Numerous plant-based foods contain bioactive compounds, in particular polyphenols, which have antioxidant, anti-inflammatory, and metabolic regulatory effects. These so-called food bioactives (FB) are converted in the human organism, in particular by the gut microbiota and microsomal (liver/intestinal) metabolism, into numerous metabolites, which often represent the actual biologically active molecules. As part of the European HORIZON-MSCA Doctoral Network "BioTransform," two such food models are being studied as examples: 1. Olive products (Olea europaea L.) - representative of the Mediterranean diet, rich in secoiridoids and phenylethanols (especially hydroxytyrosol and tyrosol). 2.

Bilberry /blueberry (Vaccinium myrtillus L.) - representative of the Central European diet, rich in anthocyanosides. Two parallel human intervention studies will be conducted, one in Graz (WP1, DC5) and one in Athens (WP1, DC3). These pilot studies will generate biological samples (blood, urine, stool) and investigate the extent to which taking these standardized dietary supplements influences glucose metabolism and markers of oxidative stress and low-grade inflammation.

Inclusion Criteria:

• 30-50 years old,
• BMI> 25 kg/m2
• prediabetic stage
• hsCRP> 2mg/ L
• HbA1c 5,7-6,4%
• Impaired fasting glucose (IFG)
• Caucasian

Exclusion Criteria:

• No signed informed consent
• Supplementation or probiotic usage in the past 8 weeks
• Chronic gastrointestinal, inflammatory or metabolic diseases
• Alcohol misuse
• Pregnancy or breastfeeding
• Acute infection during the past month