Obesity is a risk factor for both susceptibility to infections including postoperative infections and other nosocomial infections and the occurrence of a more severe disease course. The main cause of obesity is the energetic imbalance due to increased caloric intake and little expenditure. This induces metabolic and hormonal changes that increases the risk of developing type 2 diabetes mellitus (T2DM), heart disease, and stroke. T2DM is a non-reversible but preventable condition with overweight and obesity being major risk factors. Nutrition and diets can promote the functioning of the immune system as a preventive measure by reducing both inflammation and oxidative stress that might be caused by various factors. The Mediterranean diet, rich in fruits, vegetables, fibre, can help prevent T2DM. Moreover, bioactive compounds such as polyphenols also have great impact on immunity. Seaweeds, particularly brown seaweeds, are a valuable source of natural bioactive compounds, and thus have generated a massive interest. The main objective of the present project is to study the influence of beneficial diets on the immune system of prediabetic patients and its potential to counteract infections. A clinical, an in vitro and an in vivo approach will be used to study the influence of a seaweed supplement and a diet rich in components from a Mediterranean diet on a Salmonella typhimurium infection in prediabetic subjects. Immune system, inflammation, microbiota and bile acids will be assessed and metabolic and lipidomic analysis will be performed in different samples from the different cohorts of the study. At the end of this project, we will provide evidence on the potential of these nutritional interventions to counteract infection, which are of high relevance to the society to reduce the burden of T2DM and obesity.