The study, involving almost 2,500 Finnish men, aimed to test a suggested link between intakes of cholesterol (and eggs as a major source of dietary cholesterol) and cognitive decline in both the general population and in a group of people genetically 'at risk' of dementia.
Led by Maija Ylilauri from the University of Eastern Finland, the team found that a relatively high intake of dietary cholesterol, or eating one egg every day, was not associated with an increased risk of dementia or Alzheimer's disease.
Furthermore, no link was found in people carrying the APOE4 gene - a gene that is known to affect cholesterol metabolism and increase the risk of memory disorders.
"Neither cholesterol nor egg intake is associated with an increased risk of incident dementia or AD in Eastern Finnish men," said the team. "Instead, moderate egg intake may have a beneficial association with certain areas of cognitive performance."
Writing in the American Journal of Clinical Nutrition, the Finnish research team said the results suggest that a high-cholesterol diet, or frequent consumption of eggs, does not increase the risk of memory disorders - even in persons who are genetically predisposed to a greater effect of dietary cholesterol on serum cholesterol levels than others because of the APOE4 gene.
A Beneficial Effect?
Instead, the research data suggested that a moderate intake of eggs may actually offer certain cognitive benefits.
"We investigated the associations of cholesterol and egg intakes with incident dementia, Alzheimer disease (AD), and cognitive performance in middle-aged and older men from Eastern Finland," explained the team.
A total of 2,497 dementia-free men, aged between 42 and 60 years old during the recruitment window (1984-1989) were enrolled in the study, however Ylilauri and colleagues noted that information on the Apo-E phenotype was available for 1,259 men.
During an average follow-up time of almost 22 years, the team reported that 337 men were diagnosed with dementia, while 266 men were diagnosed with AD.
While neither cholesterol nor egg intake was found to be associated with a higher risk of incident dementia or AD, the team did identify a possible link between egg consumption and better memory.
"Egg intake was associated with better performance on neuropsychological tests of the frontal lobe and executive functioning, the Trail Making Test, and the Verbal Fluency Test," Ylilauri and colleagues wrote.
Old Egg Myths Die Hard
Our society's bias against saturated fat and cholesterol has become so strong that we often forget that in nature those are the exact foods where the most nutrients are found. Egg yolks are no different.
Nutritionist Dr Carrie Ruxton has challenged studies vilifying egg yolks as a contributor to coronary artery disease.
It was previously thought that eggs raised blood cholesterol levels or increased LDL cholesterol. The yolk in a single large egg contains five grams of fat, so many nutritionists assumed that eggs clogged up people's arteries, especially since they also contain dietary cholesterol.
Another myth was that LDL cholesterol is fat when it's actually a protein. Cholesterol is a waxy substance that resembles fat, but has little to do with it. Today, scientists know that cholesterol content in food and the cholesterol in our blood aren't intimately connected at all.
First you must understand that there is no such thing as bad cholesterol in the body. Nothing innately within the human body from birth is bad. There is even evidence proving that people with high so-called bad cholesterol live the longest.
Evidence showing that eating a lot of dietary cholesterol doesn't increase blood cholesterol was discovered during a statistical analysis conducted over 25 years by Dr. Wanda Howell and colleagues at the University of Arizona. The study revealed that people who consume two eggs each day with low-fat diets do not show signs of increased blood cholesterol levels.
Most studies on the elderly have shown that high cholesterol is not a risk factor for coronary heart disease at all. On the Medline database many studies address that question. Specifically how high cholesterol may protect against infections and atherosclerosis.
It's a myth we must put to rest because LDL cholesterol is only good and body needs it. LDL is needed by the body to build new muscle, which is important as we age. LDL can protect the brain as we age, and low levels of it can escalate problems such as dementia and memory loss.
Two years ago Canadian researchers claimed that eggs actually helped lower blood pressure.
They suggested that when eggs are digested they produce proteins that mimic the action of powerful blood pressure-lowering drugs, known as Ace inhibitors.
Once more a U.S. government study found that modern eggs contain 13 percent less cholesterol and 64 percent more vitamin D compared with a decade ago.