The Effects of Vitamin C on Acute-Exercise in Postmenopausal Females

NCT07109115 | Not Yet Recruiting

• 1 other identifier: 302767
• Study Type: interventional
• Target: 30
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study is looking at whether vitamin C can help improve oxidative stress and blood vessel health in females after menopause. We will see if taking different amounts of vitamin C for a few days changes how the body handles stress from exercise. This could lead to safer ways to protect females from heart disease without using hormone therapy.

Conditions

Females; Males; Menopause; Sedentary; Healthy Participants

Keywords

Vitamin C; Postmenopausal Females; Exercise; Oxidative Stress; Vascular Health

Outcome Measures

Primary Outcomes (4)

• Flow-Mediated Dilation (FMD%) - Brachial Artery Endothelial Function

  Brachial artery endothelial function will be measured by flow-mediated dilation (FMD) in each participant 5x (at baseline and after 0mg (placebo) 200mg, 500mg, and 1000mg of vitamin C). Participants will be placed in a supine position with their left forearm slightly extended and supinated with legs straight. The brachial artery will be imaged using a high-resolution 7.5MHz linear array transducer at rest, during 5 minutes of forearm occlusion via cuff inflation (250mmHg), and continuously for 2 minutes post-occlusion; an EKG trigger will be used to capture images during end-diastole of the cardiac cycle.

  5x: Baseline/un-supplemented; after 3-days of 200mg of vitamin C supplementation; after 3-days of 500mg of vitamin C supplementation; after 3-days of 1000mg of vitamin C supplementation; after 3-days of 0mg of vitamin C/placebo supplementation

• Basal ROS Concentrations - plasma 8-Isoprostane (8-iso) and malondialdehyde (MDA)

  A venous blood sample will be collected from a vein in the antecubital fossa. Plasma will be separated out and stored at -80C until concentrations of 8-Isoprostane (8-iso) and malondialdehyde (MDA) are measured via commerically available ELISA kits. ROS concentrations will be measured at 5x points: at baseline and after 0mg (placebo), 200mg, 500mg, and 1000mg of vitamin C

  baseline and after 0mg/placebo, 200mg, 500mg, and 1000mg dose of vitamin C for 3-days each

• Resting ROS/NO Balance - plasma N-oxides (nitrite and nitrate)

  Venous blood samples will be collected from an antecubital fossa vein. Plasma will be separated out and stored at -80C until analysis. Plasma N-oxides (nitrite and nitrate) will be evaluated from the plasma via ozone-based chemiluminescence using a Sievers NOA model 280i. The N-oxides will be compared with the basal ROS also measured to calculate a ROS/NO balance.

  Baseline and after 3-days of placebo, 200mg, 500mg, and 1000mg doses of vitamin C

• Exercise-Induced ROS (plasma 8-Isoprostane (8-iso) and malondialdehyde (MDA)) and NO (plasma nitrate and nitrite)

  An intravenous catheter will be placed into a vein in the antecubital fossa. Participants will complete 4 high-intensity exercise sessions (\~200kcals). Each exercise session will be after 3-days of vitamin C supplementation (0mg/placebo, 200mg, 500mg, and 1000mg). Blood will be collected immediately before, immediately after, 15-min after, and 30-min after exercise. Plasma will be separated out and used to evaluate the changes in ROS (plasma 8-Isoprostane (8-iso) and malondialdehyde (MDA)) and NO (plasma nitrate and nitrite) from baseline/rest.

  16x points: 4 exercise session with blood will be collected immediately before, immediately after, 15-min after, and 30-min after exercise

Secondary Outcomes (7)

• Vitamin C

  5x points over 5-6 weeks: (1) baseline/unsupplemented and after 3-days of (2) 0mg/placebo, (3) 200mg, (4) 500mg, and (5) 1000mg of vitamin C supplementation

• Oral Nitrate Reducing Capacity

  5x points over 5-6 weeks: (1) baseline/unsupplemented and after 3-days of (2) 0mg/placebo, (3) 200mg, (4) 500mg, and (5) 1000mg of vitamin C supplementation

• Pulse Wave Analysis and Velocity

  5x points over 5-6 weeks: (1) baseline/unsupplemented and after 3-days of (2) 0mg/placebo, (3) 200mg, (4) 500mg, and (5) 1000mg of vitamin C supplementation

