Ranked by evidence
Best supplements for hair loss and thinning hair
Supplements help hair loss mainly when they correct a deficiency that is driving the shedding, such as low iron, zinc or vitamin D. A 2023 systematic review of 30 studies in people without a known deficiency found that the positive results came from small trials of single branded products and that the overall evidence is low quality. Picks are ranked by the evidence for hair, and because each depends on a blood test or a specific hair problem, all of them are situational.
Picks are ranked by the strength of published evidence for this goal in otherwise healthy adults. A persistent symptom needs a clinician's evaluation, and no supplement on this list replaces treatment.
Evidence last reviewed: October 2026
Situational
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| Iron | Strong evidence | shedding with low ferritin | Women with non-scarring hair loss have lower ferritin than women without it, and correcting iron deficiency restores growth. Repletion uses 60–120 mg elemental iron on alternate days, far more than hair formulas contain, and only after a confirmed low ferritin. | View |
| Zinc | Moderate evidence | proven zinc deficiency | Zinc deficiency causes shedding and correcting it restores growth, at 15–30 mg a day and only in deficiency. Above 40 mg a day for long periods, zinc causes copper deficiency. | View |
| Vitamin D3 | Strong evidence | only when blood levels are low | A meta-analysis of 23 studies found people with non-scarring hair loss more often vitamin D deficient, but that is an association, not proof that supplementing regrows hair. Test 25-OH-vitamin D and correct a deficiency with your doctor. | View |
| Orthosilicic Acid (ch-OSA) | Moderate evidence | fine, brittle hair, not shedding | In a randomized trial in women with fine hair, choline-stabilized orthosilicic acid increased hair tensile strength after 9 months. It strengthens hair rather than stopping hair loss, and nearly all the trials come from one manufacturer. | View |
Popular for this goal — but the evidence says skip
- Biotin (Vitamin B7) Limited evidence
No randomized trial shows it improves hair in people with normal biotin status, and doses of 5–10 mg a day can falsify troponin and thyroid tests, so stop it 48–72 hours before blood work.
- Hair-Skin-Nails Formulas Limited evidence
They are built around megadose biotin, with iron and zinc far below repletion doses, and the few positive trials are small, sponsor-funded and specific to single branded products.
- Saw Palmetto Limited evidence
The hair trials are small, short and often unblinded, the effects are far below finasteride's, and it may interfere with PSA readings.
- Pumpkin Seed Oil Limited evidence
The hair claim rests on one small 24-week trial of 400 mg a day in men that has not been replicated.
- Keratin Limited evidence
One small manufacturer-funded trial in 50 women supports it, and eaten keratin is digested to amino acids like any other protein.
- Marine Protein Complex Limited evidence
Every placebo-controlled trial comes from the maker of a single branded ingredient, with no independent replication and no comparison against minoxidil or finasteride.
Our verdict
Before buying anything, ask your doctor for ferritin, thyroid and zinc tests and treat what turns up; that is the evidence-based move. Skip biotin, which does nothing without a deficiency and can falsify heart and thyroid blood tests, along with hair formulas, keratin and saw palmetto. Sudden or patchy hair loss needs a medical workup.