As you get older, your mental processes gradually decelerate. You think slower, write slower, drive slower, take longer to fill out forms, start losing to the kids at Scrabble. You want to hang on to as much brain power as possible for as long as possible.

For protecting the brain from aging, nothing tops acetyl-L-carnitine (ALC). This stuff is incredible. Your body makes its own ALC. But as with phosphatidylserine and other key anti-aging nutrients, production drops off with age. For optimum brain health, you need to maintain ALC at pre-decline levels. Studies indicate that in people over 40, ALC supplementation dramatically slows and even reverses cerebral aging. It resuscitates nerve cells and enhances memory, alertness, and learning. It restores mental vitality.

According to one researcher, “We don’t know how much brain life extension we can get out of taking ALC, because nobody has been taking it supplementally for long enough to find out. But if animal studies are correct, we can expect a lot of extra ‘brain years.’ ”

The Multipurpose Neuronutrient

ALC is remarkably versatile. An inventory of the nutrient’s beneficial functions reads like a Renewal wish list.

Acetyl-L-carnitine supercharges energy production in the mitochondria. In nerve cells, the mitochondria are concentrated in the terminal buds because this is where energy is needed for neurotransmitter synthesis. ALC literally loads up fat molecules in the cell’s cytoplasm (the viscuous substance inside the cell), hauls them through the mitochondrial membrane into the inside of the power plant, and drops them off right where they are burned to release energy. Like a train hauling coal to a power plant, ALC shuttles fuel to the furnaces of your brain.

ALC also assists in the production of acetylcholine, one of your body’s main neurotransmitters. Acetylcholine production declines with age, causing memory loss and cognitive decline. (The “acetyl” portion of acetylcholine comes from acetyl-L-carnitine. The “choline” portion comes from another neuronutrient, called phosphatidylcholine.)

But ALC goes beyond merely enhancing and maximizing brain energy and neurotransmitter production. For starters, it prevents age-related loss of nerve cells by shoring up brain structure. How does it do this? Once again, those all-important cell membranes loom large.

As you age, your cell membranes go through certain changes, such as losing fluidity and elasticity because of free radical damage. These changes have long been considered irreversible. For a nerve cell, that’s bad news. Because unlike all other types of cells, nerve cells can’t replicate. You’re born with a certain number of them, and once they’re gone, they’re gone.

In chapters 2 and 3 of Renewal: The Anti-Aging Revolution, I explained how the largest and potentially the most destructive free radicals are unleashed in the mitochondria during energy production, sort of like sparks from a fire. Since these particular free radicals hover right next to the mitochondrial membranes, they can easily oxidize the fats in these membranes —a process called lipid peroxidation—unless they are rapidly and efficiently snuffed out. (You can find out the rate at which lipid peroxidation occurs in your body by having your serum lipid peroxide level checked. This blood test can be performed at your local laboratory, but it requires a prescription.)

The job of protecting the mitochondrial membranes falls to coenzyme Q10 and glutathione. These two nutrients position themselves near the mitochondria, ready and able to neutralize free radicals. ALC serves as an able assistant to coenzyme Q10 and glutathione. A potent free radical scavenger in its own right, ALC protects nerve cells against oxidative stress and defends them against lipid peroxidation. With a helping hand from ALC, coenzyme Q10 and glutathione molecules are under much less stress. They’re free to protect your body elsewhere. That’s what I call antioxidant protection with a capital P.

ALC supports the mitochondria in another way as well: It repairs their run-down, worn-out membranes. In fact, ALC maintains the membranes of all nerve cell structures, including the terminal buds.

The presence of optimum amounts of ALC in the body translates into a host of benefits for the brain. Scientists say that ALC “promotes membrane stability,” “improves neuronal energetics,” “improves neuronal repair mechanisms,” and “restores age-related membrane changes.” We can simply call it age-proofing the brain.

The Research Verdict

Many population studies have substantiated the brain-boosting powers of acetyl-L-carnitine. In one study, for example, Italian researchers gave 20 senile patients 500 milligrams of ALC three times a day for 40 days. Another 20 patients received placebos. Intellectual performance—the ability to think and remember—improved significantly in the ALC-takers.

Of course, this was a relatively short experiment. A longer one would almost certainly produce even better results. For maximum benefit, I suggest a trial period of at least 60 and preferably 90 days.

In another study, a group of senile patients took 1,500 milligrams of ALC daily for six months. They improved significantly in all parameters studied, including cognitive ability, motor activity, behavioral performance, and self-sufficiency. According to the researchers, patients achieved “an effective recovery of...quality of life and improved participation in family and social life.”

Other research has shown that ALC is highly effective at treating depression in older people, particularly those with senility. It also slows (but doesn’t reverse) the progressive deterioration associated with Alzheimer’s disease.

Does ALC have any benefit for younger people? To investigate the nutrient’s ability to enhance attention span and reflex velocity, 17 men and women between the ages of 22 and 27 took 1,500 milligrams of ALC every day for a month. Ten of the study participants were involved in competition-level sports, while the remaining seven were sedentary. The researchers used special devices to evaluate reaction time to an auditory stimulus as well as learning time, as measured by speed and error rate in getting out of a video game maze. For comparison, the researchers also tested a second group of young people who had not taken ALC.

The ALC-takers not only reacted faster but also solved the maze faster, and with a fraction of the number of errors. Their overall performance scores far surpassed those of the non-ALC-takers.

Who Should Take It?

Acetyl-L-Carnitine’s beneficial effects would be potentiated by the use of these neuronutrients: lithium, ginkgo biloba, vitamin B-12, and phosphatidyl serine.

Another approach would be to take the combination product Brain Power, which contains acetyl-L-carnitine, ginkgo, and phosphatidylserine, and a host of other brain nutrients, (but not lithium).

I consider ALC an invaluable addition to the Anti-Aging Supplement Program. Anyone interested in improving their mental performance can benefit from ALC. This includes older people as well as students, businessmen and businesswomen, and people who are under stress or experiencing depression. The usual dose is 500 to 1,500 milligrams once or twice daily. (I take 1,000 to 2,000 milligrams a day.)

In my practice, I recommend ALC to patients with ARCD, Alzheimer’s disease, dementia, post-stroke amnesia, memory loss, Parkinson’s disease, depression, and chronic fatigue syndrome. The dose is the same as above.