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Dianabol Dbol Cycle Guide, Results, Side Effects And Dosage

# The Impact of Antioxidant Supplementati>4000 IU/d) are associated with modest reductions in total testosterone and increases in SHBG. In females, evidence is inconsistent; most studies show no effect on ovarian hormones or menstrual cycle characteristics. |
| **Dose–response** | Doses ≥4000 IU/d (especially >10 000 IU/d) tend to produce the largest changes in testosterone/SHBG, while 90 nmol/L)** | 4000–10,000 IU/day | >90 nmol/L |

\\* The higher range is often required to achieve serum levels above 90 nmol/L (≈36 ng/mL), which studies suggest correlates with maximal testosterone and better metabolic outcomes.

**Important:** 10,000 IU/day is the upper limit of what is considered safe for most adults without medical supervision; beyond that may increase risk of vitamin D toxicity.

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### 3. How Vitamin D Affects Testosterone

| Mechanism | Evidence |
|-----------|----------|
| **Binding to vitamin‑D receptor (VDR) in Leydig cells** – promotes steroidogenic enzyme expression (e.g., CYP17A1, HSD3B1). | In vitro Leydig cell studies show increased testosterone production when exposed to 1,25‑dihydroxyvitamin D. |
| **Reducing oxidative stress** – vitamin D antioxidant properties protect Leydig cells from ROS that impair steroidogenesis. | Animal models with induced oxidative stress exhibit higher testosterone after vitamin D supplementation. |
| **Modulating immune/inflammatory pathways** – reduces pro‑inflammatory cytokines (IL‑6, TNF‑α) that negatively affect testicular function. | Clinical studies demonstrate lower inflammatory markers and improved sperm parameters with vitamin D therapy. |

### 2.4 Evidence from Human Studies

| Study Type | Population | Vitamin D Intervention | Key Findings |
|------------|------------|------------------------|--------------|
| Randomized Controlled Trial (RCT) – 2020 | 50 men, age 25‑35, low baseline 25(OH)D (

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