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Nutritional Supplements and Vitamins: Alternatives to help Parkinsonís Disease?
A growing percentage of the U.S. population is turning to nutritional supplements in the hope of improving general health and well-being. It's no surprise, then, that more and more people with Parkinson's (PWPs) are asking whether vitamins or other supplements could benefit Parkinson's disease (PD) itself. In a recent study carried out at the Johns Hopkins University School of Medicine by Stephen Reich M.D. and colleagues, approximately 40 percent of PWPs attending a specialty clinic used at least one non-prescribed therapy for their Parkinson's disease. Vitamins and herbs topped the list, with acupuncture and massage not far behind.
Although these potential therapies are considered "alternative" by some within the medical community, interest in studying them is growing among scientists. A small clinical trial of Tai Chi suggests that the technique helps improve balance in PWPs, and a study of acupuncture has shown that it is safe and well-tolerated in PD. In addition, several vitamins and other nutritional supplements are now being actively studied in the laboratory or in clinical trials to determine whether they have a role to play in treatment of PD. Unfortunately, PWPs are often in the position of having to make decisions about supplements without the necessary information; their doctors may not know about them and there has been little, until recently, in the way of good clinical trials. These problems are compounded by the sheer number of different preparations available, including vitamins, products that affect cellular metabolism (such as creatine and glutathione), or herbal products (such as Gingko biloba or Milk Thistle) which may have complex pharmacological activities and affect metabolism. What is more, gleaning the necessary facts often requires sifting through vast amounts of information much of it spurious and unscientific.
So, what vitamins, herbal remedies or nutritional supplements are taken by PWPs? Do they work and, more important, are they safe? Although a comprehensive review is beyond the scope of this article, we'll address some of these questions as well as try to provide some background on the rationale for such an approach. Interested readers can find more details in the literature listed at the end of this article.
Can dietary supplementation improve metabolism and help PD?
There are no interventions that we know for sure slow down the progression of PD, but recent research suggests that one potential means to this might be found in modifying nerve cell metabolism. Most cells in our body contain "energy generators" called mitochondria; their function is vital, and the brain in particular uses high amounts of energy. Researchers think that deficiencies in the functioning of mitochondria may play a role in PD, raising the question as to whether changing the energy balance in nerve cells could be protective. One compound that has attracted a lot of attention lately in this connection is Coenzyme Q10 (CoQ10), a common nutritional supplement. CoQ10 plays an important role in the mitochondria and is also a potent antioxidant. In a multi-center trial published in 2002, patients with early PD took either a placebo or CoQ10, at 300mg to 1200mg per day. The results showed that CoQ10 was well tolerated and was safe at these doses. What caught people's attention, though, was that over a sixteen-month period those PWPs who were on the higher dose showed slower disease progression than the others. It is too early to say for sure whether PWPs should start CoQ10, and what the best dose might be, but the preliminary data is promising.
Another supplement that likely acts through its effects on energy metabolism and could be useful in Parkinson's is creatine. This compound increases levels of phosphocreatine, an energy source in the muscle and brain, and in experimental studies it protects against nerve cell injury. The National Institute of Neurological Disorders and Stroke (NINDS) has now funded a multi-center pilot study of creatine (along with another agent, minocycline) in PWPs who have not yet taken any medicines for their PD. (To find out about participating in this trial, which is called Net-PD, call the NINDS information line on (800) 352-9424). The supplement has few reported side effects and is also of interest as a potential therapy for muscle disease as well as other chronic diseases such as Lou Gehrig's disease (amyotrophic lateral sclerosis) or Huntington's chorea.
Glutathione, a compound with multiple effects on nerve cell metabolism as well as a powerful antioxidant, is of particular interest for PWPs because of studies showing its depletion in the substantia nigra (the site of major nerve cell damage in PD). With promising effects in the laboratory though, it is still not clear what is the best way for PWPs to take this, what would be the best doses and very importantly, what are the risks particularly over the long term. Other supplements at earlier stages of investigation in the laboratory include nicotinamide, riboflavin, acetyl carnitine and lipoic acid, but so far there is not enough evidence to recommend them specifically to PWPs.
