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)
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
10
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
Dep. Human Nutrition, LIFE, University of Copenhagen
Frederiksberg C, Denmark
Department of Nutrition, Exercise and Sports, University of Copenhagen
Frederiksberg C, Denmark
Change in blood pressure from baseline to two weeks
Measured by a standard arm cuff by a trained bioanalyst
Time frame: baseline to two weeks
Change in waist-to-hip circumference ratio
Measured manually by a trained bioanalyst
Time frame: Change from baseline to two weeks
Change in fecal microbiota profile
RFLP of 16S cDNA
Time frame: change from baseline to two weeks
Change in total cholesterol
Total plasma cholesterol in lipoproteins measured by a clinical chemistry kit
Time frame: change from baseline to 2, 4, and 24 hours and 2 weeks
Change in HDL cholesterol
High density Lipoprotein Cholesterol in plasma measured by an immunokit
Time frame: change from baseline to 2, 4, and 24 hours and 2 weeks
Change in plasma triacylglycerides
Triacylglycerides in plasma measured by an immunokit
Time frame: change from baseline to 2, 4, and 24 hours and 2 weeks
Change in blood coagulation parameters
thromboelastography measurements, fibrinogen etc. in plasma
Time frame: 0-4 hours
Change in whole-blood hematocrit
hematocrit by standard clinical chemistry
Time frame: 0-14 days
Change in whole-blood haemoglobin concentration
haemoglobin concentration by standard clinical chemistry
Time frame: 0-14 days
Change in body weight
Measured in triplicate on a calibrated balance
Time frame: 0-14 days
Change in serum VCAM-1
Determined with standard kits
Time frame: 0-14 days
Change in serum IL-6
Determined with standard kit
Time frame: 0-14 days
Change in serum TNF-alpha
Determined with standard kit
Time frame: 0-14 days
Change in faecal metabolic profiles
Untargeted metabolomics by LC-QTOF profiling of polar metabolites
Time frame: 0-14 days
Change in faecal pH
pH by a pH-meter in a 50% aqueous fecal slurry
Time frame: 0-14 days
Change in faecal bile acids
bile acids measured by LC-TQD
Time frame: 0-14 days
Change in urine metabolomic profiles
Untargeted metabolomics by LC-QTOF profiling of polar metabolites
Time frame: 0-14 days
Change in urine pH
pH by a pH-meter
Time frame: 0-14 days
Change in plasma insulin (multivariate ANOVA)
Insulin measured at baseline before meals and at 2, 4 and 24 hours, 2, 7 and 14 days after the start of intervention.
Time frame: 0-14 days
Change in plasma glucose (multivariate ANOVA)
Glucose measured at baseline before meals and at 2, 4 and 24 hours, 2, 7 and 14 days after the start of intervention.
Time frame: 0-14 days
Change in HOMA
Change in HOMA measured at baseline before meals and at 14 days after the start of intervention.
Time frame: 0-14 days
Change in ISI240 (Matsuda insulin sensitivity index 0-240)
Change in ISI240 measured from 0-240 minutes after the first test meal.
Time frame: 0-240 minutes
Change in erythrocyte Glutathione Reductase
Measured by automated colorimetric assays
Time frame: 0-2 weeks
Change in erythrocyte superoxide dismutase
Measured by automated colorimetric assays
Time frame: 0-2 weeks
Change in erythrocyte catalase
Measured by automated colorimetric assays
Time frame: 0-2 weeks
Change in erythrocyte glutathione peroxidase
Measured by automated colorimetric assays
Time frame: 0-2 weeks
Change in plasma untargeted metabolic profile
LC-QTOF profiling of polar metabolites and polar lipids
Time frame: 0-2 weeks
Change from baseline in leucocyte gene expression profile
Selected genes by RT-PCR
Time frame: 0, 2, 4 and 24 hours and 2 weeks
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