Effect of Short-chain Fatty Acids on Aerobic Endurance

Randomized, double-blind, placebo-controlled crossover study designed to determine the effects of increasing colonic short-chain fatty acid (SCFA) content on aerobic endurance in healthy adults, and to identify underpinning mechanisms. In random order, healthy physically active adults will consume provided diets low in fiber and supplemented with SCFA-enriched high amylose maize starch (a poorly digested resistant starch considered a fermentable fiber) or low amylose maize starch (a rapidly digestible starch) for 1-week separated by a ≥2-week washout. At the end of each intervention period, participants will complete an endurance exercise bout followed by a time trial. Biological samples will be collected to assess muscle and whole body metabolism, gut microbiota, inflammation, and gastrointestinal function.

Study Overview

• Status: Recruiting
• Conditions: Metabolism; Aerobic Endurance
• Intervention / Treatment: Other: Low-amylose maize starch; Dietary supplement: High-amylose maize starch+acetate/butyrate

• Study Type: Interventional
• Enrollment (Estimated): 12
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: J. Philip Karl, PhD; Phone Number: 508-206-2318; Email: james.p.karl.civ@health.mil

Study Locations

• United States
  • Massachusetts
    • Natick, Massachusetts, United States, 01760
      • Recruiting
      • United States Army Research Institute of Environmental Medicine
      • Contact: J. Philip Karl, PhD; Phone Number: 508-206-2318; Email: james.p.karl.civ@health.mil

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Men and women aged 18 - 39 years (active-duty personnel who are 17 yr of age will also be allowed to participate).
• In good health.
• Routinely participate in moderate or higher intensity aerobic and/or resistance exercise at least 4 days per week for ≥20 min/d.
• Meet Army weight for height and body composition standards as defined in Army Regulation 600-9.
• Self-reports a usual bowel movement frequency of every other day or more often.
• Willing to refrain from the use of caffeine, alcohol, and nicotine while consuming study diets.
• Willing to refrain from all dietary supplements beginning 2 weeks prior to study start and throughout study participation.
• Willing to refrain from consumption of any foods containing live microorganisms (e.g., yogurt, kefir, kombucha) or added prebiotics (e.g. Fiber One products) beginning 2 weeks prior to study start and throughout study participation.
• Willing to participate in all study procedures.
• Females must have normal menstrual cycles between 26-32 days in duration; 5 menstrual cycles within the past 6 months; or be using an oral/hormonal contraceptive which contains low-dose estrogen/progesterone to maintain continuous levels throughout the 28-day cycle (i.e., no placebos).

Exclusion Criteria:

• Females who are pregnant, expecting to become pregnant during the study, or breastfeeding.
• Any of the following medical conditions:

Cardiac disease (including arrhythmia or fast or skipped heart beats) Hypertension Musculoskeletal injuries that compromise exercise capability Metabolic or cardiovascular abnormalities (e.g., kidney disease, diabetes, etc.) Disease of the GI tract including, but not limited to diverticulitis, inflammatory bowel disease, irritable bowel syndrome, peptic ulcer disease, Crohn's disease, and ulcerative colitis Allergy to skin adhesive or Lidocaine (or other local anesthetic being used in place of Lidocaine) Suspected or known strictures, fistulas, or physiological/mechanical GI obstruction History of gastric bezoar Swallowing disorders; severe dysphagia to food or pills Implanted or portable electro-mechanical medical devices (e.g., pacemaker)