Antioxidant therapy for PD: What's the evidence?
Based on strong evidence linking oxidative damage of nerve cells to PD, there has been much hope that antioxidants could play a role in slowing the progression of the disease. (As mentioned above, CoQ10 has powerful antioxidant properties.) Many PWPs take antioxidants such as vitamin E or vitamin C; indeed, the Johns Hopkins study note above showed that more PWPs take vitamin E than any other supplement. Vitamin E can combat the damage caused by so called "free radicals", and high dietary intake of vitamin E has been linked to lower risk of PD. Unfortunately, optimism over its use in PD has not been confirmed. A rigorous trial of a decade ago - the so-called DATATOP study - found no evidence that even high doses of vitamin E (up to 2000 IU per day) had any effect on progression or symptoms of PD. Still, given that vitamin E has very few side effects, many PWPs elect to take it at daily doses of 400 IU or more. Another potent antioxidant that may have some impact on PD is to be found in fermented papaya preparation available as a health food. Blueberries are also rich in antioxidants, and early experimental results have raised the possibility of their effectiveness in slowing nerve cell loss and age-related changes.
Herbal remedies may aid memory lapses and depression
Coordination and balance difficulties are only some of the problems faced by PWPs; for many, such effects as depression and memory decline may be even more troubling. One substance that seems to have mild benefit for memory in Alzheimer's disease is ginkgo biloba, a plant extract consisting of a complex mixture of different chemicals. Studies show that doses between 120-240mg/day of the extract seem to have small but significant effect. It also seems to protect nerve cells from MPTP, a neurotoxin that leads to Parkinson's disease. As yet, we don't know whether it could be a good way to treat mild memory lapses in PD, and PWPs should discuss with their doctors how best to address these problems if they are present.
In efforts to ease the depression that is commonly associated with PD, some patients take St. John's Wort (Hypericum perforatum). However, since it has properties similar to medicines such as Prozac or Paxil, it should not be taken alongside other antidepressants because of the risk of serious side effects. Finally, many PWPs look to herbal remedies for insomnia, calming properties or overall well-being. Although there is no rigorous evidence to support the efficacy of these remedies, individual PWPs may feel they contribute to a better quality of life.
So, what's the bottom-line? For people who are interested in exploring complimentary approaches to easing PD, there does seem to be increasing scientific evidence of the efficacy of some available supplements, but safety has to come first. "Natural" remedies are not necessarily free of side effects or drug interactions. There are reports of serious side effects from some of these treatments, including movement disorders with Parkinson's-like symptoms linked to Kava-Kava, a herbal supplement sometimes used for anxiety. In addition, supplements may be expensive, can vary widely between different manufacturers or even batches, and are regulated differently from the processes that govern prescription drugs.
As the medical community extends its efforts to determine whether individual supplements are of benefit in PD, opportunities increase for PWPs to participate in clinical trials. Although this means knowing you may be given placebo, it ensures tight monitoring and a reliable source of supplement, avoids expense, and means that the results of your experience will contribute to better treatment of PD in the future. Encouragingly, there is increasing information that is readily accessible to PWPs, caregivers and their doctors about possible benefits, risks and contraindications of available supplements; you should discuss with your physician any supplements you take, just as you would with all your medicines, and how best you can individualize your therapy.
The New York Times Guide to Alternative Health (2001), Ed. Denise Grady, although not aimed at PD, is well balanced with a wealth of factual information on supplements, herbal remedies and the surrounding industry in general. The Physician's Desk Reference (PDR) for Herbal Medicines (2000), 2nd edition, Eds. Joerg Gruenwald, Medical Economics Staff and PDR for Nutritional Supplements (2001), Eds. Sheldon Saul Hendler, David Rorvik both provide reliable, although highly technical information including suggested doses, potential side effects and pharmacological properties.
Claire Henchcliffe MD DPhil
Assistant Professor and Director, Parkinson's Institute, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York