Vitamin A, a family of related molecules including retinoids and retinol, plays an important role in your health. Several cells throughout your body can respond to circulating vitamin A molecules, and these chemicals help to guide cell development, nourish your visual system and boost your immune system. In addition, vitamin A also contributes to the health of your skin, playing a role in maintaining the numerous cell types that contribute to skin tissue.
Components of Skin Tissue
Your skin contains a number of specialized cells and structures that help form a waterproof barrier between your internal organs and the environment. Among the most abundant cells in your skin are keratinocytes, specialized cells that contain high levels of the protein keratin. Dead keratinocytes make up the surface of your skin, and slough off over time, revealing younger cells underneath. Another cell type in your skin are melanocytes, the pigment cells that contribute to your skin coloring. In addition, your skin contains several sweat and oil glands, as well as thousands of hair follicles.
Keratinocyte Differentiation
One way vitamin A helps your skin is by guiding the maturation, or differentiation, of keratinocytes. Keratinocytes first undergo cycles of cell proliferation, to increase cell numbers, before differentiating into mature keratinocytes, which then slowly move towards the surface of your skin until they slough away from your body. Retinoids, a type of vitamin A molecule, helps to guide both initial keratinocyte proliferation, as well as the development of mature cells, according to a study published in the "Journal of Dematological Science" in 2010. As a result, defects in vitamin A signalling might disrupt normal keratinocyte development, harming your skin's health.
Melanocyte Differentiation
Vitamin A also contributes to healthy skin by guiding the differentiation of melanocytes, pigment cells within your cells. The ability to generate new melanocytes proves important to your health: your body relies on melanocytes to generate pigments after exposure to ultraviolet rays, causing a sun tan that helps protect your skin from sun damage. A study published in the "Journal of Investigative Dermatology" in 2002 indicates that a form of vitamin A, called ATRA, can help promote the maturation of melanocytes from immature precursor cells in laboratory experiments. While the effect of vitamin A in melanocyte development is not yet understood, the vitamin may play a role in the normal development of these cells.
Hair Growth
The hair follicles that make up a part of your skin tissue also rely on vitamin A for proper functioning. Each hair follicle within your skin undergoes cycles of hair growth: a stage of hair elongation, a static period where the hair remains within the follicle without additional growth, an a stage where the hair falls out. Cells around and in your hair follicles respond to vitamin A molecules within your body, reports a study published in the "Journal of Investigative Dermatology" in 2004. The study indicates that vitamin A plays a role in all stages of the hair growth cycle within your follicles, helping to maintain healthy follicles in your skin.
References
- "Journal of Dermatological Science;" Keratinocyte Differentiation Induced by Calcium, Phorbol Ester or Interferon-Gamma Elicits Distinct Changes in the Retinoid Signalling Pathways; T. Karlsson et al.; 2010
- "Journal of Investigative Dermatology;" All-trans Retinoic Acid Induces Differentiation and Apoptosis of Murine Melanocyte Precursors with Induction of the Microphthalmia-Associated Transcription Factor; H. Watabe et al.; 2002
- "Journal of Investigative Dermatology;" Hair Cycle-Specific Immunolocalization of Retinoic Acid Synthesizing Enzymes Aldh1a2 and Aldh1a3 Indicate Complex Regulation; H. Everts et al.; 2004
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