Supporting Skin Ageing From the Inside

The ingestible beauty category is one of the fastest-growing in the supplement market, and one of the least honestly reported. This guide applies the evidence hierarchy from our longevity supplements guide to supplements for skin ageing — including collagen, the category's biggest seller and its most contested.

Products in this category are routinely sold on trials funded by the companies that make them, with effect sizes that sound impressive as percentages and look modest in a mirror. That does not mean nothing works. It means the honest version of this article looks different from most of what you will read.

Some ingredients have real randomised trial data. One intervention — which is not a supplement — outperforms all of them and costs a few pounds a month. And the single largest determinant of how your face ages was mostly decided by how much unprotected sun you have had, not by what is in your cupboard. Below: what the evidence supports, what the contested findings actually say, and where your money is best spent.

What actually causes visible skin ageing

Intrinsic versus extrinsic ageing

Skin ages through two separate processes. Intrinsic ageing is chronological and genetically programmed: collagen synthesis slows, the dermis thins, elastin degrades, cell turnover reduces. Extrinsic ageing is environmental, and it is dominated by ultraviolet radiation — the process dermatologists call photoageing, which produces the deep wrinkling, uneven pigmentation, broken capillaries and leathery texture most people are actually trying to address.

You can see the difference on yourself. Compare the skin on the inside of your upper arm — rarely sun-exposed — with the back of your hand or your face. Both areas are exactly the same chronological age. The visible difference between them is close to a personal demonstration of how much of "ageing" is actually accumulated sun exposure.

The distinction matters commercially, because supplements act on the intrinsic side at the margins, while the extrinsic side is where the large, modifiable effect sits.

Why this is under-reported

Photoageing is inconvenient for the ingestible beauty industry because the intervention that addresses it is cheap, boring and not a supplement. A capsule with a proprietary blend and a percentage improvement on a hydration meter makes a better product page than "wear sunscreen daily for the next twenty years". That does not make the capsule useless. It does mean the ranking of interventions you see online is shaped by what can be sold rather than by effect size.

The most effective intervention is not a supplement

This is the finding that reframes the whole category, and it comes from an unusually good study.

The Nambour trial in Queensland, Australia randomised 903 adults under 55 to four groups: daily broad-spectrum sunscreen with 30 mg beta-carotene, daily sunscreen with placebo, discretionary sunscreen with beta-carotene, and discretionary sunscreen with placebo. After 4.5 years, the daily sunscreen groups showed 24% less skin ageing on micro-topographic measurement than the discretionary use groups (relative odds 0.76, 95% CI 0.59–0.98). Beta-carotene supplementation showed no effect on skin ageing at all [1].

What that means for your budget

A sensible order of spending looks like this: daily broad-spectrum SPF first, then a retinoid or other evidenced topical, then not smoking, then sleep and diet, and only then ingestible supplements. Supplements are the last few percent, not the foundation. Any brand telling you otherwise is selling rather than informing.

Collagen peptides: an honest reading of the evidence

What the positive trials show

There is genuine randomised data here. A double-blind, placebo-controlled trial randomised 64 participants to either placebo or 1,000 mg of low-molecular-weight collagen peptide daily for 12 weeks. Skin hydration was significantly higher in the collagen group at both 6 and 12 weeks, and at 12 weeks the visual assessment score and three parameters of skin wrinkling were significantly improved compared with placebo [2].

A systematic review and meta-analysis of 19 randomised, double-blind controlled trials covering 1,125 participants aged 20 to 70 (95% women) found favourable results for hydrolysed collagen versus placebo on skin hydration, elasticity and wrinkles, with hydration and elasticity confirmed in subgroup analysis. The authors concluded that 90 days of hydrolysed collagen is effective at reducing markers of skin ageing [3].

On that basis, collagen looks well supported. Then a more recent analysis complicated the picture considerably.

The funding-source problem

A 2025 systematic review and meta-analysis published in the American Journal of Medicine pooled 23 randomised controlled trials with 1,474 participants. Across all 23 trials combined, collagen supplements significantly improved skin hydration, elasticity and wrinkles — consistent with the earlier reviews.

But the authors then split the studies by funding source and by quality. Trials that did not receive pharmaceutical or industry funding showed no effect on hydration, elasticity or wrinkles. High-quality studies likewise showed no significant effect in any category, while low-quality studies showed a significant improvement in elasticity. The authors' stated conclusion was that there is currently no clinical evidence to support the use of collagen supplements to prevent or treat skin ageing [4].

