Skincare vs Supplements: What Works on Your Skin, and What Works From Within
Some ingredients work best applied to the skin, some work from within, and some do both in different ways. Collagen, for example, supports skin from the inside but can't be replenished by a cream. Vitamin A works best as a topical retinoid, while omega-3s are mostly an inside job. Knowing which is which makes it easier to decide where to spend your money.
Why does it matter where an ingredient works?
Skin is built in layers. The outer layer, the stratum corneum, acts as a barrier, so what you apply mostly acts on the surface and upper layers. The dermis sits underneath, and it's where collagen and the skin's structure are made and maintained. Food and supplements work from within, supporting the deeper layers through your body's own processes.
That's why the same ingredient can behave very differently depending on how you use it, and why the best approach often combines both.
Does collagen work in skincare or supplements?
Collagen is active in the dermis, the deeper layer that gives skin its structure. Collagen molecules in creams are too large to pass through the skin's outer barrier, so they can only hydrate the surface temporarily. They won't replenish your collagen stores or support the skin's structural scaffolding.
From within, protein and vitamin C support your body's own collagen production. Some women also consider collagen peptide supplements, which I cover below.
What are peptides, and how are they different from collagen?
Peptides are short chains of amino acids, and they're much smaller than collagen.
On the skin: peptides may support firmness and hydration. They're generally gentle and soothing for sensitive skin, and may help support skin barrier resilience. Results tend to be subtle and build over time.
From within: collagen peptides (hydrolysed collagen) may support elasticity, though the evidence is mixed, and the form and molecular weight are significant. Protein at every meal is the foundation.
What does vitamin C do for skin?
Vitamin C is useful in both places.
On the skin: brightening, antioxidant protection and firmness.
From within: it supports collagen synthesis and your antioxidant defences. Peppers, citrus fruit, berries, kiwi and broccoli are all good sources.
What does vitamin A do for skin?
Topical vitamin A, in the form of retinoids (including tretinoin), does most of the heavy lifting.
On the skin, retinoids:
support skin cell turnover
target fine lines and firmness
support texture and tone
help with acne by regulating cell shedding and oil production, supporting clearer pores and fading of post-acne marks
From within: vitamin A provides antioxidant support and helps regulate sebum production. Pre-formed vitamin A is found in some animal foods, and beta-carotene in plant-based foods.
Retinoids aren't suitable in pregnancy. Use SPF daily and build up slowly. Tretinoin is prescription-only in the UK. Oral vitamin A supplements should be guided and monitored by a healthcare professional.
What about AHAs, BHAs and PHAs?
Acids are a skincare job, and there's no food or supplement equivalent. They exfoliate to support smoother, brighter skin.
AHAs (such as glycolic and lactic acid) suit dullness and uneven texture.
BHAs (such as salicylic acid) suit congestion.
PHAs are gentler, which makes them a good option for sensitive skin.
Do omega-3s help skin?
Omega-3s work from within. The omega-3s in oily fish (salmon, mackerel, anchovies, sardines) support the skin barrier and moisture levels, and help regulate the skin's inflammatory response. The evidence for omega-3s applied topically is limited, so I wouldn't rely on them in skincare.
FREQUENTLY ASKED QUESTIONS
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They can temporarily hydrate the skin's surface, but they can't replace the collagen in the dermis. Supporting your body's own collagen production, with enough protein and vitamin C, is where nutrition comes in.
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The evidence is mixed, and the form and molecular weight matter. Protein at every meal is a stronger foundation, and I'd look at that first. If you're considering a supplement, it's worth discussing in the context of your own health.
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Yes. Topical products act on the surface and upper layers, while nutrition supports the deeper layers from within. Both matter.
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Oral vitamin A supplements should be guided and monitored by a healthcare professional, and this matters particularly if you could be pregnant or are using prescription retinoids. Food sources are a different matter and don't carry the same concerns - although in pregnancy high pre-formed vitamin A foods should also be guided.
If you'd like help working out what your skin needs, you can book a free 15-minute introductory call.
If you'd like a focused look at your skin and skincare, you can also book a Skin Strategy Session.
You can read more about my skin health support, or how nutritional therapy works.
If you're curious about why a meal plan is only part of the picture, I've written about why personalised nutrition is more than a meal plan.
Written by Jodie Abrahams, Registered Nutritional Therapist (BANT, CNHC)
