Vitamin B2 & Exercise: What You Need to Know

observational-study PMID: 34836352

Quick Summary: This study looked at how exercise affects vitamin B2 (riboflavin) levels in women. It found that a single workout didn't change vitamin B2 status, regardless of how fit the women were.

Does Exercise Affect Vitamin B2 Levels?

The research aimed to see if a single workout session would impact vitamin B2 levels in women with different fitness levels. The study measured vitamin B2 status before and after a 60-minute cycling session. The results showed that a single bout of exercise didn't significantly change vitamin B2 levels in either group of women, whether they were highly fit or less fit.

Study Details

Who was studied: 32 women who regularly exercised. Half were considered highly fit, and half were less fit.

How long: The study looked at the women's vitamin B2 levels before and after a single 60-minute cycling workout.

What they took: The women did not take any extra vitamin B2. Their vitamin B2 levels were measured using a blood test.

What This Means For You

This study suggests that if you're a woman who exercises for about an hour at a moderate intensity, you likely don't need to worry about immediately increasing your vitamin B2 intake. Your body seems to handle the exercise without a sudden drop in this important vitamin. However, this study only looked at a single workout. More research is needed to understand the long-term effects of regular exercise on vitamin B2 needs.

Study Limitations

Small Group: The study only included 32 women, so the results might not apply to everyone.

Only Women: The study focused on women, so the findings may not be the same for men.

Short-Term: The study only looked at the immediate effects of exercise. We don't know how regular exercise over time might affect vitamin B2 levels.

No Diet Control: The study didn't control what the women ate, so their vitamin B2 intake varied.

Specific Exercise: The study only looked at cycling. Other types of exercise might have different effects.

Key Findings

The study found no significant difference in vitamin B2 status, measured by erythrocyte glutathione reductase activation coefficient (EGRAC), between high- and low-fitness females after a single 60-minute cycling session at 70% VO₂ max. Baseline EGRAC levels were similar in both groups (high-fit: 1.29 ± 0.13, low-fit: 1.31 ± 0.14; p=0.78). Post-exercise EGRAC increased slightly in high-fit females (1.33 ± 0.15) but decreased in low-fit females (1.28 ± 0.12), though these changes were not statistically significant (p=0.11 and p=0.23, respectively). Overall, acute exercise did not alter vitamin B2 status in either group, suggesting that short-term physical activity does not acutely increase riboflavin demand in females, regardless of fitness level.

Study Design

This observational cross-sectional study included 32 recreationally active females (16 high-fit, 16 low-fit), categorized based on VO₂ max thresholds representing long-term physical activity levels. Participants underwent baseline blood tests, completed a 60-minute cycling session at 70% VO₂ max, and had follow-up EGRAC measurements overnight post-exercise. The study duration spanned a single exercise bout with short-term follow-up (24 hours).

Dosage & Administration

No riboflavin supplementation was administered. Vitamin B2 status was assessed endogenously via EGRAC, a biomarker reflecting functional riboflavin deficiency.

Results & Efficacy

Baseline EGRAC: No difference between high-fit (1.29 ± 0.13) and low-fit (1.31 ± 0.14) groups (p=0.78).
Post-Exercise EGRAC: High-fit increased to 1.33 ± 0.15 (p=0.11 vs. baseline), while low-fit decreased to 1.28 ± 0.12 (p=0.23 vs. baseline). Neither change reached statistical significance.
Group Comparison Post-Exercise: No interaction effect between fitness level and EGRAC response (p=0.11).
Correlation: Exercise duration or intensity did not correlate with EGRAC changes (p>0.05).

Limitations

Sample Size: Small cohort (n=32) may limit power to detect subtle differences.
Population Specificity: Results apply only to recreationally active females; findings may not generalize to males, older adults, or elite athletes.
Short-Term Focus: Measured effects only overnight post-exercise; longer-term impacts of repeated bouts unknown.
No Dietary Control: Riboflavin intake was not standardized, potentially confounding baseline status.
Single Exercise Modality: Findings limited to moderate-intensity cycling; high-impact or prolonged exercise effects untested.

Clinical Relevance

This study suggests that a single 60-minute exercise session at moderate intensity does not acutely compromise vitamin B2 status in females, regardless of fitness level. For supplement users, these results imply that short-term riboflavin requirements are unlikely to spike post-exercise, though long-term needs in high-fit individuals remain unclear. Practically, females engaging in similar exercise protocols may not require immediate riboflavin adjustments, but further research is needed to confirm these findings in diverse populations and exercise contexts.

Source: PubMed (2021)