Pantothenic Acid (B5) vs Vitamin D3

Mechanism

Pantothenic acid is converted to Coenzyme A (CoA), the universal acyl-group carrier essential for >100 metabolic reactions. CoA is required for: fatty acid synthesis and beta-oxidation, citric acid cycle (acetyl-CoA entry), steroid hormone synthesis (pregnenolone from cholesterol), acetylcholine synthesis, melatonin synthesis, and Phase II detoxification (acetylation reactions). Pantethine (the active form) supports healthy lipid metabolism by inhibiting hepatic HMG-CoA reductase and fatty acid synthase, while stimulating fatty acid oxidation.

Standard Dosing

500mg pantothenic acid or 300mg pantethine twice daily

Timing

With meals. Split doses for pantethine.

Cycle Duration

ongoing

Side Effects

• Diarrhea at high doses
• GI discomfort
• Contact dermatitis (topical dexpanthenol)

Contraindications

• Hemophilia (theoretical concern: pantethine may have mild antiplatelet effect at high doses)

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Mechanism

Vitamin D3 (cholecalciferol) is hydroxylated in the liver to 25(OH)D (calcidiol), then in the kidneys to 1,25(OH)2D (calcitriol), the active hormone. Calcitriol binds the nuclear vitamin D receptor (VDR), forming a heterodimer with RXR that regulates >1000 genes. Key actions: upregulation of intestinal calcium/phosphorus absorption (TRPV6, calbindin), modulation of innate immunity (cathelicidin LL-37 antimicrobial peptide production), suppression of adaptive immune overactivation (Th1/Th17 to Treg shift), regulation of PTH and osteocalcin for bone mineralization, and modulation of insulin secretion from beta cells.

Standard Dosing

5000 IU daily (125 mcg)

Timing

With largest fat-containing meal of the day (fat-soluble). Morning preferred.

Cycle Duration

ongoing (lifelong for most people in northern latitudes)

Side Effects

• Hypercalcemia at excessive doses (>10,000 IU/day long-term without monitoring)
• Nausea/vomiting (toxicity)
• Kidney stones (with excessive calcium)
• Metallic taste (toxicity sign)

Contraindications

• Hypercalcemia
• Granulomatous diseases (sarcoidosis, some lymphomas — unregulated 1-alpha hydroxylase conversion)
• Primary hyperparathyroidism (without monitoring)
• Williams syndrome

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