Best Supplements for Hair Growth and Thickness

Biotin alone won't grow hair. Here's the evidence-based stack that actually addresses thinning and shedding.

Most hair-growth supplements lean heavily on biotin marketing. The truth: biotin only helps if you're actually deficient (rare), and even then only mildly. The real levers for hair are iron, vitamin D, zinc, protein, and the connective-tissue support nutrients.

Start with bloodwork

Before adding anything, check ferritin (the storage form of iron). Low ferritin is the #1 cause of unexplained hair shedding in women, even when standard iron tests look fine. Aim for ferritin >50 ng/mL, ideally 70+.

1. Iron (if ferritin <50)

Dose: 25-50 mg of iron bisglycinate, every other day, on empty stomach.

Don't supplement iron without testing, too much is harmful. Bisglycinate is the gentlest form (no constipation). Take with vitamin C, separate from coffee, calcium, and zinc by 2 hours.

2. Vitamin D3

Dose: 2,000-5,000 IU daily.

Hair follicles have vitamin D receptors and need it to cycle properly. Low D status is associated with alopecia areata and telogen effluvium. Get tested annually.

3. Zinc

Dose: 15-30 mg zinc picolinate, with food.

Essential for keratin synthesis and hair follicle integrity. Deficiency causes brittle hair and increased shedding. Long-term high doses (>40 mg) can deplete copper, balance with 1-2 mg copper if needed.

4. Collagen peptides

Dose: 10-20 g daily.

Provides the amino acids (proline, glycine) used to build keratin. Trials show improvements in hair tensile strength and thickness over 12-24 weeks.

5. BioSil (ch-OSA)

Dose: 5-10 mg ch-OSA daily.

A patented form of bioavailable silicon that activates the body's own keratin synthesis enzymes. The most clinically-impressive single ingredient for hair thickness in placebo-controlled trials, effects emerge over 5-9 months.

Honourable mention: Pumpkin seed oil

In men with androgenetic alopecia, 400 mg/day pumpkin seed oil increased hair count 40% vs placebo over 24 weeks. Works via mild DHT inhibition. Less data in women.

Skip these

• Biotin megadoses (10,000 mcg+), pointless unless deficient, and interferes with thyroid lab tests
• Generic 'hair vitamins' with 30 ingredients at sub-clinical doses
• Anything claiming hair growth in 30 days, hair growth biology takes 3+ months minimum

Realistic timeline

Hair grows ~1 cm per month. Even ideal supplementation takes 3 months to see new thickness and 6+ months to see length. Stay consistent or don't bother.

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