N-acetyl-carnosine (NAC) is commonly used in eye drops for the improvement of vision health and cataracts. What are the other benefits attributed to this supplement?
N-acetyl-carnosine is a naturally occurring form of carnosine. Carnosine is a dipeptide molecule formed by a union between beta-alanine and l-histidine; two amino acids.
The only difference in structure between carnosine (C9H14N4O3) and NAC (C11H16N4O4) is that NAC contains one additional acetyl group (CH3CO). An acetyl group is a methyl group (CH3) attached to a carbonyl by a single bond.
Whereas carnosine is rapidly degraded in humans by an enzyme called carnosinase, N-acetylcarnosine is resistant to its effects. If NAC is deacetylated by losing its acetyl group, then it becomes carnosine.



- Supports athletic peformance & muscle vitality
- Anti-oxidant with anti-glycation effects
- May boost immune system & anti-inflammatory
N-acetyl-carnosine Eye Drops
Related Topics
Cataracts are the leading cause of vision impairment worldwide. They account for roughly 42% of all blindness. Currently, more than 17 million people are believed to either have cataracts or be in the process of developing them.
About 28,000 new cataract cases are reported daily. It is estimated that people over 60 years of age have roughly a 20% chance of cataract development in one or both eyes. Those over 75 years of age have about an 80% chance for the same.
N-acetyl-carnosine is effective for improving various eye and vision disorders. It is primarily used in 1% concentrated solutions to reverse the formation of senile cataracts.
It is also able to prevent cataracts from developing in the first place. This may occur by NAC slowing down lipid peroxidation in eye lenses.
In one randomized, placebo-controlled human trial, administration of 1% NAC eye drops improved lens transparency in cataract patients. 2 drops twice each day in affected eyes improved symptoms significantly within 4 months.
One Russian study monitored 49 people with mild to severe cataracts. Cataract surgery had not yet been recommended for these patients. Their average age was 65 years. Each eye affected by cataract development was treated with two drops of 1% NAC, twice daily.
Substantial improvements were noted in eyes treated with N-acetyl-carnosine eye drops. Within 6 months of treatment, the following was achieved:
- Between 7 and 100% improvements in visual sharpness (acuity) in 90% of treated eyes;
- Between 12 and 50% increased transmissivity to light in 42% of treated eyes;
- Between 27 and 100% decreased glare sensitivity in 89% of treated eyes;
These improvements were maintained successfully with the same dosage rate for an additional 18 months.
Patients who did not receive treatment experienced worsened vision and cataract development. Visual acuity decreased in placebo controls by 89% within 24 months.
N-Acetyl-Carnosine vs. Carnosine
The Natural Medicines Comprehensive Database (NMCD) states that carnosine and NAC are most commonly used for treating cataracts, renal dysfunction and complications due to diabetes mellitus.
Carnosine is also being recommended as an anti-aging supplement due to its anti-glycation effects.
The dipeptide carnosine was discovered by Russian researchers in 1900. Because of tense relations with the Soviet government, little research on carnosine or NAC was shared with western researchers.
Today, there is still little reliable clinical evidence on the use of carnosine or NAC supplements for medicinal benefits.
Carnosine and certain carnosine derivatives, including N-acetyl-carnosine are found mainly in skeletal muscle tissues. However, they are also found in the heart muscle and the brain.
Different carnosine derivatives display differing amounts of antioxidant activities. The free radical scavenging properties of NAC are believed to be its main mechanism against cataracts.
Using Carnosine Supplements
Most people do not gain sufficient quantities of carnosine from their diets. The primary reason for this is that carnosine is rapidly disassembled in the body after ingestion by the carnosinase enzyme.
The Carnosinase enzyme reduces carnosine back into its basic constituents: beta-alanine and l-histidine.
Carnosine is believed to be most concentrated in skeletal muscles because carnosinase is not present there. Carnosine acts as a buffer of hydrogen ions in muscle tissues.
It is believed to be effective for reducing hydrogen ion accumulations which cause muscular “burning,” which can compromise physical endurance.
Because of the actions of carnosinase, supplementation with carnosine is not an effective method for increasing serum carnosine levels.
Beta-alanine is the rate-limiting precursor of carnosine. Increasing beta-alanine, not l-histidine, is the best way to increase carnosine.
Carnosinase is also not believed to be found in eye lenses. This may account for its advantageous effects inside lenses.
N-acetyl-carnosine is believed to be resistant to the degrading effects of carnosinase; increasing its capacity to work in the form of liquid carnosine eye drops.
Although research into exogenous administration of N-acetyl-carnosine and carnosine is currently limited, both compounds are believed to exhibit several important biologic effects, particularly concerning antioxidant and anti-inflammatory roles.
Antidiabetic, cardioprotective, anticancer, antiaging, chemopreventive and neuroprotective potentials are also being explored.
N-Acetyl-Carnosine Side Effects
NMCD states that there is insufficient evidence of adverse effects of carnosine and NAC to rate its safety. No adverse effects are currently associated with using these compounds appropriately.
Carnosine is believed to lower blood pressure. Use cautiously with antihypertensive medications or herbal supplements. Do not supplement your diet with carnosine or N-acetyl-carnosine if you are pregnant or nursing.
If you are considering using a beta-alanine, carnosine or NAC supplement, then it is best to speak to your doctor about it first.
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Article last updated on: March 12th, 2018 by Nootriment