Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Vitamin A (Retinol) | Vitamin B6 (P5P) | |
|---|---|---|
| Category | Vitamins | Vitamins |
| Standard Dose | 5000-10,000 IU retinol (1500-3000 mcg RAE) daily | 25-50mg P5P daily |
| Timing | With fat-containing meal. Best with vitamins D and K for synergistic fat-soluble vitamin balance. | Morning with food. Often included in B-complex. |
| Cycle Duration | ongoing | ongoing |
| Evidence Level | strong_human | strong_human |
Retinol is converted to retinal (for vision, rhodopsin cycle in rod photoreceptors) and retinoic acid (for gene regulation). Retinoic acid binds RAR/RXR nuclear receptors, regulating >500 genes involved in cell differentiation, immune function, and embryonic development. It is essential for mucosal barrier integrity (gut, respiratory, skin epithelial cell turnover), T-cell differentiation (promotes Treg and Th2 over Th1/Th17), IgA secretion, and natural killer cell function. Works synergistically with Vitamin D — both share the RXR receptor as a heterodimer partner.
5000-10,000 IU retinol (1500-3000 mcg RAE) daily
With fat-containing meal. Best with vitamins D and K for synergistic fat-soluble vitamin balance.
ongoing
Pyridoxal-5-phosphate (P5P) is the active coenzyme form of vitamin B6, required by over 150 enzymes. Key roles: transamination and decarboxylation of amino acids, serving as a cofactor for aromatic L-amino acid decarboxylase (converting 5-HTP to serotonin and L-DOPA to dopamine), glutamic acid decarboxylase (producing GABA), cystathionine beta-synthase (homocysteine transsulfuration to cysteine), serine hydroxymethyltransferase (one-carbon folate metabolism), glycogen phosphorylase (glycogenolysis), and aminolevulinic acid synthase (heme synthesis).
25-50mg P5P daily
Morning with food. Often included in B-complex.
ongoing
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