TL;DR: Most baby washes rely on sodium lauryl sulfate (SLS) to create lather — but research shows SLS disrupts skin's protective proteins at the molecular level. Soapwort (Saponaria officinalis), a plant-derived alternative, cleans effectively while leaving skin's natural lipid barrier intact. It's the surfactant behind our Baby Shampoo & Body Wash, and the science is why we chose it.
If you've ever flipped over a bottle of baby body wash and squinted at the ingredient list, chances are "sodium lauryl sulfate" or "sodium laureth sulfate" was somewhere near the top. They're the cleansing agents — the reason baby wash lathers up the way it does. For a long time, most of us assumed that if a product was made for babies, someone had already done the safety vetting.
But once you start actually reading the research — which is what tends to happen at 11pm with a quiet house and a cup of tea — the picture becomes more nuanced. Not alarming. Just worth knowing. And that nuance is exactly what led us to formulate our Baby Shampoo & Body Wash around soapwort instead.
Why Does the Surfactant in Baby Wash Actually Matter?
Surfactants are the workhorses of any cleanser. Short for "surface-active agent," they're molecules with one end that attracts water and one that attracts oils — which is what allows them to lift dirt and sebum from skin and rinse it away.
Not all surfactants are equally selective about what they remove. Some are so effective that they strip your skin's own protective oils right along with the dirt. On a baby — whose skin barrier is still maturing and measurably thinner than adult skin — that trade-off matters more than it might for an adult in the shower.
What Does SLS Actually Do to Skin at the Molecular Level?
SLS is the most widely studied surfactant in dermatology, which actually tells us a lot: it became the gold standard for inducing controlled skin irritation in research settings because it's so reliable at doing so.
In a study published in the Journal of Investigative Dermatology, Törmä et al. found that SLS exposure altered the expression of key proteins responsible for skin barrier integrity — including involucrin, profilaggrin, and enzymes called kallikreins that regulate the skin's natural repair process. These molecular disruptions were measurable days after a single exposure.
In plain language: SLS doesn't just rinse off neutrally. It interacts with the structural proteins in skin, temporarily compromising the barrier that protects your baby from irritants, allergens, and moisture loss. That's not a reason to panic — it's a reason to pay attention to what you're choosing.
What Is Soapwort, and Why Does It Behave Differently?
Soapwort (Saponaria officinalis) is a flowering plant that has been used as a natural cleanser for centuries. Its cleaning action comes from saponins — naturally occurring compounds found in many plants, including quinoa, spinach, and legumes — that behave like surfactants: they foam, emulsify oils, and rinse clean.
The difference is in how those saponins interact with skin compared to synthetic detergents.
How Did Soapwort Perform Against SLS in Direct Lab Testing?
A 2021 study published in Molecules put soapwort extract head-to-head against synthetic surfactants including SLS and CAPB using models designed to mimic human skin cell membranes. The results were striking:
- Synthetic surfactants completely solubilized model lipid bilayers — essentially dissolving the protective fat layer that forms a skin cell membrane
- Soapwort extract penetrated bilayers without solubilizing them, preserving membrane structure
- When testing protein interaction, SLS solubilized 86% of test proteins; soapwort extract solubilized just 6%
- Soapwort required concentrations roughly ten times higher than SLS to cause comparable cell damage — a dramatically wider safety margin
In practical terms: soapwort cleans without stripping. It respects the lipid layer that keeps skin hydrated and protected.
Does Soapwort Have Any Skin-Calming Properties Beyond Cleansing?
Recent research suggests the benefits extend beyond gentle cleansing. A 2025 study in Plants (Basel) evaluated saponin-rich Saponaria officinalis extract and found significant anti-inflammatory activity — reducing pro-inflammatory markers including TNF-α, IL-1β, and IL-6 in laboratory models. Clinical patch testing with 30 volunteers showed a mean irritation index of just 0.28, indicating excellent skin compatibility even for sensitive users.
For parents navigating eczema-prone or dry skin in their little ones, that kind of data point is worth having in your back pocket.
Does Choosing a Gentler Surfactant Mean Compromising on Clean?
Not at all. Soapwort's saponins still emulsify oils, lift away grime, and rinse clean — everything a baby wash needs to do. What they don't do is compromise the skin's barrier proteins or strip the protective lipid layer the way a conventional detergent would.
Clean doesn't have to mean stripped. That's the whole premise behind our formula.
Frequently Asked Questions
Is SLS dangerous for babies?
SLS is not classified as toxic, and products containing it are widely sold for infants. However, research shows it disrupts the skin's barrier proteins and may increase skin sensitivity with repeated use — particularly relevant for babies with eczema-prone or sensitive skin. Many ingredient-conscious parents choose to avoid it as a precaution.
Does soapwort clean as effectively as SLS?
Yes. Soapwort's natural saponins emulsify oils and rinse away dirt and sebum effectively. A 2021 peer-reviewed study confirmed its cleansing function while demonstrating a far gentler interaction with skin cell membranes compared to synthetic alternatives.
What are saponins and are they safe?
Saponins are naturally occurring compounds found in many common foods and plants — including quinoa, beans, and spinach. In Saponaria officinalis, they function as plant-derived surfactants. Clinical testing has shown excellent skin compatibility, with a very low irritation index even for sensitive skin.
Is soapwort safe for newborns?
Soapwort is a plant-derived ingredient without the known barrier-disrupting properties of synthetic detergents. Our Baby Shampoo & Body Wash was formulated with sensitive skin in mind. As always, consult your pediatrician for specific concerns about your newborn's skin.
Why don't more baby brands use soapwort instead of SLS?
Soapwort is less widely available, requires more careful formulation, and produces a lighter lather than synthetic surfactants — foam being something many consumers have been conditioned to associate with effectiveness. The prevalence of SLS in baby products has been driven largely by cost and convention, not skin science.
If you're ready to make the switch, our Baby Shampoo & Body Wash uses soapwort as its primary cleanser — no SLS, no synthetic fragrance, no shortcuts. See the full ingredient list at shopkindrednaturals.com.
Written by Mike & Carly Pronsky, founders of Kindred Naturals.