La Roche-Posay UVMune 400: Science and Review

The La Roche-Posay UVMune 400 range has been super hyped up because it contains a brand new sunscreen ingredient: Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate (MCE), or Mexoryl 400. It’s currently exclusive to L’Oreal, and was developed in conjunction with BASF.

I’ve mentioned in passing that I don’t think it’s as much of a game changing “must have” for everyone that some people have made it out to be – here are my longer, more fleshed-out thoughts. There’s also a video version of the scientific part (with slightly less detail).

Technological aspects

I think it’s super cool to have a new filter – this is likely to be one of the last ones we’ll have for a while, due to animal testing bans (ingredient developments take a long time, so the animal safety studies for these were done over a decade ago). I’m really impressed by the innovation behind it.

UV absorbance efficiency

MCE has a really high absorption for its weight (i.e. you get more protection per %, although this varies with the formula). It’s even higher than avobenzone, which I’ve said before is pretty hectic.

This is roughly how the UV absorbance spectrum of MCE looks on the same scale as some other UV filters:

Wavelengths covered

You can also see MCE’s main selling point in this diagram – its peak is in the longer UVA1 region, between 370-400 nm. Other filters don’t cover this region as well.

Not much visible absorbance

I’m also really impressed by how the absorbance plummets close to the visible region (from 400 nm upwards/rightwards). This means you get minimal visibility on skin, as long as it’s dissolved properly in the formula.

The UVMune 400 sunscreens with MCE do look a bit yellower than their older MCE-free versions, which could be because of the MCE absorbing some violet light. But it’s probably not a big problem unless your skin is very pale and cool-toned.

Clinical evidence

I’m also really impressed by the clinical trials on MCE – it seems like they’re trying put it through its paces properly.

I was especially impressed by this recent study from Flament and coworkers. SPF 50 sunscreen with and without MCE were compared, with 2 hours of daily sun exposure for 8 weeks on the face and arms.

Here’s what the absorption spectra of the two sunscreens tested looked like:

The fact they measured any difference when the two absorbance spectra aren’t wildly different was pretty cool! (Note: UV protection is based on the area under the curve, so for 370-400 nm, it looks like roughly an additional 1/3 protection overall, from about an extra 1/8 at 370 nm, to 2-3 times more at 400 nm.)

But in my opinion, the clinical trial results are unlikely to translate into hugely noticeable differences for most people:

The benefits mostly seem to be in fading pigmented spots, in more pigment-prone skin types. All the studies I’ve come across used Phototype III and IV skin, except for that newest Flament study which had some type II “European” subjects from Brazil.

These clinical trials were run largely by L’Oreal employees. This is expected for a proprietary ingredient, and I don’t think it’s a huge red flag for research misconduct or anything like that, but it’s worth keeping in mind that these expensive, large clinical studies are designed to showcase the most likely benefits, based on their previous research (including non-clinical data).

There is some longer wavelength UVA1 coverage already, with products on the market:

• Avobenzone does cover some of this range, as seen in the UV filter and sunscreen formula UV absorbance spectra above.
• Iron oxides (not shown in the spectra) in tinted products do cover UV and visible wavelengths (albeit relatively weakly, and likely this varies a lot between products – we really need a visible light protection standard!)
• Of course, shade, UV protective clothing, hats, sunglasses and window tints protect against a broad range of wavelengths.

The research on how longer UVA1 wavelengths impact skin is a bit sparse, but we do know how the wavelengths on either side impact skin (shorter wavelength UVA1 and blue/violet light):

Overall, to me, it seems like the people who would benefit most from filling in the long UVA1 “gap” – more melanocompetent skin types who want to fade pigment – are probably using a lot of other longer UVA1 protection methods already, along with pigment-fading products, and very likely not getting 2 hours of direct sun a day. So I wouldn’t expect the differences with this extra UVA1 protection to be very noticeable for most people, in a real life situation.

But I do think it fills a few important niches:

• The biggest benefit is for people who aren’t using many other UVA1 protection options, like people who work outdoors, and don’t want to wear tinted products or broad brimmed hats
• It’s also more beneficial for parts of your skin where some of the other methods don’t work as well – for example, hats and sunglasses don’t protect the lower face very well if you’re getting a lot of sun
• Plus if your skin is very responsive to these longer wavelengths, you might benefit from the higher protection from these sunscreens, layered with everything else.

Related post: Do Hats and Umbrellas Protect Well From the Sun?

But whether it’s a “must have” is very subjective, especially since they’re pretty pricey to get if you’re outside Europe. There are also some cosmetic downsides compared to previous Anthelios formulas, which could sway the risk/benefit balance for you, and might result in lower application – I’m assuming they were necessary compromises to incorporate the MCE. There are very mixed opinions on how acceptable these are. 

UVMune 400 sunscreen reviews

I’ve tried 5 UVMune 400 products so far:

• Invisible Fluid Fragrance-Free
• Tinted Fluid
• Oil Control Gel-Cream
• Hydrating Cream Fragrance-Free
• Hydrating Cream Tinted

Interestingly, all of the formulas claim water resistance, which I haven’t seen before on older Anthelios products. This could be because I’m used to the Australian versions, which have no water resistance claims – I’m guessing they either didn’t meet the stricter Australian water resistance standard, or it wasn’t worth the extra testing (Australia requires minimum 2 hours water resistance, and the SPF after immersion needs to exceed the labelled SPF).

