Good for those with or without cataracts

N-Acetylcarnosine Helps
Prevent Eye Aging

More evidence is compiling in support of the
use of N-acetylcarnosine for improved vision
By Will Block
There was a time when meadow, grove, and stream,
The earth, and every common sight
To me did seem
Apparelled in celestial light,
The glory and the freshness of a dream.
It is not now as it has been of yore;
Turn wheresoe’er I may
By night or day
The things which I have seen I now can see no more.

[Emphasis added]
— Ode: Intimations of Immortality from
Recollections Of Early Childhood (verse 1 of 11)

William Wordsworth, 1807

William Wordsworth

t is a serious misfortune, as Wordsworth grieves in his poem, that we lose our ability to “see” as we age. While Wordsworth is referring to the “freshness” of sight, rather than its function, maintaining good vision is the foundation of seeing the beauty that surrounds us [“Heaven lies about us in our infancy!” (from verse 5).] The trap many people fall into—as much today as in the 19th Century—is that aging is “natural.” Following this, we fall prey to the belief that we should accept the degeneration of our senses and resign ourselves to the loss of the “celestial light,” which our sight makes possible.

Rather than complaining about our losses, isn’t it decidedly better to resolve to do something to solve the problems? Indeed, in the broadest sense, if we understand and outsmart the process of aging—by preserving our mind, our bodies, and our senses as long as we can—we can still be here when the future arrives. Then, with the help of advanced biomedical science, we may yet reclaim our youth, as well as full vision.

If you want to live a long and full life, you need to take care of the biomachinery that provides you with your principal source of knowledge, your eyes. Maintaining good vision is your best defense, and your eyes are your greatest tool for acquiring the knowledge to do just that. Your goal is to be able to say, “The things which I have seen (in my youth) I now can see once more!”

Our Eyes Are Vulnerable to Cataracts

Among the diseases known to cause blindness, the most common is cataract, an insidious condition that degrades the lens and clouds our vision. It’s by far the primary cause of blindness worldwide, but it rarely leads to that in the more advanced countries, where corrective surgery is readily available and affordable. In the United States, for example, the leading causes of blindness are age-related macular degeneration, glaucoma, and diabetic retinopathy.

From the prevalence of cataracts, it would appear that our eyes are increasingly vulnerable to damage as we grow older. Indeed they are, but it’s not for Mother Nature’s lack of trying to protect them from harm. Because they’re so vital to us, our eyes have evolved to contain an arsenal of defensive weapons, most of which are geared to counteract the damaging effects of oxidative stress, the principal culprit in cataract formation.

Antioxidants Are Key . . .

Normal lens and lens with cataract.
To defend against free radicals and other reactive oxygen species, we need antioxidants. Some are native to the body, whereas others must be ingested as food or supplements. Chief among the former is glutathione, our most important and abundant antioxidant. It’s found in the lens, where it protects against oxidative degradation not only of the principal structural proteins, called crystallins, but also of certain proteins that act as ion transporters in the cell membranes. Also important are certain antioxidant enzymes, namely, catalase, glutathione peroxidase, and superoxide dismutase.

Antioxidants that we must ingest include vitamin E, a lipid-soluble compound that accumulates in cell membranes, where it helps protect against lipid peroxidation, a process that degrades and weakens the membranes. Also necessary is vitamin C, a water-soluble compound that accumulates in the cytoplasm, the cells’ aqueous interior. Vitamin C is so important for ocular health that its concentration in the eyes is about 25 times higher than in the blood.

. . . But Their Levels Decline with Age

Obviously, though, the antioxidant protections mentioned above are not sufficient to protect us indefinitely. Perhaps it’s because we’re living so much longer than nature “intended.” To put it more scientifically, we are far outliving the evolutionary adaptations of our species. Only a century ago, the average life expectancy of a newborn child was 47 years (and that was in the USA, not the world as a whole). During such a brief lifespan, the levels of glutathione and the antioxidant enzymes may remain high enough to ensure reasonably good ocular health—not to mention the health of the rest of the body. With advancing age, however, these levels decline, as do those of many other vital substances.

To help prevent cataracts, therefore, it becomes ever more important to find effective nutritional means—all the more so because surgery, although highly successful, is costly, inconvenient, and not without some risk of complications. Prevention is always preferable to therapy in any case.

Carnosine Is Helpful Against Cataracts . . .

A group of researchers in New Zealand has published a review paper on the medical (as opposed to surgical) treatments for cataracts, with a focus on nutritional supplements rather than prescription drugs.1 They pointed out that various drugs are currently available for this purpose, but “all are without adequate proof of efficacy.” Unfortunately, the same can be said of the supplements that have been tried for cataracts—but a lack of adequate proof of efficacy does not mean there is a lack of evidence of efficacy, even if the evidence is still preliminary and unconfirmed.

