A question that I'm often asked is whether aspartame can worsen PD
symptoms. There are many, many reports on the Internet about
aspartame and its possible harmful effects on people with various
conditions, including Parkinson's disease. While there are no simple
answers to this question, it's certainly a good idea to examine these
concerns.

What is aspartame?
Aspartame (also known by the brand names NutraSweet® and Equal®) is a
chemical that is 200 times sweeter than sugar; it's used to sweeten
foods without adding significant calories. It is among a class of
chemicals known as excitotoxins — compounds that react with certain
receptors in the brain. It's found in soft drinks, chewing gum,
breakfast cereals, candies, desserts, and many other prepared foods.
When digested, it is broken down into amino acids, aspartic acid and
phenylalanine, and a small amount of methanol.

Is it dangerous?
This is a question in many minds. The American Dietetic Association's
position is that consumers can safely enjoy a range of nutritive and
non-nutritive sweeteners when consumed in moderation and within the
context of a diet consistent with the Dietary Guideline for
Americans.

At the opposite end, there are a number of Internet hoaxes making
unproven claims about the dangers of aspartame. These hoaxes can
usually be distinguished by emotionally-charged, fear-inducing
language accompanied by numerous testimonials from people claiming
that their diseases, such as multiple sclerosis, lupus, Parkinson's
disease, and other conditions, have been quickly cured by stopping
use of aspartame. On the other hand, there are many anecdotal reports
that, while they do not constitute scientific research, are too
numerous and too consistent to be ignored.

To help put the controversy into perspective, here is a quote from a
neurosurgeon who has studied aspartame extensively, Dr. Russell L.
Blaylock, MD; this is taken from the preface to his book
Excitotoxins, the Taste That Kills : "While there is little evidence
that food borne excitotoxins are the cause of these disorders, there
is growing evidence that they can aggravate these conditions and that
they may even precipitate them in sensitive individuals. Certainly
the scientific evidence is far too strong to ignore the possibility
that excitotoxic food additives may cause such conditions to appear
sooner and to a more serious degree."1

Still another health professional reports: "...despite what appears
to be a concerted effort on the part of aspartame's makers to negate
the allegations of health problems, adverse reactions from aspartame
are real. This was eloquently borne out in 1996, when Ralph G.
Walton, MD, professor and chairman of the Department of Psychiatry at
Northeastern Ohio Universities College of Medicine conducted an
analysis of all the medical studies — 164 of them at the time —
dealing with human safety as it relates to the use of aspartame. The
studies were separated into two categories: 74 were sponsored by the
aspartame industry and 90 were non-industry-sponsored studies. Dr.
Walton found that of the 74 studies sponsored by the aspartame
industry, 100 percent of them claimed there were no health problems
associated with aspartame use. Of the 90 studies that had no
connections to industry, all but seven of them identified one or more
problems with aspartame use. Interestingly, of the seven studies that
did not find problems, the FDA had conducted six. Critics suggest
that since a number of FDA officials eventually went to work for the
aspartame industry, these six studies should be considered industry-
sponsored research as well."2 (Reprinted from "Aspartame = Diet-
astrous Results" by Rebecca Ephraim, RD, CCN, Conscious Choice
Magazine, May 2001, (www.consciouschoice.com)

Very few research studies have been done that examine aspartame use
in people with specific conditions, including depression,
diabetes/poor blood glucose control and Parkinson's disease. Let's
examine the research studies as well as individual reports and see if
we can draw any conclusions regarding its use by people with PD.

Aspartame and depression
In the only aspartame study conducted on individuals with depression,
40 people with unipolar depression and 40 people without a history of
depression were studied to determine whether people with mood
disorders were affected by aspartame use.3 Rarely, a study is halted
if it is ascertained that subjects may be endangered by the study
protocol. In this study, 13 out of the 40 subjects with depression
suffered severe reactions, while the control group (those without
depression) did not. The severity of reactions among those with
depressive disorders was so great that the Institutional Review
Board, responsible for ensuring that the rights and welfare of study
participants are protected, halted the project.

