion, our study originally demonstrated that PS-ALA rescued ER stress, enhanced mitochondrial biogenesis, and thus ameliorated NAFLD.

Comment on Tauriainen et al.: Serum, liver and bile sitosterol and sitostanol in obese patients with and without NAFLD

This short article provides a comment on the recent article by Tauriainen et al. [Bioscience Reports (2018) 38, BSR20171274 https://doi.org/10.1042/BSR20171274].