• Colonoscopy within 3 months of study participation.
• Any use of antibiotics or antimycotics, except topical antibiotics/antimycotics, within 3 months of study participation.
• Regular (i.e., weekly or more frequent) use of over-the-counter medications (including antacids, laxatives, stool softeners, and anti-diarrheals) unless approved by study PI.
• Use of medication (i.e., diabetes medications, statins, corticosteroids, etc.) that affects macronutrient utilization and/or the ability to participate in strenuous exercise.
• Anemia (HCT <38 for men and <34 for women) or Sickle Cell Anemia/Trait.
• Not willing or able to follow all study procedures and diet/exercise restrictions.
• Allergies, intolerances, unwillingness or inability to eat provided foods and beverages.
• Following vegetarian/vegan diet or other highly restrictive diet (e.g., ketogenic diet, very high protein diet, Paleo diet, etc.).
• Any previous blood donation within the previous 8 weeks that when combined with the volume of blood collected for the study within any 8-week period would exceed 550mL.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Low-amylose maize starch; Low-amylose maize starch (AMIOCA; Ingredion, Inc).	Other: Low-amylose maize starch; Rapidly digestible low-amylose maize starch (0% amylose, 100% amylopectin) sold commercially as AMIOCA (Ingredion, Inc).
Active Comparator: High-amylose maize starch+acetate/butyrate; High-amylose maize starch, (Hylon VII; Ingredion, Inc.) to which the SCFA acetate or butyrate has been chemically added.	Dietary supplement: High-amylose maize starch+acetate/butyrate; High-amylose maize starch (HAMS), commercially available as Hylon VII (Ingredion, Inc.), to which the SCFA acetate or butyrate has been chemically added. Hylon VII is a HAMS containing ~70% amylose and used in a variety of food products. To produce SCFA-enriched HAMS, Hylon VII is chemically modified through esterification with the SCFA acetate or butyrate.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Run time	Time to complete a 5km treadmill run	Phases 1 and 2, day 8

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Muscle glycogen content	Muscle glycogen content	Phases 1 and 2, day 8
Plasma glucose turnover	Glucose production, utilization and metabolic clearance rate measured during endurance steady state exercise using 6,6-[2H2] glucose tracer	Phases 1 and 2, day 8
Whole body substrate oxidation	Carbohydrate and fat oxidation rates measured during endurance steady state exercise using indirect calorimetry	Phase 1 and 2, day 8
Serum short-chain fatty acid concentrations	Serum acetate, butyrate and propionate concentrations	Phases 1 and 2, day 8. Measured fasted (-300 minutes) and before (0 minutes) and at the end (80 minutes) of steady state endurance exercise
Fecal short-chain fatty acid concentrations	Fecal acetate, butyrate and propionate concentrations	Phases 1 and 2, days 1 and 7
Intestinal permeability	Small and large intestine permeability measured by saccharide excretion in urine	Phases 1 and 2, day 8
Intestinal pH	pH of the small intestine and large intestine measured using the SmartPill Gastrointestinal monitoring system	Phases 1 and 2, day 8

