Why the layer under your sunscreen matters.
The short version: sunscreen handles UV, and nothing on this page changes that. But the condition of your skin barrier and how your skin responds to UV appear to be linked, and in a country with one of the highest skin cancer rates in the world, that link is worth understanding.
The number, properly
New Zealand’s peak UV Index runs approximately 40% higher than at comparable Northern Hemisphere latitudes. NIWA attributes the gap to three things: the Earth’s elliptical orbit places our summer closest to the sun, Southern Hemisphere summer ozone levels are lower because ozone forms at the equator and disperses poleward more efficiently at these latitudes, and our air is markedly cleaner.
SourceNIWA (Earth Sciences New Zealand), UV and Ozone
Summer UVI is generally about 12, and can exceed 13 in the far north of the country. A UV Index of 12 corresponds to a burn time of about twelve minutes.
SourceNIWA, UV Index Information
One correction worth making
It gets repeated constantly, so: the Antarctic ozone hole is not the reason. The hole sits well to the south of New Zealand, and NIWA’s Richard McKenzie puts it bluntly — “the skin cancer rates we have in New Zealand have nothing to do with the ozone hole” and “if there were no ozone hole, we’d still have high skin cancer rates in New Zealand.” The relevant factor is our lower baseline summer ozone, which is a different thing.
What UV does to skin’s barrier
Beyond sunburn, UVB exposure measurably increases transepidermal water loss and disorders the arrangement of lipids in the stratum corneum — the layer that holds water in. Notably, the total amount of those lipids does not change much; it is their organisation that does.
An honest caveat
Much of this work is in animal models or at high doses, and the effect is dose-dependent in both directions: low, sub-burning UVB over short periods appears to have a mildly positive effect on barrier function. We’re not going to overstate it.
The finding most people haven’t heard
The more interesting relationship runs the other way.
A 2019 report from Kao’s research laboratories, published in Photodermatology, Photoimmunology & Photomedicine, measured barrier function and UV sensitivity in 285 volunteers. It found a significant negative correlation between transepidermal water loss and minimal erythema dose — the UV dose needed to produce visible redness. Skin with poorer barrier function reddened at a lower dose. The correlation was reproduced twice more, each time in over 250 volunteers.
SourceKao Corporation research release, 26 July 2019 (sample sizes and replication)
A 2022 study in the Journal of Cosmetic Dermatology replicated the correlation in a Korean cohort and went further: when the skin barrier was deliberately disrupted, minimal erythema dose fell significantly.
Put plainly: barrier condition and UV response appear to be connected.
What this does and doesn’t mean
It does mean
That in a country with one of the highest skin cancer rates in the world, looking after your barrier isn’t a cosmetic afterthought. It’s part of the same conversation as sun protection.
It does not mean
That moisturiser prevents sunburn. It doesn’t. It does not mean these products reduce UV sensitivity — we have not tested that and we are not claiming it. The studies above are correlational, were conducted in Japanese and Korean cohorts, and they tested skin condition, not our products. We have no New Zealand-specific test data for our own formulas yet.
What it means practically: wear broad-spectrum SPF every morning. Then look after what’s underneath it. That second part is what we make.
What we built, and why
A layering product first.
If you wear sunscreen most days, your moisturiser is the layer underneath, so absorption and texture are requirements. Both formulas are designed to absorb quickly and layer cleanly under SPF.
Hydrating ingredients with published evidence.
Pentavitin® in Resilience, Aquaxyl™ in Balance, niacinamide at 2% in Resilience: named ingredients with published or supplier evidence behind them.
An ingredient paper trail.
Every active we name comes with supplier documentation, and we hold it. Section 06 sets out what that evidence says.
The evidence. No proprietary blends.
We publish the active, the concentration, and the supplier data. You should know exactly what you are paying for.
| Active ingredient | Formula | Supplier test summary | Source |
|---|---|---|---|
| Pentavitin® (Saccharide Isomerate) | Barrier Resilience | Binds to keratin. In supplier in-vivo testing, Pentavitin® demonstrated up to 43% more moisturisation than glycerin on dry skin. | DSM Nutritional Products |
| Aquaxyl™ (Xylitylglucoside complex) | Barrier Balance | Supplier testing shows a cream with 1.5% Aquaxyl™ and 3% glycerin delivers 30% more moisturisation than glycerin alone. | SEPPIC |
| Niacinamide (2%) | Barrier Resilience | Stated at an active 2% concentration. Published literature validates its role in lipid synthesis and reducing trans-epidermal water loss. | Published literature |
| TEGO® Natural Betaine | Barrier Balance | A naturally derived humectant that holds water in the skin as external humidity fluctuates. | Evonik |
| Centella Asiatica Extract | Barrier Resilience | Botanical extract used for skin conditioning and comforting tight skin. | Nature Science Tech |
The above figures describe testing conducted by ingredient suppliers on individual raw materials. They illustrate ingredient capability and are not finished-product results for sootheKA formulas.
