Nonalcoholic fatty liver disease (NAFLD) is a liver disease characterized by an abnormal accumulation of fat not due to alcohol or drug consumption that can evolve into steatohepatitis (NASH), fibrosis and cirrhosis. Its prevalence is high, affecting approximately 20-30% of the general adult population and is also growing in pediatric age. Obesity, insulin resistance and type 2 diabetes (T2DM) are common and well-known risk factors for NAFLD, which is approximately 2-3 times more prevalent among obese and diabetic individuals. Despite the high and increasing prevalence of NAFLD in the population, its pathophysiology is not fully understood and there is currently no pharmacological treatment available. Recent evidence suggests that dietary polyphenols may have specific beneficial effects on hepatic steatosis and associated sequelae by polyphenol metabolites and their phase II derivatives. Therefore, the aim of our study is to evaluate whether medium-term consumption of a beverage rich in polyphenols extracted from red grape pomace is able to exert beneficial effects on hepatic steatosis, cardiometabolic risk profile and microbiota composition of patients with type 2 diabetes.
A randomized, crossover, placebo-controlled study will be conducted. Twenty patients with type 2 diabetes mellitus (T2DM) recruited from the Diabetes Unit of the University Hospital of Naples "Federico II" who meet the inclusion criteria will be studied. After a 2-week run-in period during which they will stabilize their habitual diet, participants will be randomly assigned to receive either 150 ml/day of a polyphenol-rich red grape pomace beverage (RG) or 150 ml/day of a control beverage (Placebo) for a 6-week period each. The two treatments will be separated by a 2-week wash-out period. At the end of the run-in, wash-out, and both treatment periods, participants will undergo fasting blood samples to evaluate key metabolic parameters. After each treatment period (RG or placebo), a standardized meal (960 kcal, 18% protein, 30% fat, 52% carbohydrates) will be administered along with 150 ml of either the polyphenol-rich beverage or the control beverage, for postprandial metabolic evaluations. At the end of both treatments, hepatic fat content, fasting and postprandial metabolic parameters, microbiota composition and continuos glucose monitoring will be assessed. Energy intake and habitual dietary composition will be evaluated at the end of the run-in, and at 6 weeks after the start of each treatment period using a 7-day food diary.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
20
Participants were instructed to consume, over a 6-week period, within the context of a Mediterranean diet, a polyphenol-rich drink RGPD (150 mL) containing 1.5 g of polyphenols. After this treatment period, participants underwent a two-week washout period before switching to the alternative treatment with control drink (Placebo) devoid of polyphenols. To evaluate metabolic responses during both fasting and postprandial states, participants participants consumed a standardized test meal at the end of the 6 weeks. This standard meal was preceded by the consumption of the RGPD 60 minutes prior.
Participants were instructed to consume, over a 6-week period, within the context of a Mediterranean diet, a control drink (Placebo) (150 mL) containing 0 g of polyphenols. After this treatment period, participants underwent a two-week washout period before switching to the alternative treatment with a polyphenol-rich drink RGPD (150 mL) containing 1.5 g of polyphenols. To evaluate metabolic responses during both fasting and postprandial states, participants participants consumed a standardized test meal at the end of the 6 weeks. This standard meal was preceded by the consumption of the Control drink (Placebo) 60 minutes prior.
Federico II University
Naples, Italy
Differences in liver fat content
Differences in liver fat content after the intake of polyphenol rich drink (RGPD) for 6 weeks, as compared to Control drink (Placebo). Liver fat content will be assessed by magnetic resonance spectroscopy (MRI).
Time frame: At baseline and at the end of 6 weeks of each treatment
Differences in glycemic variability
Differences in glycemic variability after the intake of polyphenol rich drink (RGPD) for 6 weeks, as compared to control drink (placebo). Glycemic variability will be assessed by Continuos Glucose Monitoring (CGM) during the 7 days before the end of each treatment.
Time frame: At baseline and at the end of 6 weeks of each treatment
Differences in glucose response
Differences in fasting and postprandial plasma glucose response to a standard test meal at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Plasma glucose concentration will be assessed by enzymatic colorimetric methods.
Time frame: At the end of 6 weeks of each treatment
Differences in insulin response
Differences in fasting and postprandial plasma insulin response to a standard test meal at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Plasma insulin concentration will be assessed by ELISA method.
Time frame: At the end of 6 weeks of each treatment
Differences in fasting lipid concentrations
Differences in fasting plasma triglycerides, total cholesterol, HDL-cholesterol and LDL-cholesterol concentration at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Plasma lipid concentrations will be assessed by enzymatic colorimetric methods.
Time frame: At the end of 6 weeks of each treatment
Differences in postprandial triglyceride response
Differences in postprandial plasma triglycerides concentration at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Plasma triglyceride concentrations will be assessed by enzymatic colorimetric methods.
Time frame: At the end of 6 weeks of each treatment
Differences in gastrointestinal hormones response
Differences in fasting and postprandial plasma GLP-1, PYY and Ghrelin concentration at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Plasma concentrations of GLP-1, PYY and Ghrelin will be assessed by ELISA methods.
Time frame: At the end of 6 weeks of each treatment
Differences in inflammatory markers
Differences in fasting and postprandial serum hs-CRP concentration at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Serum concentrations of hs-CRP will be assessed by immunoturbidimetric method.
Time frame: At the end of 6 weeks of each treatment
Differences in gut microbiota composition
Differences in microbiota composition at the end of the 6-week treatment with polyphenol rich drink (RGPD) as compared to control drink (placebo). Microbiota analysis will be assessed on feacal samples by metagenomics.
Time frame: At the end of 6 weeks of each treatment
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