Acetyl L-Carnitine is marketed as "protection for the brain." What do the medical sites say? According to the GlutathionePro site: "Acetyl L-Carnitine is able to pass through the blood brain barrier and reach deep within the brains cells; ridding them of harmful toxins. Even able to regenerate neurons that have been damaged by free radicals. Helping form the chemical in the brain called Acetylcholine, ALC helps keep the mitochondria working efficiently by clearing out the harmful fatty-acid metabolites that cause severe damage to our cells. "For those suffering from Alzheimer's disease, dementia or another cognitive impairment you can help slow down its progression and even help to reverse it altogether. By clearing the brain cells of harmful toxins and reversing the damage caused by free radicals you can help improve brain function and reverse the damage that led to the cognitive disorder in the first place." So Acetyl L-Carnitine is good for the brain. But it might also help prevent cataracts. To understand why, you need to know about glutathione. Glutathione is found in the eye. Cataract development corresponds with lowered levels of glutathione. What does that mean? Does a decrease in glutathione cause cataracts? Or is this decrease just a symptom of cataracts? If you increase your glutathione levels, will that prevent cataracts? No one's sure, but some alternative health practitioners believe that increasing glutathione levels in the eye might possibly prevent, stall, or even reverse cataracts. The problem: How to increase glutathione levels in the eye? The human body creates its own glutathione, but produces less as you age. Some experts say that glutathione does not survive the human digestive tract, and so oral supplements will not increase your glutathione levels. Some possible solutions involve bypassing the digestive system. Humans can absorb nutrients via the eyes, under the tongue, through the colon, via the nose, or directly into the bloodstream. * Some companies market sublingual glutathione tablets , to be absorbed under the tongue. * Other companies sell glutathione suppositories , to be inserted into the rectum. * Other companies sell glutathione nasal sprays . * Daily injections of glutathione into the bloodstream is prohibitively expensive and inconvenient. * Glutathione eyedrops seem the most logical route. However, I read of a study in India in which doctors tested glutathione eyedrops. Subjects taking the eyedrops did not experience fewer cataracts than those who didn't take the eyedrops. Which indicates (but doesn't conclusively prove) that any glutathione supplementation -- eyedrops, nasal sprays, suppositories, etc. -- would be ineffective, because lower glutathione levels correspond to, but are not a cause of, cataracts. * Some manufacturers claim that "reduced" glutathione , taken in large doses (500 mg a day), results in enough glutathione surviving the digestive system so as to make a difference. * Finally, we have Acetyl L-Carnitine, which survive human digestion -- and boosts glutathione levels. According to the Life-Enhancement website: "acetyl-L-carnitine (ACL) ... boosts glutathione levels via a more indirect route -- in rats, at least, and presumably in humans as well. As rats grow old, their glutathione levels decline, to the detriment of their health. At the same time, their levels of oxidized glutathione (the molecular form that results from neutralizing a free radical) are elevated. ... ALC supplementation (150 mg per kg of body weight) upregulated glutathione levels in the rats' brains to those of normal adult (12-month-old) rats, and their oxidized glutathione was brought down to normal adult levels. ALC's ability to restore glutathione levels has broad implications beyond the obvious antioxidant benefit." So Acetyl L-Carnitine supplements will increase your glutathione levels. Which in turn might -- might -- prevent cataracts. I developed tiny cataracts in my 30s. I began taking many nutritional supplements for my eyes, including oral glutathione (but not the "reduced" kind). Even so, after 18 years my cataracts progressed where I needed surgery. Did the glutathione at least slow the progression of my cataracts? Who can say? But if you're worried about cataracts, you might want to add Acetyl L-Carnitine to your other eye supplements