Independent safety testing
Both formulas were subjected to independent, 24-hour occlusive patch testing on human volunteers with sensitive skin, under direct dermatological supervision. Both returned a verified non-irritant result. The certificates supporting these claims are held on file.
Independent patch test on adults with sensitive skin, under dermatological supervision. It tests for irritation only. It is not an allergy test and cannot predict your individual reaction. Patch test on your inner forearm before first use.
Can I see the report?
The full report belongs to the testing facility and is marked confidential. We cannot publish or distribute it. Questions about the testing: hello@sootheka.com.
Ingredients
Aquaxyl™
Hydration complexA xylitol-derived hydration complex.
Supplier testing shows a cream with 1.5% Aquaxyl™ and 3% glycerin delivers 30% more moisturisation than glycerin alone.
Xylitylglucoside (and) Anhydroxylitol (and) Xylitol
Balance
Pentavitin®
Moisture binderA biomimetic moisture-binder that attaches to keratin in the skin's outer layer.
In supplier in-vivo testing, Pentavitin® demonstrated up to 43% more moisturisation than glycerin on dry skin.
Saccharide Isomerate
Resilience
Niacinamide
Vitamin B3Stated plainly at an active 2% concentration. One of the most studied actives in skincare, researched for its role in lipid synthesis and reducing trans-epidermal water loss.
Niacinamide
Resilience
Centella Asiatica
Calming botanicalBotanical extract used for skin conditioning and comforting tight skin.
Traditional use. We hold no test data of our own.
Centella Asiatica Extract
Resilience
Betaine
HumectantA naturally derived humectant that holds water in the skin as conditions change — which, in a climate that swings between 74% and 89% humidity, they constantly do.
Betaine
Balance
Sodium Hyaluronate / Hyaluronic Acid
HumectantA skin-identical humectant that draws water into the upper layers of skin. Sodium Hyaluronate in Balance, Hyaluronic Acid in Resilience.
Sodium Hyaluronate (Balance) · Hyaluronic Acid (Resilience)
Both
Barrier Balance — complete ingredient list (INCI)
Aqua (Water), Disodium EDTA, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Polyacrylate Crosspolymer-6, Sodium Lactate, Glycerin, Isopropyl Myristate, Squalane, Caprylic/Capric Triglyceride, Sesamum Indicum (Sesame) Seed Oil, Betaine, Sodium Hyaluronate, Xylitylglucoside (and) Anhydroxylitol (and) Xylitol, Chamomilla Recutita (Matricaria) Flower Extract, Glyceryl Glucoside (and) Glycerin, Panthenol, Propanediol, Tocopherol, Phenoxyethanol (and) Ethylhexylglycerin, Fragrance, Linalool, Benzyl Salicylate, Limonene.
Barrier Resilience — complete ingredient list (INCI)
Aqua (Water), Disodium EDTA, Ceteareth-20, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Saccharide Isomerate (and) Aqua (and) Citric Acid (and) Sodium Citrate, Hyaluronic Acid, Panthenol, Glycerin, Niacinamide, Allantoin, Aloe Barbadensis Leaf Extract, Centella Asiatica Extract, Cetearyl Alcohol (and) Ceteareth-20, Glyceryl Stearate (and) Cetearyl Alcohol (and) Sodium Lauroyl Lactylate (and) Decyl Glucoside (and) Caprylic/Capric Triglyceride (and) Phytosterols, Glyceryl Stearate (and) PEG-100 Stearate, Caprylic/Capric Triglyceride, Isopropyl Myristate, Isoamyl Laurate, Decyl Oleate, Butyrospermum Parkii (Shea) Butter, Theobroma Cacao (Cocoa) Seed Butter, Cetearyl Olivate (and) Sorbitan Olivate, Titanium Dioxide, Propylene Glycol, Phenoxyethanol (and) Ethylhexylglycerin, Tocopherol, Fragrance, Linalool, Benzyl Salicylate, Limonene, Hydroxycitronellal.