Amino Acids for Hair Growth: What the Research Shows

Amino acids are the building blocks of protein, and they are common in hair supplements. We found no trial of a single amino acid taken alone for hair growth. The trials that exist test blends that also contain vitamins, minerals, collagen and other ingredients, so the amino acids can't be credited.

Here's what those blend trials found.

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Key Takeaways

• We found no trial of a single amino acid alone for hair growth in people.
• In an 83-person randomized trial, a supplement with hydrolyzed fish collagen, taurine, cysteine, methionine, iron and selenium, added to drug treatment, produced better global scores than drug treatment alone at 12 weeks.
• A 20-woman, uncontrolled study of a supplement with sulfur-containing amino acids and trace elements reported improvement over 6 months in telogen effluvium.
• A randomized comparison of two supplements in telogen effluvium found improvement over 180 days, with only the multi-nutrient blend improving trichoscopy.

What Are Amino Acids?

Amino acids are small molecules that make up proteins. Hair is made of protein, and some amino acids, such as cysteine and methionine, contain sulfur.

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Do Amino Acid Supplements Help Hair?

Possibly as part of a blend in some hair loss conditions, but the trials don't tell us which ingredient did the work.

Using Amino Acid Supplements Sensibly

• Get enough protein through food first.
• Treat blend trials as blend trials. A result for one product does not apply to a single amino acid.
• See a doctor for ongoing hair loss, because treatment depends on the cause.

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What The Research Shows

A Randomized Trial

In a 12-week, assessor-blinded randomized trial, 83 people with androgenetic alopecia or chronic telogen effluvium either took a tablet with hydrolyzed fish collagen, taurine, cysteine, methionine, iron and selenium in addition to their drug treatment, or had drug treatment alone. At week 12, the global assessment score was higher with the supplement (1.67 against 0.66, p < 0.001), and 50% against 23% scored 2 or more. It was well tolerated (Milani et al., 2023). The supplement was added to drugs, so the effect of the supplement alone isn't known.

A Small Uncontrolled Study

Twenty women with telogen effluvium, some with mild androgenetic alopecia, took a supplement with L-cystine, L-methionine, liposomal glutathione, zinc, copper, iron, selenium, ubidecarenone and vitamin B5. Over 6 months, trichoscopy showed improvement in hair density and diameter in most, and all tolerated it well (Starace et al., 2023). There was no control group.

Two Supplements Compared

Female patients with telogen effluvium were randomized to one of two oral supplements for 180 days. One combined zinc, biotin, iron, vitamins and keratin and collagen amino acids; the other combined calcium pantothenate, cystine, thiamine, yeast, keratin and aminobenzoic acid. Both groups improved clinically, and only the first improved significantly on digital trichoscopy (Sant'Anna Addor et al., 2018). There was no placebo group.

For one amino acid on its own, see L-cysteine and hair.

For one ingredient often found in amino acid blends, see taurine and hair.

For one sulfur amino acid in detail, see L-methionine and hair.

To see how this fits with the other nutrients hair needs, read our guide to the best vitamins for hair growth.

For the foods that matter most for hair, see our guide to protein-rich foods for hair growth.

Frequently Asked Questions

Which amino acid is best for hair growth?

We found no trial that tests a single amino acid. The trials used blends.

Do amino acid supplements work?

In blends, some trials reported improvement, but the designs can't isolate the amino acids.

Is it safe?

The trials reported good tolerability, but check with your doctor first.

References

1. Milani M, Colombo F, GFM‐O‐Trial Investigators Group. Efficacy and tolerability of an oral supplement containing amino acids, iron, selenium, and marine hydrolyzed collagen in subjects with hair loss (androgenetic alopecia, AGA or FAGA or telogen effluvium). A prospective, randomized, 3-month, controlled, assessor-blinded study. Skin Res Technol. 2023. PubMed
2. Starace M, Carpanese MA, Alessandrini A, et al. Oral supplementation in female telogen effluvium: a clinical and instrumental objective evidence of efficacy and tolerability of new oral cosmetic treatment. Ital J Dermatol Venerol. 2023. PubMed
3. Sant'Anna Addor FA, Donato LC, Melo CSA. Comparative evaluation between two nutritional supplements in the improvement of telogen effluvium. Clin Cosmet Investig Dermatol. 2018. PubMed