Vitamin A & Retinoids
— The Language of Skin Renewal
Retinoids are considered the most thoroughly documented class of active ingredients in modern dermatology. What they biologically achieve, why they have more to do with cell communication than aggression – and how a calm, thoughtful routine can support the skin for years.
- A Class of Active Ingredients, Not a Trend
- What Retinoids Do Biologically
- Retinol, Retinal, Retinoic Acid — the Hierarchy
- Collagen Communication and Renewal
- Irritation, Tolerance, and Managing Reaction
- Night Rhythm: Why Retinoids Work in the Evening
- A Modern Retinoid Routine
- A Note on Dermatology
- Frequently Asked Questions
- References
A Class of Active Ingredients, Not a Trend
Few ingredients in skincare are as thoroughly researched as Vitamin A and its derivatives. Since the 1960s, dermatological literature has described how these molecules act in the skin – initially in the context of acne treatment, later as a reference class for controlling skin renewal. In recent years, the perspective has shifted again: away from the concept of corrective application, towards an interpretation that understands retinoids as signaling molecules.
This shift is not a stylistic matter. It describes a biologically more precise approach to this class of active ingredients. Retinoids do not irritate the skin – they speak to it. They bind to receptors in the cell nucleus, influence which genes are active, and thereby change how keratinocytes differentiate, how fibroblasts read collagen, and how the skin's architecture organizes itself over weeks. What may appear as redness or flaking is the transitional phase of skin whose renewal rhythm is being recalibrated.
A modern interpretation of retinoids therefore follows a different logic than the classic "more is more." It relies on low concentrations, longer acclimatization phases, and a skincare environment that supports the barrier – not challenges it.
dermatological research
Retinol → Retinoic Acid
retinoid signaling pathways
What Retinoids Do Biologically
Retinoids are a family of chemically related molecules, all derived from the basic structure of Vitamin A (retinol). In the skin, they are converted through several stages into their active form – retinoic acid. This binds to specific receptors (RAR and RXR) in the cell nucleus and from there controls the activity of a multitude of genes. The consequence is not a single effect, but an orchestrated pattern of renewal, differentiation, and structural change.
Retinoic acid binds to retinoic acid receptors (RAR) and retinoid X receptors (RXR) in the cell nucleus. These act as transcription factors – they directly regulate which genes are read. The effect of retinoids is therefore not a surface reaction, but a change within the cell.
In the epidermis, the maturation of keratinocytes is retimed. Cell turnover increases, the stratum corneum reorganizes, and hyperkeratoses resolve. What may initially appear as fine flaking is an expression of this shift – not damage.
In the dermis, retinoids promote fibroblast activity and increase the production of procollagen Type I and III. At the same time, they inhibit matrix-degrading enzymes (MMPs) activated by UV exposure. The dermal matrix gains density over months.
Melanocytes react to retinoids with an altered pigment distribution – one of the documented effects in post-inflammatory hyperpigmentation. They have a modulating effect on the sebaceous glands: production is reduced, and composition shifts.
Retinoids do not act on the skin. They speak with the skin – via receptors that are already part of its cell biology.
Retinol, Retinal, Retinoic Acid — the Hierarchy
What is colloquially called "Retinol" actually describes a whole family of related molecules. They differ in how many enzymatic steps the skin needs to convert them into their active form – retinoic acid. The closer a molecule is to retinoic acid, the more direct the effect – and the higher the irritation potential.
Very mild precursors like retinyl palmitate or retinyl acetate. They require three enzymatic steps to retinoic acid. Low irritation potential, but also lower efficacy – suitable for very sensitive skin or as an entry point.
The standard form in cosmetic care. Two enzymatic steps to retinoic acid (retinol → retinal → retinoic acid). Common in concentrations from 0.1 to 1%. Extensive study data, good balance of efficacy and tolerability.
Only one enzymatic step to retinoic acid – thus significantly more potent than retinol with comparable tolerance. In the literature, retinal is described as the most effective cosmetically available form, with additional antibacterial properties.
The directly active form. Tretinoin, adapalene, and tazarotene are prescription medications with defined indications. Not approved for cosmetics – their effect belongs in dermatological hands.
Newer derivatives such as Hydroxypinacolone Retinoate (HPR) or Retinyl Retinoate are described in the literature as receptor-directly active, without the need for complete enzymatic conversion. Their data is still newer than that of classic retinol.
Collagen Communication and Renewal
The most consistently described effect of retinoids in dermatological literature concerns the dermal matrix. Fibroblasts – the cells that form collagen and elastic fibers – respond to retinoic acid with increased activity. Over weeks, the balance between synthesis and degradation shifts in favor of synthesis.
This happens in two ways simultaneously. Firstly, the synthesis of new collagen fibers is stimulated, especially Procollagen Type I, which forms the main structural protein of the dermis. Secondly, the activity of certain matrix-degrading enzymes – matrix metalloproteinases (MMPs) – is inhibited. These enzymes are increasingly activated under UV exposure and are a central factor in photo-induced skin aging.
Retinoids are not aggression, but language. They tell the skin what it can do anyway – only clearer, more distinct, more precise.
This dual effect – more synthesis, less degradation – is the biological background of what is clinically described as refined skin texture, more even skin tone, and reduced wrinkle depth. The changes are not acutely visible; they result from consistent application over several months.