How to interpret this honestly

We sell collagen, so it would be convenient to leave that last paragraph out. Here is our actual reading:

• The mechanism is plausible. Collagen peptides are absorbed as dipeptides that appear in the dermis and can stimulate fibroblast activity. This is not homeopathy.
• The effect, if real, is modest. Nobody in these trials went back a decade. The measured differences are instrument-detected changes in hydration and wrinkle depth over 8 to 12 weeks.
• The funding pattern is a genuine warning sign. When benefit disappears in independently funded and higher-quality trials, the honest position is uncertainty, not confidence.
• It is low risk. Collagen peptides are a protein source with a good safety profile. Trying it for 90 days and judging for yourself is a reasonable thing to do.

Our position: collagen is a reasonable optional purchase with realistic expectations, not a first purchase and not a substitute for sun protection. If your budget is limited, spend it on SPF and adequate dietary protein first.

If you try it

Trials typically use 2.5–10 g of hydrolysed collagen peptides daily, with the low-molecular-weight trial above using 1,000 mg of a specific tripeptide-rich preparation [2]. Give it a full 90 days, since that is the duration at which the meta-analysis found effects [3]. Powder is more cost-effective than capsules at these doses. See the Welzo collagen collection, our comparison in astaxanthin vs collagen, and glutamine vs collagen for gut health if that is also a goal.

Note for vegans: all collagen is bovine, porcine or marine. There is no vegan collagen — see our vegan longevity supplements guide for what the plant-based alternatives actually are.

The other ingredients with human trial data

Astaxanthin — the UV-protective angle

Astaxanthin is a carotenoid produced by microalgae, and it is interesting here precisely because it acts on the photoageing side rather than the collagen side.

A randomised, double-blind, placebo-controlled trial assigned 23 healthy Japanese participants to 4 mg astaxanthin or placebo over a 10-week study. The astaxanthin group showed an increased minimal erythema dose — meaning it took more UV exposure to produce visible redness — and a reduced loss of skin moisture in the irradiated area compared with placebo [5].

That is a small trial, and increasing your threshold for UV redness is emphatically not a reason to use less sunscreen. But it is a mechanistically coherent finding in the right direction. See the Welzo astaxanthin collection.

Hyaluronic acid — oral, not just topical

A placebo-controlled, randomised, double-blind trial of 120 mg daily oral hyaluronan for 12 weeks in 40 healthy adults aged 35–64 found significant improvements versus placebo in wrinkle assessment, stratum corneum water content, transepidermal water loss and elasticity, with wrinkle, hydration and elasticity measures significantly improved from baseline at both 8 and 12 weeks [6].

Again: small trial, instrument-measured endpoints, modest effect. See the hyaluronic acid range.

Vitamin C — the cofactor argument

Vitamin C is a required cofactor for the prolyl and lysyl hydroxylase enzymes that stabilise the collagen triple helix. Without adequate vitamin C, collagen synthesis is measurably impaired — this is textbook biochemistry, demonstrated most dramatically by scurvy.

The honest limitation: this establishes that vitamin C is necessary, not that extra vitamin C in an already-sufficient person produces better skin. If you eat fruit and vegetables regularly you are almost certainly replete. If your diet is genuinely poor, correcting it matters. See the vitamin C collection.

Omega-3

Long-chain omega-3s are structural components of cell membranes, including in skin, and have anti-inflammatory activity relevant to inflammatory skin conditions. The European Food Safety Authority considers 250 mg combined EPA and DHA daily adequate for adults, with supplemental intakes up to 5 g/day not raising safety concerns [7]; a review in Nutrition Research Reviews found 250 mg/day the most frequently recommended adult intake internationally [8]. Worth having covered as general health baseline rather than as a targeted skin intervention. See the omega-3 collection.

Vitamin D and general micronutrient adequacy

NHS guidance advises everyone in the UK aged four and over to consider 10 micrograms (400 IU) of vitamin D daily during autumn and winter, and year-round for those with little sun exposure [9]; the British Heart Foundation states the same [10]. There is an obvious tension for skin: the sun exposure that generates vitamin D is the same exposure that drives photoageing, which is a good argument for supplementing rather than sunbathing.

Broader adequacy matters too. Analysis of UK National Diet and Nutrition Survey data across 3,238 adults in mid-life found 19% of those in their twenties below the Lower Reference Nutrient Intake for magnesium, and 50.3% of women below the LRNI for selenium [11] — a reminder that skin is one of the first tissues to show a generally poor diet. Zinc in particular is required for skin repair; see the zinc collection and hair, skin and nails range.