Currently the most promising supplement, in the authors’ opinion, is N-acetylcarnosine, a derivative of the natural dipeptide carnosine (from the Latin carō, carn-, flesh), which is found mainly in the heart and skeletal muscles and the brain. Research conducted in Russia has indicated that carnosine is helpful in both preventing and treating cataracts. It can be administered topically to the eye, but with poor bioavailability: because of its low solubility in lipids, it does not penetrate readily into the lens, where it’s needed.

. . . And So Is Its Derivative N-Acetylcarnosine

That’s where N-acetylcarnosine (NAC) is helpful—it’s more lipid-soluble (it’s also water-soluble) and thus more effective in this regard, acting as a “delivery vehicle” for the parent compound. Like carnosine, NAC occurs naturally in the body, and it too is believed to be effective in preventing and treating cataracts when applied topically. It has been shown to improve vision by partially reversing the development of the cataract, thus increasing the lens’s transmissivity to light and allowing improved vision.

NAC acts both as an antioxidant (particularly against lipid peroxidation) and as an antagonist of glycation, the harmful process that results in advanced glycation endproducts (AGEs); these are sugar-protein complexes that degrade cellular functions in many of the body’s organs and tissues, including our lenses.

NAC Produces Impressive Results

The New Zealand authors described the one human clinical trial that has been conducted with NAC thus far—a 24-month Russian study involving 49 elderly patients and a total of 76 cataract-afflicted eyes.* Using a 1% aqueous NAC solution (2 drops twice daily), the researchers found substantial improvements in visual acuity, glare sensitivity, and lens transmissivity after 6 months, and these improvements were sustained for the duration. The controls’ untreated eyes showed significant deterioration during the same period.

* We reported on this study in 2003, based on a paper published in 2001.2 (See N--Acetylcarnosine May Help with Cataracts,” August 2003.) The paper cited by the New Zealand authors, reporting on the same study (identical results), was a different one, however, published in 2002.3 It must also be noted that the principal researcher and four of his colleagues were employed by a company that makes N-acetylcarnosine.

The New Zealand authors acknowledged that these results were impressive, but they also pointed to the study’s numerous shortcomings and suggested that an independent study of higher quality is needed to validate the results. They also mentioned the “interesting basic physiology” underlying the use of NAC as an anticataract agent. We have previously reported on some of these aspects of NAC function. (See “Fighting Cataracts with N-Acetylcarnosine” and “Clear Eyes with N-Acetylcarnosine” in the April 2006 and December 2006 issues, respectively.)

Value of N-Acetylcarnosine Confirmed and Extended

In a new study, eye drops containing N-acetylcarnosine (NAC) have once again been shown to be beneficial for the nonsurgical treatment of age-related cataracts.4 This study also found benefit for those who do not have cataracts. Two groups of patients, one with cataracts in one or both eyes (n=75, ages 53–83, 48% female) and another without cataracts (n=72, ages 54–78, 53% female), were divided using the double-blind method and treated with 1% aqueous NAC solution (2 drops twice daily) or placebo for 9 months. Subjects in both of these groups had reported glare disabilities. Delayed glare recovery is a visual change that occurs with aging that can increase the risk of driving a car and increase the number of accidents, especially in the elderly. Glare can also compromise visually demanding computer tasks. Along with glare sensitivity, visual acuity was also measured.

After the 9 months of treatment with 1% aqueous NAC solution eye drops, most patients’ glare disability scores were improved or returned to normal. The NAC eye drops were found to improve the vision of the older adult subjects whether they had cataracts or not, but the improvement of visual acuity was significantly better in the group of cataract subjects versus the non-cataract matched older adult group.

Furthermore, patients who had the poorest pretreatment vision were as likely to regain better visual function after 9 months of treatment with NAC solution eye drops than those with the best pretreatment vision. As noted above, in earlier studies the principal researcher and several of his colleagues were associated with companies that make or market a 1% N-acetylcarnosine eye drop formulation. They still are. Especially interesting, the report noted that the repurchasing behavior from more than 50,000 users has given continued use a strong vote of confidence.

What Causes Cataracts?

Cataracts sneak up on you when you’re not, uh, looking. Some people have a genetic predisposition to this disease. A few other risk factors, notably aging, are also inflexible. Most, however, can be mitigated or avoided. Among the major causes of cataracts are:

    How to get cataracts (and a lot more).
  • Aging – About 20% of all people over 60 have at least the beginning of a cataract in one or both eyes, and that figure rises to 80% for people over 75. As the population itself ages, the already huge numbers of cataract victims will increase.

