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

The Effects of Vitamin C on Exercise-Induced Oxidative Stress in Postmenopausal Females

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.

Cardiovascular disease (CVD) remains the leading cause of death in the United States. After menopause, females face a significantly increased risk of CVD due to declines in estrogen, which negatively impact nitric oxide (NO) production and vascular health. This coincides with an increase in reactive oxygen species (ROS), leading to an imbalance in redox signaling that may blunt beneficial adaptations to exercise.

Vitamin C (ascorbic acid) is a potent antioxidant that may restore redox balance and endothelial function. However, most studies have been conducted in males using high doses that may suppress beneficial ROS signaling. In contrast, this trial focuses on the dose-response effects of short-term vitamin C supplementation (200 mg, 500 mg, and 1000 mg/day for 3 days) on ROS/NO balance, both at rest and in response to acute exercise, in PMF versus age-matched males.

The study includes 15 sedentary PMF and 15 sedentary age-matched males, ages 45 and older. Participants complete 5-6 total study visits: one baseline/screening visit and four intervention visits in a randomized crossover design. Each intervention visit consists of 3 days of supplementation followed by fasting blood draws, vascular testing, and a 200-kcal high-intensity exercise bout on a cycle ergometer.

Inclusion Criteria:

• 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)

Exclusion Criteria:

• 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