Resistant starch is a non-digestible fibre that ferments in the large intestine. Consumption of such starch has been previously shown to have a positive effect on metabolism, in animal studies. New research now indicates that resistant starch, while positively affecting metabolism, could also help reduce liver injury and inflammation.
Published in the journal Cell Metabolism, researchers report that consumption of resistant starch helps in lowering the risk of developing non-alcoholic fatty liver disease (NAFLD).
A build-up of fat in the liver can cause NAFLD and can lead to severe liver disease, contributing to other medical conditions, such as type-2 diabetes and cardiovascular disease. These conditions also make it more likely that a person would develop NAFLD. Currently, there is no approved medicine available to treat NAFLD and doctors usually recommend dietary changes and exercise to alleviate the conditions.
“We think it would be very meaningful if we can find an effective approach, maybe through identifying new therapeutic targets, to manage NAFLD,” said Dr Huating Li, one of the co-authors on the study from Shanghai Sixth People’s Hospital.
For their study, the researchers recruited 200 people with NAFLD and provided them with a balanced diet designed by a nutritionist. Half of the participants received a resistant starch powder derived from maize. The other half received a calorie-matched, non-resistant corn starch. Both groups were instructed to drink 40 grams of the starch with 300 millilitres (1 ¼ cups) of water before meals twice a day for four months.
After a period of four months, the researchers discovered that the group which had received the resistant starch treatment had almost a 40% lower liver triglyceride level compared to people in the control group. They also had reduced liver enzymes and inflammatory factors associated with NAFLD. These improvements remained even after the researchers made statistical adjustments for weight loss.
“Our study shows resistant starch’s impact in improving patients’ liver conditions is independent of body weight changes,” said Dr Yueqiong Ni, one of the co-authors on the study from the Shanghai Sixth People’s Hospital and Leibniz Institute for Natural Product Research and Infection Biology in Germany.
In the second phase of this study, the researchers analysed faecal samples from the participants and found that the resistant starch group had a different microbiota composition. The treatment group had a lower level of Bacteroidesstercoris, a type of bacteria that can affect fat metabolism in the liver.
The researchers then transplanted faecal microbiota from the resistant starch treatment participants to mice with a high fat, high cholesterol diet. They observed a significant reduction in liver weight and triglyceride levels, and improved liver tissue grading in the mice compared to those that received microbiota from the control group.
“We are able to identify a new intervention for NAFLD and the approach is effective, affordable and sustainable. Compared with strenuous exercise or weight loss treatment, adding resistant starch to a normal and balanced diet is much easier for people to follow through,” Dr Li explained.
