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Role of Gastrointestinal Microbes on Digestion of Resistant Starch and Tryptophan Availability to Humans

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02974699
Recruitment Status : Unknown
Verified May 2017 by Paul Burghardt, Wayne State University.
Recruitment status was:  Recruiting
First Posted : November 28, 2016
Last Update Posted : May 4, 2017
Information provided by (Responsible Party):
Paul Burghardt, Wayne State University

Brief Summary:
There is currently a critical gap in knowledge of how intestinal bacterial communities alter metabolic substrates available to the host thereby influencing central and enteric nervous system (CNS/ENS) neurotransmitter levels involved in regulating carbohydrate consumption in humans. Understanding these relationships is essential for developing strategies to improve blood glucose control and to reduce the risk of transitioning from prediabetes to type-2 diabetes (T2D). The investigators' long-term goal is to determine the biological underpinnings of behaviors that impact food intake and blood glucose control that contribute to the development of T2D. The objective of this proposal, which is an essential next step in attaining the investigators' long-term goals, is to determine how bacterial populations in the digestive system impact circulating tryptophan (TRP) and large neutral amino acid (LNAA) levels that regulate production of monoamine 5-hydroxytryptamine (5-HT, serotonin) in the ENS and in gastrointestinal system and the brain. The central hypothesis is that a reduced ratio of TRP producing (TRPp) to TRP consuming (TRPc) bacteria (decreased TRPp:TRPc ratio) in the gut will decrease TRP availability following a carbohydrate meal lowering the plasma TRP:LNAA ratio and resulting in less TRP for ENS/CNS production of 5HT. Further, dietary interventions that promote TRPp bacterial abundance within the gut will increase TRP availability to the host. The investigators will test the central hypothesis and, thereby, accomplish the overall objective for this project by pursuing the following specific aims: 1) Assess impact of divergent microbiota on plasma TRP:LNAA ratio in response to acute carbohydrate consumption, and 2) Assess the impact of dietary supplementation with resistant starch (RS) on gut microbiota and circulating TRP:LNAA ratio. During Aim 1, stool samples will be collected from healthy participants. Participants will be stratified based on gut TRPp:TRPc ratio and the response to an acute meal will be assessed by determining plasma TRP:LNAA ratios. During Aim 2 the capacity for 4-weeks of pre-biotic RS (Potato Starch) supplementation to increase the TRPp:TRPc bacterial ratio in the gut will be determined from stool samples. Additionally, plasma TRP:LNAA ratio following acute carbohydrate consumption before and after supplementation will be determined. The scientific contribution will be to determine the impact of RS on TRPp and TRPc bacteria abundance in the gut, and how bacterial populations impact circulating TRP:LNAA levels, that can impact ENS and CNS 5HT production in humans. This contribution will be significant because it will have direct translational implications for human diseases with altered 5HT signaling.

Condition or disease Intervention/treatment Phase
Type II Diabetes Dietary Supplement: Potato Starch (Bob's Red Mill) Dietary Supplement: Pregelatinized Starch (Resource ThickenUp) Early Phase 1

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 20 participants
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single (Participant)
Primary Purpose: Basic Science
Study Start Date : January 2017
Estimated Primary Completion Date : December 2017

Resource links provided by the National Library of Medicine

Drug Information available for: Starch

Arm Intervention/treatment
Experimental: Potato Starch (Bob's Red Mill)
Daily dietary supplementation with Potato Starch (48g total/day) suspended in water. 24g will be consumed 2 times per day.
Dietary Supplement: Potato Starch (Bob's Red Mill)
Subjects will be assigned to Potato Starch (active) following assessment of their gut microbiome.

Placebo Comparator: Resource ThickenUp Pregelatinized Starch
Daily dietary supplementation with Pregelatinized Starch (48g total/day) suspended in water. 24g will be consumed 2 times per day.
Dietary Supplement: Pregelatinized Starch (Resource ThickenUp)
Subjects will be assigned to Pregelatinized Starch (placebo) following assessment of their gut microbiome.

Primary Outcome Measures :
  1. Plasma Amino Acid Levels [ Time Frame: Baseline ]
  2. Plasma Amino Acid Levels [ Time Frame: Following 4 weeks of supplementation ]

Secondary Outcome Measures :
  1. Change in Plasma Amino Acid Levels [ Time Frame: Baseline vs. 4-weeks ]
    Difference in plasma amino acid levels between baseline and following 4-weeks of supplementation

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. Male and female
  2. Age 18 - 65 years old
  3. Non-Obese (BMI ≤ 30 kg/m2 and >17 kg/m2 )

Exclusion Criteria:

  1. Urine toxicology positive,
  2. Pregnant (female)
  3. Alcohol intake 48 hours prior to studies,
  4. Evidence of inherited disorders of lipid metabolism,
  5. History of Cancer within the last 5 years,
  6. Human immunodeficiency virus (HIV) antibody positive,
  7. Patients with solid organ transplants,
  8. Unstable angina or NY heart association class II failure or above,
  9. Gastrointestinal disease specifically GI motility disorders,
  10. Unstable neuropsychiatric disease including major depression/anxiety, eating disorder such as bulimia or anorexia,
  11. End stage renal or hepatic disease,
  12. Autoimmune disorders (e.g. SLE),
  13. Prior bariatric surgery,
  14. A history or current alcohol/substance abuse or nicotine containing products or illicit drugs of abuse during the preceding 6 months,
  15. Treatment within one month with sedative hypnotic medications (benzodiazepines, barbiturates), or over the counter sleeping aids
  16. Women: any selective estrogen receptor modulator or aromatase inhibitor Men:

    androgen ablation/deprivation hormonal therapies

  17. Any medical condition, which in the opinion of the investigator would make the patient unsuitable for recruitment, or could interfere with the patient participating in or completing the protocol
  18. Any previous adverse events or allergic reactions to acetaminophen
  19. Unwilling or unable to consent for the study.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02974699

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Contact: Paul R Burghardt, PhD 3135770107
Contact: Katlin Chappelle, BS 3135772716

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United States, Michigan
Wayne State University Recruiting
Detroit, Michigan, United States, 48202
Contact: Paul Burghardt    313-577-0107   
Sponsors and Collaborators
Wayne State University
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Responsible Party: Paul Burghardt, Assistant Professor, Wayne State University Identifier: NCT02974699    
Other Study ID Numbers: 110116M1F
First Posted: November 28, 2016    Key Record Dates
Last Update Posted: May 4, 2017
Last Verified: May 2017
Additional relevant MeSH terms:
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Diabetes Mellitus, Type 2
Diabetes Mellitus
Glucose Metabolism Disorders
Metabolic Diseases
Endocrine System Diseases