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NMU 294 – Protecting Against Parkinson’s: The Role of Glutathione and Aging

Nutrition/Natural Medicine Update No 294 (July 5, 2023)

with Dr. James Meschino

Topic: Age-Related Decline in Brain Glutathione Linked to Increased Risk of Parkinson’s disease: The Importance of Glutathione-Supporting Supplements in Aging and Parkinson’s disease Management

Source: International Journal of Molecular Science (2021)


After Alzheimer’s disease, Parkinson’s disease is the second most common neurodegenerative condition, affecting one in five hundred adults after the age of fifty. It is estimated that about nine million people will be afflicted with Parkinson’s disease by the year 2030, as the population in many countries grows older. Parkinson’s disease is known to be caused be a combination of genetic and environmental factors, but ultimately the generation of unmitigated free radicals (oxidative stress) is established as a major cause of the disease. High levels of free radicals within dopamine-producing brain cells ultimately kills these cells triggering the onset of Parkinson’s disease and promoting its progression. Studies also show that the age-related decline brain glutathione levels is a primary reason why free radicals s become elevated in the aging process, contributing to the development of Parkinson’s disease as well as other neurodegenerative diseases, such as Alzheimer’s disease and ALS.

Unfortunately, as we age, cells in the brain synthesize less glutathione, which is the brain’s primary antioxidant required to quench and neutralized free radicals. Even though the brain comprises only 2% of the body’s weight, brain cells use 20% of the body’s oxygen for their very demanding energy requirements. A side effect of this is the production of oxygen free radicals that can do a great deal of damage to brain cells if there is insufficient glutathione present to neutralize them.  As I stated, studies confirm that brain cells make less glutathione as we get older, leaving our brain cells exposed to dangerously high concentrations of damaging free radicals. As such, in recent years researchers began investigating ways to increase brain glutathione levels in older subjects to help protect brain cells from free radical damage, and also to see if raising brain glutathione levels can be helpful in the management of existing cases of Parkinson’s disease.


The good news is that researchers have discovered ways to protect our brain against the age-related decline in glutathione levels, and that raising brain levels of glutathione does help to improve the management of existing Parkinson’s disease cases in many cases. The 2021 meta-analysis published in the journal Experimental and Therapeutic Medicine reviewed all relevant studies where Parkinson’s patients were given glutathione supplements, and it showed that glutathione is an effective adjunct in the treatment of Parkinson’s disease. The researchers stated, “the study provided medical evidence-based support for the effectiveness and safety of GSH (glutathione treatment)”.More specifically, glutathione treatment improved muscle and movement function, including tremor reduction, in the 450 patients, whose data was reviewed in this meta-analysis. The researchers note that there is no cure for Parkinson’s disease at this time, but the use of glutathione can play an important role in blocking the damage to mitochondria that plays a key role in the onset and progression of this disease. So, glutathione treatment not only helps to reduce the symptoms Parkinson’s disease, but it also helps to inhibit steps involved in the underlying cause of the disease. This 2021 meta-analysis looked at studies where Parkinson’s patients were given either 300 or 600 mg of glutathione oral supplementation per day. The problem, as noted by other researchers (see reference 2 and 3), is that glutathione supplements are largely broken down in the intestinal tract and do not reach the bloodstream intact.  As well, it is well known that glutathione does not cross the blood-brain barrier very well. As such, taking glutathione supplements is not considered to be the best way to increase blood, tissue, and brain levels of glutathione, especially as you get older.

Other researchers have shown that the best way to raise brain glutathione levels via oral supplementation, is by taking a supplement that contains N-acetylcysteine (NAC).  NAC has been shown to be absorbed intact, it enters the bloodstream and easily crosses the blood-brain barrier, even in older subjects. Once NAC is in the brain, it quickly stimulates synthesis of glutathione. In fact, when NAC is administered to Parkinson’s patients via IV, it has been shown to raise brain levels of glutathione by 55% within a very short period (see refence 3).  Other nutrients shown to raise blood and tissue levels of glutathione include, Alpha-lipoic acid, Silymarin from Milk thistle and L-Glutamine. Because our blood, body and brain levels of glutathione decline with age, and because glutathione plays such an important role in quenching damaging free radicals throughout the body and in brain cells, as well as the fact that our liver and kidneys (and some other cells) require glutathione to detoxify many environmental carcinogens known to cause cancer, many anti-aging experts suggest that  we should take a supplement each day that helps maintain more optimal glutathione blood, tissue and brain levels, by the time we reach 45-50 years of age.  I personally like a supplement capsule that combines:

N-acetylcysteine (NAC), with

Alpha-lipoic acid

Silymarin (from Milk thistle) and


These four nutrients work synergistically to raise glutathione levels and they each exert other important anti-aging and health-promoting effects.

I have included the key references on glutathione in Parkinson’s disease and other neurodegenerative conditions, in the text below.


  1. Wang H-L et al. Potential use of glutathione as a treatment for Parkinson’s disease. Exp Ther Med. 2021;21(2): 125
  2. Smeyne M. Glutathione metabolism and Parkinson’s disease. Free Radic Biol Med. 2013; 62: 13-25
  3. Aoyama K. Glutathione in the brain. Int J Mol Sci. 2021; 22(9): 5010
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