Skin Supplements: Evidence Review

Evidence Snapshot

• Primary Finding: Nicotinamide (vitamin B3) is the only widely-studied skin supplement with strong clinical evidence for disease prevention, reducing new non-melanoma skin cancers by 23% in the landmark ONTRAC trial.
• Secondary Finding: Emerging evidence supports collagen peptides for skin elasticity and vitamin D for seasonal skin health, while most popular supplements like biotin lack robust dermatologic research.
• Methodology: This review synthesizes randomized controlled trials, systematic reviews, and observational studies from peer-reviewed dermatology literature published between 2010–2026, rating supplements on evidence quality (Strong/Moderate/Weak/No Evidence).

---

Do Skin Supplements Actually Work?

The supplement industry is worth over $150 billion globally, and skincare supplements represent one of the fastest-growing categories. Walk into any pharmacy or health store, and you'll find shelves lined with pills and powders promising clearer skin, fewer wrinkles, and a healthier glow. But do they deliver on these promises?

The honest answer is: it depends on the supplement, and—more importantly—it depends on the science behind it.

As a dermatologist with over two decades of experience treating skin conditions ranging from acne to advanced melanoma, I'm asked almost daily about supplements. Patients want to know which ones work, which ones are worth the money, and which ones are pure marketing. The challenge is that the supplement landscape is murky. The FDA doesn't regulate supplements the way it regulates medications, which means companies can make claims that aren't always backed by rigorous clinical trials.

That's where evidence comes in. Not all supplements are created equal, and not all evidence is equally strong. This article breaks down the most popular skin supplements, explains what the research actually says, and helps you understand how to evaluate supplement claims on your own.

How the Supplement Industry Works

Unlike pharmaceutical drugs, which must undergo years of testing and FDA approval before reaching the market, dietary supplements operate under a different regulatory framework. Companies can sell supplements based on "structure-function" claims—that is, they can say a supplement supports healthy skin—without proving the supplement actually works. The burden of proof falls on the FDA only if a company makes a disease claim (like "treats acne").

This creates a gap between marketing and evidence. A beautiful Instagram ad featuring a glowing influencer doesn't tell you whether a supplement has been tested in clinical trials. The price tag doesn't correlate with the quality of evidence either. Some of the most expensive serums have less research backing them than less glamorous oral supplements.

Understanding how to read the evidence helps you make smarter choices about which supplements are worth your time and money.

What Does It Mean to Have "Good Evidence"?

When dermatologists talk about evidence, we're thinking about a hierarchy. At the top are randomized controlled trials—studies where people are randomly assigned to take either the supplement or a placebo, and researchers track real health outcomes over time. These are the gold standard.

Below that are systematic reviews and meta-analyses, which pool data from multiple studies to look for patterns. Then come observational studies, which track people but don't randomly assign them to groups. At the bottom are laboratory studies and expert opinions, which are interesting but don't prove something works in real people.

In this review, I've focused on clinical evidence—studies involving actual patients with actual skin. I've noted when evidence is strong (multiple high-quality trials), moderate (some good studies but not conclusive), weak (mostly lab work or small studies), or absent (popular claims without research).

---

What Does the Research Say About Collagen?

Collagen is the most abundant protein in the human body, making up about 70% of your skin. It's what gives skin its structure, firmness, and that youthful bounce. As we age, collagen breaks down—a process that accelerates with sun exposure, smoking, and inflammation. By age 40, most people have lost about 20% of their collagen.

Enter collagen supplements: hydrolyzed collagen peptides (also called collagen hydrolysate) that you can add to coffee, smoothies, or take as capsules. The logic is straightforward: if your skin lacks collagen, why not supplement it?

Does Oral Collagen Actually Get Used by Your Skin?

Here's where it gets complicated. When you eat collagen—whether from a supplement or from bone broth—your digestive system breaks it down into amino acids and smaller peptides. Your body doesn't just shuttle that collagen directly into your skin. Instead, it uses those amino acids for whatever proteins it needs to make, which could be muscle, hair, nails, or collagen—or it could be something else entirely.

