The Effect of Whole Grain on Gut Microbiome and Metabolic Health (3G)

• HOMA-IR [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Homeostasis Model Assessment of fasting Insulin Resistance (HOMA-IR: glucose (mmol/l( x insulin (pmol/l)/22.5)
  
  
• Metagenomic profile [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Altered quantitative metagenomics at bacterial gene- and species levels, which is a non-specific outcome, but included as the main hypothesis of the project is to test if HOMA-IR is affected via changes in the gut microbiome.
  
  

• Mean intestinal transit time [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Participants are instructed in swallowing capsules containing different small non-invasive and non-absorbable plastic pellets for 6 consecutive days. On the seventh day they are having an X-ray of the abdomen taken.
  
  
• Gastrointestinal permeability, Lactulose/ mannitol ratio [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  5 hours urine collection following intake of lactulose and mannitol
  
  
• Colonic fermentation [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Measurement of breath hydrogen excretion (at before and 30, 60, 90, 120, 150, 180 after intake of standard breakfast) and plasma short-chain fatty acids (fasting and 30, 60, 120, 180 minutes after standard breakfast)
  
  
• Saliva microbial flora [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Determination of fasting microbial composition of flora.
  
  
• Blood pressure [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Measurement of supine systolic and diastolic blood pressure (3 times)
  
  
• Appetite hormones [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Determination of different appetite hormones in fasting and postprandial blood samples (30, 60, 120, 180 minutes after standard breakfast)
  
  
• Blood lipid profile [ Time Frame: At the end of the interventions periods ] [ Designated as safety issue: No ]
  Measurement of different blood lipids in fasting and postprandial blood samples (30, 60, 120, 180 minutes after standard breakfast)
  
  
• Body composition [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Measurement of body fat mass and percentage via bio-impedance
  
  
• Subjective appetite sensation [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessment of subjective appetite sensation via visual analogue scales
  
  
• Energy intake [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessment of energy intake at an ad libitum meal 3 hours after a standard breakfast
  
  
• Ex vivo cytokine production [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Production of cytokines (such as IL-1beta, IL-6) in stimulated whole blood cultures.
  
  
• Gene expression [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessed by mRNA qPCR in whole blood and cells from whole blood stimulation. Main focus is put on genes involved in immune function and metabolic regulation.
  
  
• Immune cell profiling [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessed by flow cytometry of whole blood.
  
  
• Immune markers [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Fasting plasma cytokines, hsCRP, and LPS/LPS-BP
  
  
• Blood immune cell content [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessed by hematological cell counts
  
  
• Markers og glucose hemostasis [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Measurement of plasma concentrations of Insulin, Proinsulin and HbA1c
  
  
• Markers of one-carbon metabolism [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessed by plasma homocystein, SAM/SAH and betain
  
  
• Plasma adipokines [ Time Frame: December 2015 ] [ Designated as safety issue: No ]
  Leptin and adiponectin
  
  

• 4-days precoded food diary [ Time Frame: December 2014 ] [ Designated as safety issue: No ]
  Assessment of dietary intake via food frequency questionnaire as a measure of compliance
  
  
• n-3 fatty acid status [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Assessed as DHA percentage in a whole blood fatty acid analysis. Included as a potential effect modificator in relation to immune function and metabolic outcomes.
  
  
• Alkyresorcinol [ Time Frame: At the end of the intervention periods ] [ Designated as safety issue: No ]
  Measured in plasma as a marker of compliance to the whole grain intervention.
  
  

The study is designed as a randomized, controlled, single-blinded, cross-over intervention trial consisting of two 8-week interventions periods, separated by a 6-week wash-out period. A total number of 60 participants will be included. Participants consume, in randomized order, a diet rich in whole grain in the active treatment period and a refined grain diet during the control period.

Measurements: Insulin sensitivity will be assessed by means of a meal challenge test and by the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) which is the primary outcome of this study. Secondary outcomes include metabolic and inflammatory markers, appetite hormones, transit time, and GM composition. Furthermore, selected control measures are included; 4-day food records and a study intervention diary.