Growth Factor Skincare: The Jan Marini Transformation Guide

Growth factors are signalling proteins made by fermentation and listed on an ingredient list under names that begin "sh-". They sit in a different category from retinoids or acids, and it is the category where the published evidence is thinnest. That does not make them a bad choice. It makes them a choice to make deliberately, because they are among the hardest steps in a routine to judge by feel, and the marketing around them is louder than the data behind it.

Jan Marini's Transformation range, a face serum, a face cream and an eye treatment, is the worked example here, because its three products show how differently formulas inside a single "system" can behave. What follows applies to the category in general: what these ingredients are, what the research does and does not support, how the three products differ, and whether a growth factor step earns its slot ahead of a retinoid, a vitamin C or a well-chosen peptide serum.

What does "growth factor" mean on an ingredient list?

Growth factors are proteins the body makes naturally to carry signals between cells. They are not exotic. They are part of ordinary skin biology. What is relatively new is putting versions of them into a cosmetic.

On an INCI list they show up with an sh- prefix, which flags a synthetic-human protein: the gene sequence is copied and the protein is then grown by fermentation, usually in E. coli. Nothing is harvested from human tissue. Three you will meet in the Transformation range, and in growth factor skincare generally:

• sh-Polypeptide-22, a recombinant version of transforming growth factor beta 1 (TGF-β1), the ingredient the Transformation name is best known for.
• sh-Oligopeptide-4, derived from thymosin beta 4, a small naturally occurring protein.
• sh-Polypeptide-9, a recombinant version of vascular endothelial growth factor (VEGF).

Here is the structural point brands rarely lead with: most of these are much bigger molecules than the peptides in a typical firming serum. A pentapeptide is five amino acids long. TGF-β1 runs to a little over a hundred amino acids in its mature form, and the common VEGF-A version to around 165, an order of magnitude larger. But the category is not uniform. Thymosin beta 4 is only 43 amino acids, closer to a long peptide than to a bulky protein, so "growth factor" on a label tells you less about molecule size than you might assume. Size matters for a topical product, because the skin surface is a barrier to large molecules, and how much of an applied growth factor ends up anywhere useful is genuinely debated. No brand can settle that with marketing copy.

What does the evidence on growth factors actually show?

The most useful summary to date is a 2023 systematic review in the Journal of Cosmetic Dermatology (Quinlan, Ghanem and Hassan), which pooled 33 studies covering 1,180 participants across 23 different topical growth factor preparations. Two findings are worth carrying with you:

• The direction of travel is positive but modest. Studies reported improvements in skin texture, in the appearance of fine lines and in overall facial appearance, but the effects were incremental rather than dramatic.
• The evidence base is weak in structure. Only nine of the 33 studies were randomised controlled trials; the rest were uncontrolled case series. Formulations varied enormously, other active ingredients in the same products were often undisclosed, assessment methods were not standardised, and whether improvements last beyond six months is simply not known.

Safety came out well, with a low risk of adverse events across the studies. So the honest position is: plausible, well tolerated, under-evidenced. That is not a reason to avoid growth factors, but it is a reason not to let them push aside a category with decades of controlled data behind it. If you want to see how that data hierarchy works in practice, our guide to the science behind medical-grade ingredients is a good companion read.

Is Jan Marini growth factor skincare available in the UK?

Jan Marini's UK distribution is patchy and the Transformation line in particular comes and goes, so check the Jan Marini collection before you get attached to a specific bottle. The breakdown below is still worth reading if it is out of stock, because it sets out what a growth factor range is trying to do, and the last section covers what fills the same slot in a routine.

What are the three Jan Marini Transformation products for?

They are not interchangeable, and the differences run deeper than texture.

Transformation Face Serum (30ml)

The lightest of the three and the one meant to sit closest to the skin, under everything else. If you are only going to use one product from the range, this is the one designed to do the work; the cream is positioned as the moisturising layer on top rather than a substitute.

Transformation Face Cream (28g)

A mid-weight moisturiser combining the same growth factor complex with peptides and hyaluronic acid, applied sparingly morning and evening across the face and neck. This is the sensible pick for anyone whose skin already runs dry, because it removes the need for a separate moisturiser on top.

