Relationship between Diet and Non-alcoholic Fatty Liver Disease: A Review Article

Abstract

Background: Diet plays a key role in the development of non-alcoholic fatty liver disease (NAFLD). The aim of this study was to review systematically observational studies available regarding the relationship between food intakes and NAFLD.

Methods: We searched Scopus, PubMed, and Cochrane Library databases to identify English observational studies on food groups, dietary patterns, and NAFLD. Cross-sectional, case-control and cohort studies were selected and then duplication, topic, type of study, study population, variables examined and quality of data reporting of the articles were evaluated.

Results: We identified 2128 studies in the initial search, of which 33 were reviewed in full text and 7 articles were included in this systematic review. Intakes of red meat, fats, and sweets were high whereas consumption of whole grains, fruits and vegetables were less in NAFLD patients. Moreover, there was a positive association between the Western dietary pattern and the risk of NAFLD, while adherence to the Mediterranean diet was significantly associated with the severity of hepatic steatosis.

Conclusion: Generally, different food group intakes and dietary patterns are associated with the progression of NAFLD and its risk factors. Because of the many limitations of available studies reviewed on this topic, more prospective studies are suggested.

Keywords: Dietary patterns; Food groups; Non-alcoholic fatty liver disease.

Fig. 1:

Flowchart of the search and selection process for articles included in the systematic review

Fig. 2:

Effects of western and healthy dietary patterns on the development of nonalcoholic fatty liver disease: a. western dietary pattern can cause NAFLD through several ways: 1) by ↑ HODE (hydroxyoctadecadienoic acids), HETE (hydroxyeicosatetraenoic acids), TBARS (thiobarbituric acid-reactive substances) and oxidized LDL (lipid oxidation products), so increase in oxidative stress, 2) by ↑ inflammation mediated by Kupffer cells and TNF-α, and 3) by alteration in secretion of adipokines from fat tissues for example: reduction in adiponectin and increase in leptin, TNF-α, interleukin-6 and resisting. b. Healthy dietary pattern can provide protection towards development of NAFLD through: 1)by effect on pancreas and so decrease in postprandial insulin responses and increase in insulin sensitivity, 2) by affecting the growth of gut bacteria (suppression in the growth of pathogenic bacteria and stimulation in beneficial ones)leading to↓ FFA uptake in Liver/adipose tissue, ↓ lipogenesis, ↓ gluconeogenesis, ↓ energy harvest from diet, ↑ VLDL secretion from liver and ↓ liver inflammation, and 3)by ↓ Kupffer cells, TNF-α and CRP and so reduction in inflammation.