Supplement analysis backed by scientific evidence · PT

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Limited evidenceGeneral health

L-Histidine

An essential amino acid and the precursor of histamine and carnosine. A couple of small trials in specific patient groups showed something; there is no case for supplementing it if you eat protein.

Evidence last reviewed: August 2026

What the science says

  • Insulin resistance in obese women Limited evidence

    A randomised controlled trial gave 4 g/day of histidine for 12 weeks to 100 obese women with metabolic syndrome and reported reduced HOMA-IR, BMI and inflammatory markers. It is one trial, in one narrow population, from one centre, and has not been replicated.

  • Atopic dermatitis Limited evidence

    An open-label pilot study of oral L-histidine in adults and young children with atopic dermatitis reported improvement in eczema severity, on the theory that histidine feeds filaggrin-derived skin moisturising factor. It was uncontrolled and small, so placebo and regression to the mean cannot be excluded.

Dosage & safety

Studied doseThe metabolic-syndrome trial used 4 g/day in divided doses. Supplement labels typically suggest 500–1000 mg/day. A normal mixed diet supplies roughly 2–3 g/day, well above requirement.
SafetyWell tolerated at gram doses in the short trials available. Because histidine is the substrate for histamine, people with histamine intolerance or mast cell disorders may not tolerate it. Contraindicated in histidinaemia, and unstudied in pregnancy. High single-amino-acid doses can unbalance other amino acids.

Scientific references

Where to buy

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