Centella asiatica’s been in skincare for a long time, but it’s really getting its time in the spotlight at the moment. What is it and what does it do? Here’s the science behind this trendy botanical ingredient.
What is Centella asiatica?
Centella asiatica, also known as Gotu Kola and Indian pennywort, is a herb that’s been traditionally used in Indian Ayurvedic medicine. In some Asian countries the leaves are used in salads and drinks. It looks like this:
What’s in Centella?
Centella asiatica contains a bunch of active ingredients known as terpenoids, which make up around 8% of the weight of the plant. The main four that have been studied for their skincare benefits are asiatic acid, madecassic acid, asiaticoside and madecassoside. They’re sometimes included in a product alone in pure form, or in combination as “Centella asiatica extract”. The terpenoids have very similar activities.
Along with the terpenoids, there are also other components that have skincare benefits: antioxidants, humectant moisturisers and vitamins.
What does Centella do?
Centella is most famous for its healing properties – a lot of Centella products contain the prefix “cica-” which, as a lot of astute readers have informed me, refers to its cicatrising or healing/scar-forming abilities.
Here’s a simple skincare trick that I’ve found ridiculously useful lately that I thought I’d share in case it helps anyone else out. I’m sure I’m not the first person to do it, but I also haven’t seen it discussed anywhere else (though I haven’t been looking very hard).
I’ve started doing something that can be best described as “multi-sunscreening”, a bit like the “multi-masking trend” that a lot of brands are jumping on. I was inspired to do this when I watched Fiddy Snails apply her sunscreen using a BB cushion puff on Instagram, when she patted her sunscreen in all over her face using the puff then went back to part in extra on her pigmentation problem areas.
Here’s my issue: I get pigmentation very quickly on the tops of my cheekbones. It’s an annoying genetic thing that a lot of East Asian people have, and I’ve managed to inherit it from my dad’s side (thaaaanks). Right now it’s not too bad, but mostly because I throw hydroxy acids and vitamin C at it all the time to try to lighten it, and cover it with high UVA protection sunscreen to stop it from getting worse.
The problem is that I also have oily skin, from my mum (again: thaaaanks). The sunscreens with the highest UVA protection that I know of come from French brands Bioderma and La Roche-Posay. And unfortunately, they’re greasy, at least on my oil slick face. Even their “fluids” designed for oily skin turn me into an unsightly mirror ball at the end of the day. So I find myself reaching for more “cosmetically elegant” sunscreens most of the time – usually Bioré Aqua Base Watery Essence – which keep my oily areas manageable but aren’t waterproof or sweatproof, and have lower UVA protection as well. I’ve noticed that my sunspots are steadily creeping back.
Here’s where multi-sunscreening has saved both my long-term skin health as well as my daily try-not-to-look-like-melting-wax efforts. My sunscreen routine now goes like this:
I was really excited to hear about L’Oréal/La Roche-Posay’s My UV Patch, a recently launched electronic wearable that can measure your UV exposure. La Roche-Posay have some of the best sunscreens on the market, so you know they’re serious about sun protection. My UV Patch is a blue heart-shaped patch that’s about the size of a large coin and half the thickness of an average strand of hair. It can be worn on your skin (the back of your hand is recommended) for up to 5 days, lasting through showers and swimming. You apply your sunscreen over the patch, so you can see how much UV protection you’re getting with your regular sunscreen.
Here’s how it works:
Stick the patch on your hand
Enter your details into the app
Scan the patch with the app when it tells you to (around every hour)
The app tells you whether or not you’re being sun-safe, and whether it’s time to reapply sunscreen
The app gives you a chart of your UV exposure throughout the day, and tells you when you’ve had too much sun (how much of your “sun stock” you’ve used)
I have a huge love of French sunscreens – while they tend to be a bit greasier than Japanese sunscreens like Biore UV Aqua Rich Watery Essence, the SPF and UVA protection (measured by PPD) is top notch. This time, I’m reviewing products from two of the highest protection sunscreen ranges available – Bioderma Photoderm Max and La Roche-Posay Anthelios.