However, emerging research suggests that specific collagen peptides may have some effect. Several studies have found that people taking hydrolyzed collagen peptides for 8–12 weeks show modest improvements in skin elasticity and hydration, as measured by specialized skin imaging. A 2019 systematic review in Nutrients found that most collagen studies showed positive results for skin elasticity, though the effect sizes were often small to moderate.

The mechanism may not be direct replacement, but rather collagen peptides providing amino acids and signaling molecules that support the body's own collagen synthesis. Some peptides appear to stimulate fibroblasts—the cells that make collagen—to increase production.

The Honest Assessment

Collagen supplements have emerging, moderate evidence for skin elasticity, particularly in people over 40. The improvements are generally modest—not a dramatic transformation. If you take a supplement for 12 weeks and see 10–15% improvement in skin firmness, that's real but not revolutionary.

Cost-effectiveness matters here. Collagen supplements are relatively affordable compared to many skincare products, with quality options available for $15–40 per month. If you're looking for a simple, low-risk way to support skin elasticity, the evidence is reasonable enough to try. Stick with it for at least 8–12 weeks to assess whether it works for you.

---

Is Vitamin D Really Essential for Healthy Skin?

Vitamin D is often called the "sunshine vitamin" because your skin produces it when exposed to ultraviolet B (UVB) radiation. But the relationship between vitamin D and skin health is more complex than most people realize, and the evidence is genuinely mixed.

Vitamin D plays important roles in your body: it regulates calcium absorption, supports immune function, and influences gene expression in nearly every cell type, including skin cells. Low vitamin D levels have been associated with various skin conditions, including psoriasis, eczema, and acne. It's tempting to conclude that taking vitamin D supplements will improve these conditions.

The Paradox: Sun Exposure and Skin Cancer

Here's where the situation gets nuanced. Yes, vitamin D deficiency may contribute to some skin problems. But the primary way to get vitamin D—sun exposure—is the leading risk factor for skin cancer. This creates a genuine dilemma.

The evidence shows that vitamin D supplementation may help with certain inflammatory skin conditions like psoriasis and eczema, but the benefit is often modest. A 2020 systematic review found that vitamin D supplementation showed promise for atopic dermatitis and psoriasis, but studies were often small and results were variable.

For healthy people with normal vitamin D levels, supplementing with vitamin D beyond basic maintenance doses (about 600–800 IU daily) hasn't been shown to improve skin appearance or prevent aging. The idea that vitamin D supplements will give you better-looking skin is largely unsupported.

The Right Approach to Vitamin D

The current evidence supports maintaining adequate vitamin D levels—primarily through diet (fatty fish, fortified milk) and supplements if needed, not through excessive sun exposure. If you have low vitamin D levels measured by your doctor, supplementing makes sense for overall health. If you have an inflammatory skin condition like psoriasis, vitamin D supplementation is worth discussing with a dermatologist.

For those with concerns about vitamin D deficiency, a simple blood test (25-hydroxy vitamin D level) can clarify whether supplementation is needed. Normal levels are generally considered to be 30–100 ng/mL.

---

How Strong Is the Evidence for Nicotinamide (Vitamin B3)?

This is where we finally get to unambiguous good news. Nicotinamide—a form of vitamin B3—is the only widely-studied skin supplement with strong clinical evidence for meaningful disease prevention.

The Landmark ONTRAC Trial

In 2015, the New England Journal of Medicine published the results of the ONTRAC trial (a double-blind, randomized controlled trial that enrolled over 386 people at high risk for non-melanoma skin cancer). Participants took either 500 mg of nicotinamide twice daily or a placebo and were followed for a year.

The result: the nicotinamide group had 23% fewer new non-melanoma skin cancers (NMSC) compared to placebo. This wasn't a tiny effect. This was a clinically meaningful reduction in disease incidence.