Individuals in both groups received 30 mg aspartame per kilogram body
weight per day, about the equivalent of ten 12-ounce cans of diet
soda daily. With today's super-sizing of portions, and the great
number of products that contain aspartame, it's not difficult for an
individual to ingest this amount of aspartame on a daily basis.

Due to the frequency of depression among people with PD, this factor
alone should give us pause. Although it's not likely that everyone is
affected adversely by aspartame, nor is everyone with PD prone to
depression, these two factors combined could raise the likelihood of
depression in those with PD.

Aspartame and diabetes
A number of my colleagues who are certified diabetes educators report
an apparent anomaly among some of their clients. Several diabetic
patients who carefully followed their diet and took medications at
the proper time, nevertheless had high blood glucose. Upon close
questioning, they all reported regular use of aspartame, mainly in
the form of diet soft drinks. When these patients stopped using
aspartame, their blood sugar dropped to a normal range. One dietitian
reports that a patient with high blood sugar and a history of
migraine headaches stopped using diet sodas and switched to regular
soft drinks. His headaches stopped within three weeks; and, despite
the use of sugary soft drinks, his blood sugars returned to normal.
While this is not true for all people with diabetes who use
aspartame, it's a good idea to be aware of the possibility.

Aspartame and PD
To the best of my knowledge, only a single study has been conducted
on apartame and PD. In the study of 18 people with PD, researchers
examined the effects of aspartame on motor fluctuations and
concluded: "Aspartame consumption in amounts well in excess of what
would be consumed by heavy users of aspartame-sweetened products has
no adverse effect on PD patients."4 However, aspartame was
administered only for one day, and in capsule form — a form that is
not absorbed in the same way as is aspartame in foods. Therefore, the
study results are not necessarily applicable to people with PD who
consume aspartame-sweetened foods.

Anecdotally, people with PD who use aspartame have reported short-
term memory loss; fatigue; muscle aches; increased tremors and/or
rigidity; bloating; headaches; aggressive behavior; shorter "on
times," and edema. Within a few weeks of discontinuing aspartame,
these patients reported longer "on times," and a decrease in PD
symptoms, including a lower need for levodopa. Such anecdotal reports
cannot be taken as proof that aspartame has adverse effects for those
with PD; but they should be taken seriously. It may well be that a
subgroup of individuals are susceptible to aspartame and cannot use
it without harmful results.

Phenylketonuria
A few people are born with phenylketonuria (PKU), a rare inherited
disease that prevents phenylalanine, a component of aspartame, from
being properly metabolized. Phenylalanine can then build up in the
body and cause health problems. Since aspartame is a source of
phenylalanine, aspartame-containing foods must be labeled with a
warning — Phenylketonurics: Contains Phenylalanine.

Conclusions
In great part, what we are told about the safety of aspartame is
based on studies funded by its makers. This has contributed to the
lingering questions many consumers have about the safety of
aspartame. I believe that at the very least, there are some people
who are affected adversely by aspartame; and I think this can be true
at many different levels of intake — from as little as a few sticks
of sugar-free chewing gum daily to those who consume six liters of
diet cola, as well as aspartame-sweetened Jell-O, yogurt, cocoa mix,
powered soft drinks, tea, breakfast cereal, puddings, breath mints,
vitamins, and ice cream daily; and put Equal in their coffee or tea.
It is further likely that some people with PD are among this group,
and that aspartame may increase PD and other symptoms, possibly
including depression.

If you have PD and use aspartame in any form, I recommend you
eliminate these products for at least one month, and note whether
there is any change in the way you feel. If not, then resume use of
the products, again noting whether there is any change in physical or
mental state. If you feel better or symptoms improve after
discontinuing use of aspartame, I would report this to your
neurologist, and ask that it be further reported to the FDA.

If you have diabetes, you should be aware that the old belief that
people with diabetes should avoid all sugar is no longer valid.
People with diabetes can include sugar in their diets; ask your
doctor for a referral to a registered dietitian who is a Certified
Diabetes Educator (CDE) for counseling.


By Kathrynne Holden, MS, RD