• Microvascular Function

  5x points over 5-6 weeks: (1) baseline/unsupplemented and after 3-days of (2) 0mg/placebo, (3) 200mg, (4) 500mg, and (5) 1000mg of vitamin C supplementation

• Exercise Capacity

  Baseline only

Study Arms (4)

Active Comparator 1: 200mg vitamin C

EXPERIMENTAL

Subjects will supplement with 200mg of vitamin C 2x a day for 3 days. 100mg will be taken in the morning and 100mg in the evening. On the 3rd day, subjects will be scheduled to return for post-supplementation testing and be instructed to take a full 200mg dose 30-minutes prior to arriving.

Dietary Supplement: Vitamin C (Ascorbic Acid)

Active Comparator 1: 500mg vitamin C

EXPERIMENTAL

Subjects will supplement with 500mg of vitamin C 2x a day for 3 days. Subjects will take half the dose in the morning and half the dose in the evening. On the 3rd day, subjects will be scheduled to return for post-supplementation testing and be instructed to take a full dose 30-minutes prior to arriving.

Dietary Supplement: Vitamin C (Ascorbic Acid)

Active Comparator 1: 1000mg vitamin C

EXPERIMENTAL

Subjects will supplement with 1000mg of vitamin C 2x a day for 3 days. Subjects will take half the dose in the morning and half the dose in the evening. On the 3rd day, subjects will be scheduled to return for post-supplementation testing and be instructed to take a full dose 30-minutes prior to arriving.

Dietary Supplement: Vitamin C (Ascorbic Acid)

Placebo Comparator 1: 0mg Vitamin C

PLACEBO COMPARATOR

Subjects will supplement with 0mg of vitamin C 2x a day for 3 days. Subjects will take half the dose in the morning and half the dose in the evening. On the 3rd day, subjects will be scheduled to return for post-supplementation testing and be instructed to take a full dose 30-minutes prior to arriving.

Dietary Supplement: Vitamin C (Ascorbic Acid)

Interventions

Vitamin C (Ascorbic Acid) DIETARY_SUPPLEMENT

Subjects will be supplemented with the following vitamin C doses: 0mg, 200mg, 500mg, 1000mg.

Active Comparator 1: 1000mg vitamin C; Active Comparator 1: 200mg vitamin C; Active Comparator 1: 500mg vitamin C; Placebo Comparator 1: 0mg Vitamin C

Eligibility Criteria

• Age: 45 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Post-menopausal (for females; defined as no menstrual cycle for 1-year)
• Sedentary (\<150min of moderate-intensity exercise per week or not engaged in a regular exercise program)
• Non-smoking
• Weight stable (+/-3 kg over the past 3 months)

You may not qualify if:

• Overt CVD
• Any condition or medication contraindicating safe exercise
• Hormone replacement therapy (last 3-months)
• Use of vasoactive medications (e.g., calcium channel blockers, statins, ACE inhibitors, ARBs, nitrates, alpha-/beta-blockers, diuretics), diabetes, or unstable medication regimens
• Diabetes
• Oral antibiotic use within previous four weeks
• Oral disease or poor oral health as determined by the Oral Health Questionnaire
• Using an antibacterial mouthwash or a mouthwash containing chlorhexidine and unwilling to discontinue use
• Cancer diagnosis

Sponsors & Collaborators

• University of Virginia: lead

MeSH Terms

Conditions

Sedentary Behavior; Motor Activity

Interventions

Ascorbic Acid

Condition Hierarchy (Ancestors)

Behavior

Intervention Hierarchy (Ancestors)

Sugar Acids; Acids, Acyclic; Carboxylic Acids; Organic Chemicals; Hydroxy Acids; Carbohydrates

Study Officials

• Jason Allen, PhD

  UVA

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Casey Derella, PhD

CONTACT

434-924-1655; bxg7vn@uvahealth.org

Ben Stephenson, M.Ed

CONTACT

434-924-1062; bls4qq@uvahealth.org

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: July 23, 2025
• First Posted: August 7, 2025
• Study Start: September 1, 2025
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): September 1, 2027
• Last Updated: August 7, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will not share