AHAs and BHAs (alpha and beta hydroxy acids) are a beauty blockbuster that claim to help reduce the signs of aging and are found in so many of the anti-ageing products we see today! Depending on their concentration they can have different levels of effects that help counter ageing skin, so Beauty by the Geeks are here to dig a little deeper and find out if they really are the wonder treatment they claim!

BHAs are comprised of a carboxylic acid group with two carbon atoms and a hydroxyl group, whereas AHA only contains one carbon atom. As a result this makes BHA’s slightly less strong, but they are still popularly used! The most popular versions of each of these compounds are glycolic acid (an AHA) and salicylic acid (a BHA); due to glycolic acid’s smaller molecular size is the most potent of the acids.

So, how do they work?
In the low concentrations (around 4%) that are found in high street products, glycolic acid in particular has been found to break down molecules called desmosomes responsible the connectivity between cells in the stratum corneum. The stratum corneum is the uppermost layer of the skin and breaking down the connection between these cells in turn causes the shedding of this top layer of skin. This allows it to act as a mild chemical exfoliant to help uniformly remove the rough cells on the skin’s surface to reveal the softer cells beneath, and glycolic acid (among other AHAs) are frequently used in many exfoliating products. Importantly, this exfoliating effect does not disrupt the barrier function of the skin, which is important for minimizing transepidermal water loss (TEWL), to maintain skin hydration.

At intermediate to high concentrations (up to 70% concentration!) AHAs are reported to help improve signs of skin ageing. Studies using a 25% concentration of glycolic, lactic and citric acid showed that each of these three AHAs were capable of opposing sunlight-inducing skin ageing by reversing markers of photoageing in both the epidermis (top layer of the skin) and dermis (the middle layer of the skin). The study showed an increase in the quality of elastic fibers that maintain the skin’s suppleness, as well as increased collagen and thickness of the dermis itself. These more intense treatments are applied to the skin for varied lengths of time depending on the “depth” of desired peeling. Alongside the benefits of the weaker peels, these stronger formulations are sometimes considered as treatments for acne, scarring and hyperpigmentation. High concentrations of glycolic acid have also been found to increase epidermal thickness accounting for a fuller less wrinkled skin. These high concentration treatments are more commonly known as ‘acid peels ‘ and are particularly popular for photo-damaged induced ageing.

Products such as ‘Nip + Fab Exfoliating Pads’ and ‘Sanctuary’s 30 Day Youth Revolution Peel Mask’ both containing concentrations of glycolic acid and are popularly used for these applications. We’ve recently had a look at FAB Facial Radiance Pads and Skin Authority’s Resurfacing Accelerator which contain AHAs, so head over to those features for some more beauty science!

Salicylic acid, a BHA, is more popularly used in acne treatments to remove dry skin and unclog pores in products like Vichy’s Normaderm Night Detox which we had a look at earlier this year!. The slightly milder effects of the BHA salicylic acid may well make it more popular for already irritated or acne-suffering skin, as they are less abrasive and a little gentler!

Whilst both AHA and BHA are talented little molecules that have taken the beauty world by storm, it is advised to take care especially with sensitive skin as they are acids and can cause mild irritation. Especially for higher concentration products, consultation with a dermatologist is often recommended and sometimes compulsory! For those wanting liking the idea of these acids, keep your eyes peeled for these ingredients and their percentages the next time you are adding to your skincare regime!