Keratin
ProteinKeratin is the family of structural proteins that form the intermediate filaments of skin, hair, and nails, providing mechanical strength and showing distinct expression patterns during repair.
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Keratinocyte
AnatomicalStructureThe predominant cell type of the epidermis, produced in the basal layer and progressively differentiating through epidermal strata to become the corneocytes that form the stratum corneum barrier.
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Keratinocyte differentiation
BiologicalProcessThe coordinated, one-way molecular programme by which a basal keratinocyte progresses through the epidermal layers to produce the structural and biochemical components of the skin barrier.
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Lactic acid
ChemicalSubstanceA dual-action AHA: exfoliates via desmosome disruption and replenishes NMF as a humectant. Better tolerated than glycolic acid at equivalent efficacy.
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Lamellar body secretion
BiologicalProcessThe calcium-triggered exocytosis event at the stratum granulosum–stratum corneum interface that delivers ceramide precursors, enzymes, and antimicrobial peptides into the extracellular space.
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LED therapy
MedicalTherapyLED light therapy uses visible and near‑infrared wavelengths to activate mitochondrial photoreceptors, boosting collagen, calming inflammation, improving barrier repair, and targeting C. acnes.
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Leptin
ProteinSatiety hormone produced by fat cells that signals energy sufficiency to the brain; levels drop during caloric restriction.
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Linoleic Acid
MolecularEntityAn essential omega-6 fatty acid with a specific structural role in the stratum corneum's lamellar lipid architecture. Precursor to GLA, DGLA, and arachidonic acid in the omega-6 metabolic pathway.
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Lip
AnatomicalStructureThe lip is the most dynamically expressive structure in the lower face and among the earliest to register the visual signs of ageing.
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Lip care occlusive and emollient agents
ChemicalSubstanceOcclusive and emollient agents that reduce TEWL and restore intercellular lipids in lips, addressing their thin barrier and lack of sebum to prevent dehydration and structural dryness.
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Lip vulnerability
MedicalConditionLips requiring external lipid sources and protective barriers due to lacking oil-producing glands found elsewhere on the face.
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Lipid synthesis
BiologicalProcessThe biological process by which skin cells produce ceramides, cholesterol, and fatty acids - the structural lipid building blocks of the stratum corneum's protective barrier.
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LL-37
ProteinA cationic antimicrobial protein that kills pathogens, shapes the skin microbiome, and can drive inflammation when overexpressed.
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Loricrin
ProteinThe dominant structural protein of the cornified envelop, co-suppressed with filaggrin by IL-4/IL-13, with NRF2 partially compensating for its loss through increased lipid barrier secretion.
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Low-carbohydrate diet
MedicalTherapyDietary approach limiting carbohydrates below 130g daily, potentially supporting natural GLP-1 production and appetite regulation.
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Lumi-Pro Lips
MedicalTherapyLumi-Pro Lips works by restoring the lip's own hydration capacity from within — delivering free HA chains that attract and bind water molecules in the tissue.
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Lympho-epithelial Kazal-type-related inhibitor
ProteinA serine protease inhibitor produced by granular layer keratinocytes whose primary function is the precise spatial and quantitative regulation of KLK5, KLK7, and KLK14 activity in the stratum corneum.
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Magnesium
ChemicalSubstanceA core cofactor for energy and repair pathways; serum levels mask depletion because magnesium is tightly held in cells and bone, not blood.
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Malonyl coenzyme A
BioChemEntityA glucose‑derived metabolite that inhibits CPT‑1, suppressing fatty‑acid oxidation and diverting lipids toward storage when carbohydrate supply is high.
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Mast cell
AnatomicalStructureDermal sentinel immune cells that detect allergens, proteases, and neuropeptides and release waves of mediators that shape inflammation, itch, and barrier dysfunction.
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Matrix metalloproteinase
ProteinMatrix metalloproteinases are zinc‑dependent enzymes that break down extracellular matrix; when chronically upregulated they drive dermal collagen, elastin, and basement‑membrane loss.
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Melanocyte
AnatomicalStructureDendritic pigment-producing cells of the basal epidermis, responsible for melanin synthesis and UV photoprotection
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Mesotherapy
MedicalTherapyA minimally invasive intradermal technique delivering vitamins, amino acids, antioxidants, and non‑cross‑linked hyaluronic acid into the superficial dermis to support skin biorevitalisation.
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Metabolic adaptation
BiologicalProcessMetabolic adaptation is the physiological reduction in resting energy expenditure that exceeds what would be predicted from changes in body weight and composition alone during caloric restriction.
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Metabolic chronodisruption
BiologicalProcessThe process by which metabolic inflexibility depletes cellular NAD⁺, stalling SIRT1 deacetylase activity and progressively dampening the molecular circadian clock.
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Microbiome-targeted skincare
MedicalTherapySkincare designed to shape the skin’s microbial ecology, supporting commensals and innate immunity through prebiotics, postbiotics, and microbiome‑friendly formulations.
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Microneedling
MedicalTherapyA minimally invasive skin treatment using fine needles to create controlled micro-injuries that trigger the body's wound healing cascade, stimulating collagen and elastin synthesis.
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Mitochondria
AnatomicalStructureMitochondria are the energy‑producing organelles in virtually all skin cells; their integrity strongly influences ageing, barrier function, pigmentation.
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Monounsaturated fatty acids
ChemicalSubstanceA class of fatty acids characterised by a single double bond in the carbon chain, placing them structurally and functionally between saturated and polyunsaturated fatty acids.
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Muscular system
AnatomicalSystemThe body's network of contractile tissue responsible for movement, posture, and structural support.