Vitamin A
Review the scientific evidence and bio-availability of Vitamin A, followed by our curated database of formulations.
Vitamin A (Retinol, Retinal, and Retinyl esters) is a group of fat-soluble compounds essential for human physiology, particularly within the realms of vision, cellular differentiation, and neurobiology. Discovered in 1913 by Elmer McCollum and Marguerite Davis at the University of Wisconsin-Madison, it was the first vitamin to be identified. Historically, the use of liver—a potent source of Vitamin A—to support visual adaptation in low-light environments dates back to ancient Egypt, though the molecular mechanism remained unknown until the 20th century. In the body, Vitamin A exists as preformed Vitamin A (found in animal products) and provitamin A carotenoids (such as beta-carotene found in plants), which are converted into active retinoids.
Clinical Benefits & Mechanism of Action
Vitamin A functions primarily through its active metabolites, retinal and retinoic acid, which act as ligands for specific protein receptors and structural components of visual pigments.
- Visual Phototransduction: In the retina, 11-cis-retinal binds to the protein opsin to form rhodopsin (in rods) and iodopsin (in cones). When light hits the retina, it triggers the isomerization of 11-cis-retinal to all-trans-retinal, initiating a G-protein coupled cascade that transmits normal electrical signals to the visual cortex.
- Genomic Regulation: All-trans-retinoic acid (ATRA) and 9-cis-retinoic acid function as signaling molecules that enter the cell nucleus and bind to Retinoic Acid Receptors (RAR) and Retinoid X Receptors (RXR). These complexes bind to Retinoic Acid Response Elements (RARE) on DNA, modulating the transcription of over 500 genes involved in healthy cell growth, development, and differentiation.
- Neuroplasticity and Cognition: Within the central nervous system, Vitamin A signaling supports healthy hippocampal function. It regulates the expression of genes involved in synaptic plasticity, such as those encoding for the NMDA receptor and CaMKII, which are vital for supporting long-term potentiation (LTP) and natural memory formation.
- Immune Homeostasis: Vitamin A is a core micronutrient for supporting natural body defences. It maintains the structural integrity of mucosal barriers and promotes the normal differentiation of regulatory T-cells (Tregs), which assists in maintaining a balanced immune response and supporting healthy systemic tolerance.