Oral versus topical: which does what

A question worth settling before you spend anything. Topicals act locally and at high concentration on the tissue you are treating, which is why retinoids and sunscreen have the evidence they do. Oral supplements are diluted across the whole body and reach skin only in whatever fraction survives digestion and first-pass metabolism.

That is not an argument against oral supplements — collagen peptides do appear in the dermis as dipeptides, and astaxanthin does reach skin tissue. It is an argument for expecting smaller effects from oral routes, and for not treating an ingestible as a replacement for a topical with better evidence. The two are complementary, and if you can only do one, the topical has the stronger case. Browse anti-ageing creams, moisturisers and the wider skincare range.

Ingredients compared

What to be sceptical of

• Biotin for skin and nails. Biotin corrects problems in people who are deficient, which is rare. In people who are not, the evidence for cosmetic benefit is weak. It also interferes with some laboratory assays, including certain thyroid and troponin tests — tell your clinician if you take it before any blood test. See the biotin collection for context.
• "Marine collagen is superior" claims. Source affects amino acid profile and molecular weight, but head-to-head evidence that marine outperforms bovine for skin outcomes is thin. Choose on price, purity and testing.
• "Vegan collagen". It does not exist. These products are vitamin C and amino acid blends intended to support your own synthesis. That is a legitimate category, but the labelling frequently blurs the distinction.
• Beauty gummies. Often underdosed relative to trial protocols, and frequently carrying several grams of sugar per serving — which is counterproductive given the glycation point below.
• Proprietary "beauty blends". If per-ingredient doses are hidden, you cannot know whether anything is present at a studied amount. See supplement fillers explained and longevity supplements that don't work.

NAD⁺, spermidine and the longevity crossover

Longevity compounds are increasingly marketed with skin claims, so it is worth being precise about what has and has not been shown.

For NMN, the human trial evidence concerns physical function and sleep rather than skin. A randomised, double-blind, placebo-controlled study of 108 older Japanese adults on 250 mg daily for 12 weeks found afternoon dosing associated with improved five-times sit-to-stand performance and reduced drowsiness [12]. A GeroScience trial found 250 mg/day raised blood NAD levels, helped maintain walking speed and improved sleep quality in older adults [13]. A meta-analysis of eight RCTs found no significant benefit on glucose or lipid markers [14]. None of these measured skin outcomes.

Spermidine and resveratrol are similarly interesting mechanistically — spermidine through autophagy, resveratrol through sirtuin signalling — without dedicated skin-ageing trial evidence in humans at consumer doses. Read our honest assessments in does resveratrol work?, spermidine vs NMN, resveratrol vs pterostilbene, fisetin vs quercetin and our ergothioneine guide.

The reasonable position: take these for the reasons they are actually evidenced, and treat any skin benefit as an unproven bonus rather than the purchase rationale. See the NAD supplement guide and longevity supplements collection.

The internal factors that matter more than any capsule

Smoking

Smoking is the second-largest extrinsic driver of facial ageing after UV. It degrades collagen and elastin, impairs dermal blood supply and produces a characteristic pattern of premature wrinkling. No supplement offsets it.

Sleep

Skin repair and cell turnover are concentrated during sleep. Chronic restriction shows up in the face faster than almost anything else. If sleep is the problem, address the sleep — see apigenin vs magnesium for sleep, the sleep and relaxation range, and if you work nights, supplements for shift workers.

Protein intake

Collagen is a protein, and your body cannot synthesise it from nothing. Total dietary protein adequacy matters more than any collagen supplement, and is the thing most commonly under-attended in people who then buy collagen powder. See the Welzo protein range.

Glycation and blood sugar

Chronically elevated blood glucose promotes the formation of advanced glycation end-products, which cross-link collagen and elastin fibres and reduce their flexibility. This is a genuine mechanism linking dietary pattern to skin quality, and an argument for the same dietary advice that helps everything else.

Alcohol

Alcohol is dehydrating, disrupts sleep architecture and dilates facial vasculature. Reduction is free and visible.

Hormonal change

Skin collagen density falls significantly in the years around menopause, which is why many women notice a step change rather than a gradual drift. This is a medical conversation rather than a supplement one — see longevity supplements for women over 40, NMN and menopause, the Ultra Purity Menopause Support supplement and, for assessment, a menopause blood test.

Test, don't guess: what's worth measuring

Skin and hair changes are frequently the visible symptom of something systemic, which is why testing sometimes reveals a cause that no cosmetic product would have addressed.