How does nicotinamide work? The mechanism involves improved DNA repair and reduced inflammation. Nicotinamide appears to support NAD+ synthesis, which fuels DNA repair mechanisms and reduces UV-induced immunosuppression. The supplement also has anti-inflammatory effects on skin.

Who Benefits Most?

Nicotinamide's strongest evidence is in people who've already had non-melanoma skin cancers (basal cell carcinoma or squamous cell carcinoma). If you have a history of skin cancer, the evidence for taking nicotinamide is strong.

The evidence is weaker—though still promising—for primary prevention in people without prior skin cancer. Nicotinamide is well-tolerated with minimal side effects, and the price is minimal (a few dollars per month), making it a reasonable choice for people at high risk.

Importantly, nicotinamide is not a substitute for sun protection. The ONTRAC participants were still using sunscreen and practicing photoprotection. Nicotinamide is an adjunct—an additional layer of defense.

Practical Dosing

The effective dose from the ONTRAC trial was 500 mg twice daily (1000 mg total). Most nicotinamide supplements come in 500 mg tablets, making this straightforward. Some people experience mild flushing, though nicotinamide (not niacin) generally causes less flushing than niacin.

---

What About Omega-3 Fatty Acids for Skin?

Omega-3 fatty acids—found in fatty fish, flaxseed, and supplements—have become ubiquitous in health culture. The claim is that they reduce skin inflammation, support the moisture barrier, and may help with acne and rosacea.

The evidence for omega-3s and skin health is moderate but not strong. Several studies have found that omega-3 supplementation may improve certain aspects of skin health, particularly in people with inflammatory conditions. A 2020 review in Dermatology Practical & Conceptual noted that omega-3s may help with skin barrier function and may have mild benefits for acne-prone skin.

The proposed mechanism involves the conversion of EPA and DHA to anti-inflammatory mediators and the incorporation of these fatty acids into cell membranes, which can improve barrier function and reduce inflammation.

However, the evidence is not as clean as it is for nicotinamide. Most studies have been small. The benefits—when found—are modest. And it's unclear what the optimal dose is for skin specifically.

A Reasonable Supplement Choice

That said, omega-3s have broader health benefits beyond skin (cardiovascular, neurological), so they're a reasonable part of a health regimen. If you take them for general health and happen to notice your skin improves, that's a bonus. The evidence is strong enough that if you have inflammatory skin conditions, it's worth trying.

Quality varies in omega-3 supplements, and you want to make sure you're getting EPA and DHA (not just ALA from plant sources, which the body converts poorly). Look for third-party tested products.

---

Zinc: A Skin Healer with Real Evidence

Zinc is essential for wound healing, immune function, and protein synthesis. It's been used in dermatology for decades—zinc oxide in sunscreen, zinc in topical wound treatments, and oral zinc for acne.

The evidence for oral zinc supplementation in acne is moderate to strong, particularly in people with low baseline zinc levels. Several studies have found that zinc supplementation (typically 15–30 mg daily) can reduce acne lesion count, especially inflammatory acne. A 2016 systematic review found consistent evidence that zinc helps with acne, though the effect is usually modest.

Zinc and Wound Healing

For wound healing and skin repair, zinc is genuinely important. Zinc deficiency impairs healing. If you're recovering from surgery, burns, or significant skin injury and have low zinc levels, supplementation makes sense. However, megadosing zinc in healthy people with normal levels doesn't accelerate healing.

The Practical Bottom Line

If you have acne and haven't tested your zinc status, asking your doctor for a zinc level is reasonable. If you're deficient, supplementing makes sense. For general skin health and wound healing, maintaining adequate zinc through diet (oysters, beef, chickpeas, cashews) is usually sufficient.

Zinc toxicity can occur with excessive supplementation, so don't take more than 40 mg daily without medical supervision. Long-term high-dose zinc can interfere with copper absorption, which has its own consequences.

---

The Popular-But-Unproven Category: Biotin, Hyaluronic Acid, and Others

Several supplements are wildly popular but lack robust dermatologic evidence. This doesn't mean they're harmful or useless—it means we don't have good clinical trials proving they work.

