A Closer Look at the Different Forms of Vitamin A
Vitamin A stands as the most influential vitamin of the skin because of its essential task in managing the regular function of all skin cells. Its vital importance for our skin lies in the fact that it helps repair and maintain normal activities of the DNA nucleus of the cell as well as the mitochondria.
Vitamin A (retinol) is a diterpene alcohol which abundantly occurs in fish liver and egg yolks. There is a whole series of esters, derivatives and provitamins:
· Retinyl Acetate, Retinyl Palmitate and Retinyl Propionate are esters of vitamin A. They are enzymatically hydrolyzed in the skin.
· Retinal is Vitamin A oxidized into an aldehyde. It occurs in the eyes and is significant for vision. Like Retinol, Retinal is oxidized in the skin into Vitamin A acid (retinoic acid).
· Beta-Carotin (provitamin A), the coloring agent of carrots, is enzymatically hydrolyzed into two vitamin A molecules. The carotenoid family consists of numerous liposoluble tetraterpenes with color ranging from red to orange to yellow. Taken orally in higher dosages for a long time, beta-carotin develops a slight photo protective action, but does not replace UV filters. In foods, it is a popular dye.
· 3-Dehydroretinol also occurs in the liver of cold water fish and is referred to as vitamin A.
Retinoids are sensitive to atmospheric oxygen. Formulations containing vitamin A should never be applied during the day, especially if exposed to the sun, which results in degradation of the Vitamin A or conversion into Vitamin A acid. Retinoic Acid is the most irritant form of vitamin A. The side effects of topically applied Retinoic Acid can include redness, irritation, flaking, dehydration and sun sensitivity. In years past, vitamin A acid has been banned in skin care products, however, as tretinoin it is licensed in dermatological applications. Isotretinoin differs from tretinoin by another position of the acid group. Retinoids
are used to treat:
1. hyperkeratosis and scars
2. compromised skin and acne caused by cornification disorders on the exits of the sebaceous glands
3. stimulation of cell growth and collagen synthesis in the epithelial tissue
4. aging skin: frequently in combination with the anti-oxidative vitamins E and C
Retinoids can cause irritations, such as erythema. The number of vitamin A receptors, however, increases with the duration of the treatment. It is recommended to start treatment with low doses, and then slowly increase the concentrations. Even though an oral overdose can result in birth defects in pregnant women, during moderate use on the skin, no relevant concentrations are reached. It is recommended to limit application to face and hand care.
In conclusion, it is important to remember that vitamin A deficiency is probably the greatest vitamin deficiency of the skin and has a relentlessly damaging effect on the DNA of the skin cell. In order to minimize this deficit in our skin, vitamin A, in the skin friendly ester forms, should be used daily. The ideal treatment would be to apply topical vitamin A at nighttime to the skin starting at an early age and continue daily replenishment into old age. This would help maintain young, healthy looking skin.