Bamboo charcoal, olive leaf, and trehalose: What research says about sebum control and pore cleansing

Introduction: Why is my skin shiny—even though I cleanse it? Anyone with oily skin knows the feeling: washed in the morning, the T-zone is shiny again by noon. Pores look enlarged, and blemishes return despite regular care. Many cleansing products promise "deep cleaning" and "detox"—but how much of that is proven, and what is just marketing? In this article, we look at three active ingredients contained in No. 05 — Carbo: bamboo charcoal, olive leaf extract, and trehalose. We cite the original studies, evaluate the results honestly, and explain why the combination is more effective than any single active ingredient alone. How sebum is formed—and why it becomes a problem Skin sebum is produced by the sebaceous glands and consists of about 57% triglycerides, 26% wax esters, 12% squalene, and 2% cholesterol. Sebum is fundamentally important: it protects the skin from drying out and forms part of the natural skin barrier. The problem begins when sebum production becomes unbalanced. Excess sebum collects in the pores, mixes with dead skin cells and environmental pollutants—and forms a breeding ground for blemishes, enlarged pores, and blackheads. Conventional cleansers often rely on aggressive surfactants (e.g., sodium lauryl sulfate), which remove sebum but simultaneously attack the skin's protective lipids. The result: the skin produces even more sebum as a reaction—a vicious cycle. Bamboo charcoal: What adsorption can really do The mechanism Bamboo charcoal is produced through the pyrolysis of bamboo wood at high temperatures. Carbonization creates a microporous structure with a massive internal surface area. A single gram of activated bamboo charcoal can have a surface area of up to 560 m²—equivalent to about the size of two tennis courts. These pores function like a physical magnet: they adsorb (not absorb) substances that adhere to their surface. These include sebum, dirt particles, and excess oil. What the study shows Zhu, Zhang, Zheng & Wang (2024) investigated the adsorption capacity of steam-activated bamboo charcoal toward triglycerides—the main component of skin sebum—in a laboratory study. Study details: Published in: Scientific Reports (Nature), Volume 14, Article 6237 Method: Orthogonal experimental design + molecular dynamics simulation Activation: 750 °C, steam, 1.5 hours Results: Activated bamboo charcoal adsorbed 27.0% of triglycerides Specific surface area was 560.0 m²/g Binding energy between activated bamboo charcoal and triglycerides was significantly stronger (−145.12 kcal/mol) than with ordinary bamboo charcoal (−132.73 kcal/mol) Per gram, activated bamboo charcoal adsorbed 1.77 × 10²¹ triglyceride molecules—over a hundred times more than ordinary charcoal (1.56 × 10¹⁹) An honest assessment This study convincingly proves the mechanism of sebum adsorption—at a molecular level, with reproducible simulation data. What it does not prove: the direct effect on human skin under realistic conditions of use. A review in the Journal of Cosmetic Dermatology (2021) summarizes the current state of knowledge: activated charcoal is safe for topical use, and its ability to bind surface oil is physically real—but the clinical evidence for specific cosmetic claims (such as permanent pore reduction) requires further studies. The Journal of the American Academy of Dermatology confirms: for a cleansing soap with regular, short skin contact, the effect is milder than with leave-on products like masks. The effect builds up over weeks, not overnight. What bamboo charcoal realistically does in a soap: Binds excess sebum on the skin's surface Removes dirt and environmental particles Leaves the skin feeling more matte and refreshed Supports a clearer complexion with regular use Olive leaf extract: The sebum regulator While bamboo charcoal adsorbs existing sebum, olive leaf extract addresses the issue one step earlier: at the level of sebum production itself. What the study shows Kim et al. (2026) investigated olive leaf extract (OLE) as an active ingredient against excessive sebum production and skin inflammation. Study details: Published in: Current Issues in Molecular Biology, Volume 48(6), Article 549 Method: In-vitro study on human SEB-1 sebocytes (sebum cells), HaCaT keratinocytes, and fibroblasts Main active ingredient: Oleuropein (a polyphenol found only in olive trees) Results: OLE significantly inhibited lipid accumulation in sebocytes—without cytotoxicity (i.e., without damaging the cells) OLE reduced pro-inflammatory cytokines (IL-8, TNF-α, PGE2) in keratinocytes triggered by acne bacteria (Cutibacterium acnes) or