In cultured human keratinocytes, yes. Nicotinamide at 1–30 µmol/L raised the rate of ceramide biosynthesis 4.1- to 5.5-fold over six days, alongside glucosylceramide (7.4-fold), free fatty acids (2.3-fold) and cholesterol (1.5-fold), by upregulating serine palmitoyltransferase (Tanno et al., 2000). Whether topical cosmetic use reproduces that magnitude on human skin is a separate question.
Published 15 September 2026 · Last reviewed 15 September 2026
The terms, defined
Niacinamide — also called nicotinamide — is the amide form of vitamin B3 and the precursor of the coenzymes NAD and NADP. The two names denote the same molecule; the pharmacological literature generally uses the second, the cosmetic literature the first.
De novo lipid synthesis is the manufacture of a lipid by the cell from small precursor molecules, as opposed to the supply of that lipid from outside. A substance that promotes it acts on the tissue's own production, not on the layer applied to the surface.
Serine palmitoyltransferase (SPT) catalyses the first and rate-limiting step of sphingolipid synthesis. Its activity sets the ceiling on how much ceramide a keratinocyte can produce.
Transepidermal water loss (TEWL) is the quantity of water passing outward through the epidermis per unit area and time. It is the standard instrumental proxy for permeability barrier competence.
What was measured in the cell model
The mechanistic reference is a 2000 study in the British Journal of Dermatology. Cultured normal human keratinocytes were incubated with 1–30 µmol/L nicotinamide for six days, and sphingolipid synthesis was quantified by incorporation of 14C-serine.
The reported result is dose-dependent: "the rate of ceramide biosynthesis was increased dose-dependently by 4.1-5.5-fold on the sixth day compared with control". Glucosylceramide rose 7.4-fold and sphingomyelin 3.1-fold over the same concentration range. The proposed mechanism is transcriptional — SPT activity increased, and so did the messenger RNA for its LCB1 and LCB2 subunits. Free fatty acid synthesis rose 2.3-fold and cholesterol synthesis 1.5-fold (Tanno et al., 2000, Br J Dermatol 143:524–531).
That last detail matters more than it first appears. The permeability barrier depends not on ceramide abundance alone but on the proportions of the three lipid classes that form its lamellae. A substance that raised ceramide production in isolation would shift those proportions; one that raises all three has at least the arithmetic shape of a barrier effect.
What was measured on skin
The same paper reports an in vivo arm: topical application of nicotinamide "increased ceramide and free fatty acid levels in the stratum corneum, and decreased transepidermal water loss in dry skin". The abstract does not state the applied concentration, which is a real limitation when reasoning from this result to a cosmetic formula.
The best-documented cosmetic concentration comes from a separate 12-week, double-blind, placebo-controlled, split-face trial in 50 Caucasian women aged 40–60, comparing a moisturiser with the same moisturiser containing 5% niacinamide. The authors report the active side to be well tolerated and significantly improved over control on fine lines and wrinkles, hyperpigmented spots, texture, red blotchiness and sallowness (Bissett et al., 2004, Int J Cosmet Sci 26:231–238). These are appearance endpoints assessed on aging facial skin; they are not measurements of barrier lipids.
What niacinamide does not do
A 2025 biophysical study in Scientific Reports examined the molecule's direct effect on isolated human stratum corneum using X-ray diffraction and dynamic vapour sorption, across 2.5, 5.0, 10 and 20 wt% in phosphate-buffered saline. Three findings deserve attention because they cut against the common shorthand.
First, the molecule is not a humectant. The authors state plainly that "NIA is non-hygroscopic". Its effect on water content is conditional on ambient humidity: treated stratum corneum held about 5 wt% more water at 95% relative humidity, but at 60% relative humidity showed "a slight but consistent reduction in SC water content (about 1 wt%)".
Second, the structural effect is on protein, not lipid alone. Keratin monomer spacing expanded from 0.98 nm to 1.04 nm under treatment — an expansion the authors put at "about 0.4-1.0 Å" — which they interpret as a plasticising effect on the keratin matrix rather than a keratolytic one.
Third, and most consequential for formulation practice, these effects "appear independent of the investigated dose regime". Across an eightfold concentration range, no dose-dependent reduction in keratin diffraction was found. The inference the authors draw is that a concentration threshold exists rather than a linear dose-response — which is an argument against the assumption that a higher percentage on the label denotes a proportionally greater effect.
