Diet High in Methionine Appears to Increase Risk of
Alzheimer’s Says Temple Researchers
Lab rats on high methionine diet had up to 40% more
amyloid plaque in brains
A brain sample taken from mice shows dark spots consistent with amyloid
plaque, indicative of the progression of Alzheimer’s disease. Mice fed
diets rich in methionine had an increased level of homocysteine and up
to 40 percent more amyloid plaque in their brains. Graphic by Temple
University Department of Pharmacology
Dec. 16, 2009 - A diet rich in methionine, an amino
acid typically found in red meats, fish, beans, eggs, garlic, lentils,
onions, yogurt and seeds, can possibly increase the risk of developing
Alzheimer’s disease, according to a study by Temple researchers.
The researchers published their findings, titled
“Diet-induced hyperhomocysteinemia increases Amyloid-β formation and
deposition in a mouse model of Alzheimer’s disease,” in the journal
Current Alzheimer Research.
“When methionine reaches too high a level, our body
tries to protect itself by transforming it into a particular amino acid
called homocysteine,” said lead researcher Domenico Praticò, an
associate professor of pharmacology in the School of Medicine.
“The data from previous studies show - even in
humans - when the level of homocysteine in the blood is high, there is a
higher risk of developing dementia. We hypothesized that high levels of
homocysteine in an animal model of Alzheimer’s would accelerate the
disease.”
Using a seven-month old mouse model of the disease,
they fed one group an eight-month diet of regular food and another group
a diet high in methionine. The mice were then tested at 15 months of age
- the equivalent of a 70-year-old human.
“We found that the mice with the normal diet had
normal homocysteine levels, but the mice with the high methionine diet
had significantly increased levels of homocysteine, very similar to
human subjects with hyperhomocysteinemia,” said Praticò.
Lead researcher
Domenico Praticò, with Postdoctoral student Jia-Min Zhuo. Photo Preston
M. Moretz/Temple University
“The group with the high methionine diet also had
up to 40 percent more amyloid plaque in their brains, which is a
measurement of how much Alzheimer’s disease has developed.
The researchers also examined capacity to learn a
new task and found it diminished in the group with the diet high in
methionine.
Still, Praticò emphasized, methionine is an
essential amino acid for the human body and
“stopping one’s intake of methionine won’t prevent Alzheimer’s. But
people who have a diet high in red meat, for instance, could be more at
risk because they are more likely to develop this high level of
circulating homocysteine,” he said.
In addition to Praticò, other researchers working
on the study included Jia-Min Zhuo and Hong Wang from Temple’s
Department of Pharmacology, Thomas J. Gould and George S. Portugal from
Temple’s Department of Psychology, and Warren D. Kruger from the Fox
Chase Cancer Center.
The study was funded by grants from the National
Institute of Health and the Alzheimer’s Association, in addition to
support from Pennsylvania Commonwealth through the Fox Chase Cancer
Center.
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