Assessment of dietary factors in patients with nonalcoholic fatty liver disease and an intervention study to investigate the effects of low glycaemic index diet
Year: 2023
Type: dissertation
Abstract: Background: Over the past two decades, non-alcoholic fatty liver disease (NAFLD) has evolved from a mostly unheard-of condition to the most common cause of chronic liver disease worldwide.Dietary components have been identified as major contributors to NAFLD and are now considered the first line treatment for this disease.However, current dietary methods applied to explore associations between diet and NAFLD, consider only energy and macronutrients and fail to discriminate at the food level necessary to understand the unique dietary components in different cultures.Moreover, inadequate food grouping methods are used that disregards the cultural variation in food type; impacts of processing and cooking methods.Furthermore, previous research has shown that in healthy study participants, regardless of energy restriction, carbohydrates characteristics affects liver fat synthesis and that the glycaemic index (GI) of food has a significant impact on liver fat levels.Thus, the low GI (LGI) diet has been proposed as a lifestyle intervention in NAFLD which is designed to reduce circulating blood glucose levels, hepatic glucose influx, insulin resistance and hepatic de novo lipogenesis.In addition, in observational studies, imbalances in gut microbiota that were induced by certain dietary components has been shown to stimulate liver fat accumulation and promote NAFLD progression.Aims: This thesis aimed to explore the associations between diet, at multiple food levels, and NAFLD in an Indian cohort (study 1) and a UK cohort (study 2) and determine the potential impact of a LGI diet on liver fat accumulation (primary outcome measure) and gut microbiome in patients with NAFLD (study 3). Methods:For study 1 and 2, a novel 'food-tree grouping' method was developed which attempted to group individual foods after deconstructing the ingredients of the composite dishes extracted from food frequency questionnaires.The food-tree method was then applied to two different geographical case-control studies (Indian cohort n=993 NAFLD vs 973 controls; UK cohort n=168 NAFLD vs 34 controls) to assess association of food-groups intakes with the likelihood of NAFLD and liver fibrosis.For study 3, a 2×2 cross-over randomised trial was undertaken involving 7 participants with NAFLD allocated to a 2-week either high GI (HGI) or LGI diet followed by a 4-week wash-out period and then the opposite diet.The impact of the LGI diet on liver fat content (utilising both 1 H-MRS and CAP-FibroScan™), liver-related blood biomarkers, appetite (using subjective visual analogue scales) and gut microbiome composition (using 16S rRNA sequencing), was identified.Results: Study 1 and 2: in both cohorts red meat consumption was significantly associated with increased likelihood of NAFLD (Odds Ratio [95% confidence interval], OR [95%CI]: India =1.48[1.21-1.82];UK =1.013[1.001-1.025])and fibrosis (Beta Coefficient [standard of errors]: Beta [SE], India
Author: Al-Awadi, Amina
Language: English
Subfield: Hepatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7026671848