  • Antioxidant malnutrition – Inadequate intake of antioxidants, particularly N-acetylcarnosine, vitamin E, and carotenoids, is believed to facilitate the damage done to lenses by oxidative stress.

  • Solar radiation – Ultraviolet radiation can damage our lenses as well as cause sunburn and skin cancer. The radiation damage from all the time we spend outdoors without sunglasses is cumulative.

  • Diabetes – This pernicious disease damages many organs and tissues, including the eyes—it’s a leading cause of blindness. It’s easily preventable in most cases—just avoid obesity.

  • Drugs – Also a major risk factor is the long-term use of some drugs, most notably the corticosteroids (aka glucocorticoids), powerful anti-inflammatory agents whose undesirable side effects include cataracts.

  • Smoking – Is there any part of the body that smoking doesn’t harm?

  • Severe dehydration – This is a common result of cholera-related diarrhea or poor nutrition in the Third World, where the rate of cataracts is high and surgical intervention is sparse.

  • Heredity – Not much you can do about this one.

  • Unknown – That’s right—cataracts can “just happen” for no apparent reason.

Vitamin E Yields Mixed Results, with New Support

Also mentioned by the New Zealand authors as being potentially useful against cataracts were multivitamin supplements, particularly vitamins E and C, which were found, in two human population studies, to correlate inversely with risk for the disease: higher levels of these vitamins meant a lower risk, and lower levels meant a higher risk.

Unfortunately, however, these promising results were not confirmed in three large clinical trials in which the subjects took supplemental antioxidant vitamins. In two of the studies, the vitamins were found to have no effect on the development or progression of the disease; in the third, there was a small positive effect in one group of patients (in the USA) but not in the other (in the UK).

Since the publication of the New Zealanders’ review, a very large population study has been published by Harvard researchers, with positive results for vitamin E (but not for vitamin C).5 The subjects were 35,551 female health professionals in the United States, whose dietary habits and ocular health were followed for an average of 10 years. Over that period, the risk for cataracts was reduced by 14% in the highest quintile (highest 20%) of daily vitamin E intake from food and supplements.

Lutein and Zeaxanthin Are Beneficial

The researchers found, furthermore, that the risk for cataracts was reduced by 18% in the highest quintile of daily intake of the carotenoids lutein and zeaxanthin. These compounds, which are found in many fruits and vegetables, are vital constituents of the human retina and exist in high concentrations in the macula, the spot on the retina that’s responsible for our acute central vision. Lutein and zeaxanthin have been found in other studies to be especially beneficial for age-related macular degeneration. (See “Carotenoids Can Help Maintain Healthy Eyes” and “Protect and Improve Your Vision with Carotenoids” in the November 2002 and March 2003 issues, respectively.)

Breaking the Dam of Cataracts and Other Visual Obstacles

Nutritional supplements are the first defense against age-related visual decline. If you value your vision, in addition to a good diet, you must use supplements. And from a growing body of evidence, an aqueous lubricant containing 1% NAC can help maintain and may even help restore proper visual function. In Wordsworth’s Intimation of Immortality, he sings, “The cataracts blow their trumpets from the steep” (from verse 3). The poet rejoices the rush and leap of the waters (cataracts), their signal notes, and their great concurrence, in one dense poetic blast. You too will rejoice when you can see more clearly once more.


  1. Toh TY, Morton J, Coxon J, Elder MJ. Medical treatment of cataract. Clin Exp Ophthalmol 2007;35:664-71.
  2. Babizhayev MA, Deyev AI, Yermakova VN, Semiletov YA, Davydova NG, Kurysheva NI, Zhukotskii AV, Goldman IM. N-acetylcarnosine, a natural histidine-containing dipeptide, as a potent ophthalmic drug in treatment of human cataracts. Peptides 2001;22:979-94.
  3. Babizhayev MA, Deyev AI, Yermakova VN, Semiletov YA, Davydova NG, Doroshenko VS, Zhukotskii AV, Goldman IM. Efficacy of N-acetylcarnosine in the treatment of cataracts. Drugs R D 2002;3:87-103.
  4. Babizhayev MA, Burke L, Micans P, Richer SP. N-acetylcarnosine sustained drug delivery eye drops to control the signs of ageless vision: Glare sensitivity, cataract amelioration and quality of vision currently available treatment for the challenging 50,000-patient population. Clin Interv Aging 2009;4(1):31-50.
  5. Christen WG, Liu S, Glynn RJ, Gaziano JM, Buring JE. Dietary carotenoids, vitamins C and E, and risk of cataract in women: a prospective study. Arch Ophthalmol 2008;126:102-9.

Will Block is the publisher and editorial director of Life Enhancement magazine.

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