Spotlight on...VITAMIN A

How does it work?

Although there are many forms of vitamin A, it’s important to understand the conversion process that all molecules undergo in order to be used on the skin. “The only form that makes any direct changes to skin is retinoic acid, which acts on the cellular DNA through various receptors,” says Dr Gabriell Prinsloo, medical director for the International Institute of Anti-Ageing (IIAA).

“All forms of vitamin A undergo a conversion process that transforms them into retinoic acid, which is used by the skin.” She explains that the natural conversion pathway for vitamin A in skin is: retinyl palmitate to retinol, to retinal and finally to retinoic acid. “All forms are converted to be stored as retinyl esters when they are applied to the skin, and they all undergo the same process to convert them to retinoic acid,” she adds.

WHAT’S THE RETINOID EFFECT?

If non-acclimatised skin is exposed to high levels of vitamin A then the complexion can react negatively, known as the “retinoid effect” – dryness, flakiness, redness, inflammation, puffiness and itchy red spots are common signs.

What are the different forms?

• Retinol – The most well-known and popular form (alcohol) of vitamin A. When applied to the skin, it converts to retinaldehyde and then to retinoic acid.

• Retinoic acid – The metabolically active form which works on the DNA of the cell nucleus. “It is only available on prescription for topical use and is the most irritating,” explains Prinsloo.

• Retinaldehyde – Typically used because it “is one step closer to the bioavailable form of vitamin A – retinoic acid”, advises Isaacs. “It must undergo only one conversion to become active.”

• Retinyl esters – Esters such as acetate and palmitate are some of the most stable storage forms of vitamin A and easier for the skin to tolerate.

• Retinyl retinoate – an ester of all-trans retinoic acid and all-trans retinol. “It has direct activity on our skin cells, requiring no conversion steps like its cousins retinol and retinal,” says Isaacs.

Is percentage the key factor?

It is believed that the key factor when choosing vitamin A products for clients is percentage, but Clare Muir, director of education at IIAA, says it needs greater consideration. While percentages on vitamin A products are equal, the strengths may not be, “which is why, based on scientific research, it is more accurate to talk about vitamin A in IU (international unit) or RE (retinol equivalents) instead of percentages,” she says. “As the weights of various forms of vitamin A are so different, scientists have had to work out a way to give them an equivalent value.”

She adds: “Various manufacturers make vitamin A in different strengths to be used in skincare products, so one version may have, for example, one million IU, and another 500,000 IU – which means that the first version at 1% will have double the strength of the second version at 1%.

"When clients FIRST START USING VITAMIN A, it can cause cells to renew themselves too quickly for their skin to catch up, leading to AN IMPAIRED SKIN BARRIER, which can cause PEELING AND IRRITATION. Eventually their skin will ADAPT TO THE NEW RENEWAL RATE"