Journal September 25, 2026 6 min read

What does the research say about the skin barrier?

A research-supply review of skin-barrier studies: vernix caseosa, peristomal skin, niacinamide riboside, collagen peptides, curcumin ethosomes, phytoceramides and more. For laboratory research use only.

peptides-pro Editorial

The skin barrier is the stratum corneum, the outermost layer of the epidermis, together with the intercellular lipid matrix and the tight junctions beneath it. It is also referred to as the epidermal permeability barrier or cutaneous barrier. In the research literature it is characterised by transepidermal water loss (TEWL), stratum corneum hydration, and skin surface pH. The work described below centres on the sphingolipid and ceramide pathway, which supplies the barrier lipids, and on the Th2 cytokine signalling that disrupts it in atopic dermatitis.

Barrier integrity is studied in newborns, in people living with a stoma, in adults with dry or sensitive skin, and in mouse models of atopic dermatitis and psoriasis. Some of the evidence below is animal-only or in vitro; each section states which.

Research Studies

Vernix caseosa retention and atopic dermatitis prevention in newborns

Vernix caseosa is a naturally occurring, white, creamy substance that covers the skin of newborns at birth and forms during the last trimester. A clinical trial is examining whether retaining vernix caseosa on newborn skin supports primary prevention of atopic dermatitis (AD), also known as eczema [1]. AD is a chronic inflammatory skin disease that usually begins in infancy and causes itching, discomfort and sleep disturbance; it affects up to one in five children worldwide [1]. The trial rationale rests on genetic and environmental factors related to skin-barrier integrity and the skin microbiome in early life [1]. This is a registered clinical study; no outcome data are reported in the evidence block.

Peristomal and non-peristomal skin barrier characterisation in people with a stoma

An exploratory study is obtaining preliminary data on peristomal and non-peristomal skin barrier characterisation in people living with a stoma [2]. It asks whether barrier characterisation differs between peristomal and non-peristomal skin, whether peristomal barrier function differs by stoma type (colostomy, ileostomy, urostomy), and whether stoma type or function influences peristomal skin characterisation [2]. Participants attend a one-hour appointment and undergo non-invasive skin procedures [2]. This is a human exploratory study; no results are reported in the evidence block.

Niacinamide riboside and facial skin aging

Niacinamide riboside (topical NR, also known as nicotinamide riboside) is an endogenous compound and a precursor to the co-enzyme nicotinamide adenine dinucleotide (NAD+) [4]. Research published by Maussudi et al. 2012 reported that skin NAD+ levels were negatively correlated with age in both males and females, and that aged skin was correlated with an increase in DNA damage [4]. A clinical trial is evaluating topical NR on the signs of facial skin aging, proposing that supporting skin NAD+ with precursors such as NR may address DNA damage associated with skin aging and support skin cell resilience [4]. The use of NR as a dietary supplement has produced effective, efficient and reproducible results according to the evidence block [4]. This is a registered clinical trial; no outcome data are reported.

AP collagen peptides and skin hydration in a mouse model of atopic dermatitis

Atopic dermatitis is characterised by impaired skin barrier function and Th2-mediated immune responses [5]. Collagen tripeptide (CTP) is an amino acid-rich dietary supplement with low antigenicity that has been reported to improve skin hydration and barrier function [5]. In an oxazolone (OXZ)-induced AD-like model using hairless mice, researchers evaluated AP collagen peptide (APCP), which contains CTP, for effects on skin hydration and inflammatory responses [5]. Skin hydration and transepidermal water loss were measured [5]. This evidence is animal-only.

Curcumin ethosomes and topical delivery in psoriasis

Psoriasis is an inflammatory skin disorder with rapidly increasing incidence [6]. Curcumin (Cur) is used as a therapeutic agent for psoriasis and is commonly administered through the cutaneous route, but poor skin permeability and retention restrict its efficacy [6]. Researchers fabricated mussel adhesion protein (MAP)-modified curcumin-loaded ethosomes (Cur-MAP-Es) to enhance permeation and retention of curcumin within the skin for topical treatment of psoriasis [6]. The average particle size of Cur-MAP-Es was 197.17 nm, and the encapsulation efficiency was 90.84%; the particles exhibited a spherical morphology [6]. This is a formulation study; the evidence block does not state whether the model was in vitro or in vivo.

Phytoceramide production in Saccharomyces cerevisiae

Phytoceramides are sphingolipids that support skin barrier integrity and hydration, making them valuable for cosmetic and pharmaceutical applications, but their intricate structures and low natural abundance pose challenges for scalable production [7]. An integrated metabolic engineering and lipidomics study enhanced phytoceramide production in Saccharomyces cerevisiae using three strategies: overexpression of SUR2 (sphinganine C4-hydroxylase) to boost phytosphingolipid formation; deletion of SCS7 (ceramide α-hydroxylase) to redirect flux toward non-hydroxylated phytoceramides; and overexpression of ISC1 (inositol phospho... [truncated in evidence]) [7]. This is an in vitro microbial study.

Oral collagen peptides and skin barrier function in women

A clinical study aims to determine whether taking two different doses of collagen-derived peptides for three months improves facial skin barrier integrity in women with dry, sensitive skin, compared with a placebo [8]. This is a registered clinical trial; no outcome data are reported in the evidence block.

Integrated drug analysis and transcriptomics in psoriasis

Psoriasis is a chronic immune-mediated inflammatory skin disease characterised by epidermal hyperproliferation, skin barrier dysfunction and immune dysregulation, with a complex pathogenesis [3]. A study investigated potential molecular mechanisms underlying the therapeutic effects of traditional Chinese medicine (TCM) compound prescriptions for psoriasis [3]. The psoriasis transcriptomic dataset GSE14905 was downloaded from the Gene Expression Omnibus (GEO) database; psoriasis-related genes and TCM compound prescriptions for psoriasis were collected; differentially expressed gene (DEG) analysis and functional enrichment analysis were performed [3]. This is a bioinformatics study.

Comparison of barrier assessment methods

Method	What it measures	Used in
Transepidermal water loss (TEWL)	Water loss through the skin	Mouse AD model [5]
Skin hydration	Water content of the stratum corneum	Mouse AD model [5]
Skin barrier characterisation	Peristomal and non-peristomal barrier function	People with a stoma [2]
Facial skin barrier integrity	Barrier function in dry, sensitive skin	Women taking collagen peptides [8]

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