• Ferritin (iron) blood test — low iron is a common and correctable cause of hair thinning and poor skin quality, particularly in menstruating women.
• Thyroid blood test — both under- and overactive thyroid produce characteristic skin and hair changes.
• Vitamin D blood test — particularly relevant if you are diligent about sun avoidance.
• Female hormone blood test — for those noticing a step change in skin around perimenopause.
• Nutrition and vitamin blood test or Full Body MOT Health Check — broader baseline in one draw.

See also biological age and how to lower your biological age for what is genuinely measurable versus marketed.

A realistic protocol and timeline

Setting expectations properly

Nothing in this article produces a visible change in two weeks. The trials that found effects measured them at 8 to 12 weeks with laboratory instruments, not in bathroom mirrors. If you cannot commit to 90 days, do not start — you will conclude nothing either way. Our guide on how long supplements take to work covers realistic timelines across categories.

Take a well-lit photograph in consistent lighting at baseline. Without it, you will not be able to tell a real change from a hopeful one.

For where this sits in a wider routine, see the minimal supplement stack, the cheap longevity stack and our longevity stack guide, plus the supplement timing chart and can you take supplements together.

Quality and safety

In the UK, food supplements are regulated as foods rather than medicines and are not assessed for efficacy before sale. Check for independent third-party testing, a published batch-specific Certificate of Analysis, and disclosed doses in named forms rather than proprietary blends. See third-party tested supplements, how to read a certificate of analysis and Welzo's ingredient quality and purity certifications. The Welzo Ultra Purity range uses single-ingredient, disclosed-dose formulations.

Who should take extra care

• Anyone with a fish or shellfish allergy — marine collagen and some astaxanthin carriers are derived from these sources.
• Anyone taking prescription medication, particularly anticoagulants, where omega-3 affects platelet function.
• Anyone due a blood test — declare biotin supplementation, as it can interfere with several common assays.
• Anyone pregnant or breastfeeding — seek advice before starting anything new, and note that vitamin A derivatives used for skin are contraindicated in pregnancy.

When to see a doctor or dermatologist

See a GP promptly, rather than reaching for a supplement, if you notice: a new or changing mole, or any lesion that bleeds, itches, changes colour or fails to heal within a few weeks; sudden or patchy hair loss; a new persistent rash; or significant unexplained changes in skin texture or pigmentation.

Sun-related skin changes and skin cancer risk are the serious end of this topic, and a supplement article is not the place to assess them. If you have had substantial sun exposure or use sunbeds, discuss skin checks with your GP. Persistent skin or hair changes accompanied by fatigue, weight change or menstrual changes warrant blood tests rather than cosmetic products.

Frequently asked questions

Do collagen supplements actually work for skin ageing?

The evidence is genuinely contested. Meta-analyses covering 19 and 23 randomised trials found improvements in hydration, elasticity and wrinkles overall [3,4]. However, the 2025 analysis in the American Journal of Medicine found that when studies were separated by funding source and quality, non-industry-funded trials and higher-quality trials showed no significant effect, and the authors concluded there is currently no clinical evidence supporting collagen for skin ageing [4]. Our reading: plausible mechanism, modest effect at best, low risk, worth a 90-day trial if you have covered sun protection and dietary protein first.

What is the single most effective thing for skin ageing?

Daily broad-spectrum sunscreen. In a randomised trial of 903 adults over 4.5 years, daily sunscreen use produced 24% less skin ageing than discretionary use, while beta-carotene supplementation in the same trial produced no effect [1]. That is the strongest evidence in this entire field, and it costs less than most supplements.

How long do skin supplements take to work?

Trials that found effects measured them at 8 to 12 weeks, using instruments rather than visual judgement [2,5,6], and the collagen meta-analysis concluded around 90 days of use [3]. Nothing here works in two weeks. Take a baseline photograph in consistent lighting, and do not judge before three months.

Is marine collagen better than bovine collagen?

There is no strong head-to-head evidence that it is. Source affects amino acid profile and typical molecular weight, and marine is usually more expensive. Choose based on price per gram, purity, third-party testing and whether you have a fish allergy. Neither is suitable for vegans. Our bovine collagen guide covers the sourcing question in more detail.

How much collagen should I take for skin?

Trials typically use 2.5–10 g of hydrolysed collagen peptides daily, though one positive trial used 1,000 mg of a specific low-molecular-weight tripeptide-rich preparation over 12 weeks [2]. Powder is more cost-effective than capsules at these amounts. See the Pure Bovine Collagen Peptides Powder.

Does astaxanthin help skin?