The Invisible Fluids and Hydrating Creams (purchased in Europe) are all SPF 50+, broad spectrum (EU) and 80 min water resistant (EU). The Oil Control Gel-Cream (sample from Singapore) is SPF 50+, broad spectrum, PA++++ and has “proven resistance to water”.

Invisible Fluid

I had high hopes for the UVMune 400 Invisible Fluid, since that’s the type of formula that’s suited me best from La Roche-Posay in the past. Unfortunately, there were a few sensory aspects that really felt like a step down from previous Fluids.

First off, MCE seems to have a noticeable smell that’s consistent across both fragrance-free products I’ve tried. It’s a sort of musty solvent smell that seems familiar, but I can’t quite place it (very annoying – as an organic chemist I’m used to being able to match functional groups to smells!). It comes and goes the whole time I’m wearing it. It isn’t a dealbreaker for me, but it does make it a less pleasant experience, and I can imagine it could really bother some people. 

I also wasn’t fond of the texture. It’s very runny, like water. The older Fluid formulas have been fluid, but much more user-friendly – with this, I can only dispense a third of the total amount on the back of my hand at a time, and I have to pay attention to not accidentally have it drip off (it did drip onto the floor a few times). For someone as absent-minded as me, it’s definitely not a safe sunscreen to apply in a rush.

This also seems to have more alcohol than previous formulas. I don’t go out of my way to avoid alcohol in products, and this didn’t feel drying on my skin, but it did sting a bit during application. After drying, the finish felt much tackier than I expected, and was a bit shiny. 

Overall, it’s still a perfectly acceptable sunscreen compared to everything else – but disappointing compared to previous Anthelios fluids. I’d imagine it’s better suited to someone with less oily skin.

Hydrating Cream

I bought the Hydrating Cream on the off-chance it would work better than the Invisible Fluid. Anthelios Hydrating Cream formulas have always been too emollient for me, so after trying the Invisible Fluid, I knew this would be worse on my oily skin. But it is a lot easier to use! 

Oil Control Gel-Cream

The UVMune 400 Oil Control Gel-Cream was launched a bit later, along with an Oil Control Fluid which I haven’t tried yet. My friend and fellow sciencey skincare content creator Hannah English brought this back for me from a La Roche-Posay event in Singapore.

I’ve generally enjoyed other Anthelios Oil Control products, and this formula is my favourite from the UVMune 400 range so far. The texture is a thick-ish, non-greasy cream, which was a relief after the stress of the fluid.

The finish is more matte than satin, but it stays that level of satin for a while. Like other Anthelios Oil Control products, it contains mattifying aerated silica microparticles to help absorb excess oil.

I’ve only tried the fragranced version. While the floral scent is stronger than I usually prefer (I’d say it’s medium strength), it does complement the musty “fragrance-free” smell quite well. 

This did sting my face a bit during application and drydown – again, I’m guessing it’s the alcohol.

Tinted Fluid and Hydrating Cream

The Tinted Fluid and Tinted Hydrating Cream were an impulse buy, and I regret it. If a European sunscreen only has one tint, it’s always awful on me (my skin is usually NC20 – warm and light-medium).

The Tinted Fluid actually had me hopeful at first. Foolish, foolish Michelle. You never learn.

As it dried, it sent me straight to Oompa Loompa land. It doesn’t look the worst from the front, I’m just a tad overcooked:

But the jawline is… conspicuous, and didn’t blend out.

The tinted Hydrating Cream was kind of promising, in that it was quite yellow-toned. Most European tinted sunscreens are more on the pink side.

Again, it darkened as it dried and, well… 

These are too pigmented to really get away with unless your skin is a pretty good colour match, though they might be more forgiving if your skin is too dark rather than too light. 

I think the target audience for these are sunbathing Europeans in the middle of summer – I can’t imagine there’s a huge proportion of Europeans with this skin tone naturally (these were largely sold out in Rome towards the end of summer, I ended up buying them online). 

Have you tried these sunscreens? What did you think?

References

Marionnet C, de Dormael R, Marat X, et al. Sunscreens with the New MCE Filter Cover the Whole UV Spectrum: Improved UVA1 Photoprotection In Vitro and in a Randomized Controlled Trial. JID Innov. 2021;2(1):100070. doi:10.1016/j.xjidi.2021.100070

Flament F, Mercurio DG, Muller B, et al. The impact of methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE) UVA1 filter on pigmentary and ageing signs: An outdoor prospective 8-week randomized, intra-individual comparative study in two populations of different genetic background. J Eur Acad Dermatol Venereol. 2024;38(1):214-222. doi:10.1111/jdv.19486

The Oil Control Gel-Cream was my friend’s PR sample. This post contains affiliate links – if you decide to click through and purchase any product, you’ll be supporting Lab Muffin financially (at no extra cost to you), thank you! For more information, see Disclosure Policy.