Impact of Dietary Phosphate Excess on Exercise Capacity and Visceral Adiposity

NCT05147909 | Recruiting DMC

• 1 other identifier: STU-2021-1068
• Study Type: interventional
• Target: 124
• Locations: 1 country
• Sites: 1

Brief Summary

Studies in mice demonstrated that dietary phosphate (Pi) loading that mimic the level of US adult consumption leads to reduced spontaneous locomotor activity, exercise capacity, and reduced resting metabolic rate when in normal mice by impairing skeletal muscle mitochondrial function and fat oxidation. However, relevance of this findings in humans remains unknown.

Conditions

Physical Inactivity; Phosphate Overload; Visceral Obesity

Outcome Measures

Primary Outcomes (1)

• oxygen uptake (VO2) during peak exercise

  VO2 (ml of oxygen consumed /min) will be measured using a metabolic cart (Medgraphics) during exercise in a stationary bicycle. Standard breath-by-breath respiratory gases (VO2) will be measured at rest and after 3 minutes of steady state exercise at both 20 and 40 Watts using a cycle ergometer (Lode). Then, the partcipants will be asked to perform exercise to maximal level to obtain peak VO2.

  4 weeks

Secondary Outcomes (4)

• Resting ATP synthesis

  4 weeks

• Phosphocreatine (PCr) depletion

  4 weeks

• submaximal VO2

  4 weeks

• Cardiac output (CO)

  4 weeks

Study Arms (2)

Sodium Phosphate (NaPO4) then sodium chloride (NaCl)

EXPERIMENTAL

Participants will be asked to take 2 capsules daily of Sodium Phosphate (containing a total of 500 mg of Pi, 372mg of sodium) ) for 4 weeks during the high Pi phase (total Pi intake 1,200 mg/d). Then, participants will be asked to take 2 capsules of Sodium Chloride (NaCl, containing a total of 372mg of sodium) to match Na content to Sodium Phosphate without extra Pi daily for 4 weeks during the low Pi phase (total Pi intake = 700 mg/d).

Dietary Supplement: Sodium Phosphate; Dietary Supplement: Sodium Chloride

NaCl then NaPO4

EXPERIMENTAL

Participants will be asked to take 2 capsules daily of Sodium Chloride (NaCl, containing a total of 372mg of sodium) for 4 weeks during the low Pi phase (total Pi intake = 700 mg/d). Then, participants will be asked to take 2 capsules of Sodium Phosphate daily for 4 weeks Sodium Phosphate (containing a total of 500 mg of Pi, 372mg of sodium) for 4 weeks during the high Pi phase (total Pi intake 1,200 mg/d).

Dietary Supplement: Sodium Phosphate; Dietary Supplement: Sodium Chloride

Interventions

Sodium Chloride DIETARY_SUPPLEMENT

Sodium Chloride 2 capsules daily (NaCl, containing a total of 372mg of sodium)

Also known as: NaCl

NaCl then NaPO4; Sodium Phosphate (NaPO4) then sodium chloride (NaCl)

Sodium Phosphate DIETARY_SUPPLEMENT

Sodium Phosphate 2 capsules daily (containing a total of 500 mg of Pi, 372mg of sodium)

Also known as: NaPO4

NaCl then NaPO4; Sodium Phosphate (NaPO4) then sodium chloride (NaCl)

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• The randomized crossover trial will be performed in on otherwise healthy subjects without diabetes mellitus, chronic kidney disease (CKD), preexisting cardiovascular disease or treatment with any vasoactive agent that might alter cardiovascular responses to exercise.

You may not qualify if:

• history of cardiopulmonary disease or chronic kidney disease,
• treatment with antihypertensive medications,
• estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73m2, (4) diabetes mellitus or other systemic illness,
• (5) pregnancy, (6) hypersensitivity to sodium phosphate, (7) any history of substance abuse or current cigarette use, (8) any history of psychiatric illness, (9) history of active malignancy, (10) serum phosphorus \< 2.4 or \> 4.5 mg/dL.

Sponsors & Collaborators

• University of Texas Southwestern Medical Center: lead

Study Sites (1)

University of Texas Southwestern

Dallas, Texas, 75209, United States

RECRUITING

MeSH Terms

Conditions

Sedentary Behavior; Obesity, Abdominal

Interventions

sodium phosphate; Sodium Chloride

Condition Hierarchy (Ancestors)

Behavior; Obesity; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Chlorides; Hydrochloric Acid; Chlorine Compounds; Inorganic Chemicals; Sodium Compounds

Study Officials

• Wanpen Vongpatanasin, MD

  Wanpen.Vongpatanasin@UTSouthwestern.edu

  PRINCIPAL INVESTIGATOR

Central Study Contacts

John Giacona, PA-C

CONTACT

2146484403; john.giacona@utsouthwestern.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: Investigational drug service at UT Southwestern will dispense Sodium Phosphate vs. NaCl tablets and the study subjects will be blinded to the type of supplement they receive.
• Purpose: PREVENTION
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor of Medicine

Study Record Dates

• First Submitted: November 23, 2021
• First Posted: December 7, 2021
• Study Start: September 14, 2022
• Primary Completion (Estimated): March 31, 2027
• Study Completion (Estimated): March 30, 2028
• Last Updated: February 17, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: 12 months after study is published

Locations

US (1)