Phytotherapy and NAFLD--from goals and challenges to clinical practice.

Non-alcoholic fatty liver disease (NAFLD) is a global problem and one of the most common liver diseases in the world. Various pharmacological and non-pharmacological therapies seem to be non-effective and the patients are often advised not to expect a positive outcome. Hence, even in the modern Western society many patients reach for traditional herbal products. Silymarin, a lipophilic extract derived from milk thistle (Silybum marianum) has been used in liver and bile disorders for centuries. Strong antifibrotic, antioxidant, antiviral and anti-inflammatory activities of silymarin joined with its metabolic effect proven in vitro make it ideal as a drug candidate in the therapy of NAFLD. Several recent randomized clinical studies have demonstrated that silymarin versus placebo significantly contributes to amelioration of the liver condition affected by NAFLD since it reduces steatosis severity, liver ballooning and fibrosis, followed by lowered aminotransferase levels in both short and long lasting therapies. Silymarin is also as efficient as an insulin sensitizer in the NAFLD therapy, but with less adverse effects. Phase III clinical trials have confirmed silymarin to be currently the best medication for the NAFLD patients, but the problems associated with its standardization, formulation and dosage are yet to be solved. However, green tea (Camellia sinensis) and licorice (Glycyrrhiza glabra) root extracts have also been studied in the clinical trials in the therapy of NAFLD patients. Some other herbal products, which have been tested on animals and have the potential to be used in clinical trials, are briefly summarized in this paper.