Carnosine

L-carnosine, beta-alanyl-L-histidine, β-alanyl-L-histidine; related: N-acetylcarnosine (eye drops), zinc-L-carnosine / polaprezinc (gut medicine)

Recovery, repair & tissue

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Summary

Class: Naturally occurring dipeptide (2 amino acids: beta-alanine and L-histidine) found at high concentration in human skeletal muscle, heart and brain. Also sold as a food supplement
Mechanism: Buffers acid in muscle, scavenges reactive oxygen species and reactive aldehydes, chelates metals, and blocks the formation of advanced glycation end-products (AGEs) that stiffen and damage proteins
Routes studied: Oral (nearly all human work, 0.5–2 g/day); intravenous and intraperitoneal (animal); topical eye drops as N-acetylcarnosine; community subcutaneous injection
Dose range reported: Human trials: 500 mg to 2 g/day orally, usually 1–2 g/day, for 8–24 weeks. Beta-alanine (the precursor, 3.2–6.4 g/day) is the standard way to raise muscle carnosine in sports science. Community injection: 100–500 mg/day; no study supports this route
Half-life: Oral carnosine is largely broken down by the blood enzyme carnosinase within minutes; plasma half-life is on the order of minutes in most people, with wide genetic variation. Muscle carnosine, once built up, declines over weeks
Storage: Powder is stable at room temperature when dry. Reconstituted solutions: refrigerate; community practice is use within a couple of weeks
Regulatory status: Legal food supplement in most countries; injectable not approved anywhere. Zinc-carnosine (polaprezinc) is an approved stomach-ulcer medicine in Japan

Doses are as reported in studies or by the community — never recommendations.

1What it is

Carnosine is a molecule your body makes and stores in large amounts — a few grams in total, mostly in fast-twitch muscle fibres. It was discovered in meat extract in 1900, which is where the name comes from (Latin carnis). Humans synthesise it from beta-alanine and histidine; beta-alanine supply is the limiting step, which is why beta-alanine supplements are the usual way to raise muscle carnosine for exercise performance.

Its levels in muscle fall with age and are lower in vegetarians (meat is the dietary source). Interest in it for longevity comes from its ability to neutralise some of the chemistry of ageing — oxidative damage, glycation (sugar sticking to proteins), and reactive aldehydes from fat breakdown. In the 1990s it extended the lifespan of cultured human fibroblasts and later of mice in some studies.

It is a well-characterised, naturally occurring nutrient with a long safety record as an oral supplement, which puts it in a different category from most peptides on this site. The injectable route is a community practice without supporting research.

2How it's thought to work

pH buffering. the imidazole ring of histidine accepts protons in the physiological range, so carnosine helps muscle resist the acid build-up of hard exercise. This is the best-established function.

Anti-glycation. carnosine reacts with sugars and reactive carbonyls (e.g. methylglyoxal) before they can attach to proteins, reducing AGE formation. AGEs are implicated in diabetic complications, skin ageing and vascular stiffness.

Aldehyde scavenging. quenches lipid-peroxidation products such as 4-hydroxynonenal and acrolein.

Metal chelation and antioxidant. binds copper and zinc; scavenges hydroxyl and peroxyl radicals.

Other proposed actions. modulation of nitric-oxide synthesis, support of mitochondrial function, and in the eye, N-acetylcarnosine as a lens-protective prodrug.

Carnosine, a beta-alanyl-L-histidine dipeptide concentrated in skeletal muscle and brain. Its imidazole ring buffers the acid produced during intense work and captures reactive carbonyls before they cross-link proteins. Oral doses are largely broken down by carnosinase before reaching tissue.Schematic — not to scale

The limiting problem is carnosinase. Most people have high levels of this serum enzyme, so oral carnosine barely rises in blood; the benefits seen in trials may come from the released beta-alanine, from brief exposure, or from tissues with low carnosinase.

3What the research shows

Exercise performance (via beta-alanine loading)

Dozens of show beta-alanine supplementation raises muscle carnosine 40–80% and modestly improves high-intensity exercise lasting 1–4 minutes (meta-analysis: Saunders 2017, Br J Sports Med). This is strong evidence for the role of carnosine, but via the precursor, not carnosine itself. [2]

Graded A (small)

Glucose control and metabolic health

In overweight or obese non-diabetic adults, 2 g/day carnosine for 12 weeks prevented the worsening of insulin resistance and glucose tolerance seen with placebo (de Courten 2016, Obesity). In type 2 diabetes, 1 g/day for 12 weeks lowered fasting glucose and HbA1c in one trial (Houjeghani 2018, Nutr Res). A 2023 meta-analysis of carnosine/histidine-containing dipeptide trials reported modest improvements in HbA1c and fasting glucose (Menon 2023). Small trials; moderate consistency. [3][4]

Graded A (small)

Cardiovascular and lipid markers

Pooled trials show modest reductions in triglycerides and some inflammatory markers; blood pressure effects are inconsistent (Menon 2023 meta-analysis). The CARDIAC-ACP and related trials are ongoing or recently completed †.