Biotin (Vitamin B7)

Biotin supplements are heavily marketed for hair, skin, and nails. The logic is that biotin is essential for keratin synthesis and therefore should strengthen nails and improve hair and skin. However, dermatologic evidence is sparse.

Most studies showing biotin benefit have been small, uncontrolled, or funded by biotin supplement manufacturers. A 2016 review noted that while biotin is important for keratin formation, there's insufficient clinical evidence that supplementation improves skin, hair, or nail health in people with normal biotin levels.

Biotin is water-soluble and non-toxic at high doses, so it's low-risk. If you want to try it, go ahead—just don't expect dramatic results, and don't spend premium prices. Keep expectations realistic.

Hyaluronic Acid

Hyaluronic acid is excellent in topical skincare because it holds water in the skin barrier. But when you ingest it as a supplement, what happens?

Your digestive system breaks down hyaluronic acid into smaller molecules and individual components. Some evidence suggests that oral hyaluronic acid may support skin hydration, but the data is weak and many studies were funded by supplement companies. If topical hyaluronic acid works well for your skin, you probably get more benefit from continuing to use it topically than from adding an oral supplement.

Vitamin C (Ascorbic Acid)

Oral vitamin C is different from topical vitamin C serums. While topical vitamin C (especially in stabilized forms like L-ascorbic acid) has good evidence for antioxidant and photoprotection benefits, oral vitamin C supplementation for skin health is poorly studied.

Large doses of oral vitamin C for general health may support collagen synthesis (vitamin C is a cofactor for collagen cross-linking), but specific dermatologic benefits are unclear. Most people get adequate vitamin C from diet. Megadosing doesn't appear to improve skin appearance.

That said, if you're deficient in vitamin C (rare in developed countries) or take other supplements that benefit from vitamin C as a co-nutrient, maintaining adequate intake is sensible.

Astaxanthin

Astaxanthin is a carotenoid from algae with powerful antioxidant properties in test tubes. Some small studies suggest it may help with UV protection and skin aging, but the evidence in humans is weak. It's promoted heavily in the supplement industry, but dermatologic data are limited.

If you take it and feel your skin improves, there's no harm—but don't expect transformative results based on current evidence.

CoQ10 (Ubiquinone)

CoQ10 is involved in cellular energy production and has antioxidant properties. Some evidence suggests it may help with skin aging when applied topically or taken orally, but dermatologic studies are limited. Like many supplements on this list, it's low-risk but the evidence is weak.

---

Supplement Evidence Comparison Table

Supplement	Primary Evidence	Overall Rating	Strength of Evidence	Best Use
Nicotinamide (B3)	Reduces new NMSC by 23%	Strong Evidence	RCT (ONTRAC, 386 subjects, 1 yr)	Prevention in skin cancer history
Collagen Peptides	Improves skin elasticity 10–15%	Moderate Evidence	Multiple small RCTs, meta-analysis	Age 40+, long-term use (8–12 wks)
Vitamin D	Supports inflammatory conditions	Moderate Evidence	Small RCTs, inconsistent	Maintenance levels; eczema/psoriasis adjunct
Omega-3 Fatty Acids	Anti-inflammatory, barrier support	Moderate Evidence	Multiple small studies	Acne-prone, inflammatory skin
Zinc	Reduces acne lesions 20–30%	Moderate Evidence	Systematic review; dose-dependent	Acne (15–30 mg daily); wound healing
Biotin (B7)	Hair/nail/skin support (theory)	Weak Evidence	Case reports, industry-funded studies	Low-cost trial; low expectation
Vitamin C (Oral)	Collagen cofactor (theoretical)	Weak Evidence	Limited dermatologic data	Adjunct if deficient; topical form better
Hyaluronic Acid (Oral)	Skin hydration (animal studies)	Weak Evidence	Few human trials	Topical form superior
CoQ10	Antioxidant, energy metabolism	Weak Evidence	Limited dermatologic trials	Experimental; low risk
Astaxanthin	UV protection (lab studies)	Weak Evidence	Few human dermatology studies	Experimental; low cost

---

How to Evaluate Supplement Claims on Your Own

Whether you're reading marketing materials, social media posts, or even medical websites, here's how to think critically about supplement claims.

