Mad cows and Alzheimers
Scientists link infectious prion proteins to brain-wasting diseases
Dear “Earth Talk”: Is there a connection between “mad cow” disease and Alzheimer’s disease? — Jon Luongo, Brooklyn, N.Y.
Despite limited evidence, some researchers fear that just such a connection exists. In his 2004 book Brain Trust, biochemist Colm Kelleher argues that mad-cow disease (also known as bovine spongiform encephalopathy, or BSE) has actually been in North American cattle since long before 1993, when the first case was publicly “discovered” in a beef cow in Canada’s Alberta province.
According to Kelleher’s research, undocumented cases date back at least a quarter-century and may have tainted many a steak and hamburger already consumed. Further, Kelleher speculates that the infectious “prion” proteins that cause mad-cow disease and its brain-wasting human variant, Creutzfeldt-Jakob disease, are a factor in the substantial increase in the incidence of Alzheimer’s disease in recent years.
Some other research bears out Kelleher’s claims, although blaming all of the increase in Alzheimer’s on rampant prions might be pushing it. Dr. Michael Greger, director of public health and animal agriculture for the Humane Society of the United States, cites several studies indicating that perhaps 12 percent of all senile-dementia or Alzheimer’s cases diagnosed in North America these days are actually cases of CJD.
“It would seem CJD is seriously underdiagnosed at present,” says Greger. He notes that the symptoms and pathology of Alzheimer’s and CJD overlap, and epidemiological evidence, he says, suggests that people who eat red meat more than four times a week for prolonged periods have a three times greater chance of dementia than do longtime vegetarians.
“We don’t know exactly what’s happening to the rate of CJD in this country, in part because CJD is not an official illness,” says Greger, explaining that the U.S. Centers for Disease Control does not actively monitor incidence of the disease. He adds that several clusters of CJD outbreaks have been reported across the continent in recent years and stresses that more studies need to be done to determine just how many of the 5 million North Americans with Alzheimer’s-like symptoms actually have CJD.
Regardless, nutritionists hardly need more evidence about the potentially negative health effects of eating red meat. For starters, the saturated animal fat in red meat contributes to heart disease and atherosclerosis. Recent research also shows that frequent red-meat eaters face twice the risk of colon cancer as do those who indulge less often. Red meat is also thought to increase the risks of rheumatoid arthritis and endometriosis.
Whereas red meat is a key source of protein and vitamin B12 in North American diets, nutritionists explain that properly planned meat-free diets easily provide these important nutrients while keeping you healthier in the long run.