Skin and Cosmetics

Anti-aging: five ingredients with evidence

Of the hundreds of ingredients sold for ageing skin, five have data that hold up: sunscreen, vitamin A derivatives, vitamin C, niacinamide and alpha hydroxy acids. In the largest trial of its kind, 903 adults who used sunscreen every day for 4.5 years showed 24 per cent less skin ageing than those who used it when they felt like it; the other four need 4 to 12 weeks before you see anything. Everything else, hyaluronic acid and collagen included, is support rather than repair.

The most important ingredient is the cheapest

The largest single driver of visible ageing is ultraviolet light. It breaks down collagen in the dermis, switches on the pigment cells behind age spots and thickens the surface into the leathery texture no serum reverses. The best evidence for any single product therefore comes from a sunscreen trial, not from a cream.

In Nambour, Queensland, 903 adults under 55 were randomised to use a broad-spectrum sunscreen either every day or as they saw fit, from 1992 to 1996. After 4.5 years the daily group showed no measurable increase in skin ageing at all, and 24 per cent less ageing than the discretionary group, judged from silicone casts of the back of the hand by assessors who did not know the allocation. A daily 30 mg beta-carotene supplement in the same trial did nothing.

For you that means SPF 30 or higher every morning, all year. SPF 30 filters about 97 per cent of UVB, SPF 50 about 98, so the habit matters more than the number. Check for UVA protection too (the UVA symbol in a circle in the EU, 4 or 5 stars in the UK), because UVA passes through cloud and window glass. The tested dose is 2 milligrams per square centimetre, roughly half a teaspoon for face and neck and 6 to 8 teaspoons for the whole body; most people apply about half that. Outdoors, reapply every 2 hours. The Sun Exposure Timer shows how fast your skin type reaches its limit.

Retinoids set the benchmark

Vitamin A derivatives are the only cosmetic ingredient group with decades of controlled trials behind them. Prescription tretinoin has the strongest data and has been used on sun-damaged skin since the 1980s. Over the counter you get retinol, retinaldehyde and retinyl esters, which the skin converts step by step into retinoic acid; retinol is roughly 10 to 20 times weaker than tretinoin, retinyl palmitate weaker still. All of them speed up cell turnover, thicken the living epidermis and, over months, prompt fibroblasts to lay down new collagen.

The timescale is long. In a randomised study of 36 care home residents with an average age of 87, a 0.4 per cent retinol lotion applied up to 3 times a week for 24 weeks cut fine wrinkling scores by 1.64 points on a 9-point scale, against 0.08 for the plain lotion, and biopsies showed more procollagen. Expect the first visible change after 8 to 12 weeks and the full effect at about 6 months. The first 2 to 4 weeks usually bring dryness, flaking and redness. Start with the weakest formula, every other night, a pea-sized amount for the whole face, evenings only, sunscreen in the morning.

Since 2024 the EU has capped retinol and its esters at 0.3 per cent retinol equivalent in face and hand creams and rinse-off products and 0.05 per cent in body lotions, following a 2016 opinion of the Scientific Committee on Consumer Safety that added up vitamin A from food, supplements and skin care. Products above those limits have not been allowed onto the market since 1 November 2025 and must be off the shelves by 1 May 2027. Retinoids are out during pregnancy and breastfeeding. If you take isotretinoin, leave topical retinoids and acids alone until the course has ended and your dermatologist clears you.

Vitamin C, niacinamide and fruit acids

Vitamin C (L-ascorbic acid) neutralises the free radicals that UV creates, is a cofactor for collagen synthesis and slows pigment formation, which is why it evens out tone. Its problem is delivery. Absorption studies found that L-ascorbic acid only penetrates at a pH below 3.5, that uptake plateaus at 20 per cent, and that the skin's reservoir is saturated after 3 daily applications with a half-life of about 4 days. That defines the useful product: 10 to 20 per cent, acidic, in an opaque airless bottle, used daily. A serum that has turned yellow or brown has oxidised. Derivatives such as magnesium ascorbyl phosphate are more stable but deliver less. Plan on 8 to 12 weeks.

Niacinamide (vitamin B3) is the quiet one. In a double-blind study, 50 women applied 5 per cent niacinamide to one half of the face and the base cream to the other, twice a day for 12 weeks: fine lines, pigment spots, red blotchiness and yellowing all decreased on the treated side, and elasticity improved. It strengthens the barrier, calms redness and tolerates every other ingredient. Concentrations of 2 to 5 per cent are the norm; 10 per cent adds little and stings more often. Expect 4 to 8 weeks.

Alpha hydroxy acids (glycolic, lactic, mandelic) loosen the bonds between dead cells so the surface sheds evenly and reflects light better. Consumer products run at 5 to 10 per cent with a pH of 3.5 or higher; professional peels go to 20 to 70 per cent and belong in trained hands. Two or 3 nights a week is enough. Acids raise sun sensitivity during use and for about a week after you stop, so they are pointless without the sunscreen from the first section. Results show after 4 to 8 weeks, mostly as texture and glow rather than fewer wrinkles.