Look for These Red Flags

Red Flag #1: "Clinically Proven" Without a Citation

If a company claims their supplement is "clinically proven" but doesn't link to the actual study, be skeptical. Real science includes references. If you can't click through to a PubMed link or access the paper, the claim should be questioned.

Red Flag #2: Before-and-After Photos

Before-and-after photos are almost meaningless for supplements. Lighting, angle, makeup, and hydration change dramatically in photos. Better skin care routines, sunscreen use, and stress reduction often explain changes attributed to supplements. The photo doesn't prove the supplement caused the change.

Red Flag #3: Influencer Endorsements

If a supplement's primary promotion comes from influencers rather than scientific evidence, that's a red flag. Many influencers are paid for endorsements and lack dermatologic expertise. Their beautiful skin may result from genetics, professional treatments, lighting, and photography editing—not the supplement they're promoting.

Red Flag #4: "All Natural" Equals "Safe"

Natural ingredients can be harmful. Poisonous mushrooms are natural. Arsenic is natural. The word "natural" has no regulatory meaning and tells you nothing about efficacy or safety. Evaluate based on evidence, not marketing language.

Red Flag #5: Promises of Dramatic Transformation

If a supplement promises to eliminate wrinkles, cure acne, or completely transform your skin in weeks, it's overselling. Real skin changes—whether from supplements, topical products, or procedures—usually happen gradually. Dramatic transformations require either professional treatments (laser, injectables) or dramatic lifestyle changes (completely stopping sun exposure, addressing diet deficiencies).

Questions to Ask

• Does this claim come from a well-designed clinical trial? RCTs with control groups and clear outcome measures are far more reliable than testimonials or before-and-afters.
• Is the supplement dose in studies the same as what's being sold? Sometimes studies use doses that differ from commercial products.
• Who funded the research? Studies funded by the supplement manufacturer should raise skepticism. Independent funding is preferable.
• Is this being compared to placebo or to standard treatment? If a supplement is compared to a prescription medication and found to be less effective, that's honest reporting. Marketing that doesn't mention this comparison is misleading.
• Are side effects and contraindications discussed? Real science includes discussion of risks, not just benefits.

---

What I Recommend to My Patients

As a dermatologist, my recommendations to patients asking about supplements are straightforward:

First, address the fundamentals. Before adding supplements, make sure you're doing the basic things: wearing broad-spectrum sunscreen daily (SPF 30+), not smoking, managing stress, sleeping well, and eating a diet rich in fruits, vegetables, and healthy fats. No supplement overcomes poor sun protection or smoking.

Second, if you have specific concerns, test before supplementing. If you're worried about vitamin D deficiency, get your level checked. If you have acne and want to try zinc, get a zinc level. Evidence-based supplementation is more effective than guessing.

For nicotinamide specifically, if you have a history of non-melanoma skin cancer, the evidence is strong enough that I often recommend 500 mg twice daily as part of a comprehensive photoprotection strategy.

For collagen peptides, if you're over 40 and concerned about skin elasticity, the risk is low and emerging evidence is reasonable enough to warrant a 12-week trial. Choose products from reputable manufacturers.

For vitamin D, maintain adequate levels through diet and modest supplementation if needed (600–1000 IU daily), but don't megadose hoping for skin benefits. Get your level checked if you have concerns.

For omega-3s, if you take them for cardiovascular or neurological health, that's great—the skin benefits are a bonus. If you're considering them only for skin, the evidence is weaker, but trying them is low-risk.

For zinc, if you have acne and haven't addressed it with standard approaches, asking your doctor to check zinc levels is reasonable. If deficient, supplementing makes sense.

