Effects of dietary protein on the metabolism in liver and adipose tissue

Contact: PD Dr. Olga Ramich

In this project, we investigate effects of dietary protein on the hepatic and adipose tissue metabolism in humans in cooperation with the Department of Endocrinology, Diabetes and Nutrition of the Charité – Universitätsmedizin Berlin.

Fig. 1: Effect of diets rich in animal or plant protein on the liver fat content in subjects with type 2 diabetes. *** p<0.001 (Markova, Pivovarova et al. Gastroenterology 2017)

In previous human studies (Markova, Pivovarova et al., 2016; Xu et al., 2020), we showed that in subjects with type 2 diabetes and prediabetes the high-protein diet potently reduces the liver fat content (Fig.1) and improves the insulin sensitivity. It has beneficial effects on body weight, preserving of muscle mass, levels of blood lipids, inflammatory markers and HbA1c. Moreover, the levels of the hepatokine fibroblast growth factor 21 (FGF21) and of the oxidative stress markers were affected (Pivovarova-Ramich et al., 2020). These effects were independent from the protein origin (plant or animal protein). Our results demonstrate that the high-protein diet is an effective nutritional strategy for the prevention and therapy of the nonalcoholic fatty liver disease, obesity, type 2 diabetes and associated metabolic dysfunctions.

Fig 2: Effects of the high-protein diet on the genetic network in human subcutaneous adipose tissue. The color of the edges represents the quantity of the correlation coefficients (blue: 0.75>τ≥0.5; black: 0.5>τ≥0.3). (Markova, Pivovarova et al. Gastroenterology 2017)

We currently investigate molecular mechanisms which contribute to metabolic effects of high-protein and low-protein diets. We analyze the influence of the dietary protein on the tissue transcriptome, autophagy, mitochondrial activity, lipogenesis and lipolysis as well as on inflammation in human adipose tissue (Fig. 2) and in the liver. Moreover, we study the role of miRNA in the metabolic regulation induced by the high-protein diet.