Dietary biomarkers are compounds in biofluids that directly reflect the intake of specific foods or food groups. Their exploration and use in the field of dietary assessments could provide an objective measure of actual intake complementing classical assessment methods (e.g. food frequency questionnaire, 24h recalls). To date, only a limited number of foods have been covered by validated biomarkers.

The study is part of the international project "The Food Biomarker Alliance (FOODBALL)". The study described here has been assigned to assess biomarkers of the intake of milk and cheese. Up to now, there is an evident lack of data on specific and validated biomarkers of milk and cheese (dairy products), which belong to the most relevant public health related foods in Europe. This study will further provide novel insights into the influence of fermentation of milk-based foods on metabolic effects and postprandial adaptations, which has not yet been studied in depth before using cheese as fermented product. Outcomes will support and expand earlier findings on correlation between the intake of fermented dairy products intake and human health.

This is an acute, randomized, controlled, cross-over study designed to identify dietary biomarkers of milk and cheese intake and to asses metabolic effects after the ingestion of a non-fermented product (milk) and a fermented product (cheese) in healthy subjects.

Twelve healthy participants (six women, six men) in fasted state will consume three different foods in a randomized order on three different study days. Two days prior to each dietary intervention, the run-in period is initiated, during which participants have to follow a restricted diet. Participants will receive a standardised meal for the last dinner during run-in phase. The same meal will be served on the day of the dietary intervention for lunch and for dinner (period of controlled diet). Before and after ingestion of the test foods, blood samples and urine samples will be collected (up to 6 hours). Additionally, 24h-samples will be collected. Primary outcomes (metabolites) will be measured in blood serum and plasma collected at 6 different time points and in urine collected at 7 different time points. Transcriptomics analysis will be performed on whole blood samples collected at 4 time points while clinical chemistry parameters will be assessed in blood samples withdrawn at 6 different time points.

Inclusion Criteria:

• Healthy males and females
• Aged 18 - 40 years
• BMI > 18.5 and < 30 kg/m2
• Daily consumption of milk
• No adverse effects after intake of 600 ml of milk

Exclusion Criteria:

• Smokers
• Diagnosed health condition (chronic or infectious disease)
• Taking medication (oral contraceptive pill is allowed)
• Taking nutritional supplements (e.g. vitamins, minerals)
• Pregnant, lactating
• Antibiotics treatment 6 months prior to intervention
• Allergy to milk
• Allergy to soy
• Known intolerance to lactose
• Other food allergies or intolerances (e.g. histamine)
• Anemia (hemoglobin < 120 g/l) at the screening visit
• Iron deficiency (ferritin < 30 µg/l) at the screening visit
• Not willing/able to consume all test foods (milk, cheese and soy drink)
• Not willing/able to consume standardized meals
• Not willing to avoid drinking alcohol during study days
• Not willing to follow nutritional restrictions during study days