Published online Mar 7, 2019. doi: 10.3748/wjg.v25.i9.1116
Peer-review started: November 1, 2018
First decision: December 5, 2018
Revised: February 15, 2019
Accepted: February 15, 2019
Article in press: February 15, 2019
Published online: March 7, 2019
Non-alcoholic steatohepatitis (NASH) is one of the leading causes of chronic liver disease in western countries. The ideal approach to reduce hepatic inflammation and liver fat content is not found yet. Dietary restrictions and physical activity have been shown to be effective, however there is no gold standard established so far.
Many different dietary approaches may be effective in weight reduction. We have shown that by meal replacement therapy with a high-quality soy protein supplementation as well as by comprehensive lifestyle change a weight reduction without loss of muscle mass is achievable. Both interventions can reduce fat mass and liver fat mass. However, blood lipids are changed in different ways with these two interventions. Now we wanted to study whether liver fat quality is differently affected with either intervention.
The main questions of this study were: is there a correlation between loss of liver fat and reduction in body fat, and is one intervention superior to the other in this respect? Is it possible to analyze liver fat quality, and is there a difference in changes in liver fat quality between the two therapeutic interventions?
For body composition analysis a Bod pod device was used. Liver fat content was measured by magnetic resonance imaging. For analysis of liver fat quality a magnetic resonance spectroscopy protocol was adapted to quantify the mean chain length and grade of saturation of liver fat. For meal replacement therapy we used a commercially available product based on a soy-yogurt-honey preparation. The lifestyle intervention program consisted of guided exercise sessions orientated on individual exercise capacity and dietary counselling.
Both groups significantly reduced body mass index, fat mass and liver fat content. The lifestyle intervention group showed a tendency for greater weight loss. In both groups ALT and AST declined significantly. Triglycerides significantly decreased only in meal replacement group. With respect to liver fat quality the grade of saturation and mean chain length of hepatic fatty acids were quantifiable in a subset of participants. Total unsaturated lipids and mean chain length were significantly reduced only by meal replacement.
With both interventions body fat and liver fat content were significantly reduced. Though the participants tended to lose more weight by lifestyle intervention the reduction of liver fat was comparable in both groups. Thus, for the reduction in liver fat a meal replacement strategy could be more effective in relation to body weight loss than a lifestyle intervention. This study confirms the finding of preserving muscle mass during a weight reduction period once high quality protein supplementation or physical activity is added in a guided and supervised manner. The pronounced reduction of serum triglycerides is attributed to specific soy properties. Given the study protocol further analysis of liver fat in humans by magnetic resonance spectroscopy was possible. Both interventions had different effects on liver fat quality.
In conclusion, with both approaches a significant weight loss and loss of intrahepatic fat content is achievable. Reduction in fat content is accompanied by a decline in hepatic inflammation, reflected in reduction of aminotransferases. In patients with NASH both therapeutic interventions can be advocated in order to reduce liver fat content and hepatic inflammation.
Both interventions had distinct effects on liver fat quality. The reduction of serum triglycerides is a known effect of soy protein supplementation thus, we hypothesize that the different changes in liver fat quality were also related to soy protein intake. However, the physiologic consequence of a shortened chain length or of a different grade of saturation in hepatic lipids is not clear yet. This has to be addressed in future investigations. Furthermore, our research results demonstrated the practicability of magnetic resonance spectroscopy to analyze liver fat quality. The validity has to be confirmed by further studies.