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gastrointestinal symptoms	Gastrointestinal symptoms (bloating, pain, nausea, flatulence, discomfort, urge to defecate) measured by 10 cm (0 = low, 10 = high) visual analog scale	Phases 1 and 2, daily on days 1 through 8
Gastrointestinal transit time	Transit time through the stomach, small intestine and large intestine measured using the SmartPill Gastrointestinal monitoring system	Phases 1 and 2, day 8
Circulating biomarkers of substrate utilization	Serum/plasma glucose, insulin, free fatty acids, glycerol, lactate and beta-hydroxybutyrate	Phases 1 and 2, day 8. Measured before (-300minutes, 0minutes) and during (20, 40, 60, 80minutes) steady state endurance exercise.
Total protein content in muscle	Total protein content measured in muscle collected before and after steady state endurance exercise.	Phases 1 and 2, day 8
Total protein expression of molecular markers associated with regulation of muscle metabolism.	Muscle protein signalling measured by Western blotting in muscle collected before and after steady state endurance exercise. Total protein expression of molecular markers associated with regulation of muscle metabolism will be measured to include (but not be limited to): Akt, p-AktSer473, AMPKα, p- AMPKαThr172, PGC-1α , SIRT1, ACC, p-ACCSer79, p53, p-p53Ser15, PDK4, IRS1, p-IRS1Ser302, GSK-3β, p-GSK-3βSer9, GSK-3α , p-GSK-3α Ser21, GS, p-GSSer641, and GLUT4.	Phases 1 and 2, day 8
Phosphorylation status of molecular markers associated with regulation of muscle metabolism.	Muscle protein signalling measured by Western blotting in muscle collected before and after steady state endurance exercise. Phosphorylation status of molecular markers associated with regulation of muscle metabolism will be measured to include (but not be limited to): Akt, p-AktSer473, AMPKα, p- AMPKαThr172, PGC-1α , SIRT1, ACC, p-ACCSer79, p53, p-p53Ser15, PDK4, IRS1, p-IRS1Ser302, GSK-3β, p-GSK-3βSer9, GSK-3α , p-GSK-3α Ser21, GS, p-GSSer641, and GLUT4 .	Phases 1 and 2, day 8
Pyruvate dehydrogenase activity in muscle	Pyruvate dehydrogenase activity in muscle before and after steady state endurance exercise measured colorimetric assay.	Phases 1 and 2, day 8
Gene expression	Expression of genes regulating carbohydrate and fat oxidation in muscle collected before and after steady state endurance exercise. Individual primers will be used to determine the mRNA expression of known intracellular targets regulating substrate metabolism to include (but not limited to): FAT, PDK4, HADHA, PGC-1α, PPARδ, PPARγ, FABP, CPT1a, ACOX1, GS, GSK3α, GLUT4, and HK2.	Phases 1 and 2, day 8
microRNA expression	Expression of genes and microRNA regulating carbohydrate and fat oxidation in muscle collected before and after steady state endurance exercise. microRNA analysis will be conducted using microarray, assessing microRNA that may be associated with substrate metabolism.	Phases 1 and 2, day 8
Gut microbiota composition	Relative abundance of bacterial taxa measured by 16S rRNA amplicon sequencing	Phases 1 and 2, days 1 and 7
Gut microbiome gene content	Relative abundances of microbial genes measured by shotgun metagenomics sequencing	Phases 1 and 2, days 1 and 7
Circulating biomarkers of inflammation	Serum interleukin (IL)-6, IL-10, IL-17, IL-8, IL-1ralpha, IL-1beta, tumor necrosis factor-alpha, interferon gamma	Phases 1 and 2, day 8. Measured before (-300minutes) and at the end (80minutes) of steady state endurance exercise.
Circulating biomarkers of gut barrier function	Serum claudin-3, intestinal fatty acid binding protein and zonulin	Phases 1 and 2, day 8. Measured fasted (-300minutes) and before (0minutes), during (40minutes) and at the end (80minutes) of steady state endurance exercise.
Circulating microRNA	Serum C-microRNA	Phases 1 and 2, day 8. Measured fasted (-15minutes) and at the end (80minutes) of steady state endurance exercise.
Appetite	Appetite (hunger, fullness, desire to eat, prospective consumption) measured by 10 cm (0 = low, 10 = high) visual analog scale	Phases 1 and 2, daily on days 1 through 7
Breath hydrogen and methane	Breath hydrogen and methane concentrations	Phases 1 and 2, day 8. Measured fasting (-300minutes) and before (0minutes) and at the end (80minutes) of steady state endurance exercise

Collaborators and Investigators

• Sponsor: United States Army Research Institute of Environmental Medicine
• Investigators: Principal Investigator: J. Philip Karl, PhD, United States Army Research Institute of Environmental Medicine

Study record dates

Study Major Dates

• Study Start (Actual): July 21, 2023
• Primary Completion (Estimated): June 1, 2024
• Study Completion (Estimated): September 30, 2025

Study Registration Dates

• First Submitted: August 21, 2023
• First Submitted That Met QC Criteria: September 19, 2023
• First Posted (Actual): September 26, 2023

Study Record Updates

• Last Update Posted (Actual): September 26, 2023
• Last Update Submitted That Met QC Criteria: September 19, 2023
• Last Verified: September 1, 2023

More Information

Terms related to this study

• Keywords: microbiome; endurance; gastrointestinal; resistant starch; fiber; short-chain fatty acid
• Other Study ID Numbers: 23-13H; M-11031 (Other Identifier: HQ US Army Medical Research and Development Command IRBO)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: De-identified data and samples will remain under the control of the Principal Investigator and may be shared with outside collaborators for future research with appropriate data sharing agreements and legal/ethical approvals. De-identified microbiome sequencing data may be posted in a publicly available data repository.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No