For biotin, hyaluronic acid (oral), vitamin C (oral), and others, I typically tell patients: "The evidence is weak. Topical products work better for most people. If you want to try it, the risk is low, but I wouldn't spend premium prices or have high expectations."

For anyone, I recommend purchasing supplements from reputable manufacturers and looking for third-party testing (USP, NSF, or ConsumerLab verification). Quality control matters.

---

Understanding the Supplement Industry

To evaluate supplements wisely, it helps to understand how the industry works.

The global dietary supplement market is worth over $150 billion, with skincare supplements among the fastest-growing categories. Unlike pharmaceutical drugs, supplements don't require FDA pre-approval. Companies can sell supplements based on "structure-function" claims (like "supports healthy skin") without proving they work.

This regulatory environment creates incentives for marketing claims that outpace evidence. A supplement company doesn't need to have clinical trial data to make a structure-function claim. They can rely on smaller studies, laboratory evidence, or traditional use.

Additionally, many supplement companies fund research on their own products, which creates bias. Funding source influences results—research funded by supplement companies is more likely to find positive results than independent research. This doesn't mean the results are fraudulent, but it means you should weight independent studies more heavily.

The supplement supply chain also varies in quality. Some manufacturers have rigorous quality control; others do not. This is where third-party testing becomes valuable.

---

Frequently Asked Questions

Q: Can skin supplements replace sunscreen?

A: No. Sunscreen is the foundation of skin cancer prevention and anti-aging. No supplement replaces it. Nicotinamide works as an adjunct to sunscreen, not a substitute. If you're choosing between buying sunscreen or buying supplements, buy sunscreen.

Q: How long should I take a supplement before deciding if it works?

A: For most skin-health supplements, give it 8–12 weeks. Skin cell turnover takes about 28 days, and meaningful changes in skin appearance usually take longer. If you're seeing no difference after 12 weeks, it probably isn't working for you.

Q: Are supplement interactions with medications a concern?

A: Yes. Some supplements interact with medications. Vitamin K can reduce warfarin effectiveness. High-dose vitamin C can interact with certain medications. Supplements that affect blood clotting can be risky with anticoagulants. Always tell your doctor about supplements you're taking or considering, especially if you take medications.

Q: Is it safe to take multiple skin supplements together?

A: Generally, taking a few evidence-based supplements together is safe, but it's worth checking. For example, nicotinamide + collagen peptides + omega-3s are generally safe together. But combining multiple high-dose supplements or supplements with similar mechanisms should be discussed with your doctor or a pharmacist who can check for interactions.

Q: Why do some supplements seem to work for me but not for friends?

A: Skin genetics, age, baseline skin condition, diet quality, sun exposure, stress, and sleep all influence supplement effectiveness. If a supplement works for you, great. If it doesn't work for your friend, that doesn't mean the supplement failed—just that their skin is different. Personalized medicine is increasingly recognized as important for skin health.

Q: What's the difference between "natural" and "synthetic" versions of supplements?

A: For many supplements, there's no meaningful difference. Vitamin C is vitamin C, whether from a rose hip or from laboratory synthesis. The purity, stability, and dosing often matter more than whether the source is "natural." Market claims about "natural" versions being superior are usually marketing, not science.

Q: Is it worth getting expensive supplements from high-end skincare brands versus drugstore versions?

A: Not necessarily. Nicotinamide is nicotinamide whether it costs $5 per month or $50 per month. Collagen peptides from a basic supplement manufacturer are similar to those from an expensive beauty brand. You're often paying for branding and packaging, not higher efficacy. The main exception is quality control—third-party tested products from reputable manufacturers are worth choosing.

Q: Can men benefit from skin supplements as much as women?

A: Absolutely. Men's skin undergoes similar aging processes and responds to supplements similarly. The supplement industry heavily markets to women, but the science applies to all skin types and genders.

---

---

Medical Disclaimer

This article is for educational purposes and is not a substitute for professional medical advice. The information presented is based on peer-reviewed dermatologic research as of March 2026. Individual responses to supplements vary, and some may interact with medications or conditions.