Transformation Eye Cream (14g)

Read the full ingredient list on this one before you assume it is the gentle option. Alongside the growth factors and peptides it contains glycolic acid, retinyl palmitate and ascorbic acid, an exfoliating acid, a retinoid ester and a vitamin C, plus fragrance with limonene and linalool. That is an active formula for a thin area of skin. It is directed to be applied sparingly to the lower eyelids and brow bone, and that instruction is not decorative: product creeping into the lash line is the usual cause of stinging. If you are still working out what an eye product should do for you at all, start with our comparison of eye creams and eye serums.

Growth factors vs peptides vs retinoids: how do you choose?

These three categories get presented as rivals. They are better understood as different trade-offs between evidence, irritation and effort.

• Retinoids have the deepest research base of the three and the widest range of visible changes attributed to them, and the highest chance of a rough first six weeks. If your skin tolerates one, this is where the strongest case sits. Our guide to retinol and its gentler relatives covers how to build up without the flaking.
• Peptides are small, stable, comfortable and easy to layer with almost anything. The evidence for any individual one is patchy and highly ingredient-specific, but the tolerability is excellent, which is why they turn up in nearly every firming and eye cream formula on the market.
• Growth factors are the newest and least settled of the three, with good tolerability and modest reported results. Their real-world argument is a practical one: they give people who cannot use retinoids somewhere else to go.

A workable decision rule. If you have never used a retinoid and your skin is not reactive, try one first; you will learn more about your skin, faster. If you have tried and abandoned retinoids, are pregnant or breastfeeding, or already run a full routine and want an extra low-irritation step, a growth factor serum or a peptide-led product is the more realistic next move. Browsing by concern rather than by ingredient is often quicker: the anti-ageing collection and our guide to building an anti-ageing routine both start from the change you want to see rather than the molecule.

Where do growth factors go in a routine?

Growth factor serums are undemanding to place, which is part of the appeal.

1. Cleanse, then apply to dry skin. Not damp. Water on the surface dilutes the layer you have just applied and can drag it around unevenly.
2. Thinnest first. The serum goes on before any cream, and before oils or SPF.
3. Do not stack it with a direct acid in the same application. If you use a glycolic or lactic toner, use it on alternate evenings, or put the acid on at night and the growth factor step in the morning.
4. Keep retinoid nights separate. Alternate nights, or growth factor in the morning and retinoid in the evening, is the usual arrangement. Layering both in one sitting mostly buys irritation.
5. Finish the morning with SPF. Without it you are running an anti-ageing step in the morning and undoing it by lunchtime.

Our ingredient layering guide goes through the awkward combinations in more detail, including where vitamin C fits.

Who should think twice about growth factors?

• Pregnancy and breastfeeding. The Transformation Eye Cream contains retinyl palmitate, a retinoid ester, a category commonly avoided during pregnancy. Growth factors themselves have not been studied in this group. Ask your GP or midwife rather than the internet.
• Fragrance-sensitive skin. The eye formula is fragranced and contains limonene and linalool. If you have reacted to fragranced products before, this is not the place to test your luck.
• Anyone mid-course of professional treatment. If you are having peels, needling or laser, take your practitioner's advice on when to restart actives. Post-procedure care instructions override any product's own directions.

What results can you realistically expect?

Give any growth factor product a full twelve weeks, photograph your skin in the same light on day one, and change only one product at a time. The review above found improvements that were real but incremental, the kind you notice in a photograph rather than the mirror. Anyone promising a dramatic change in a fortnight is selling something.

Be clear too about what a cosmetic can be expected to do: change how skin looks and feels. Firmer-looking, smoother-looking, better hydrated, softer-focused lines. That is the honest ceiling here, and a perfectly respectable one.

What can you use instead when Transformation is out of stock?

The closest like-for-like swap within the brand is Regeneration Booster, and it is worth being precise about why: it is not a peptide alternative, it is another growth factor formula. It carries the same sh-Polypeptide-22 (TGF-β1) that Transformation is known for, alongside sh-Oligopeptide-1 (a recombinant epidermal growth factor) and sh-Polypeptide-3 (a keratinocyte growth factor). Same category, same evidence picture, same caveats as everything above, so if it is the growth factor step you want, that is the one to look for. Age Intervention Peptide Extreme is the peptide-led option instead: a different trade-off, designed to be layered under a moisturiser. The Jan Marini collection will show which is currently stocked.

And if what appealed about Transformation was "results without irritation", the answer need not be a growth factor at all. It might be a well-formulated peptide serum, a gentler retinoid used less often, or simply a better-chosen moisturiser. Working through targeted serums by concern, or the retinol range if retinoids deserve a second, slower attempt, will get you further than matching an ingredient name.