There is a small but mechanistically interesting evidence base. A randomised, double-blind, placebo-controlled trial in 23 participants found 4 mg astaxanthin over a 10-week study increased the minimal erythema dose — the UV exposure needed to produce visible redness — and reduced moisture loss in irradiated skin versus placebo [5]. It is a small trial, and it is not a substitute for sunscreen.

Should I take biotin for skin, hair and nails?

Only if you are deficient, which is uncommon. In people with adequate biotin status, evidence for cosmetic benefit is weak. Importantly, biotin can interfere with several laboratory tests including some thyroid and cardiac assays, so tell your clinician if you take it before any blood test.

Can supplements reverse wrinkles I already have?

No. The trial evidence describes modest, instrument-measured changes in hydration, elasticity and wrinkle depth over 8 to 12 weeks — not reversal of established photoageing. Even the sunscreen trial, which had the strongest result, showed slowed accumulation of ageing rather than reversal of existing damage [1]. Established deep wrinkling is a dermatology conversation, not a supplement one.

Is there such a thing as vegan collagen?

No. All collagen peptides are bovine, porcine or marine in origin. Products marketed as "vegan collagen" are blends of vitamin C, amino acids and other cofactors intended to support your own collagen synthesis. That can be a reasonable product, but it is not collagen — see our vegan longevity supplements guide.

Does NMN help with skin ageing?

There is no human trial evidence for NMN on skin outcomes specifically. The randomised trials in older adults measured physical function, drowsiness, blood NAD levels and sleep quality [12,13], and a meta-analysis of eight RCTs found no significant effect on glucose or lipid markers [14]. Take NMN for the reasons it is actually evidenced and treat any skin benefit as unproven. See the NMN pillar guide.

References

1. Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Annals of Internal Medicine. 2013;158(11):781–790. https://www.acpjournals.org/doi/10.7326/0003-4819-158-11-201306040-00002
2. Kim DU, Chung HC, Choi J, Sakai Y, Lee BY. Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study. Nutrients. 2018;10(7):826. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073484/
3. de Miranda RB, Weimer P, Rossi RC. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. International Journal of Dermatology. 2021;60(12):1449–1461. https://pubmed.ncbi.nlm.nih.gov/33742704/
4. Myung SK, Park Y. Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. The American Journal of Medicine. 2025. https://www.amjmed.com/article/S0002-9343(25)00283-9/abstract
5. The Protective Role of Astaxanthin for UV-Induced Skin Deterioration in Healthy People — A Randomized, Double-Blind, Placebo-Controlled Trial. Nutrients. 2018;10(7):817. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073124/
6. Oral Hyaluronan Relieves Wrinkles and Improves Dry Skin: A 12-Week Double-Blinded, Placebo-Controlled Study. Nutrients. 2021;13(7):2438. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8308347/
7. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the Tolerable Upper Intake Level of EPA, DHA and DPA. EFSA Journal. 2012;10(7):2815. https://efsa.onlinelibrary.wiley.com/doi/abs/10.2903/j.efsa.2012.2815
8. An overview of national and international long chain omega-3 polyunsaturated fatty acid intake recommendations for healthy populations. Nutrition Research Reviews, Cambridge University Press. Read on Cambridge Core
9. NHS. Vitamin D — Vitamins and minerals. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
10. British Heart Foundation. Vitamin D: deficiency, supplements, sunlight and diet. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/nutrition/ask-the-expert/vitamin-d
11. Derbyshire E. Micronutrient Intakes of British Adults Across Mid-Life: A Secondary Analysis of the UK National Diet and Nutrition Survey. Frontiers in Nutrition. 2018;5:55. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2018.00055/full
12. Kim M, Seol J, Sato T, et al. Effect of 12-Week Intake of Nicotinamide Mononucleotide on Sleep Quality, Fatigue, and Physical Performance in Older Japanese Adults. Nutrients. 2022;14(4):755. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8877443/
13. Morifuji M, Higashi S, Ebihara S, Nagata M. Ingestion of β-nicotinamide mononucleotide increased blood NAD levels, maintained walking speed, and improved sleep quality in older adults. GeroScience. 2024;46(5):4671–4688. https://pmc.ncbi.nlm.nih.gov/articles/PMC11336149/
14. Effects of Nicotinamide Mononucleotide on Glucose and Lipid Metabolism in Adults: A Systematic Review and Meta-analysis of Randomised Controlled Trials. Current Diabetes Reports. 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11557618/
15. Skin Anti-Aging and Moisturizing Effects of Low-Molecular-Weight Collagen Peptide Supplementation in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12438954/

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