Diet plays an important role in a variety of diseases – including Alzheimer’s disease – the most common form of senile dementia – a disease that progressively destroys a person’s memory and ability to communicate with others. Currently, five million people live with this devastating neurological disease, and estimates are that the number will double in the next fifty years. Obviously, any steps a person can take to lower their risk of developing this disease would be of importance. Now, there’s even more evidence that diet plays a role in Alzheimer’s related brain changes. A new study published in the journal Alzheimer’s Disease Research shows that a diet rich in a particular amino acid called methionine may raise the risk of Alzheimer’s disease.
The Risk of Dementia and Methionine: What’s the Scoop?
Researchers fed one group of mice a diet high in methionine and another group a regular diet. When tested, the mice receiving the diet rich in methionine had higher levels of homocysteine – an amino acid associated not only with an increased risk of Alzheimer’s disease, but heart disease and stroke as well. When too much methionine is taken in through diet, it’s converted to homocysteine, an amino acid which increases the risk of dementia and other health problems. When they looked at the brains of these mice, they found forty percent more amyloid plaques in mice that had eaten the methionine rich diet compared to the mice given a conventional diet. Amyloid plaques are protein fragments that are the hallmark of Alzheimer’s disease.
Where Do You Find Methionine?
The amino acid methionine is an essential amino acid meaning the body can’t synthesize it and must obtain it from food sources. The best sources of methionine are from animal products including red meat and fish – although nuts and seeds are also rich in this amino acid. The two best sources? Spinach and peppers – although most fruits and vegetables are low or completely deficient in this amino acid.
The Risk of Alzheimer’s Disease and Animal Products
Because methionine is so abundant in animal products such as meat and fish, it raises the question of whether a diet high in animal protein increases the risk of Alzheimer’s disease. Few studies have shown an association between red meat consumption and the risk of dementia, although the Mediterranean diet which is low in animal protein reduces the risk according to most studies. At least one component of fish and nuts – omega-3 fatty acids lowers the risk of Alzheimer’s disease. Saturated fats which are abundant in many red meat and dairy products appear to increase the risk.
The Bottom Line?
Keep in mind that this is only an animal study and it’s not clear whether the same findings apply to humans. Because fish and nuts provide so many positive benefits including omega-3’s which may reduce the risk of dementia, it would be unwise to eliminate them despite their higher levels of methionine. The best plan may be to limit red meat which is a source of methionine and saturated fats – both of which potentially raise the risk of dementia and Alzheimer’s disease. Eating more fruits and vegetables with their high levels of antioxidants may also offer some protection.