What hyaluronic acid and collagen creams actually do

Hyaluronic acid binds up to 1,000 times its weight in water. In a cream it sits in the outer layers and holds moisture there, so the skin looks plumper within minutes and fine dehydration lines soften. That lasts hours, not weeks, and it fills no wrinkle from below. The molecules are far too large to pass the barrier: the stratum corneum lets little through above about 500 daltons, while cosmetic hyaluronic acid weighs 50,000 to over 1,000,000 daltons and collagen about 300,000. Only injected hyaluronic acid reaches the dermis, a different product with different rules, covered in the guide on hyaluronic acid as cream and filler.

Collagen in a jar therefore works as a humectant and film former, nothing more. Peptides, the short protein fragments sold as collagen messengers, have a few small studies behind them, most paid for by the manufacturer and rarely longer than 12 weeks. Treat them as a bonus in a moisturiser, not a reason to spend more. A wrinkle that needs rebuilding is the territory of laser resurfacing or injections, not of a cream.

How to read a product before you buy

Article 19 of Regulation (EC) No 1223/2009, the cosmetics regulation applied across the EU since 11 July 2013 and kept in UK law, requires every ingredient to be listed in descending order of weight down to 1 per cent; below 1 per cent the order is free. That is the fastest check without a laboratory. Preservatives such as phenoxyethanol are capped at 1 per cent, so anything listed after them is present at under 1 per cent. For vitamin C, niacinamide and acids, a headline ingredient behind the fragrance means traces. Retinol is the exception: at 0.1 to 0.3 per cent it belongs near the end by law, so look for the stated percentage instead. The Ingredient Decoder reads a list for you.

Second, packaging. Vitamin C and retinoids degrade in light and air. An open jar is the wrong container for them; an opaque tube or airless pump is right. The open-jar symbol with a number (6M, 12M) states the months of use after opening, and products that keep for more than 30 months need no expiry date at all.

Third, introduce one new ingredient at a time and give it 4 weeks before you add the next. Starting a retinoid, an acid and a vitamin C serum in the same fortnight is the most common route to a sore, red face that looks older than before. Test anything new on the inner forearm for 48 hours. Fourth, price is not a signal: a 30 ml serum at 15 euros and one at 150 euros can carry the same 10 per cent vitamin C, and the list, not the box, tells you which.

Five checks before you buy

Frequently asked

Which single ingredient gives the most?

Daily sunscreen of SPF 30 or higher. In a randomised trial of 903 adults, daily users showed 24 per cent less skin ageing after 4.5 years than those who applied it at their own discretion, and it is the only ingredient that prevents damage rather than repairing it.

How long before I see a result?

Retinoids and vitamin C need 8 to 12 weeks, niacinamide and fruit acids 4 to 8. If you switch products earlier than that, you will never see the effect of any of them.

Does hyaluronic acid in a cream fill wrinkles?

No. It binds water in the outer skin layers and makes the surface look plumper for a few hours. Only hyaluronic acid injected as a filler reaches the dermis and lifts a wrinkle from below.

Can I use retinol and vitamin C together?

Yes, but not in the same step: vitamin C in the morning under sunscreen, retinol in the evening. Introduce them 4 weeks apart, and if the skin protests, use the retinol every other night.

Is a stronger retinol always better?

No. A 0.4 per cent retinol lotion used 3 times a week produced measurable wrinkle improvement within 24 weeks, and the EU caps cosmetic retinol at 0.3 per cent anyway. More strength means more irritation, not more collagen.

Which of these are safe in pregnancy?

Sunscreen, niacinamide, hyaluronic acid and vitamin C are considered safe. Retinoids of every kind are out during pregnancy and breastfeeding, and strong acid peels are usually postponed as well.

Sources

• Regulation (EC) No 1223/2009 on cosmetic products, Article 19 (labelling) · ingredients in descending order of weight down to 1 per cent, period after opening symbol, 30-month rule
• Scientific Committee on Consumer Safety, opinion on vitamin A (retinol, retinyl acetate, retinyl palmitate), SCCS/1576/16 · safe maximum 0.05 per cent retinol equivalent in body lotion and 0.3 per cent in other products, basis of Regulation (EU) 2024/996
• Hughes MC et al., Sunscreen and prevention of skin aging: a randomized trial, Annals of Internal Medicine 2013 · 903 adults, 4.5 years, 24 per cent less skin ageing with daily sunscreen
• Bissett DL et al., Niacinamide: a B vitamin that improves aging facial skin appearance, Dermatologic Surgery 2005 · 5 per cent niacinamide, 50 women, split-face, 12 weeks
• Kafi R et al., Improvement of naturally aged skin with vitamin A (retinol), Archives of Dermatology 2007 · 36 care home residents, mean age 87, 0.4 per cent retinol lotion up to 3 times a week for 24 weeks, fine wrinkling score -1.64 versus -0.08

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This guide is for general information. It does not replace medical or professional cosmetic advice or an examination.