Diet high in methionine could increase risk of Alzheimers

Dec 16, 2009
Diet high in methionine could increase risk of Alzheimers
A brain sample taken from mice used in the study 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. Image: Temple University Department of Pharmacology

(PhysOrg.com) -- Temple study suggests that an amino acid found in red meats, fish, beans and other foods may increase possibility of dementia.

A rich in methionine, an amino acid typically found in red meats, , beans, eggs, garlic, lentils, onions, 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 Praticň, 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 . 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 Praticň. “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, Praticň 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 Praticň, 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.

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Jim1965
not rated yet Dec 17, 2009
Ok, it's absurd to mention onions or lentils as a source of methionine in the same list as red meat and yogurt. One cup of plain yogurt contains 414 mg of methionine. Yes, that's high. But one medium onion? - 2.2 mg. That's very low. Lentils? -approximately 0 mg. Anyone wanting to reduce their AD risk should zealously consume lentils and onions while avoiding high methionine foods.
Jim1965
not rated yet Dec 17, 2009
One cup of chopped broccoli contains 34 mg of methionine, still very low compared to the high methionine sources. 3 oz. of ground beef yields 520 mg of methionine! Looking to cut down on your methionine? Try reducing your beef consumption before you go on a broccoli fast.
murray
not rated yet Dec 17, 2009
Well, as a low-carb eater of fish, yoghurt, cheese and meats, my homocysteine level tests in the very lowest range. Plainly the relationship between dietary methionine and serum homocysteine has more to it than that. Sounds reminiscient of ill-informed dietary cholesterol scares some 30 years ago, since debunked.
holders66
not rated yet Dec 17, 2009
Vitamin B12 is necessary to convert homocysteine back to methionine, thus high homocysteine levels can occur in B12 deficiency. Fortunately, meat and fish are good sources of B12, and the Institute of Medicine recommends that adults over the age of 50 should get some synthetic vitamin B12. I hope those poor mice were getting some B12!
melajara
not rated yet Dec 17, 2009
Except for red meat and over consumption of eggs, the other mentioned food is considered very healthy (remember the Mediterranean diet).
This study is worrisome to say the least.
DMorse
not rated yet Dec 18, 2009
“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,"

DMorse
not rated yet Dec 18, 2009
“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,"“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,"

marianne
not rated yet Dec 23, 2009
I'd be willing to bet that portion control of the protein sources, eating an abundance of leafy green and cruciferous veggies as well as fruits, especially the orange, red and purple ones, would offset any problems with too much methionine.

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