UVB radiation The mechanism: inhibition of the PPAR-γ and SREBP-1 signaling pathways, which are responsible for sebum secretion Oleuropein alone showed comparable results, confirming it as a key active ingredient Clinical data A pilot study by Wanitphakdeedecha et al. (2020) in the Journal of Cosmetic Dermatology tested a cream containing OLE on human subjects: Applied twice daily for 2 months Significant reduction in transepidermal water loss (TEWL) — p = 0.007 Significantly increased skin hydration — p = 0.004 Improved skin texture in 64% of participants Significant wrinkle reduction — p < 0.001 An honest assessment The in-vitro study (Kim et al.) shows a convincing mechanism: olive leaf extract acts directly on the cells that produce sebum. This is promising, but in-vitro is not in-vivo—the journey from the petri dish to real skin is a long one. The clinical pilot study (Wanitphakdeedecha et al.) confirms skin improvements but tested a leave-on cream, not a soap. In a rinse-off application, the contact time is shorter—the effect builds up more slowly. What olive leaf extract realistically does in a soap: Regulates sebum production at the cellular level Has an anti-inflammatory effect against acne bacteria Protects the skin from oxidative stress Supports a clearer, less oily complexion over weeks Trehalose: Why charcoal soap needs moisture protection Every thorough cleansing carries a risk: if too much oil is removed, the skin dries out—and reacts with even more sebum production. This is exactly where trehalose comes in. What is trehalose? Trehalose is a naturally occurring disaccharide (a simple sugar) that plays a remarkable role in nature: so-called "resurrection plants" survive extreme drought because trehalose protects their cell membranes and proteins from drying out. This principle can be applied to the skin. What the study shows In a randomized, placebo-controlled, double-blind study (published in PMC, 2024), sodium trehalose sulfate was tested on subjects with dry skin. Results: After 4 weeks: significant reduction in transepidermal water loss (TEWL) Increased water content of the stratum corneum—the skin retains more moisture In 3D skin models: increased expression of filaggrin (important for natural moisturizing factors), ceramides (skin barrier lipids), and transglutaminase 1 (structural protein) Another study (Nagase, 14-day protocol) showed: at a 3% trehalose concentration, skin hydration improved significantly compared to placebo. In dry environments, moisture retention was even better than with glycerin. Why this is so important in a charcoal soap Carbo contains 4% trehalose—a deliberately high proportion. The reason: bamboo charcoal adsorbs sebum; that is its job. But without a counterpart, the skin would feel dry and tight after washing. Trehalose compensates for this by: Binding and retaining moisture in the skin Actively strengthening the skin barrier (ceramides, filaggrin) Supporting the skin microbiome as a prebiotic The result: Thoroughly cleansed, but not dried out. More matte skin that remains supple. The other active ingredients in Carbo Lauroylglutamic acid — the mild surfactant Carbo uses no sodium lauryl sulfate (SLS) and no traditional soap surfactants. Instead: lauroylglutamic acid, an amino acid-based surfactant derived from glutamic acid and lauric acid. A review by Ananthapadmanabhan et al. (2019) in Tenside Surfactants Detergents describes amino acid surfactants as the "gold standard" for mildness. Glutamate surfactants are considered "non-delipidants"—they remove surface dirt without attacking the skin barrier's intercellular lipids (ceramides, cholesterol). This means: Carbo cleanses thoroughly, but the skin barrier remains intact. Purslane Extract (Portulaca oleracea) — the soother Portulaca oleracea (purslane) is listed by the WHO as one of the most widely used medicinal plants in the world. It is the green plant richest in omega-3 fatty acids (α-linolenic acid) and contains β-carotene, vitamins C and E, as well as powerful antioxidants. Samimi et al. (2023) conducted a randomized, double-blind, placebo-controlled study on 70 patients with chronic hand eczema (Journal of Integrative and Complementary Medicine): After 4 weeks: significantly less itching (p = 0.041), less dryness (p = 0.045), and reduced overall symptoms (p = 0.023) No serious side effects In Carbo, purslane serves as a soothing counterpart to the cleansing charcoal: anti-inflammatory, skin-protecting, and lipid-replenishing. Lemon Fruit Extract — the natural astringent Lemon fruit extract contains citric acid (a natural alpha-hydroxy acid), flavonoids, and vitamin C. The citric acid acts as a mild exfoliant that loosens