Irritation, Tolerance, and Managing Reactions
In the first few weeks of retinoid use, the skin may react. Mild redness, a feeling of tightness, fine flaking, and increased sensitivity to external stimuli are documented in the literature. This phase is described as "retinization" – it is an expression of adaptation, not damage. Over time, the skin builds tolerance, the reaction subsides, and the care becomes stable.
What intensifies this phase is usually the skincare environment – not the retinoid itself. An already stressed barrier, acids used in parallel, high concentrations, or too frequent application increase the likelihood of a reaction. A calm routine during this phase can make the difference between discontinuation and long-term tolerability.
- Low concentration at the start (0.1–0.3% retinol)
- 2–3 applications per week, slow increase
- Apply to dry skin after cleansing
- Sandwich technique: moisturizer before and after the retinoid
- Ceramides and squalane in accompanying care
- Panthenol for temporary reactions
- Mineral sun protection during the day, without exception
- Immediate start with high concentration
- Daily application without a build-up phase
- AHA, BHA, or Vitamin C on the same night
- Mechanically abrasive peels
- Alcohol denat. in toners or serums
- Synthetic fragrances in leave-on care
- UV exposure without consistent sun protection
Tolerance is not a constant. It is built up over weeks and may need to be recalibrated after breaks, seasonal changes, or periods of increased stress. Skin that tolerates 0.5% in summer may remain more stable with 0.3% in winter.
Night Rhythm: why retinoids work in the evening
Retinoids are not applied in the evening out of convention, but for two interconnected biological reasons. The first concerns the molecule itself: retinoids are light-sensitive. UV radiation can photochemically alter them and neutralize their effect – evening application protects the active ingredient's integrity.
The second reason lies in the skin itself. Circadian research describes night as the phase when skin renewal unfolds its highest activity: keratinocyte division rate increases, DNA repair is more intense, the barrier becomes more permeable and absorbs active ingredients better. A retinoid meets the skin in this phase not by chance – it meets it in its renewal mode.
Retinoids leverage the phase when the skin renews most intensely anyway. They don't fight against the skin's rhythm – they follow it.
A Modern Retinoid Routine
A contemporary retinoid routine does not follow the idea of maximum active ingredient density, but the principle of continuous support. It starts cautiously, gives the skin time, builds up over months, and then remains consistent. The effect unfolds not in weeks – but in the sum of seasons.
Building Up Application
In the first four to six weeks, a retinoid in a low concentration is applied two to three times a week to dry skin – after cleansing, before moisturizer. The sandwich technique – a thin film of moisturizer before and a richer one after the retinoid – can significantly improve tolerability without reducing the effect. If the skin tolerates this frequency, it can be gradually increased.
Care Around Application
The accompanying care is not secondary, but part of the effect. A calm, lipid-rich night care with ceramides, squalane, and panthenol can stabilize the transition phase. During the day, mineral sun protection is not an option, but a prerequisite – retinoids measurably increase the skin's photosensitivity.
NATURFACTOR® follows this logic in the conception of the Blue Crystal Drops. The lipid-rich night formulation is not designed as a retinoid carrier, but as a care product that can work alongside a retinoid routine – as an element of Barrier Balance in the phase when the skin renews most intensely. It takes the burden of the transition phase out of the routine, without overriding the retinoid's effect.
A Note on Dermatology
Prescription retinoids like tretinoin or adapalene are medicines with defined indications – their use belongs under dermatological supervision. During pregnancy and breastfeeding, the use of topical retinoids is advised against. For very sensitive skin, persistent reactions, or concomitant use of other active ingredients, a specialist's assessment is advisable.
Frequently Asked Questions
How long does it take for retinoids to show visible effects?
In the literature, initial changes in skin texture are described after eight to twelve weeks. Changes in the dermal matrix – i.e., the collagen structure – develop over six to twelve months of consistent application. Retinoids are not a short-term intervention.
Are retinoids suitable for all skin types?
Generally yes, but not in every concentration and frequency. Sensitive, reactive, or already irritated skin benefits from low concentrations and a slow build-up phase. For active rosacea, eczema, or open irritations, stabilization care is usually applied first before a retinoid is introduced.
Can vitamin A be used during pregnancy?
Topical retinoids are not recommended during pregnancy and breastfeeding. International literature is consistently cautious here. Specialist medical advice is advisable during these phases before continuing or starting a routine.
Which active ingredients should not be used simultaneously with retinoids?
Highly concentrated AHAs, BHAs, or Vitamin C at a low pH should be avoided in the same application – they increase the propensity for irritation. In separate routines (e.g., Vitamin C in the morning, retinoid in the evening), they are usually well combinable. The order and time interval are more important than strict separation.
- Mukherjee, S. et al. (2006). Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clinical Interventions in Aging, 1(4), 327–348.
- Kafi, R. et al. (2007). Improvement of Naturally Aged Skin With Vitamin A (Retinol). Archives of Dermatology, 143(5), 606–612.
- Quan, T. et al. (2009). Solar Ultraviolet Irradiation Reduces Collagen in Photoaged Human Skin by Blocking Transforming Growth Factor-β Type II Receptor / Smad Signaling. American Journal of Pathology.
- Sorg, O. et al. (2006). Retinoids in cosmeceuticals. Dermatologic Therapy, 19(5), 289–296.
- Matsui, M.S. et al. (2023). Circadian Oscillations in Skin and Their Interconnection with the Cycle of Life. International Journal of Molecular Sciences, 24(6), 5635.
- Babamiri, K. & Nassab, R. (2010). Cosmeceuticals: the evidence behind the retinoids. Aesthetic Surgery Journal, 30(1), 74–77.
