- The nonalcoholic fatty liver disease is the most common disorder that can have life-threatening effects.
- A high-protein diet may reduce liver fat in people with type 2 diabetes.
- Both plant and animal sources of protein reduced liver fat by 48 percent within six weeks.
Non-alcoholic fatty liver disease (NAFLD) is a common disorder where there is an accumulation of excess fat in the liver. A diet rich in protein can reduce liver fat by up to 48 percent in patients with type 2 diabetes, according to a study conducted by the German Institute of Human Nutrition (DIfE).
Effect of High-Protein Diet in Reducing Liver Fat
‘The high-protein diet was found to reduce fat content in the liver, improve insulin sensitivity and lipid metabolism in people with type 2 diabetes.
NAFLD is highly prevalent in Europe and the United States. The disease could cause type 2 diabetes and liver cirrhosis, causing to life-threatening complications.
"Since the number of affected persons is increasing, it is, therefore, more important than ever to work together with our partners to develop effective dietary strategies that prevent the disease," said endocrinologist Andreas F. H. Pfeiffer of DIfE, who led the study.
The study was conducted by a team of scientists Mariya Markova, Olga Pivovarova, Silke Hornemann and Andreas F. H. Pfeiffer of DIfE, a partner of the German Center for Diabetes Research (DZD).
The effects of high-protein diets on the human metabolism have been studied for years. High-protein diets have shown beneficial effects on body weight, liver fat, blood lipid levels, blood glucose levels and muscle mass retention. Some studies have also shown that a high-protein diet can reduce insulin activity and affect renal function.
Some of the protein food sources are lean meat, fish, eggs, dairy products, legumes, nuts, and seeds. The daily recommended intake of protein for an adult is 0.8 grams per kilogram of body weight.
Researchers at DIfE conducted the study to find out whether the protein source was decisive for the particular effect. The study group involved 37 female and male subjects between the ages of 49 and 78 years suffering from type 2 diabetes and fatty liver.
Plant and Animal Protein Sources
The researchers investigated the effects of both plant and animal-based protein diets. The plant protein group consumed noodles and bread enriched with pea protein. The subjects in animal protein group consumed low-fat milk products, white meat and fish. The energy intake of each participant was adjusted to ensure that their body weight remained stable during the study period.
The protein content contributed to 30 percent of the dietary intake. Carbohydrate and fats contributed to 40 and 30 percent of the energy supply respectively. All the study participants were advised to maintain an equal intake of mono-and-polyunsaturated fatty acids. Before the study, the protein intake of the participants was 17 percent, carbohydrate (42 percent) and fat (41 percent).
The findings of the study showed that all the participants benefited from the high-protein diet. The liver fat content reduced by more than 50 percent in half of the study participants within six weeks.
"As our results show, all study participants benefited from the high-protein diet, whether based on plant or animal protein. Negative effects on renal function or glucose metabolism were not observed," said first author Markova.
"Liver fat content decreased significantly, in half of the study participants by more than 50 percent. In conjunction with this, we observed favorable changes in the liver and lipid metabolism, improved insulin sensitivity of the participants and also a significant reduction in the hormone fibroblast growth factor 21 in the blood," added Olga Pivovarova, who along with Mariya Markova and Silke Hornemann coordinated the current study.
"Larger and longer studies are needed to understand better the metabolic mechanisms underlying the observation, to study the long-term effects, and to see whether also younger patients would benefit from the change in diet," said Pfeiffer.
"The favorable effects we observed in the study may also be age-dependent because the study participants were on average older than sixty years of age. If no renal disease is present, sufficient protein supply plays an important role, particularly in this age group. For example, a decrease in muscle mass is often associated with age," Pfeiffer added.
The researchers noted that further studies are needed to elucidate the hormonal regulation mechanism. However, considering the environmental aspects, the researchers concluded that consumers should prefer plant-based protein sources.
The findings of the study are published in the journal Gastroenterology.