Effect of dietary carbohydrate and lipid modification on clinical and anthropometric parameters in nonalcoholic fatty liver disease: a systematic review and meta-analysis

Nonalcoholic fatty liver disease (NAFLD) is estimated to affect approximately 25% of the adult population, making it one of the most common chronic liver diseases worldwide and a major public health problem. Still, there is no consensus on the most appropriate nutritional intervention for disease treatment.To systematize and synthesize the results of randomized controlled trials that have evaluated the effect of dietary interventions with different, quantitative, macronutrient compositions on hepatic steatosis attenuation, serum levels of alanine aminotransferase, aspartate aminotransferase, lipid profile, glucose metabolism markers, and anthropometric parameters of adults and the elderly (age ≥ 60 years) with NAFLD.MEDLINE databases via PubMed, Embase, Science Direct, LILACS, Web of Science, ClinicalTrials.gov, and Cochrane Library were searched. Randomized controlled trials that compared interventions as diets with values ≤ 45% or 20% of the total daily energy intake from carbohydrates or lipids, respectively, compared with dietary reference intakes, were included.Risk of bias was assessed through the Cochrane Collaboration tool. The meta-analysis was only performed to evaluate the effect of carbohydrate-modified diets on the outcome variables. The number of participants and mean values and respective standard deviations of the outcome variables were extracted and used to calculate weighted mean differences and their respective 95%CIs.The search strategy resulted in 21 146 studies, of which 10 were retained for qualitative analysis and 6 were included in the meta-analysis. From the analysis of 10 studies were identified 8 articles in which low-calorie diets were evaluated and 3 interventions that used an isocaloric diet. Only 3 studies were classified as having low risk of bias.The observed effects on hepatic steatosis, serum alanine aminotransferase and aspartate aminotransferase levels, parameters of lipid and glucose metabolism, and anthropometric variables were mostly related to a hypocaloric diet. The use of reduced macronutrient interventions had no efficacy.PROSPERO registration no. CRD42018088824.