Vitamin A and its derivatives (retinoids) are important for development and maintenance of multiple epithelial tissues including skin, hair, and sebaceous glands, as severe, adverse effects are seen in vitamin A deficiency or excess.
IS IT SAFE? ARE THERE SIDE EFFECTS?
Retinol is considered safe just at the right concentration, both lack and excessive Retinol will produce hair loss. Most common side effect is scalp redness and irritation.Topical vitamin A can reverse the impairment of wound healing seen in patients receiving corticosteroids, perhaps by restoring the normal inflammatory reaction in the wound.
EFFECTS ON HAIR LOSS
Topical retinol increase blood flow to hair follicles and encourage new blood vessel formation. The anti-inflammation capabilities seen in topical retinol have made it widely accepted by the scientific community as a potential treatment for hair loss (Rahman & Bagchi, 2014). It is thought that retinol regulates hair follicle growth through biological manipulation of the immune system (Everts, Sundberg, King, & Ong, 2007). Retinol significantly improves the scalp skin condition and promotes hair growth,in terms of the keratinization of skin and hair.Retinoic acid, the active metabolite of vitamin A, has been reported to play an important role in the growth, differentiation and maintenance of hair follicles.
STRUCTURE & SYNTHESIS
Vitamin A or Retinol is present in many animal tissues, and is readily absorbed from such dietary sources in the terminal small intestine. Liver is clearly the richest dietary source of vitamin A.
Plants do not contain vitamin A, but many dark-green or dark-yellow plants (including the famous carrot) contain carotenoids such as beta-carotene that serve as provitamins because they are converted within the intestinal mucosa to retinol during absorption.
Vitamin A is stored in the liver as retinyl esters and, when needed, exported into blood, where it is carried by retinol binding protein for delivery to other tissues.
Retinol is transported into the cell via the protein called Stimulated by RA6 (STRA6) and binds cellular retinol binding protein 1 (RBP1, aka CRBP)
MECHANISMS OF ACTION
Vitamin A is stored in the liver and extra-hepatic tissues as retinyl esters (O’Byrne et al., 2005). Retinol bound to retinol binding protein (RBP4) is the main circulating form of vitamin A (Blaner et al., 2002) and maintained at a constant blood level (Blomhoff et al., 1991) The retinoid metabolism is commonly altered in patients with both cicatricial and adrogenic alopecia.