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Amino Acid Plays Part In Dementia

A recent study tells us that a diet containing high levels of the amino acid known as methionine, which can be found in red meat, dairy products, and fish, ups the risk factor for developing dementia and Alzheimer's disease. Lead author of this study, Domenico Praticò, associate professor of pharmacology at Temple University's School of Medicine explains, "When methionine reaches too high a level, our body tries to protect itself by transforming it into a particular amino acid called homocysteine. 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."

Brain Plaque

Philadelphia's Temple University researchers studied Alzheimer's disease in seven-month old mice. Over the course of an eight-month period, one group of mice was fed a normal diet while a second group was fed a methionine-high diet. The mice were then tested at 15 months or at the rodent equivalent of a human being aged 70.

The investigatory team saw that the mice fed on a normal diet had normal levels of homocysteine, an amino acid that is found in blood. Meanwhile, the mice fed on the methionine-rich diet had elevated levels of homocysteine. The researchers noted that the group on the high-methionine diet had 40% more amyloid brain plaque, a measure of Alzheimer's disease progression. When the team tested learning skills in the high-methionine group, they discovered that those mice displayed a low aptitude as compared to those mice on the normal diet.

The investigators believe that high levels of homocysteine play an integral role in the development of Alzheimer's disease, and also speeds up the progression of the disease in those already diagnosed. Methionine is an essential amino acid which the body requires for normal growth, functioning, and metabolism. The only way to acquire the amino acid is through diet. Therefore, based on this study, experts must conclude that moderating the diet to limit methionine levels is wise.

Red Meat

Praticò says that stopping methionine intake won't stop Alzheimer's, but those who eat a lot of red meat, for example, may have a higher risk for the disease because of the resultant high level of homocysteine circulating in the bloodstream. The National Institute of Health and the Alzheimer's Association funded this study. The Pennsylvania Commonwealth also contributed through the Fox Chase Cancer Center. This study was published in Current Alzheimer's Research.