Nutrition for non-alcoholic fatty liver disease: Green tea extract and vitamin E in the spotlight

18 Feb 2020 --- Non-alcoholic fatty liver disease (NAFLD) and its subtype non-alcoholic steatohepatitis (NASH) affect approximately 30 percent and 5 percent, respectively, of the US population, according to the American Liver Foundation. As these numbers continue to soar, the conclusions of a new US mice study indicate that a combination of green tea extract and exercise may provide a novel avenue for research on fatty liver disease. Meanwhile, Canadian research has highlighted the central role vitamin E supplementation may play in treating NASH in HIV-infected patients. NutritionInsight investigates the current groundwork laid in this field and what potential it holds for NAFLD and NASH treatment.

The combination of green tea extract and exercise reduced the severity of obesity-related fatty liver disease by 75 percent in mice fed a high-fat diet, according to researchers at Penn State University, in the US. Although untested in human trials, their study results suggest a potential health strategy.

A combination of green tea extract and physical exercise was key to improving NAFLD-related symptoms.“We think the polyphenols in green tea interact with digestive enzymes secreted in the small intestine and partially inhibit the breakdown of carbohydrates, fat and protein in food. If a mouse doesn’t digest the fat in its diet, that fat and the calories associated with it pass through the mouse’s digestive system and a certain amount of it ends up coming out in its feces,” says Joshua Lambert, Associate Professor of Food Science, Penn State University.

Notably, the combination of both green tea extract and exercise appear to be key. In the study, mice fed a high-fat diet for 16 weeks that consumed green tea extract and exercised regularly by running on a wheel were found to have just a quarter of the lipid deposits in their livers compared to those seen in the livers of a control mice group. Mice that were treated with green tea extract alone or exercise alone had roughly half as much fat in their livers as the control group.

Lambert calls for subsequent research to see if there is a synergy created by green tea extract and exercise working together to reduce fat deposited in the liver, or if the effects are simply additive. “I believe that engaging in more physical activity and replacing high-calorie beverages with decaffeinated, diet green tea – which has no calories – is a smart move,” he notes. “Combining the two might have health benefits for people, but we don’t have the clinical data yet.”

Vitamin E to treat NASH in HIV patients
Being a severe form of NAFLD, NASH can be safely treated with vitamin E for patients with HIV, a McGill-led study has found. Dr. Giada Sebastiani, Associate Professor of Medicine, McGill University Health Centre and the study’s lead author, tells NutritionInsight that the optimism surrounding the NASH treatment is based on vitamin E’s antioxidant properties.

“Vitamin E is a lipophilic antioxidant essential for human health, which protects cell membranes from oxidation and regulates apoptotic pathways. People living with HIV have particularly high oxidative stress, due to the HIV virus itself and to the use of antiretroviral medications which are required for the entire life. As such, an antioxidant may work particularly well in the setting of HIV-associated NAFLD,” she affirms.

While the study has yielded “promising” results for HIV patients with a high frequency of fatty liver disease, Dr. Sebastiani hints that it may still be too early to provide strong nutritional recommendations for dietary intake of vitamin E in the specific context of NAFLD. 

Both studies highlight the importance of physical exercise in supporting liver health.The researchers gave 27 patients with HIV and NASH vitamin E in an easily-tolerated dose of two pills per day. Dr. Sebastiani affirms that given the dosage was almost 40 times the recommended amount of vitamin E intake from food, it is unclear whether a lower dose could achieve some effect. “In our study in people living with HIV, we used soft-gelatin capsules of alpha-tocopherol, 800 IU daily, natural form. It remains unclear if the synthetic form could achieve the same effect,” she says. 

Moreover, the study’s test subjects took vitamin E for “only” six months. “We still need to understand the efficacy and side effects of vitamin E supplementation if taken for longer periods. As such, this antioxidant supplement should be taken after a careful medical evaluation, a clear diagnosis of NAFLD made by an expert physician and a regular follow-up.”

Echoing Lampert’s appeal for physical exercise in combination with supplement treatment, Dr. Sebastiani highlights that lifestyle modifications are the cornerstone in the treatment of NAFLD. She also emphasizes that the guidelines of the European Association for the Study of the Liver recommend 150 to 200 minutes of moderate-intensity aerobic physical activities per week.

Treating NAFLD with nutrition
While dietary recommendations are still in their infancy at both studies’ current stages, earlier research indicates that diet may yet have a significant role to play in treating NAFLD. Foremost, Dr. Sebastiani highlights that a Mediterranean diet has been shown to improve NAFLD. Moreover, a diet low in free sugars – those added to foods and beverages and occurring naturally in fruit juices – resulted in significant improvements in NAFLD in adolescent boys, according to a US study from last year.

Additionally, the use of BASF’s Hepaxa can correct nutritional deficiencies of omega-3 fatty acids in patients with NAFLD, thereby offering a viable option for managing the condition, a BASF study found.

Increasing the amount of protein in the diet may also reduce the liver’s fat content and lower the risk of diabetes in people with NAFLD, a study published in the American Journal of Physiology Endocrinology and Metabolism found. After two years of weight loss management, the study participants’ reduced liver fat content was associated with an increase in dietary protein intake. More than half of the participants who were previously diagnosed with NAFLD no longer had a fatty liver. 

By Anni Schleicher