MILAN, ITALY – FEBRUARY 23: Model Maartje Verhoef is seen backstage at the Boss fashion show on February 23, 2020 in Milan, Italy. (Photo by Rosdiana Ciaravolo/Getty Images)

Sure, we know our skin needs vitamins to function optimally, but why and how they work is a mystery to behold. When you add the concept of topical application (that is, through skincare) the plot only thickens – what are they actually doing (if anything).

To help, we called on the expertise of Dr. Michele Squire. A PhD-qualified scientist, science educator, and former Registered Nurse who has been researching skincare science for more than 17 years, Dr. Squire is the founder of QR8, an incredible business that works to curate effective skincare routines using what already exists on the market. Her decisions are based in fact, and sifts through all the marketing fluff, false claims and sub-par formulations beauty is inundated.

Dr. Squire has kindly offered her skill set to help us pull together a mini series on skin (see her acne explainer here), but here, she outlines all there is to know about how to properly deploy the power of vitamins in your skincare routine.


The concept that topically applied vitamins nourish skin in the same way that dietary vitamins work in the body is a marketing ploy often employed by beauty companies to sell cosmetics. Cosmetics are not food – there are only a few vitamins with robust science underpinning their use in topical formulations. Note: the ‘if its’ safe enough to eat, it’s safe enough to put on your skin’ marketing technique also has no basis in science!

Vitamin B3

Also called niacinamide/nicotinamide.

What does it do?

Topical vitamin B3 activates enzymes that work in multiple skin processes, so has a variety of beneficial actions in skin: sebum inhibition, increased epidermal lipids, reduced inflammation, increased collagen production, increased dermal elasticity, reduced pigmentation.

Who is it for?

Because it’s a multi-function ingredient, it is suitable for a wide range of skin types and issues.

Important information:

Some forms of B3 (called nicotinic acid, myristoyl/myristyl nicotinate and benzyl nicotinate) can dilate blood vessels, leading to ‘flushing’ or redness (not just temporary pink skin, but major rash-like redness, which may be accompanied by stinging or burning if skin is dry or there are barrier issues). To avoid this, stick to formulations with niacinamide/nicotinamide not the other forms of Vitamin B3

Product recommendation:

Clear Skincare B3 Serum

MILAN, ITALY – FEBRUARY 23: Model Adut Akech is seen backstage at the Boss fashion show on February 23, 2020 in Milan, Italy. (Photo by Rosdiana Ciaravolo/Getty Images)

Vitamin B5

Also called panthenol, pantothenyl alcohol, dexpanthenol or pro-vitamin B5.

What does it do?

B5 functions as a humectant (attracts and holds water in the skin) and emollient (seals in moisture) as well as enhancing the production of skin’s own lipids and assisting with wound healing. Moisturisers containing up to 1% B5 (often in conjunction with glycerine and ceramides) are used to improve skin hydration and roughness, repair skin barrier function, and to reduce irritation and inflammation.

Who is it for?

Because of its skin soothing effects, B5 is very well tolerated by all skin types, but especially those with sensitive, inflamed, dehydrated, barrier-impaired or xerotic (dry) skin. You will also find it in skin products for those with psoriasis, eczema or atopic dermatitis.

Product recommendation:

La Roche-Posay Cicaplast Baume B5 Balm

Vitamin C

Also called ascorbic acid, L-ascorbic acid, magnesium ascorbyl phosphate, sodium ascorbyl phosphate, ascorbyl palmitate, ascorbyl tetraisopalmitate, ascorbyl glucoside, 3-O-ethyl ascorbate, tetrahexyldecyl ascorbate, Ascorbyl 2‐ phosphate 6‐ palmitate.

What is it?

Vitamin C (in its active form, L-ascorbic acid) is the major water-soluble antioxidant in skin where it keeps free radical levels in check and recycles vitamin E to its active form.

Who is it for? 

Topically-applied L-ascorbic acid also works as an antioxidant to quench free oxygen radicals in the skin, helping to reduce the harmful effects of UV exposure. It can also lighten skin dyspigmentation and stimulate collagen synthesis at less than 10% concentration.

Vitamin C can be used by most people, although high concentrations are reported to cause breakouts in those prone to acne. Like vitamin E, L-ascorbic acid is best used in the daytime under sunscreen in an acidic formulation to assist in skin penetration.

Important information:

Vitamin C is a hot commodity in skincare right now, but due to instability of the active form (L-ascorbic acid), many vitamin C esters also exist in cosmetic formulations. The problem with these is that not all forms of vitamin C have robust science to back up their claims in skincare. As a consumer, it’s difficult to know if your expensive vitamin C contains the correct chemical form, or the right concentration of vitamin C, to actually get results you’re after.

Product recommendation:

Skinceuticals C E Ferulic serum