What’s Put in Your Mouth Could Go to Your Head
Thursday, November 09, 2000
By Laurie Barclay, MD
WebMD Medical News
Reviewed by Dr. Jacqueline Brooks
Nov. 8, 2000 — There’s good news and bad news when it comes to diet and
memory. The bad news is that the artificial sweetener aspartame may make
memory worse, but the good news is that eating breakfast, fruits, and
vegetables may help make it better. That’s according to research presented
at a Society for Neuroscience meeting this week in New Orleans.
Since NutraSweet, or aspartame, became popular as a sugar substitute for the
weight conscious, some users have complained of memory problems and
headaches that disappear when they cut back on how much they use. Previous
studies couldn’t confirm this link, suggesting that the types of memory
impairments studied were different from those reported by the patients,
explains researcher Timothy M. Barth, PhD, chairman of psychology at Texas
Christian University in Fort Worth.
Or, aspartame users might be dieting because of low self-esteem and anxiety
over their body image. If they also were anxious about their intellectual
function, they might be more prone to report perceived memory problems.
To help sort out the possibilities, Barth’s group gave 90 college students a
nutrition survey and a memory questionnaire. Aspartame users reported more
memory problems than nonusers, especially forgetting that a task was
completed until it was started again, forgetting to perform a task at a
certain time, or forgetting a regular routine.
Although these findings suggest that aspartame users as a whole believe they
have memory problems, they performed about the same as nonusers on short-
term memory tests, like remembering a word list, a phone number, or a series
of faces. While these tests measure memory for something that just happened,
they may not reflect memory problems these people have in their lives
outside of the study.
“I always have problems with studies investigating the effects of diet on
behavior in uncontrollable real-life situations,” C.R. Markus, PhD, a
neuroscientist at Utrecht University in the Netherlands, tells WebMD.
Markus, who was not involved in the study, recommends a study comparing
behavior in subjects given varying amounts of aspartame.
Aspartame is broken down into substances that are unhealthy for the brain,
but the body may be able to protect the brain from limited amounts. “Maybe
the normal safeguards break down with time, with stress, and with heavy
exposure,” Barth says. People with brain injury may be especially vulnerable
to the effects of aspartame, as are the elderly and young children. And
future studies might need to look at long-term memory problems after years
of heavy aspartame use.
Many students in Barth’s study drank four to six diet sodas — or more each
day. “Occasional use might be OK, but no one in my lab drinks diet soda,”
If you drink a diet soda every now and then, don’t despair — there may be
other strategies to boost your memory, like not skipping breakfast. In
research supported by General Mills, USA, the makers of some breakfast
foods, seniors had memory tests up to an hour after a high-carbohydrate,
high-sugar breakfast consisting of whole wheat cereal, 1% milk, and white
grape juice. Relative to seniors given only water at breakfast, these
seniors did better on remembering a word list and a paragraph after a 20-
“Performance improvements after eating breakfast have previously been
reported in school children,” Steven H. Zeisel, MD, PhD, tells WebMD.
Zeisel, who was not involved in this study, is the associate dean for
research, and professor and chairman of nutrition, at the School of Public
Health of University of North Carolina at Chapel Hill.
“Is it just the calories that help the brain function better, or is it the
sugar itself?” asks researcher Carol Greenwood, PhD, a research scientist at
Baycrest Center for Geriatric Care in Toronto. Further studies will look at
breakfasts varying in protein, fat, and carbohydrate, to see which might be
best for brain function.
And who says you can’t teach an old dog new tricks? Researchers at the
University of Toronto and the University of California at Irvine did just
that while studying the effects of antioxidants in the diet — like vitamins
A, E, and C — on memory in elderly beagles.
As they get older, dogs, like humans, get worse with memory tasks and have
some of the same types of changes in the brain, explains researcher N.
William Milgram, PhD, a professor of psychology and pharmacology at the
University of Toronto. His study divided young and old beagles into groups
receiving either a regular diet or a diet enriched in antioxidants.
Antioxidants protect the brain from damaging free radicals — natural
substances produced in the body as it ages, Milgram tells WebMD. “But there
are many different types of free radicals, so we need a broad spectrum of
antioxidants to protect against them.”
Young dogs, in whom free radical damage is presumably small, did no better
on the special diet. But older dogs fed the antioxidant-enriched diet for
five weeks did better on two tasks involving the type of memory that may be
affected by aging.
“This study is consistent with … studies suggesting that antioxidants
protect against [intellectual] loss in aging humans,” Zeisel says.
“It’s encouraging that we saw effects after a relatively short period of
time,” Milgram says. But Markus and Zeisel find this somewhat surprising, as
damage from free radicals is thought to “slowly accrue over a lifetime,
rather than over a few weeks,” Zeisel says. To see if antioxidants can
prevent age-related changes, researchers will look at young dogs who stay on
an antioxidant diet into old age.
“Antioxidants may prevent against death of brain cells, as well as
decreasing the risk of diabetes and heart disease,” Greenwood says. “So it
makes sense to eat a diet rich in fruits, vegetables, and whole grains.”
One important dietary antioxidant is vitamin A, studied by Sharoni Jacobs
and colleagues from the Salk Institute in La Jolla, Calif. Their work
provides the first direct evidence that vitamin A is required for memory and
learning, as mice fed diets low in the vitamin from birth were impaired in
long-term memory and learning. Restoring vitamin A to their diet reversed
As tens of millions of humans, especially children, suffer from vitamin A
deficiency, they may be affected by previously unrecognized, yet reversible,
mental impairment. “This very interesting study … re-emphasizes the
importance of certain nutrients in maintaining adequate brain development
and function,” Zeisel says.
2000 WebMD Corporation. All rights reserved.
Timothy M. Barth has 16 studies listed in PubMed, 1982-2000.
Tmothy M. Barth Department of Psychology email@example.com
Texas Christian University TCU Box 298920 Fort Worth, TX 76129
Chairman, Physiological Psychology 817-921-7410
One of the most important issues facing behavioral neuroscience
today is identifying the neural and behavioral mechanisms that
mediate recovery after damage to the brain. My research program
is aimed at investigating these mechanisms in rats with lesions
in the neocortex. There are three areas of study:
1) determination of functional subdivisions of the rat neocortex
through the development of neurological tasks that are sensitive
to sensory and motor impairments after brain damage;
2) comparison of the recovery patterns and mechanisms of
recovery in animals that received brain injury as infants or adults; and
3) investigations of the effects of various drugs on the recovery and
maintenance of function following cortical lesions.
Barth, T. M., & Stanfield, B. B. (1994).
Homotopic, but not heterotopic, fetal cortical transplants can result
in functional sparing following neonatal damage to the frontal cortex in
Cerebral Cortex, 4, 271-278.
Barth, T. M., Marks, B. B., & Young, L. S. (1994).
Behavioral Neuroscience, 108, 4, 1-5.
Prof. Steven H. Zeisel, MD, PhD firstname.lastname@example.org
Editor in Chief, Journal of Nutritional Biochemistry
Carol Greenwood, PhD
Baycrest Centre for Geriatric Care
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