As we age, many of us experience subtle changes in our mental clarity—we can’t remember a name, we experience difficulty multitasking, or we forget where we left our keys. For decades, scientists have believed that cognitive decline was an inevitable part of growing older, a process termed “age-related memory impairment.” But what if this cognitive decline is preventable, or even reversible?
Researchers have suggested a simple combination of two amino acids—glycine and N-acetylcysteine (NAC), collectively known as GlyNAC—may not only slow down but actually reverse brain aging. The implications are profound. It’s possible they may have found a nutritional approach to promote healthier cognitive functioning.
Understanding the Aging Brain’s Energy Crisis
Our brains consume roughly 20% of our body’s total energy despite representing only 2% of our body’s weight. As we age, our brains go through several changes that contribute to cognitive decline. We have lower levels of the antioxidant glutathione, our cells experience more damage from a process known as “oxidative stress”, and the parts of our cells that produce energy (i.e. mitochondria) don’t work as well. Also, our bodies struggle to use sugar for energy, deal with ongoing inflammation, and produce less of the proteins (neurotrophins) that keep brain cells healthy and alive. Researchers believe these are responsible for the memory and thinking difficulties that many older people face.
What’s particularly concerning is that as our brain ages, its ability to move glucose (a sugar that is the brain’s main fuel source) into neurons declines. Making this problem worse is the fact that mitochondria, which use glucose to produce energy, also malfunction with age. This mitochondrial dysfunction may be one of the reasons why our cognitive abilities decline.
The Master Antioxidant and Its Precursors
Glutathione (GSH), which is often called the body’s “master antioxidant,” is one of the most important antioxidants in the body. Our cells contain more glutathione than any other antioxidant. This master antioxidant has three main functions: it counters the harmful effects of oxidative stress, it supports the functioning of our mitochondria, and it helps remove toxins from our body. Unfortunately, the amount of glutathione in our bodies drops significantly as we get older.
Scientists at Baylor College of Medicine have discovered that this deficiency occurs because older adults can’t make enough glutathione. The production of this antioxidant requires three amino acids: glutamate, cysteine, and glycine. As we grow older, we develop deficiencies of glycine and cysteine, which limits glutathione production.
This discovery led to a simple intervention: supplying the body with the missing building blocks. By providing glycine and NAC (which the body converts to cysteine), researchers hypothesized they could restore glutathione production and reverse age-related defects.
Clinical Trial Results
In a 2023 study, researchers tested whether giving GlyNAC to older people could improve their age-associated problems. The study included 24 older adults and 12 younger adults for comparison.
The results were remarkable. After taking GlyNAC for 16 weeks, older adults experienced a number of improvements. Their glutathione levels increased, oxidative stress decreased, and mitochondrial function improved to levels approaching those seen in younger adults. Also, their muscle strength, walking speed, and exercise capacity improved.
Most importantly for brain health, this treatment improved cognitive functioning and showed benefits in several characteristics of aging including mitochondrial dysfunction, inflammation, cellular aging, and chromosomal damage. These aren’t just superfician changes; they actually repair the basic ways that aging cells function.
Antioxidant Essential Reads
Direct Effects on the Aging Brain
While human studies can only measure the effects on the whole body, research in mice allows scientists to examine what happens directly in their brains—something that is impossible to do in living humans.
In a study published in the journal Antioxidants, researchers compared young mice, old control mice, and old mice receiving GlyNAC supplementation. Prior to treatment, the old mice showed significant cognitive impairment. They took longer to complete maze tests and made more errors compared to young mice.
When researchers examined their brains, they found several problems: low levels of glutathione, increased damage to cells from oxidative stress, impaired mitochondrial functioning, reduced ability to transport glucose into brain cells for energy, increased inflammation, damage to DNA, and lower levels of proteins that are essential for keeping brain cells healthy and functioning properly (i.e. neurotrophins).
After just eight weeks of GlyNAC, the old mice showed dramatic improvements. Brain glutathione levels increased, oxidative stress decreased, mitochondrial function improved, glucose uptake into neurons improved, and levels of neurotrophins increased. Most impressively, cognitive performance improved. The mice navigated mazes faster and made fewer errors.
The “Power of 3” Mechanism
Researchers refer to GlyNAC’s effectiveness as the “Power of 3“—the synergistic combination of glycine, NAC (cysteine), and the glutathione they help the body produce. This trio works together to create rapid and wide-ranging improvements that none of these amino acids can achieve alone.
The wide range of these improvements suggests that increasing glutathione may be the key to improving multiple systems that deteriorate with age.
Implications for Healthy Brain Aging
These findings offer hope for developing simple strategies to protect and/or improve cognitive function. Unlike many anti-aging interventions that target single pathways, GlyNAC appears to correct multiple problems at the same time, and also addresses root causes rather than merely treating symptoms.
This treatment appears to be safe as individuals have tolerated the supplements for several months of use. However, researchers note that the benefits declined after people stopped taking them, suggesting it may be necessary to continue taking the amino acids in order to maintain the improvements.
Looking Forward
While these results are encouraging, larger clinical trials are needed to confirm these findings and to determine the optimal doses of these amino acids. Research is currently being carried out to determine whether GlyNAC might help specific conditions such as Alzheimer’s disease and mild cognitive impairment.
It’s now clear that the traditional view of cognitive aging as inevitable and irreversible may be outdated. By understanding and correcting the cellular problems that occur with age, we may be able to maintain sharper minds and a better quality of life well into our later years.