Cognition and neurodegeneration

Anserine/carnosine blends improved some memory measures in older adults in small Japanese RCTs (Hisatsune 2016, J Alzheimers Dis); a small trial in Parkinson's disease reported improved symptoms with carnosine added to standard therapy (Boldyrev 2008). Rodent models of Alzheimer's and stroke show protection. Evidence is early. [3][5]

Graded A (small, mixed)

Autism spectrum disorder

An 8-week RCT in children (n=31) reported behavioural improvement with 800 mg/day (Chez 2002, J Child Neurol); later trials have been mixed or negative. Not established. [6]

Cataract (N-acetylcarnosine eye drops)

Small Russian trials reported improved lens clarity; independent replication is lacking and a Cochrane review found insufficient evidence (Dubois 2017, Cochrane). [9]

Graded C/D

Lifespan and ageing

Extended lifespan of cultured human fibroblasts (McFarland & Holliday 1994, Exp Cell Res) and of senescence-accelerated mice (Boldyrev 1999). Lifespan benefit in normal mice is inconsistent. No human longevity data. [7]

Injected carnosine

No human studies. Rodent injection studies exist for stroke and kidney models (C), but community use is extrapolation.

4Reported side effects and interactions

Literature-reported

Literature (oral). very well tolerated across trials at up to 2 g/day; occasional mild gastrointestinal upset. Beta-alanine causes a harmless tingling (paraesthesia) at doses above ~800 mg at once; carnosine itself rarely does.

Community-reported

oral — mild stomach upset, occasionally vivid dreams or restlessness if taken late. Injection — injection-site irritation, warmth or flushing, occasional headache. Some report a tingling similar to beta-alanine.

Theoretical. histidine load is trivial at these doses. People with very low carnosinase activity (a genetic minority) will have higher and longer exposure; no harm is documented. Zinc-carnosine carries zinc-related cautions (copper depletion with long-term high intake).

Interactions. none clinically established. Carnosine may modestly lower glucose; worth noting alongside diabetes medicines. Theoretical additive effect with other chelators or antioxidants.

Markers researchers commonly monitor

Marker	Why it's watched
HbA1c and fasting glucose	the main human outcome in metabolic trials.
Fasting insulin / HOMA-IR	insulin resistance improved in the de Courten trial.
Triglycerides and lipid panel	modest changes in pooled trials.
Advanced glycation end-products (skin autofluorescence or serum CML)	the mechanistic target; not routinely available.
Urinary carnosine or serum carnosinase activity	research-only, but explains large individual differences in response.
Muscle carnosine (via MRS)	in sports-science settings only.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Oral carnosine needs no preparation. For the community injectable route, powder is often supplied in 1–5 g quantities or pre-mixed solutions because doses are in hundreds of milligrams — far larger than most peptides, so volumes and concentrations differ substantially from the usual microgram maths. Dissolves readily in water; refrigerate once mixed.

Open in calculator, pre-loaded →

6Commonly studied alongside

Beta-alanine (the precursor; the two are often discussed as alternatives), anserine (its methylated cousin, in Japanese cognition trials), zinc (as polaprezinc for the stomach), NAD+ precursors and other longevity compounds in community protocols (no combined trials).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Lawful dietary supplement ingredient (oral). Injectable not FDA-approved; not on the 2023 Category 2 list †
European Union	Permitted food supplement ingredient in most member states; injectable not authorised
United Kingdom	Sold as a food supplement; injectable not licensed
Australia	Permitted in listed complementary medicines; injectable not approved
South Africa	Available as a supplement; injectable not registered
Sport	Not prohibited by WADA; beta-alanine and carnosine are widely used in sport

8Open questions

Does oral carnosine act as carnosine, or mostly as a beta-alanine source after carnosinase breaks it down?
Can the metabolic benefits be confirmed in larger, longer trials with hard outcomes?
Is there any rationale for injection given the enzyme in blood that destroys it within minutes?

9References

1Boldyrev AA, Aldini G, Derave W (2013). Physiology and pathophysiology of carnosine. Physiol Rev. PubMed · DOI
2Saunders B et al. (2017). β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Br J Sports Med. PubMed · DOI
3de Courten B et al. (2016). Effects of carnosine supplementation on glucose metabolism: pilot clinical trial. Obesity. DOI
4Houjeghani S et al. (2018). L-Carnosine supplementation attenuated fasting glucose, triglycerides, advanced glycation end products, and tumor necrosis factor-α levels in patients with type 2 diabetes: a double-blind placebo-controlled randomized clinical trial. Nutr Res. PubMed · DOI
5Hisatsune T et al. (2016). Effect of anserine/carnosine supplementation on verbal episodic memory in elderly people. J Alzheimers Dis. PubMed · DOI
6Chez MG et al. (2002). Double-blind, placebo-controlled study of L-carnosine supplementation in children with autistic spectrum disorders. J Child Neurol. PubMed · DOI
7McFarland GA, Holliday R (1994). Retardation of the senescence of cultured human diploid fibroblasts by carnosine. Exp Cell Res. PubMed · DOI
8Hipkiss AR (2009). Carnosine and its possible roles in nutrition and health. Adv Food Nutr Res. PubMed · DOI
9Dubois VD, Bastawrous A (2017). N-acetylcarnosine (NAC) drops for age-related cataract. Cochrane Database Syst Rev. PubMed · DOI

† Being confirmed by our reviewers against current sources.

10Community

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11Page history

25 Oct 2026Profile published — awaiting medical review

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