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Best vitamins for skin: the evidence-based guide

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The OneVit Team

The OneVit Team

Updated on

4th September 2026

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8 min

Best vitamins for skin: the evidence-based guide

Discussions about skincare typically tend to focus on the surface layer - serums, moisturisers, lotions. But skin is your body's largest organ, and what you're taking in internally (food, supplements etc.) also makes a big difference.

If you're trying to work out the best vitamins you can take for your skin, this guide walks through the commonly referenced supplements (vitamin C, biotin, omega-3 and marine collagen), what each one actually does, what the evidence supports, and how to build a sensible routine around them.

What are the best vitamins for skin?

If you only take one thing from this article, the best evidenced vitamins for skin are vitamin C, which plays a vital role in collagen formation, and biotin, which contributes to normal skin maintenance. Alongside these, marine collagen and omega-3 are two of the most actively researched ingredients in skin-focused supplements, but don't currently have the same level of evidence as the previous two.

Vitamin C: the collagen-building vitamin

Vitamin C has one of the clearest, best-established roles of any nutrient in skin health. It contributes to normal collagen formation5 by acting as a "cofactor" (a molecule that helps make chemical reactions happen) for the enzymes that build and stabilise collagen fibres.2,3 Collagen is crucial for skin health and function as it's the structural protein that gives skin its firmness.

Adults aged 19 to 64 need 40mg of vitamin C a day, which most people get through a normal diet - citrus fruit, peppers, broccoli and berries are all good sources.1 Vitamin C can't be stored in the body, so a consistent daily intake matters more than occasional large doses. The NHS notes that taking less than 1,000mg a day of vitamin C supplements is unlikely to cause harm, though there's no need to exceed your daily requirement unless you have a specific reason to.1

OneVit Vitamin C is a straightforward way to cover this baseline, particularly if your diet is inconsistent or you're not reliably hitting five portions of fruit and veg a day.

Marine collagen: what the evidence says

Collagen supplements are one of the most talked-about categories in skin-focused nutrition, and the research is promising.

A 2023 systematic review and meta-analysis of 26 randomised controlled trials, involving 1,721 participants in total, found that hydrolysed collagen supplementation was associated with statistically significant improvements in both skin hydration and elasticity compared with placebo.4 A separate review of ten placebo-controlled trials reported similar findings for hydration and elasticity, typically after 8 to 12 weeks of consistent use. That said, the authors of these reviews were candid about a real limitation - many of the underlying studies had a moderate-to-high risk of bias, and researchers agree that larger, more independent trials are needed before the evidence can be considered as fully conclusive.4

This is an area where the science is still developing, but the clinical trial evidence for oral collagen and skin hydration/elasticity is more substantial than for many trending skincare-from-within ingredients, which is why products like OneVit Marine Collagen Complex - formulated with hydrolysed marine collagen alongside vitamin C to support natural collagen formation - have become a staple in this space.

Biotin and normal skin maintenance

Biotin (vitamin B7) contributes to the maintenance of normal skin, which has been confirmed by an EFSA scientific opinion that also covers biotin's role in hair, nails and normal energy-yielding metabolism.5,6 Severe biotin deficiency is rare, but when it does occur it causes a recognisable pattern of skin symptoms, including a scaly, red rash, which is one reason biotin's link to skin health is well established.7

One thing to note - there's no official UK Reference Nutrient Intake for biotin. The European Food Safety Authority's Adequate Intake guideline is 40 micrograms a day for adults, and the standard reference value used on UK supplement labels is 50 micrograms, both values that are comfortably covered by a varied diet including eggs, oily fish, nuts and seeds. For people who are not deficient, the evidence that additional biotin improves skin beyond what a sufficient intake already provides is somewhat limited.7 Where biotin supplementation tends to help most is topping up an intake that's genuinely falling short - for example, if your diet is restrictive or inconsistent.

OneVit Biotin is a simple way to make sure that baseline is covered.

Omega-3 and your skin barrier

Omega-3 fatty acids - specifically EPA and DHA - are proven to contribute towards heart function, brain function and vision.5 There is a growing body of peer-reviewed evidence that suggests omega-3s also support the lipid layer that forms your skin's barrier, helping it retain moisture and manage inflammatory responses, but this is still emerging science.8

It can also be beneficial for people managing eczema-prone or easily irritated skin. Omega-3 is one of the nutrients most commonly flagged in the research alongside vitamin D as autumn approaches and skin barriers tend to come under more pressure.8 It's not a treatment for eczema, but it's a nutritional support that's worth being aware of.

OneVit Omega 3 delivers EPA and DHA in each serving if fish is a small part of your diet.

Other nutrients worth knowing about

Vitamin C, biotin, collagen and omega-3 have the strongest and most relevant evidence base for this article, but a handful of other nutrients come up regularly in skin health research and are worth a brief mention.

