L-Lysine for Hair: What the Research Shows

L-lysine is an essential amino acid, and it has more hair research behind it than most amino acids, though from a small number of authors. Reviews report that women with increased shedding responded to L-lysine plus iron in double-blind data, and that depleted iron stores compromised by low lysine intake may be a main cause of chronic shedding. A separate safety review found lysine well tolerated up to about 6 g a day.

Here's what that research says, what it doesn't, and how much has been tested for safety.

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Key Takeaways

• Authors reviewing nutrition and hair loss report that double-blind data confirmed an open study in which a significant proportion of women with increased hair shedding responded to L-lysine and iron therapy.
• In women with chronic telogen effluvium, the main cause was suggested to be depleted iron stores, compromised by suboptimal intake of L-lysine, and it can take many months to correct.
• A systematic review of 71 articles (3,357 subjects) found lysine's adverse events were mainly mild gastrointestinal symptoms, and set a provisional no-observed-adverse-effect level at 6.0 g a day.
• Lysine was tested together with iron, so its effect on its own is not established.

What Is L-Lysine?

L-lysine is an essential amino acid, meaning your body can't make it and you need it from the diet.

Does Lysine Help Hair?

Possibly, in combination with iron and for women with increased shedding. The reported evidence comes from a small group of authors, and the studies paired lysine with iron.

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Using Lysine Sensibly

• Ask your doctor to check your iron (ferritin) before supplementing either one.
• Don't self-treat hair shedding. A doctor can look for the cause.
• Stay within studied doses and talk to your doctor before taking supplements.

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What The Research Shows

Lysine And Iron In Shedding

A review of nutritional factors and hair loss concluded that the role of the essential amino acid L-lysine in hair loss also appears to be important. Double-blind data confirmed the findings of an open study in women with increased hair shedding, where a significant proportion responded to L-lysine and iron therapy. The same review found no evidence that low serum zinc causes hair loss and warned that excessive supplement intake may itself cause hair loss (Rushton, 2002).

Chronic Shedding In Women

A second review from the same group reported that in women the major cause of hair loss before age 50 is nutritional, affecting 30%. Increased persistent shedding (chronic telogen effluvium) and reduced hair volume were the principal changes, and the main cause appeared to be depleted iron stores compromised by a suboptimal intake of L-lysine. The authors noted it can take many months to redress (Rushton et al., 2002). Both reviews come from the same research group.

How Much Has Been Tested

A systematic review of 71 articles with 3,357 subjects looked at oral L-lysine supplementation, with doses up to 17.5 g a day and dosing periods from 1 to 1,095 days. Adverse events were mainly subjective gastrointestinal symptoms, and the risk of GI symptoms was not significantly higher (risk ratio 1.02). The provisional no-observed-adverse-effect level was 6.0 g a day (Hayamizu et al., 2020). That review wasn't about hair.

See also: Can Hair Regrow Naturally in 3 Weeks? What the Research Shows · Pea Protein for Hair: What the Research Shows

Frequently Asked Questions

Does L-lysine help hair growth?

Reviews report that women with increased shedding responded to L-lysine plus iron. Lysine on its own hasn't been shown to grow hair.

Is L-lysine safe?

A systematic review found mild GI symptoms mainly and set a provisional safe level at 6.0 g a day. Talk to your doctor first.

Should I take lysine and iron together?

That is a question for your doctor. Excess supplements can cause problems, and iron needs depend on your levels.

References

1. Rushton DH. Nutritional factors and hair loss. Clin Exp Dermatol. 2002. PubMed
2. Rushton DH, Norris MJ, Dover R, et al. Causes of hair loss and the developments in hair rejuvenation. Int J Cosmet Sci. 2002. PubMed
3. Hayamizu K, Oshima I, Nakano M. Comprehensive Safety Assessment of l-Lysine Supplementation from Clinical Studies: A Systematic Review. J Nutr. 2020. PubMed