Bioderma Photoderm Max Milk (Lait) and Max Ultra Fluid SPF 50+ PPD 42
Bioderma’s Photoderm Max range has ridiculously high PPD (UVA protection) values – greater than 40, compared to Japan’s highest PA++++ which translates to around PPD 16+. The main difference between the Bioderma sunscreens is texture. Bioderma Photoderm Max Milk (Lait) is a slightly runny cream that feels like a regular body sunscreen, while Bioderma Photoderm Max Ultra Fluid is a runny liquid (there’s also the Cream and Aquafluid available).
I much prefer the Milk, which rubs in reasonably well on my skin, though it leaves a slightly tacky layer that goes away when I douse it with some translucent powder. The Ultra Fluid claims to have a “non-oily texture” but on my oily skin it just feels like straight-up oil. It contains a lot of cyclopentasiloxane, and silicones have never played well with my skin so I really should’ve known better. If your skin likes silicones, you might have better luck. They’re also both fragrance free and paraben free, if you’re sensitive to either of these. As with most European sunscreens, the full ingredient listings can be easily found on the packaging or online.
The catch is… they’re not available in Australia, and as far as I know Bioderma have no plans to bring the Photoderm line here. Boo! I’m guessing the reason is that Australian sunscreen regulations are very stringent due to our crazy UV levels and thin ozone (lots of in vivo tests on human volunteers required), so it’s pretty expensive to get new sunscreen products approved. It’s available in the US and in Europe, and it’s very reasonably priced in France. Load up if you or a friend go on holiday there!
Pros: awesome UVA protection, complete ingredient listings available, fragrance-free and paraben-free (only relevant if you’re sensitive), reasonably priced in France (about 8€ for 40 mL), different textures available
Cons: not available in Australia, expensive in most places outside of France
If you walk into a pharmacie in France, you’ll immediately bump into a giant display of thermal water spray cans. A whole host of French skin care brands like Avène, La Roche-Posay, Uriage and Vichy sell thermal water sprays. What is it, what’s in it, what does it do and how is it different from regular water?
What is thermal water?
Thermal water comes from hot springs. The water in these hot springs come from deep in the ground, where it’s heated by geothermal activity (the Earth’s natural heat which also causes lava to be molten).
What’s in thermal water?
It’s mostly water, of course, but it isn’t “just water in a can”! As the thermal water rises to reach the spring, it passes through rocks and soil which dissolve to add minerals to the water. The mineral content of a particular thermal water depends on where it comes from. The minerals include the ones found in your skin’s natural moisturising factor (NMF), like chlorides, sodium, potassium, calcium, and magnesium.
Here are the compositions of the 4 most popular thermal waters (source: Bacle et al., Int J Dermatol 1999, brand marketing materials). There’s some variation between batches of course, since it’s a natural mixture.
Composition (mg/L or ppm)
Total dry residue
As you can see, the composition varies a fair bit, with Uriage, the thermal water with the highest mineral content, being 55 times more concentrated than Avène, which has the lowest mineral content.
“-” in the table means no data, since different thermal water brands like to highlight different aspects of their water. La Roche-Posay talks a lot about the selenium content of their water, while Uriage emphasises the high calcium concentration. Avène talks a lot about the 2:1 ratio of calcium and magnesium in their water.
There’s also nitrogen gas inside the can that acts as a propellant, to push the water out as a spray. Paula’s Choice writes that the nitrogen “can generate free-radical damage and cause cell death”, which luckily isn’t true, since nitrogen gas (N2) make up 78% of the air we breathe! It’s actually very unreactive, so unreactive that it’s commonly used in laboratories to flush out more reactive things like oxygen and water. (The papers cited in the Beautypedia article actually involve chemicals that just contain nitrogen atoms, not nitrogen gas itself.)
Your skin is covered in a thin protective layer of dead cells (the stratum corneum) which naturally shed over time in a process called desquamation. Sometimes this layer gets too thick, resulting in dull, rough skin. Exfoliants help the shedding along, resulting in more even, “glowier” skin.
What’s chemical exfoliation?
Chemical exfoliants help cells shed in a more indirect way than physical exfoliation, which works using friction between the tool or scrub and the skin. The mechanism of how chemical exfoliants work aren’t always obvious, but the most common theories and methods of how they work are:
by normalising cell turnover – that is, how quickly cells in the epidermis die and migrate to the stratum corneum, pushing old cells out. Exfoliants do this by travelling to living cells under the dead layer and telling them to change how they behave – in more technical terms, they act on receptors to upregulate cell division. (Technically, any ingredient that does this is a drug, but regulations around these “cosmeceuticals” is pretty iffy.)
by unsticking the cellular glue (desmosomes) holding dead cells together in the stratum corneum.
