Vitamin A is the name of a group of fat-soluble molecules referred to as retinoids. Retinoids belong to the terpene family and are sourced from both flora (plants) and fauna (animal sources). Terpenes occur in aromatic substances and spice plants, cellular structuring substances, hormones, and vitamins.¹ Their molecular structures include retinol, retinaldehyde, retinoic acid. Retinoic acid shows the most biological activity.² Retinoic acid modulates gene expression and influences cellular processes in both the epidermis and dermis. Vitamin A has an entire series of derivatives and provitamins.³ Vitamin A esters include retinyl acetate, retinyl palmitate, and retinyl propionate. These ingredients are enzymatically hydrolyzed in the skin.

Vitamin A is obtained from the foods that are consumed. They also require some fat in the diet to support absorption. Within the gut, dietary retinyl esters are hydrolyzed to retinol.⁴ The liver will either store it as an ester form or release it as retinol into the circulatory system, so it reaches nuclear receptors in the skin cells.

Product formulations require careful consideration as to the vitamin A molecular structure, its dose, and choice of accompanying ingredients. Manufacturers using retinoid technology in their product lines also formulate with antioxidants and other supporting ingredients directed towards treating various skin conditions. Vitamins A, C, E, liposomal vitamin B₃ (niacinamide), B_5, carnosine, and other anti-inflammatory constituents support gradual skin improvement with an increase of vitamin A reserves. The result may be the restoration of the barrier function, wrinkle reduction, and overall improvement of the skin. 

Lastly, and most notably, the internal consumption of balanced nutrition is essential when attempting to correct compromised skin and other vitamin A-deficient conditions.

Resources

1. Co.KG, KOKO GmbH &. “Retinoids and Their Use in Cosmetics.” Retinoids and their use in cosmetics, 2015. https://dermaviduals.com/english/publications/special-actives/retinoids-and-their-use-in-cosmetics.html.
2. “Office of Dietary Supplements - Vitamin A.” NIH Office of Dietary Supplements. U.S. Department of Health and Human Services, 2020. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/.
3. Lautenschlaeger, Dr. Hans. “Vitamins in Cosmetics .” Vitamins in cosmetics, 2014. https://dermaviduals.com/english/publications/special-actives/tiny-life-helpers-vitamins-in-cosmetics.html.
4. O'Byrne, Sheila M, and William S Blaner. “Retinol and Retinyl Esters: Biochemistry and Physiology.” Journal of lipid research. The American Society for Biochemistry and Molecular Biology, July 2013. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679378/.
5. Szalay, Jessie. “What Are Carotenoids?” LiveScience. Purch, October 15, 2015. https://www.livescience.com/52487-carotenoids.html.
6. Huang, Zhiyi, Yu Liu, Guangying Qi, David Brand, and Song Guo Zheng. “Role of Vitamin A in the Immune System.” Journal of clinical medicine. MDPI, September 6, 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162863/.
7. Tang, Guangwen. “Bioconversion of Dietary Provitamin A Carotenoids to Vitamin A in Humans.” The American journal of clinical nutrition. American Society for Nutrition, May 2010. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854912/.
8. “Vitamin A and Skin Health.” Linus Pauling Institute, January 2, 2020. https://lpi.oregonstate.edu/mic/health-disease/skin-health/vitamin-A.
9. Fernandes, MD, Des, Eiselen, MD, & Ernst. Vitamin A Skin Science: A Scientific Guide to Healthy Skin. London : Fernro Publishing, 2018.