Understanding the impact of ultra-processed beef on lipid metabolism in Wistar rats by using metagenomics and proteomics

The purpose of this Master Thesis was to clarify the effect of the intake of severely oxidized processed meat on physiology and health, assessing especially the effects on lipid metabolism, microbiota and liver damage. The study was performed on three groups of Wistar rats fed with different diets: control feed (C), feed rich in beef (B) and feed rich in oxidized-beef (B-OX). The main object was fulfilled through the analysis of health markers such as markers of oxidative stress, inflammation, hepatic function as well as some advanced “OMICS” techniques such as metagenomics (microbiota analysis) and proteomics (liver). Initial results shown on the one hand that animals fed with higher meat content consumed more water and feed during the trial but, on the other hand, there are no evident difference in weight gain among the three groups. Despite of these results, there are clear differences in adiposity level among the three groups especially regarding intra-cavitary adipose tissue. As expected, the intake of the oxidized beef, which caused adiposity, impaired lipid metabolism and liver damage in Wistar rats, also led to lipid steatosis as compared to rats fed on regular (non-oxidized) beef. Liver proteomics also revealed in the one hand, that livers from rats fed ultra-processed beef featured and proteome compatible with that of a fatty liver, with upregulated protein/amino acid catabolism, gluconeogenesis and lipogenesis. Oxidized components from B-OX may also impair protein activation (i.e. myristoylation) and cellular transduction signalling mechanisms (i.e. Rab-proteins mediated) that may affect to liver responses to hormones such as insulin. It was also confirmed that dietary oxidized beef leads to dysbiosis in Wistar rats by modifying the ratio between Bacteroidetes. In conclusions, the intake of ultra-processed meat could be convoluted in the occurrence of numerous diseases, mainly related to lipid metabolism and with the functioning of organs such as liver.