Chemical exfoliation is touted to be gentler than physical exfoliation, mostly because it’s less prone to user error. However, how well it works depends largely on the formulation of the product. A poorly formulated product might not work, or it might work so well that it irritates your skin and causes uneven pigmentation and chemical burns.
Hydroxy acids are the most common ingredients in chemical exfoliants. There are two main types:
Alpha hydroxy acids (AHAs), which includes ingredients like glycolic acid, lactic acid, malic acid and mandelic acid. Glycolic and lactic acids are most common in skincare, and the vast majority of scientific studies on AHAs are based on the action of glycolic acid.
Beta hydroxy acids (BHAs), of which salicylic acid is the only one commonly used in skincare (I’ll be using the terms “BHA” and “salicylic acid” interchangeably).
A few ingredients are technically both alpha and beta hydroxy acids such as citric acid, which acts more like an AHA.
It’s not 100% clear how AHAs and BHAs work to exfoliate the skin – it’s likely to be a combination of the two actions described at the beginning: increasing cell turnover at the epidermis and unsticking stratum corneum cells. As well as just removing build-up of skin, they can also improve hyperpigmentation and reduce the appearance of wrinkles.
Solubility: The commonly used AHAs (glycolic acid, lactic acid) are water soluble, while salicylic acid is oil soluble. Theoretically this means salicylic acid is better for treating oily skin and clogged pores because they can penetrate through sebum and sebum plugs, but there’s a lot of variation between people’s experiences. You’ll generally find AHAs in products for dry, ageing skin, and BHA in products for oily, acne-prone skin.
Sun sensitivity: Glycolic acid is documentedto causesun sensitivity for a while even after you finish using it, while salicylic acid isn’t. Salicylic acid has a UV protective effect while on the skin, due to the benzene ring in its structure which lets it act as a chemical sunscreen. You need to wear sunscreen while you use alpha hydroxy acids, and for at least a week after you finish – otherwise, you can actually cause more wrinkles and uneven pigmentation and sagginess than you started off with! And you should use sunscreen with salicylic acid anyway.
Other effects: Salicylic acid can have some anti-inflammatory action, depending on whether enough gets through the skin – it’s actually one of the active forms of aspirin. Glycolic and lactic acids are humectants that act to slow down the evaporation of water from the skin.
It’s the end of 2014 and it’s gone by so quickly! I decided to do a round-up of my favourite products I discovered this year – I tried a LOT of products, so these are the best of the best! La Roche-Posay Cicaplast – This has been amazing for my chapped areas. It’s soothing and protects raw skin until it’s …
Here’s the next installment in my sunscreen review series – this time we’re looking at La Roche-Posay Anthelios XL Comfort Creme SPF50+and Uriage Bariésun Creme SPF30.
Both of these French sunscreen are targeted at dry/normal skin, not oily/normal skin like mine, so it’s quite likely that they’ll behave differently on drier skin. Unlike the fluid sunscreens I’ll be reviewing next time, they have less alcohol, which means they’re a bit less dehydrating for your skin, if your skin is dehydration-prone.
(I think this might be the same as the Melt-In Cream, just renamed.)
This comes out as a yellow-tinged cream. It’s a bit hard to rub in, and has a bit of that greasy feel that body sunscreens have, despite having alcohol relatively high on the ingredients list (alcohol usually helps sunscreens sink in). However, despite the greasy first impression, I can apply this in the morning, blot the oil off gently with blotting paper half an hour later and apply translucent powder, and it doesn’t need blotting again until the late afternoon.
The sunscreen ingredients are bemotrizinol, titanium dioxide, avobenzone, Uvinul T 150, Mexoryl XL and Mexoryl SX – the Meroxyl components are particularly stable UVA absorbers, giving this sunscreen an impressive PPD of 42 in addition to an SPF of 50+, which means it’s pretty much top of the class in both UVA and UVB protection.
However, when I applied this to my dry, clean skin, it balled up slightly and rolled off, which means it was incredibly difficult to apply the recommended 1/4 teaspoon required for full sun protection, and more sunscreen balled off when I tried to apply make-up over it. Here’s what the balling looks like on my clean hand: