Hepatic Biomarkers in Diabetes as Modulated by Dietary Phytochemicals

Abstract

Both type 2 diabetes (T2D) and features of the metabolic syndrome are associated with hepatic insulin resistance, which may gradually progress to nonalcoholic fatty liver disease (NAFLD) and fibrosis. Biomarkers, including those related to glycemia, serum lipid profiles, lipid oxidation, inflammation, and levels of enzymes reflecting hepatocellular damage (e.g., aminotransferases), may reflect liver function in diabetes. New epidemiological data suggest that noninvasive imaging techniques, such as computed tomography (CT) scans, may provide better predictive biomarkers for NAFLD than circulating liver enzymes. Phyto-chemicals or plant-derived bioactive compounds present in foods, beverages, and herbal supplements have been shown to modulate biomarkers of liver function in clinical trials and mechanistic studies. Mediterranean diet and dietary phytochem-icals, such as polyphenols derived from green tea, berries, olive oil, and resver-atrol, have been shown to lower liver enzymes, liver fat content, and to improve hepatic insulin resistance and related biomarkers of oxidative stress and inflam-mation, especially in the presence of adiposity and the metabolic syndrome. Herbs, such as silymarin and those used in traditional Chinese medicine (for example, hawthorn fruit extract), have also been shown to lower hepatic enzymes and markers of oxidative stress and to increase hepatic antioxidant status in patients with NAFLD. Other emerging biomarkers, such as cytokines and microRNAs, are also being evaluated for efficacy in monitoring and predicting liver dysfunction. Thus, selected phytochemicals, especially those occurring naturally in berries and grapes, tea, olives, nuts, and legumes, when used in the context of a low-calorie diet may have a role in treating liver dysfunction. The use of herbal supplements to modulate hepatic biomarkers requires further evaluation of safety and efficacy.