What works, what does not, and what is dangerous. Reviewed by theAvelor Research Team.
Effective Dose
15-65mg elemental iron
Telogen effluvium (hair shedding) commonly linked to ferritin <30 ng/mL. Repletion reverses shedding in 2-4 months.
PMID: 30998812Effective Dose
15-30mg with copper balance
Deficiency causes hair loss and brittle nails. Correct only if blood zinc is low.
PMID: 23960398Effective Dose
1000-4000 IU/day
Low vitamin D correlates with alopecia areata and telogen effluvium.
PMID: 29086317Effective Dose
2.5-15g daily hydrolyzed
Roughly 20% improvement in skin elasticity and wrinkle depth over 12 weeks. Mostly industry-funded studies.
PMID: 31627309Effective Dose
1-2g daily
Modest improvement in hair density in women in some trials.
PMID: 25573272Biotin (if not deficient)
No benefit for hair, skin, or nails without deficiency. Deficiency is rare.
"Hair, Skin, Nails" Megavitamins
Usually just high-dose biotin with some filler vitamins. Weak evidence, real lab interference risk.
Silica Supplements
Tiny, inconsistent signal for hair thickness. Not worth the spend.
Generic Multivitamin for Hair Loss
Masks the cause. Test ferritin, zinc, thyroid before supplementing.
FDA warning: causes false troponin, false low TSH. Has caused missed heart attacks.
Reduces thyroid absorption. Separate by 4 hours.
Teratogenic risk. Use beta-carotene form instead.
Redundant mechanism, additive hormonal effect.