Table 1.

Summary of common supplements used for hair, skin, and nails

Supplement	Purported use	Does it work?	Maximum or recommended safe dosages	Concerns and considerations
Biotin	Improves the appearance of skin, hair, and nails	May improve skin and hair findings if they are primarily caused by biotin deficiency (rare)	Toxicity is uncommon, even in very high doses	May interfere with laboratory results, including TSH and troponin levels
Zinc	Improves wound healing	May improve skin and hair findings if they are primarily caused by zinc deficiency	40 mg daily (FDA guidelines)	GI Toxicity at high levels. May result in copper deficiency. Excess zinc may also interfere with the efficacy of medications such as antibiotics
DHEA	Increases skin hydration and thickness	Limited data to ascertain if the benefits outweigh the risks	25 to 50 mg/d in older participants7	Increase in testosterone may cause hirsutism and acne. Theoretical increased risk of hormone-sensitive cancers
Pre- and Pro-biotics	Increase the diversity of the skin microbiome	May increase skin barrier protection	Varies with the type of prebiotic/probiotic	Limited data about risks
Nicotinamide	In vitro studies show restoration of age-related mitochondria function decline	Can decrease the prevalence of actinic keratoses in higher-risk populations	3,000 mg/d	Limited clinical trials Hepatotoxicity at high doses
Hyaluronic acid	Reduces the appearance of wrinkles	Can improve skin appearance due to increased water retention	200 mg/d in clinical trials	Limited clinical trials Industry-funded studies
Collagen	Improves the appearance of skin, hair, and nails	Can improve skin density and hydration, brittle nails	Varies with formulation	Limited clinical trials Industry-funded studies
Antioxidant: Vitamin C	Collagen synthesis, photoprotection	Specialized, stabilized serum formulas of Vitamin C may help with skin hydration	2,000 mg/d	Deficiency causes scurvy Toxicity causes GI side effects
Antioxidant: Vitamin E	Photoprotection	May help with reducing UV-induced damage	1,000 mg/d	High doses increase risk of death, bleeding risk, and drug-drug interactions
Antioxidant: Vitamin A and carotenoids	Increases skin turnover	Diminishes the appearance of wrinkles and acne scars	3,000 mcg/d	Deficiency may cause follicular hyperkeratosis. Excess may cause GI effects, liver problems, hair loss, and birth defects

DHEA, dehydroepiandrosterone; GI, gastrointestinal; TSH, thyroid stimulating hormone; UV, ultraviolet.