What is the best supplement for promoting hair growth?

Best Hair Supplement for Promoting Hair Growth

There is insufficient high-quality evidence to recommend any specific supplement as "best" for hair growth in the general population, and routine supplementation without documented deficiency is not supported by current evidence. 1

Evidence-Based Approach to Hair Supplements

Biotin: Popular but Unproven

• Biotin supplementation lacks clinical trial evidence for hair growth despite widespread popularity. 2
• No randomized controlled trials have demonstrated efficacy of biotin for treating alopecia or improving hair quality in humans. 2
• A double-blind, placebo-controlled study found no difference between biotin and placebo groups for hair growth. 3
• Only 38% of women complaining of hair loss actually have biotin deficiency, making indiscriminate supplementation inappropriate. 4
• Biotin's popularity is vastly disproportionate to the insufficient clinical evidence supporting its efficacy. 2

Zinc: Mixed Evidence, Context-Dependent

• The only double-blind, placebo-controlled trial of zinc supplementation (220 mg zinc sulfate twice daily for 3 months) showed no improvement in alopecia areata despite increased serum zinc levels. 1
• Zinc may benefit only specific subgroups: patients with documented serum zinc levels below 70 μg/dL showed 60% improvement with 50 mg zinc gluconate daily, though this study lacked statistical significance and a placebo group. 1
• Serum zinc levels inversely correlate with severity and duration of alopecia areata in some studies, but other studies found no differences between patients and controls. 1
• Routine zinc supplementation without documented deficiency is not recommended. 1

Other Micronutrients: Insufficient Evidence

• Copper, magnesium, and selenium show no consistent association with hair loss across multiple studies. 1
• Vitamin B12 and folate: Multiple case-control studies found no differences in levels between alopecia patients and controls. 1
• Vitamin E and beta-carotene: Conflicting results with small sample sizes preclude clinical recommendations. 1
• No clinical recommendations for routine screening or supplementation of these micronutrients can be made. 1

Multi-Ingredient Formulations

• One proprietary nutraceutical supplement (Nutrafol®) containing botanicals with anti-inflammatory, antioxidant, and DHT-inhibiting properties showed statistically significant increases in terminal and vellus hairs at 90 and 180 days versus placebo. 5
• This represents the highest quality evidence for any oral supplement, though it is a single study of a specific formulation. 5

Clinical Pitfalls to Avoid

Common Mistakes

• Do not prescribe supplements indiscriminately without assessing for underlying causes of hair loss (thyroid dysfunction, iron deficiency, other medical conditions). 6
• Avoid assuming biotin deficiency based on hair loss alone—only 11% of biotin-deficient patients with hair loss had identifiable risk factors for deficiency. 4
• Do not rely on combination therapies to draw conclusions about individual supplement efficacy, as studies mixing zinc + biotin + topical steroids cannot isolate effects. 1

What to Actually Do

• Check serum levels before supplementing: Consider zinc testing only in patients with severe or resistant alopecia areata, as serum levels may correlate with disease severity. 1
• Determine biotin levels and exclude alternative factors before initiating biotin supplementation in women with hair loss. 4
• For female pattern hair loss, consider evidence-based treatments like topical minoxidil or combination with platelet-rich plasma rather than unproven supplements. 6

Bottom Line for Clinical Practice

The widespread use of hair supplements, particularly biotin, is driven by marketing rather than evidence. 2 Most popular supplements have not been tested in clinical trials, have only in vitro evidence, or have been tested only in animals. 7 The regulatory environment allows supplements to reach consumers without proving efficacy or safety. 7

If you must recommend a supplement, the multi-ingredient botanical formulation studied by Ablon (2018) has the strongest evidence from a randomized, double-blind, placebo-controlled trial. 5 Otherwise, focus on identifying and treating documented nutritional deficiencies rather than empiric supplementation.