MONDAY, March 19 (HealthDay News) -- Researchers have suggested
that antioxidants might help thwart Alzheimer's disease, but a new
study finds that a "cocktail" of vitamins E, vitamin C and
alpha-lipoic acid has no effect on certain indicators of the brain
The supplements may even have hastened mental decline, the
"The benefit on oxidative stress in the brain was small and is of unclear significance," said lead researcher Dr. Douglas Galasko, a professor in residence in the department of neurosciences at the University of California, San Diego.
"Patients did not show cognitive improvement in this short-term study; in fact, there was a slight worsening on one test of cognition in patients who received the antioxidant combination," Galasko said.
Aging causes oxidative damage in the brain, which is extensive
in people with Alzheimer's disease. Clinical trials looking at
whether a diet rich in antioxidants could reduce that risk have had
mixed results, the researchers said.
This study does not support using any of these antioxidants once
a diagnosis is made of established Alzheimer's disease, Galasko
said. "If antioxidants continue to be tested against Alzheimer's
disease, newer approaches or drugs may be needed," he said.
This study, published in the March 19 online edition of the
Archives of Neurology, does not address whether taking antioxidants could help to prevent Alzheimer's disease, he noted. Alzheimer's disease is the most common form of dementia among older people.
For the study, Galasko's team gave antioxidant supplements to 78
patients with Alzheimer's disease who were part of a study funded
by the U.S. National Institute on Aging. The patients were placed
into three groups. One group received daily doses of vitamin E,
vitamin C and alpha-lipoic acid. A second group was given coenzyme
Q (a compound made naturally in the body to protect cells from
damage) three times a day. The third group received a placebo.
After 16 weeks, 66 patients had their cerebrospinal fluid
Among the three groups, the researchers found no difference in
markers related to Alzheimer's disease in the cerebrospinal fluid.
These markers included the amyloid-beta protein and the proteins
tau and P-tau.
Galasko's group did see lower levels of one marker called
F2-isoprostane, which could indicate a reduction in oxidative
stress in the brain. However, the use of vitamins might have
increased the pace of the disease, causing faster decline in mental
ability, they cautioned.
Greg Cole, associate director of the Alzheimer's Disease
Research Center at the University of California, Los Angeles David
Geffen School of Medicine, said that vitamin E alone has shown some
limited benefits in Alzheimer patients, but with no evidence that
it really works to reduce oxidative damage, and that alpha lipoate
-- a form of alpha-lipoic acid -- alone has also had some reported
benefits, he said.
"Unfortunately, these researchers found no impact on pathological protein levels, and in their small group of patients, their cognitive function actually declined more than in the placebo group," Cole noted.
The increased cognitive decline might be due to random
variation, he said, "or it may be a surprising but real adverse
effect from something as seemingly innocuous as an antioxidant
His research group has seen similar adverse effects from some,
but not all, antioxidant mixes, he said.
"This should be a caution to the supplement manufacturers who typically sell products throwing in some mix of what seems like a great group of sensible antioxidants," he added. "Everyone assumes that they will work well together and are good for you, but they don't test them."
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