Zinc contributes to the maintenance of normal hair, skin and nails, and is one of the nutrients found in a well-formulated multivitamin.5 Vitamin A supports normal skin cell turnover, though supplementing beyond dietary intake needs care, since vitamin A can build up in the body at high doses. Vitamin E works alongside vitamin C as part of the body's antioxidant network. None of these are the headline act here, but they're part of the bigger nutritional picture. It's the reason why a well-formulated multivitamin can act as a solid foundation or starting point before adding targeted supplements on top.

Building a skin-focused supplement routine

If you're starting from scratch, a sensible order of priority could look something like this. Consider starting off with a multivitamin like OneVit Complete Multivitamin to establish the baseline. Then, make sure your vitamin C and biotin are covered, since both are single ingreidents with direct roles in skin function. From there, consider marine collagen and omega-3 as longer-term additions rather than quick fixes - the clinical trials behind both typically ran for 8 to 12 weeks before showing measurable results, so consistency matters more than any single dose.

A few practical notes:

  • Vitamin C is water-soluble and best taken with food to reduce the chance of an upset stomach.
  • Collagen supplements are generally taken once daily and are easiest to build into a routine alongside breakfast.
  • Omega-3 is fat-soluble, so pairing it with a meal that contains some fat can support absorption.

As with any supplement, more isn't automatically better. Stick to the amount on the label unless a healthcare professional has advised otherwise.

When to see a GP about your skin

Supplements can support general skin health, but they're not a substitute for medical advice. If you're dealing with a persistent skin condition - ongoing eczema, unexplained rashes, acne - that isn't responding to over-the-counter treatment, or any skin change that concerns you, speak to a GP or pharmacist rather than relying on diet or supplements alone. This is especially true if a rash or skin change appears suddenly, spreads, or comes with other symptoms.

Frequently asked questions

What are the best vitamins for skin? Vitamin C and biotin have the strongest, most established evidence relating specifically to skin. Marine collagen and omega-3 are two of the most actively researched additions, though the evidence for each is still developing compared with core vitamins.

Can vitamin C really improve my skin? Vitamin C has a confirmed role in normal collagen formation, and collagen is central to skin structure and firmness. It won't transform your skin overnight, but a consistent daily intake supports one of the key building blocks your skin relies on.

Does collagen actually work for skin? The clinical trial evidence is genuinely promising. Systematic reviews of randomised controlled trials have found improvements in skin hydration and elasticity with hydrolysed collagen supplementation. That said, many of the underlying studies have quality limitations, so it's best thought of as an evidence-backed option rather than a guaranteed result.

How long does it take for skin supplements to work? Most of the clinical trials behind collagen and omega-3 measured results after 8 to 12 weeks of consistent daily use. Skin cell turnover is a slow process, so short-term use is unlikely to show a noticeable difference.

Can I take vitamin C, biotin, collagen and omega-3 together? Yes, there's no known interaction issue between these four. Many people take vitamin C and collagen together, since vitamin C supports the collagen formation process.

Do I need a supplement if I already eat a balanced diet? If your diet reliably includes vitamin C-rich fruit and vegetables, oily fish, eggs and a varied range of foods, you may already be meeting your baseline requirements for vitamin C, biotin and omega-3. Supplements are most useful for filling genuine gaps rather than replacing a good diet.

What's the difference between taking these as supplements versus using topical skincare? Oral supplements work from the inside, supporting the nutrients your skin cells need to function normally. Topical products act directly on the skin's surface. The two aren't interchangeable, and most of the research on vitamin C, biotin and omega-3 in this article relates to oral or dietary intake rather than topical application.

References

  1. NHS. Vitamin C. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-c/
  2. Pullar JM, Carr AC, Vissers MCM. The Roles of Vitamin C in Skin Health. Nutrients. 2017;9(8):866. https://pubmed.ncbi.nlm.nih.gov/28805671/
  3. Linus Pauling Institute, Oregon State University. Vitamin C and Skin Health. https://lpi.oregonstate.edu/mic/health-disease/skin-health/vitamin-C
  4. Pu SY et al. Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis. Nutrients. 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10180699/
  5. GOV.UK. Great Britain Nutrition and Health Claims (NHC) Register. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register
  6. EFSA. Scientific Opinion on the substantiation of health claims related to biotin. EFSA Journal. 2010. https://www.efsa.europa.eu/en/efsajournal/pub/1728
  7. National Institutes of Health, Office of Dietary Supplements. Biotin — Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional/
  8. Mode and Mechanism of Action of Omega-3 and Omega-6 Unsaturated Fatty Acids in Chronic Diseases. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12073370/

This article is for informational purposes only and does not constitute medical advice. If you are concerned about a skin condition, consult a GP or qualified healthcare professional.

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