dead skin cells—and as a natural astringent that temporarily refines pores and regulates sebum. Sodium Hyaluronate & Vitamin E Low-molecular-weight hyaluronic acid binds many times its weight in water and supports the skin's moisture supply. Vitamin E (tocopherol) protects cell membranes from oxidative stress as an antioxidant—especially important for impure, irritated skin. Why the combination is more than the sum of its parts The strength of Carbo lies not in a single "miracle ingredient," but in the interplay: Step Ingredient What it does 1. Bind sebum Bamboo charcoal Adsorbs excess oil on the skin's surface 2. Regulate sebum Olive leaf extract Inhibits lipid accumulation in sebaceous cells 3. Gently cleanse Lauroylglutamic acid Removes dirt without attacking the skin barrier 4. Soothe skin Purslane Extract Anti-inflammatory, antioxidant, lipid-replenishing 5. Protect moisture Trehalose + Hyaluronic acid Strengthens the skin barrier and binds moisture 6. Refine pores Lemon Fruit Extract Mild exfoliant and natural astringent Many charcoal soaps rely only on the "wow" effect of the black color and the cleansing action of the charcoal—without worrying about what happens afterward. Carbo is formulated differently: cleanse and protect. Realistic expectations: What happens when? We don't promise miracles after the first use. Here is what you can realistically expect: Immediately: A more matte, fresher skin feel after washing. The skin feels thoroughly cleansed without feeling tight. 1–2 weeks: The skin gets used to the routine. Less oily shine throughout the day, the complexion looks fresher. 4–6 weeks: With regular use (2–3 times a week): fewer blemishes, pores look finer, complexion is more even. 3 months: Carbo has become part of your weekly routine. The overall complexion is clearer, and blemishes return less frequently. Important: These timeframes are based on the available research on the ingredients used. Individual results will vary based on skin type, lifestyle, and overall skincare routine. Comparison table: Carbo vs. conventional cleansing Conventional cleansers No. 05 — Carbo Surfactant system SLS / SLES (aggressive) Amino acid surfactant (mild) Sebum removal Degreases the entire skin surface Targeted adsorption of excess sebum Skin barrier Often attacked Actively protected by trehalose Moisture Skin feels tight after washing Hyaluronic acid and trehalose bind moisture Sebum regulation None — only removes what is there Olive leaf extract regulates sebum production Skin soothing Often irritating for sensitive skin Purslane Extract soothes and protects References Zhu, H., Zhang, S., Zheng, H. & Wang, G. (2024). Enhanced triglyceride adsorption by steam-activated bamboo charcoal based on molecular dynamics investigations. Scientific Reports, 14, 6237. DOI: 10.1038/s41598-024-56902-9 Kim et al. (2026). Olive Leaf Extract Suppresses Sebogenesis and Inflammation via AKT/ERK and SREBP-1/PPAR-γ Signaling in Human Sebocytes. Current Issues in Molecular Biology, 48(6), 549. DOI: 10.3390/cimb48060549 Wanitphakdeedecha, R. et al. (2020). Efficacy of olive leaf extract–containing cream for facial rejuvenation: A pilot study. Journal of Cosmetic Dermatology, 19(7), 1662–1670. DOI: 10.1111/jocd.13457 Sajjad, A. et al. (2021). Cosmetic uses of activated charcoal. International Journal of Community Medicine and Public Health, 8(10), 5. DOI: 10.18203/2394-6040.ijcmph20213815 Ananthapadmanabhan, K. P. et al. (2019). Amino-Acid Surfactants in Personal Cleansing (Review). Tenside Surfactants Detergents, 56(5), 378–386. DOI: 10.3139/113.110641 Samimi, R. et al. (2023). Efficacy and safety of purslane (Portulaca oleracea) for mild to moderate chronic hand eczema; A randomized, double-blind, placebo-controlled clinical trial. Journal of Integrative and Complementary Medicine. DOI: 10.1016/j.explore.2023.10.003 Functional properties of sodium trehalose sulfate (2024). PMC/Wiley. DOI: 10.1111/jam.15878 Zhu, H. et al. (2024) — Note: The study examined adsorption in the laboratory (in vitro / molecular dynamics simulation), not directly on human skin. With a rinse-off soap with a short contact time, the effect is milder than with leave-on products. This article has been carefully researched and reflects the state of current research. Kaaeli does not invent study results and exclusively cites published, verifiable sources. Where evidence is limited, we state this openly.

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Bamboo charcoal, olive leaf, and trehalose: What research says about sebum control and pore cleansing

Introduction: Why is my skin shiny—even though I cleanse it?

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