Ask the MD: Glutathione and Parkinson’s
In this post I'm discussing a substance you may have heard of — glutathione. It's made naturally by the body but is also available in certain foods and over-the-counter supplements. Glutathione levels decrease with aging and certain conditions, including Parkinson's disease (PD). In people with PD, glutathione levels are lower in the brain, specifically in the substantia nigra (the area in which dopamine cells are lost). Also, the level of reduction in glutathione has been associated with Parkinson's disease severity (less glutathione, more advanced PD).
The Role of Glutathione
Glutathione functions as an antioxidant — a compound that clears out free radicals. Free radicals are molecules that are potentially toxic to cells. They are formed in the body from normal metabolism (such as converting food to energy), but are increased by exposure to environmental toxins, such as cigarette smoke and air pollution. Buildup of free radicals contributes to a condition called oxidative stress, which is associated with aging and PD. Antioxidants may therefore offset oxidative stress by removing free radicals.
In addition to its work as an antioxidant, glutathione may support the mitochondria — the cell's energy producers. This could prevent cell death, meaning that glutathione could conceivably operate as a "neuroprotective" agent — one that could slow or stop the progression of PD.
The Research on Glutathione
For these reasons, glutathione supplementation has been and is currently being studied to determine if it could provide symptomatic benefit to people with Parkinson's. Glutathione can be given through several routes — oral, intravenous (IV) and intranasal (through the nose). Each method has advantages and limitations.
Although a pill would be ideal, oral glutathione is poorly absorbed from the digestive system and doesn't get into the brain very well.
Intravenous administration avoids these absorption concerns and raises blood levels of glutathione. Two clinical trials of IV glutathione have been conducted. The first (reported in 1996) was open-label — all nine people with Parkinson's were aware they were given IV glutathione. Participants' motor symptoms improved, and this benefit lasted for two to four months following discontinuation of glutathione. The second study (reported in 2009) was a randomized-controlled trial of 20 people with PD — half were given placebo and half were treated with IV glutathione. The therapy was shown to be safe, well tolerated and possibly beneficial for symptoms. To determine if IV glutathione is a truly efficacious symptomatic therapy for Parkinson's, larger, randomized, placebo-controlled trials need to be done. These haven't been performed, though, perhaps because of this treatment's downsides — IV glutathione can be expensive, inconvenient and associated with potential side effects (bleeding, infection, blood clots, etc.). There are also other ways to give glutathione (intranasally) that are less invasive and may be more effective.
Early research efforts toward intranasal glutathione showed that it is safe, well tolerated and raises levels of glutathione in the brain (as seen on imaging scans). An MJFF-funded Phase IIb placebo-controlled trial is currently examining the effects of intranasal glutathione on Parkinson's symptoms (both motor and non-motor). Regardless of these results (expected in 2016), Phase III trials will be designed to determine whether intranasal glutathione has a disease-modifying effect in PD.
The Current State of Glutathione
Since glutathione is categorized as a supplement, it doesn't require U.S. Food and Drug Administration approval, and is already widely available. Even though it isn't very effective, oral glutathione is offered by many retailers. Some intranasal sprays (different formulations from those being used in studies) are sold as well. And even though there is no standard dosing protocol and insurance often doesn't cover the cost, many doctors and clinics will administer intravenous glutathione.
So why not add it to your regimen? While glutathione is a promising therapy for Parkinson's, the benefit and efficacy have yet to be confirmed.
The Bottom Line
The desire and need for better symptomatic therapies and certainly for a disease-modifying treatment for those living with PD is more than understandable. We sense that urgency and are working to move promising therapies through the pipeline and to patients as quickly as possible.
Until these are proven, however, proceed with caution. Any therapy — whether it's a supplement, an over-the-counter medication, or even if it's described as "all natural" — can cause side effects and could interact with prescription drugs. Discuss all therapies with your doctor before taking them. Weigh the pros and cons, and always check the background and credentials of the physician and pharmacy providing the therapy.
The "Ask the MD" series is supported by Acorda Therapeutics. While our generous sponsors make the "Ask the MD" program possible, their support does not influence MJFF's content or perspective.
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