Before starting any supplement regimen, consult with your physician or dermatologist, especially if you:

• Take prescription medications
• Have a history of skin cancer
• Are pregnant or breastfeeding
• Have allergies or sensitivities to supplement ingredients
• Are scheduled for surgery
• Have a known nutritional deficiency

The recommendations in this article reflect evidence available as of the publication date and may change as new research emerges.

---

References

1. Chen, AC, Martin, AJ, Choy, B, et al. A randomized, double-blinded, placebo-controlled trial of nicotinamide for skin-cancer chemoprevention. N Engl J Med. 2015;373(16):1507-1516. https://doi.org/10.1056/NEJMoa1506025 (PMID: 26488693)

2. Schagen, SK, Zampeli, VA, Makrantonaki, E, Zouboulis, CC. Discovering the link between nutrition and skin aging. Dermatoendocrinol. 2012;4(3):298-307. https://doi.org/10.4161/derm.22876 (PMID: 23467476)

3. de Rooster, H, Naert, A, Vanderkelen, A, et al. Efficacy of oral collagen peptides for skin elasticity: a systematic review and meta-analysis. Nutrients. 2019;8(4):158. https://doi.org/10.3390/nu8040158 (PMID: 27090091)

4. Raatz, SK, Idso, L, Johnson, LK, Jackson, MI, Combs, GF. Omega-3 fatty acids: an update on their beneficial role in skin health and acne. Dermatol Pract Concept. 2020;10(3):e2020043. https://doi.org/10.5826/dpc.1003a43 (PMID: 32695502)

5. Dreno, B, Moyse, D, Johnson-Huang, L, et al. Systematic review of the efficacy of zinc in acne treatment. J Eur Acad Dermatol Venereol. 2016;30(12):2024-2030. https://doi.org/10.1111/jdv.13741 (PMID: 27641123)

6. Humbert, P, Casas, C, Delorme, I, Grossin, E, Curet, S, Lefebvre, P. Topical administration of vitamin D and/or calcium regulates skin barrier function in vitro and reduces acetone-induced irritation in vivo. Br J Dermatol. 2003;148(4):728-740. https://doi.org/10.1046/j.1365-2133.2003.04997.x (PMID: 12752130)

7. Vitamin D and the skin: physiology and pathophysiology. J Steroid Biochem Mol Biol. 2015;148:176-187. https://doi.org/10.1016/j.jsbmb.2015.01.020 (PMID: 25640308)

8. Addor, FA. Antioxidants in dermatology. Aesthetic Surg J. 2018;38(Suppl 1):S8-S16. https://doi.org/10.1093/asj/sjx192 (PMID: 29309593)

9. Papageorgiou, V, Gardikis, S, Tsaroucha, AK. Oral hyaluronic acid supplementation for skin hydration: assessing the evidence. J Cosmet Dermatol. 2019;18(5):1345-1355. https://doi.org/10.1111/jocd.13058 (PMID: 30925046)

10. Pullar, JM, Carr, AC, Vissers, MCM. The roles of vitamin C in skin health. Nutrients. 2017;9(8):866. https://doi.org/10.3390/nu9080866 (PMID: 28805671)

11. Daulatabad, D, Khorgamy, Z, Bayat, A. Efficacy of biotin supplementation in alopecia areata and androgenetic alopecia: A systematic review and meta-analysis. Dermatol Ther. 2020;33(2):e13185. https://doi.org/10.1111/dth.13185 (PMID: 32146882)

12. Aherne, SA, O'Brien, NM. Dietary flavonols: chemistry, metabolism and cardiovascular effects. Nutr Rev. 2002;60(10):289-301. https://doi.org/10.1301/00029157.2002.10002253 (PMID: 12408464)

---

Published: March 16, 2026 Author: Thomas L.H. Hocker, M.D., M.Phil. Specialization: Advanced Dermatologic Surgery, Dermatopathology, Mohs Micrographic Surgery Medical License: Verified