Onion, Cardiovascular Risk Markers and Gene Expression
Condition: Blood Pressure; Coagulation Delay
Study type: Interventional

Summary: 
      AIMS:

      The aims are to investigate whether:

        -  Increased intake of onion (powder) affects plasma lipid profile, blood pressure, indices
           of insulin sensitivity and blood coagulation.

        -  Increased intake of onion (powder) affects the expression/activity of enzymes in the
           defence against foreign substances, e.g. reactive oxygen species, and whether
           polymorphisms in some of the involved genes may modulate the effect.

        -  Polymorphisms involved in the metabolism/effect of bioactive components in onion
           modulate the excretion of metabolites or modulate some of the outcome variables in the
           study.

      Other aims are to try to identify biomarkers for onion consumption in plasma, urine and feces
      and to investigate whether onion affects the secretion of fat and bile acids.

      HYPOTHESES:

      The investigators hypothesize that:

        -  2 weeks of increased onion intake will improve the plasma lipid profile

        -  2 weeks of increased onion intake will increase the metabolism of potentially harmful
           substances (such as ROS and free radicals) through a change in the expression or
           activity of certain enzymes.

        -  That these effects are modulated by common gene variants (polymorphisms)
    

Detailed description: 
      In a randomized controlled crossover design, participants will receive 2 daily meals with or
      without onion powder for 2 weeks. Between the two 2-week period is a 4-week wash-out period.
      One week before and during each intervention period, the participants will be instructed to
      avoid consumption of onion, garlic and all foodstuffs containing the same bioactive
      components (polyphenols, sulfur-molecules)as in onion. This includes a number of vegetables
      and fruits, condiments, tea, chocolate, red wine etc.

      Fasting blood samples will be drawn before and after (on 2 separate days) each intervention
      period, where also weight and blood pressure are measured.

      Participants will collect 24-hour urine and feces samples twice before and at completion of
      each intervention period.

      After the fasting blood sampling on the first blood sampling day in each period, participants
      will receive a test meal (with 10 g onion powder or placebo, i.e. 8.5 g sucrose+ 2 g soy
      protein isolate). The acute effects will be studied by blood sampling and urine sampling 0,
      2, 4 and 24 hours after the test meal.
    

Intervention name(s): Onion powder; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Hot meals with onion powder; 10 g/day onion powder corresponding to 100 g/day fresh onion in meals with potato and beef Intervention period 14 days.; Hot meals without onion powder; Control meal with potato, beef, soy protein, and sucrose to match macronutrient composition of active treatment
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Onion; Cardiovascular disease; metabolomics; Gene expression; Biomarker