What each study measured
| Study | Model | Concentration | Principal reported outcome |
|---|---|---|---|
| Tanno et al., 2000 | Cultured normal human keratinocytes, 6 days | 1–30 µmol/L | Ceramide synthesis 4.1–5.5×; glucosylceramide 7.4×; sphingomyelin 3.1×; free fatty acid 2.3×; cholesterol 1.5×; increased SPT activity and LCB1/LCB2 mRNA |
| Tanno et al., 2000 (in vivo arm) | Topical application, dry skin | Not stated in the abstract | Increased stratum corneum ceramide and free fatty acid; decreased transepidermal water loss |
| Bissett et al., 2004 | 50 women aged 40–60; 12 weeks, split-face, placebo-controlled | 5% in a moisturiser | Significant improvement versus control in fine lines and wrinkles, hyperpigmented spots, texture, red blotchiness and sallowness |
| Sjöberg et al., 2025 | Isolated human stratum corneum; X-ray diffraction and dynamic vapour sorption | 2.5, 5.0, 10, 20 wt% | Non-hygroscopic; +≈5 wt% water at 95% RH; −≈1 wt% at 60% RH; keratin monomer spacing 0.98 → 1.04 nm; no dose dependence across the range |
| Ong & Goh, 2024 | Narrative review of dermal delivery and clinical evidence | 1–4% in the dermatological trials surveyed | Reviews trials in acne vulgaris, melasma, axillary hyperpigmentation and actinic keratosis |
Reading the concentrations correctly
The 2024 review in Drug Delivery and Translational Research surveys clinical work at 1% to 4% — 4% against 1% clindamycin in moderate inflammatory acne vulgaris, 4% against 4% hydroquinone in melasma, 4% with 0.05% desonide in axillary hyperpigmentation, 1% in actinic keratosis. These are therapeutic investigations of dermatological conditions, conducted under a medicinal rather than a cosmetic framework. They establish that the molecule is biologically active at those concentrations; they establish nothing about what a cosmetic product may claim.
The distinction is not pedantic. In the European Union, Commission Regulation (EU) No 655/2013 requires that claims made for cosmetic products be supported by adequate and verifiable evidence, and Regulation (EC) No 1223/2009 excludes the treatment of disease from the cosmetic category altogether. In the United States, the boundary between a cosmetic and a drug under the Federal Food, Drug, and Cosmetic Act is set by the claim rather than by the ingredient. A trial in acne is evidence about acne; it is not transferable support for a cosmetic barrier claim.
Where this leaves the mechanism
The defensible summary is narrower than the marketing version and more interesting than it. Niacinamide has a documented transcriptional route to increased synthesis of the three principal stratum corneum lipid classes, demonstrated in cultured keratinocytes with a stated mechanism at the rate-limiting enzyme. It has a documented effect on stratum corneum water content that reverses direction with ambient humidity, and a structural effect on keratin that does not scale with concentration. These are different claims about different compartments, and the evidence for each is of a different kind.
Anyone describing this molecule as a barrier ingredient is on solid ground. Anyone describing a given percentage as proportionally more effective is not.
References
- Tanno, O., Ota, Y., Kitamura, N., Katsube, T. & Inoue, S. (2000). Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. British Journal of Dermatology, 143(3), 524–531. DOI 10.1111/j.1365-2133.2000.03705.x · PMID 10971324
- Bissett, D. L., Miyamoto, K., Sun, P., Li, J. & Berge, C. A. (2004). Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin. International Journal of Cosmetic Science, 26(5), 231–238. DOI 10.1111/j.1467-2494.2004.00228.x · PMID 18492135
- Sjöberg, T., Fsahaye, A., Nilsson, E. J., Letasiova, S., Namro, I., Visdal-Johnsen, L., Hrapovic, N., Smiljanic, S., Österlund, C., Engblom, J. & Björklund, S. (2025). Niacinamide and its impact on stratum corneum hydration and structure. Scientific Reports, 15, 4953. DOI 10.1038/s41598-025-88899-0
- Ong, R. R. & Goh, C. F. (2024). Niacinamide: a review on dermal delivery strategies and clinical evidence. Drug Delivery and Translational Research, 14, 3512–3548. DOI 10.1007/s13346-024-01593-y · PMID 38722460
- Commission Regulation (EU) No 655/2013 of 10 July 2013 laying down common criteria for the justification of claims used in relation to cosmetic products.
Scope
This article describes findings reported in the published scientific literature. It is not a claim of efficacy, performance or benefit for any cosmetic product, and it is not medical advice. Cosmetic products are not intended to diagnose, treat, cure or prevent any disease.