Question & Context

Slowing skin aging – what is proven?

In brief

The best-supported protection against skin aging is daily sun protection: in a randomized trial, the skin aged measurably more slowly over years with daily use. For skin care, retinol, that is, topical vitamin A, has the most solid data against fine wrinkles. Taken internally, astaxanthin and collagen peptides show positive effects on moisture and elasticity, in the case of collagen, however, mainly in manufacturer-funded studies. For skin rejuvenation, red light has not yet been reliably proven. Changed moles and spots that do not heal should be seen by a dermatologist.

What matters first

Daily sun protection

In a randomized trial with 903 adults under 55 years of age in Australia, the group with daily broad-spectrum sunscreen showed no measurable increase in skin aging after 4.5 years. Compared with the group that applied sunscreen only at their own discretion, the skin aged 24 percent less. The face, neck and backs of the hands get the most light.

Retinol in the evening

Topical vitamin A is the best-studied skin care active ingredient against wrinkles. In a double-blind trial in 36 older people, a retinol lotion clearly improved fine wrinkles over 24 weeks compared with the base without active ingredient, and in skin samples the formation of collagen precursors increased. If you have sensitive skin, start cautiously and increase slowly.

Do not smoke

Smoking leaves visible traces. In a study of 79 identical twin pairs in which only one twin smoked or had smoked for much longer, the smokers showed more under-eye bags, deeper nasolabial folds and more wrinkles on the upper lip, especially in the middle and lower face. Sleep and a varied diet with enough protein are also part of the basics.

Cleanse gently, add moisture

An intact skin barrier retains moisture and tolerates active ingredients better. Mild cleansing and a moisturizer are unspectacular, but the basis of any routine.

When you should have this checked by a doctor

Have skin changes examined by a dermatologist if a mole newly appears, grows, changes its color or shape, itches or bleeds, if a spot does not heal, crusts or keeps opening up again, or if rough, scaly patches form on sun-exposed areas. Such signs can point to skin cancer or its precursors, which are readily treatable when detected early. In Germany there is statutory skin cancer screening. Sudden severe dryness, itching all over the body or skin changes together with other complaints are also a reason for an appointment, because they can point to internal diseases.

Why light is the biggest factor

The skin ages in two ways: from within, with the years, and from outside, above all through UV light. Light-induced aging shows as coarse wrinkles, pigment spots and slacker skin in the areas that get a lot of sun. This is exactly where sun protection comes in, and exactly where it has been tested in a randomized trial.

In the same trial, some of the participants additionally received beta-carotene as a tablet. Overall, this had no effect on skin aging. It is a good example of how protection from the outside is better supported than antioxidants from within.

Collagen and co.: what the studies show

Collagen peptides are the most popular beauty supplement. A meta-analysis of 26 randomized trials with 1,721 participants found clearly better values for skin moisture and elasticity. A more recent meta-analysis of 23 trials with 1,474 participants separated the trials by funder for the first time: only the manufacturer-funded trials showed effects, the independent and high-quality ones did not. The authors therefore currently see no clinical evidence for collagen against skin aging.

Astaxanthin also shows positive effects: across 8 pooled trials, moisture and elasticity improved, with effect sizes of 0.53 and 0.77, wrinkles not significantly. EFSA has assessed its safety and set a daily intake up to which it sees no concerns. Oral hyaluronic acid shows similar cosmetic improvements, often with manufacturer involvement.

Red light, peptides and devices

Red light masks promise firmer skin. A large overview of 15 meta-analyses with 204 randomized trials found moderate certainty of evidence for some applications such as hair density, but no reliable evidence for skin rejuvenation. This does not mean that it cannot work, but that it has not yet been cleanly shown.

Peptides such as Matrixyl or GHK-Cu have controlled cosmetic studies as active ingredients in creams. Injection of the same peptides, by contrast, has practically not been studied in humans. If you want to invest, it is best to invest first in sun protection and retinol.

What the database says

Sorted by strength of evidence. The BK-Score rates the state of knowledge, not the substance.

Vitamin C Evidence 8/10 · Well supported, heavily overhypedIndispensable for the body's own collagen formation; a severe deficiency also shows in the skin. That extra vitamin C visibly improves the skin when supply is already good has not yet been shown by any meta-analysis.
Astaxanthin Evidence 6/10 · Supported, with caveatsIn a meta-analysis of 8 randomized trials, the carotenoid from microalgae improved skin moisture and elasticity, but not wrinkle depth significantly. The effects are proven at the level of measuring devices, over weeks.
Collagen peptides Evidence 5/10 · Thin human evidenceAcross all studies, collagen peptides improve moisture and elasticity. The only analysis by funding so far, however, found the effects only in manufacturer-funded trials, not in independent ones.
Matrixyl (palmitoyl pentapeptide) Evidence 5/10 · Thin human evidenceThe topical signal peptide is the best supported of the cosmetic peptides, with controlled studies on photoaged facial skin. There are no human data for injections.
Hyaluronic acid Evidence 6/10 · Supported, with caveatsSeveral studies on oral intake show better skin moisture and elasticity after a few weeks, measured with cosmetic methods and often co-funded by raw material manufacturers. What the mechanism looks like is open.
Red light / photobiomodulation (PBM) Evidence 5/10 · Thin human evidenceRed light is well studied for some applications such as hair density; for skin rejuvenation, a large overview found no reliable evidence. Devices and doses differ greatly.
GHK-Cu (copper tripeptide) Evidence 4/10 · Thin human evidenceThe copper peptide has some controlled cosmetic studies for topical use. Human data for injection are lacking; the gene regulation narrative comes from cell experiments.

Frequently asked questions

What is best against skin aging?

Daily sun protection is the best-supported remedy; in a randomized trial, the skin aged 24 percent less with it over years. For skin care, retinol has the most solid data against fine wrinkles. Not smoking and good sleep are part of the basics.

Does drinkable collagen really work?

Many studies show better moisture and elasticity. An analysis by funder, however, found these effects only in manufacturer-funded studies, not in independent and high-quality studies. The data are therefore uncertain.

Do I need sun protection in winter too?

UV light reaches the skin all year round, more weakly in winter. In the skin aging trial, sunscreen was applied daily, not just in summer. For the face, a day cream with sun protection is a simple solution.

When should you start using retinol?

There is no fixed starting age; retinol makes sense as soon as the first fine lines become visible or the skin has had a lot of sun. Start with a low concentration and a few applications per week. During pregnancy and breastfeeding, you should discuss vitamin A products with a doctor first.

Does red light help against wrinkles?

Red light is better supported for hair density than for the skin. A large overview found no reliable evidence for skin rejuvenation; the studies are small and the devices very different. As an addition it is possible; as a replacement for sun protection, it is not.

What does astaxanthin do for the skin?

In a meta-analysis, skin moisture and elasticity improved measurably, wrinkle depth not significantly. The studies ran for a few weeks. EFSA has assessed its safety for adults.