Obesity, Inflammation
Conditions
Keywords
Walnuts, gastrointestinal microbiota, bile acid profiles, inflammation, glycemia, insulinemia
Brief summary
Obesity is a growing health issue that effects the majority of adults in the United States. Prevalence of other metabolic diseases are increased in obese adults, including systemic inflammation. There is emerging evidence that the gut microbiota have a mediating role in controlling inflammation by producing butyrate when ingested fiber is fermented. Since these microbes are modifiable by diet, the investigators plan to introduce walnuts to the diets of participants with obesity because they are rich in fiber and unsaturated fatty acids. The purpose of this study is to understand the impacts of walnut consumption on the gut microbiota and the effect they have on bile acid profiles and systemic inflammation. The investigators intention is to identify how these walnut-derived molecules influence Faecalibacterium spp., a butyrate producing microbe. Increased levels of butyrate have shown to decrease secondary bile acids and decrease inflammation.
Interventions
OTHERWalnuts
The intervention treatment will contain walnuts.
OTHERWalnut Oil
The intervention treatment will contain walnut oil.
OTHERControl
The control treatment will contain corn oil.
Sponsors
University of Illinois at Urbana-Champaign
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
25 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
Participants will include adults ages 25-75 years BMI of \> 30 kg/m2 Ability to drop-off fecal sample within 15 minutes of defecation
Exclusion criteria
* Walnut allergy or intolerance * Food allergies or intolerances * Prior diagnosis of metabolic or gastrointestinal disease (cardiovascular disease and type 1 or type 2 diabetes, chronic constipation, diarrhea, Crohn's disease, celiac disease, ulcerative colitis, irritable bowel syndrome, diverticulosis, stomach or duodenal ulcers, hepatitis, HIV, cancer, etc.) * Women that are pregnant, had a baby within the last 12 months, or lactating * Individuals that smoke, use tobacco, abuse drugs, or consume \> 2 alcoholic beverages per day. * \> 5% weight change in the past month or \> 10% change in the past year * Oral antibiotics during the previous 6 weeks * Fasting blood glucose \>126 mg/dL, blood pressure \>160/100 mm Hg, elevation in serum transaminases (i.e. \>3 times the upper limit of normal) or with evidence of liver disease, including primary biliary cirrhosis or gallbladder disease, constipation, are currently taking lipid-lowering medications, oral hypoglycemic agents, or insulin, or certain medications (laxatives, bile acid sequestrants, and opiates) * History of malabsorptive or restrictive bariatric surgeries (e.g., gastric bypass, sleeve gastrectomy, adjustable gastric band) or gall bladder removal surgery. * Are unable to consume the experimental meals/snacks. * Participants who have donated blood within the last 8 weeks * Recent diagnosis of anemia * Concurrent enrollment in another dietary, exercise, or medication study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Fecal Microbial Species | Fecal samples will be collected at the end of each 3 week condition. | Abundances of fecal Faecalibacterium spp. and Roseburia spp measured using metagenomic sequencing in walnut and walnut oil vs. control. |
| Concentration of fecal bile acids | Fecal samples will be collected at the end of each 3 week condition. | Fecal bile acid concentrations measured using HPLC in walnut and walnut oil vs. control |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Fecal Microbial Metabolites | Fecal samples will be collected once at the end of each 3 week condition. | Concentrations of fecal microbial metabolite (phenol/indoles, short chain fatty acids, and ammonia) concentrations measured using GC-MS in walnut and walnut oil in comparison to a control (corn oil) |
Other
| Measure | Time frame | Description |
|---|---|---|
| Mixed-meal tolerance test | At the end of each 3 week condition. | Blood glucose and insulin concentrations and area under the curve will be measured in blood during a mixed meal tolerance test that includes a standard glucose beverage and the respective walnut, walnut oil, or corn oil treatment. |
| Fecal Microbiome | Fecal samples will be collected at the end of each 3 week condition. | Relative abundance of microbial genes and genera measured using metagenomic sequencing of extracted fecal DNA to compare abundances between walnut, walnut oil, and corn oil. |
| Intestinal permeability | 24-hour urine collections will occur at the end of each 3 week condition | Intestinal permeability will be measured using a orally ingested sugar substitutes. 24-hour urinary appearance of the sugars will be quantified using GC-MS. |
| Inflammatory markers | Blood samples will be collected at the end of each 3 week condition. | LPS-binding protein and inflammatory markers (CRP and TNFa) concentrations in walnut and walnut oil vs. control (corn oil) |
| Serum bile acid profiles | Blood samples will be collected during a mixed-meal tolerance test that occurs at the end of each 3 week condition. | Serum bile acid concentrations will be measured using LC-ESI-MS/MS to compare concentrations between walnut and walnut oil and control (corn oil) |
Countries
United States
Outcome results
None listed