During digestion of fatty foods, the liver produces a substance called bile which helps with the absorption of fat in the gut (small intestine). Some research studies have shown that friendly bacteria that live in our gut can change the makeup of bile (referred to as bile acids) leading to a lowering of blood cholesterol levels, an important risk factor for developing heart disease. This finding has been found in people who consume diets high in dietary fibers and probiotics that enhance the growth of friendly gut bacteria, and also plant rich foods high in polyphenols (such as apples). At present, very little is known about how the makeup of bile acids can regulate blood cholesterol levels and if their measurement in blood, urine or stool samples can be used as an indicator of human health. The aim of this study is to explore how consumption of foods which enhance the growth of friendly gut bacteria (such as probiotics, prebiotics, and plant rich foods high in polyphenols) can change the makeup of bile acids after 8 weeks. Changes in the bile acids measured in blood and stool samples will then be related to markers of health, such as blood cholesterol, glucose, insulin, vascular health and inflammatory markers.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
64
2 Renetta Canada apples and 2 placebo capsules/ day
40g jumbo rolled oats with semi-skimmed milk and 2 placebo capsules / day
2 probiotic capsules and 40g cornflakes with semi-skimmed milk / day.
40g cornflakes with semi-skimmed milk and 2 placebo capsules/ day.
Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading
Reading, Berkshire, United Kingdom
RECRUITINGCirculating bile acids
Plasma bile acid profile
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Blood lipid profile
total, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol, triacylglycerol (TAG) and non-esterified fatty acids (NEFA)
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Glucose response
Fasting and postprandial blood glucose concentrations
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Insulin response
Fasting and postprandial blood insulin concentrations
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
C-peptide
Fasting and postprandial blood C-peptide concentrations
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Inflammatory markers
Fasting blood concentrations of C-reactive protein (CRP), IL-18, IL-1β and tumour necrosis factor alpha (TNF-α)
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Gut hormones
Fasting and postprandial concentrations of peptide YY, Glucagon-Like Peptide 1, Fibroblast growth factor 19
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Metabolomics
Profile of metabolites in the blood (fasting and postprandial)
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Nitric Oxide
Fasting and postprandial concentrations of nitric oxide
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Cell-adhesion molecules
Fasting and postprandial concentrations of ICAM and VCAM
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Short-chain fatty acids
Fasting and postprandial circulating short-chain fatty acids concentrations and fecal short-chain fatty acid concentrations
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response and faecal sample at both baseline and week 8
LDL receptor expression
LDL receptor expression in peripheral blood mononuclear cells
Time frame: This will be measured at baseline
Genotyping of bile acid receptor gene
Genotyping of single-nucleotide polymorphisms (SNPs) in the FXR-encoding gene NR1H4
Time frame: This will be measured at baseline
Platelets
Platelets will be collected for in-vitro studies
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Gut microbiota
Next-generation sequencing of gut bacteria and enumeration of selected bacteria using FISH (fecal samples)
Time frame: At baseline and week 8
Bile acid excretion
Fecal bile acid concentrations
Time frame: At baseline and week 8
Energy excretion
Bomb calorimetry of fecal samples
Time frame: At baseline and week 8
Urine metabolites
Markers of intervention foods/ supplements in urine (24h urine collection)
Time frame: At baseline and week 8
Blood pressure and heart rate
Ambulatory blood pressure and heart rate
Time frame: Chronic and acute effects: Fasting and 6-hour postprandial response at both baseline and week 8
Body composition
Body composition measured using bio-impedance
Time frame: At baseline and week 8
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