Best Supplements for Hair and Nails: What Works and What Doesn't
Iron, vitamin D and zinc help hair only when you're low. Biotin rarely helps and can skew lab tests. See what to test and which supplements to skip.
By the editorial team · Updated Oct 14, 2026 · 2 sources cited
The best supplements for hair and nails are the ones that correct a deficiency. Low iron, vitamin D or zinc can contribute to hair shedding, and fixing them can help. Biotin is heavily marketed, but true biotin deficiency is rare, and high doses can interfere with blood tests. Collagen has limited evidence.
Evidence-ranked options
| Supplement | Evidence | Typical dose | Notes |
|---|---|---|---|
| Iron (if ferritin is low) | B | As advised after a blood test | Low iron stores are linked to hair shedding, especially in women. |
| Vitamin D (if low) | C | 600–2,000 IU a day | Low levels are linked to some types of hair loss. |
| Zinc (if low) | C | 15–25 mg a day | Deficiency causes hair loss; excess zinc can too. |
| Collagen peptides | C | 2.5–10 g a day | Some evidence for nails and skin; little for hair. |
| Biotin | D | Not recommended without deficiency | Rarely helps; can distort thyroid and heart lab tests. |
A: strong · B: moderate · C: limited or mixed · D: good evidence of no benefit. See the evidence database.
Test before you buy
Ask your doctor about ferritin, vitamin D, thyroid tests and a complete blood count if you notice increased shedding. Treatments with good evidence for pattern hair loss, such as minoxidil, work better than supplements.
For more detail, read our guide to supplements for hair loss. Taking biotin? Tell your doctor before blood tests; our label decoder flags it.
Ingredient guides
Related guides & comparisons
Can You Take Zinc Every Day? Safe Doses and Long-Term Risks
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ComparisonsFerrous Bisglycinate vs Ferrous Sulfate: Which Iron Is Gentler and Better?
Ferrous sulfate is the cheap standard iron; bisglycinate is gentler with fewer stomach side effects in some trials. Compare absorption, dose and cost.
Dosing & SafetyHow Much Vitamin C Per Day? Needs, Upper Limit and Colds
Adults need 75–90 mg of vitamin C a day (more if you smoke), and the upper limit is 2,000 mg. Learn what high doses do, and what the research says about colds.
ComparisonsMarine Collagen vs Bovine Collagen: Which Is Better for Skin and Joints?
Marine collagen is mostly type I from fish; bovine has types I and III. Skin research shows similar results. Compare sources, diet fit and cost.
ComparisonsZinc Picolinate vs Gluconate: Which Form Should You Take?
Zinc picolinate absorbed slightly better in one small study; gluconate is cheap and used in cold lozenges. Compare elemental zinc and uses.
Frequently asked questions
Why is my hair falling out?
Common causes include genetics, stress or illness (telogen effluvium), thyroid problems, low iron and some medications. A doctor can check.
Do hair gummies work?
Mostly they supply biotin and vitamins you may not need. They help only if you're deficient in something they contain.
Sources
Educational content, not medical advice. Read our medical disclaimer.